Synergistic bactericidal effects of acrinol and tetracycline against Pseudomonas aeruginosa

Combined treatment of acrinol (Ac) and tetracycline hydrochloride (Tc) against Pseudomonas aeruginosa strains isolated from clinical specimens synergistically increased the bactericidal effect. The minimum bactericidal concentration (MBC) of Ac against P. aeruginosa strain no. 985 was 200 μg/ml, while the MBC of Ac against strains no. 47 and no. 783 was above 800 μg/ml for each. The MBC of Tc was above 400 μg/ml against each of the tested strains. However, simultaneous treatment with 25 μg/ml Ac and 200 μg/ml Tc against P. aeruginosa strain no. 985 decreased the viable cell number from 10⁷ cfu/ml to <10 cfu/ml within 24 h, while a higher concentration of Tc (400 μg/ml) with Ac (25 μg/ml) reduced the viable cell number to <10 cfu/ml within 8 h. A similar synergistic bactericidal effct of Ac and Tc was observed in strains no. 47 and no. 783 by treatment with 200 μg/ml Ac and 200 μg/ml or 400 μg/ml Tc. The degree of bactericidal effect against P. aeruginosa was proportional to the concentration of Tc under the condition of a constant concentration of Ac. Furthermore, Ac-treated cells of strain no. 47 were killed by a following Tc treatment, but cells pretreated with Tc did not show such a sensitivity to Ac. To induce the synergistic effect of Ac and Tc, Ac must be applied to P. aeruginosa before or at the same time as Tc. Received: October 26, 1999 / Accepted: February 28, 2000     

去甲泽拉木醛对T24膀胱癌细胞株药效强度的实验研究

目的：探讨去甲泽拉木醛对T24膀胱癌细胞株作用的浓度-效应关系及时间-效应关系。并以吡柔比星为对照,研究两者对膀胱癌细胞株的杀伤作用有无差异。方法：分别用两个不同浓度的去甲泽拉木醛（20μg·mL-1和40μg·mL-1）和吡柔比星（0.03μg·mL-1和0.06μg·mL-1）处理T24膀胱癌细胞株,连续用3d后用MTT法测定细胞活性,计算抑制率。结果：去甲泽拉木醛组和吡柔比星组对T24膀胱癌细胞的杀伤率随时间的延长而增高。两个浓度组的去甲泽拉木醛和吡柔比星对T24膀胱癌细胞的杀伤率的差异在第3天有统计学意义（低浓度组：0.624±0.035比0.563±0.032,P=0.015;高浓度组：0.792±0.026比0.672±0.028,P〈0.001）。在第1天和第2天,两个浓度组的去甲泽拉木醛和吡柔比星的杀伤率差异无统计学意义。（低浓度组：第1天0.152±0.063比0.127±0.055,P=0.456;第2天0.504±0.031比0.507±0.042,P=0.879。高浓度组：第1天0.266±0.068比0.231±0.057,P=0.256;第2天0.585±0.053比0.594±0.039,P=0.660）。结论：去甲泽拉木醛对T24膀胱癌细胞株有明确而强烈的抑制与杀伤作用,并在作用的第1天和第2天,其杀伤作用与相对应的浓度组吡柔比星近似。     

Clinical characteristics of vancomycin minimum inhibitory concentration of 2 μg/ml methicillin-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> strains isolated from patients with bacteremia

Recent studies demonstrated that mortality associated with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia was high when vancomycin was used to treat infections with strains that had a high vancomycin minimum inhibitory concentration (MIC). This study compared several characteristics of vancomycin MIC 2 μg/ml strains isolated from bacteremia with those isolated from infections other than bacteremia. A total of 128 episodes of MRSA bacteremia between 2005 and 2008 were followed-up, and compared with 631 MRSA infections other than bacteremia. The isolation of strains with a 2 μg/ml MIC accounted for 32.0% of isolates from MRSA bacteremia, whereas strains with a 2 μg/ml MIC comprised 9.0% of MRSA isolated from other sites (p < 0.001). The incidence of pneumonia as the source of infection was significantly higher in patients with bacteremia from strains with a 2 μg/ml MIC than in those with ≤1 μg/ml MIC. Prior vancomycin use did not correlate with the isolation of 2 μg/ml strains. The efficacy of glycopeptides as 1st line therapy in patients infected with 2 μg/ml strains was significantly lower than that for patients infected with ≤1 μg/ml strains (30.0 vs. 78.8%, p < 0.001) in bacteremia. In the analysis of infections other than bacteremia, efficacy did not reveal a significant difference according to MIC (69.0 vs. 79.6%, p = 0.109). In bacteremia, mortality was 65.8% in patients with 2 μg/ml strains and 19.5% in patients with ≤1 μg/ml strains (p < 0.001), whereas there was no significant difference in mortality from infections other than bacteremia (10.7 vs. 7.8%, p = 0.617). In multivariate analysis, bacteremia with 2 μg/ml strains, intensive care unit (ICU) stay, and liver cirrhosis were independent risk factors for death in patients with bacteremia, and initial appropriate therapy lowered the risk. Several characteristics such as a higher incidence than at other infection sites, a high incidence of pneumonia as a source of infection, a low success rate of vancomycin therapy, and poor prognosis were confirmed in 2 μg/ml MIC MRSA isolated from bacteremia; however, a low success rate of vancomycin and poor prognosis were not apparent in 2 μg/ml MIC MRSA strains isolated from infections other than bacteremia.     

Antimicrobial susceptibility by Etest of Bartonella henselae isolated from cats and human in Japan

Bartonella henselae, a small fastidious Gram-negative bacillus, is the causative agent of cat-scratch disease (CSD). Because of difficulty in isolating the organism, there has been no report on its antibiotic susceptibility in Japan. We determined the minimal inhibitory concentrations (MICs) of eight antimicrobial agents against 32 isolates of B. henselae (31 from cats and one from a human in Japan) by the Etest method. MICs of all 32 isolates were <0.016 μg/ml for minocycline and ranged from ≤0.016 to 0.064 μg/ml for erythromycin, clarithromycin, azithromycin, ceftriaxone, and amoxicillin. MICs ranges of ciprofloxacin and gentamicin were from 0.064 to 0.25 μg/ml and from 0.5 to 3 μg/ml, respectively. All isolated strains showed high susceptibility to minocycline and macrolides antibiotics, which are currently used in the primary treatment of CSD in Japan. Although in vitro result of B. henselae susceptibility testing may not necessarily correlate with clinical response, these data are relevant in the choice of drugs for CSD treatment.     

Performance evaluation of a whole blood propofol analyser

The authors evaluated an analyser for the determination of propofol concentrations in whole blood. The Pelorus 1000 (Sphere Medical) measures propofol concentrations in around 5 min without the requirement for sample preparation. The performance of the analyser was characterised with respect to linearity, precision in control solutions and whole blood and method comparison to an HPLC based reference method. In addition, the effects of substances considered to potentially affect the assay method were investigated. The analyser was found to be linear up to 12 μg/ml (R ² = 0.9993), with a lower limit of quantification of 0.75 μg/ml. Total within device imprecision in control solutions was 0.11 μg/ml at 5.32 μg/ml and 0.17 μg/ml at 10.3 μg/ml. Within run precision in whole blood was 0.04 μg/ml at 2.84 μg/ml and 0.08 μg/ml at 6.68 μg/ml and for the reference method was 0.06 μg/ml and 0.12 μg/ml respectively. In comparison to the reference method, the overall bias of the Pelorus 1000 system over the range is estimated to be 0.15 μg/ml (95% confidence interval −0.11–0.41 μg/ml). The only cross interference of note is to a highly elevated level of conjugated bilirubin, while low haematocrit levels lead to a 0.13 μg/ml under reading with respect to the HPLC reference. The system fulfils the requirements for measurement of propofol concentrations in whole blood samples with precision and accuracy suitable for elucidating propofol pharmacokinetics at clinically relevant concentrations. With no requirement for sample preparation and a fast time to results, the analyser opens up the possibility of studies to measure and respond to blood propofol concentrations in patients in close to real time.     

In vitro susceptibility to antimicrobial agents and ultrastructural characteristics related to swimming motility and drug action in Campylobacter jejuni and C. coli

Campylobacter jejuni has recently been noted as the most common cause of bacterial food-borne diseases in Japan. In this study, we examined in vitro susceptibility to 36 antimicrobial agents of 109 strains of C. jejuni and C. coli isolated from chickens and patients with enteritis or Guillain–Barré syndrome from 1996 to 2009. Among these agents, carbapenems (imipenem, meropenem, panipenem, and biapenem) showed the greatest activity [minimal inhibitory concentration (MIC)₉₀, 0.03–0.125 μg/ml]. This was followed by sitafloxacin (MIC₉₀, 0.25 μg/ml), furazolidone and azithromycin (MIC₉₀, 0.5 μg/ml), gentamicin and clindamycin (MIC₉₀, 1 μg/ml), and clavulanic acid (β-lactamase inhibitor; MIC₉₀, 2 μg/ml). All or most strains were resistant to aztreonam, sulfamethoxazole, and trimethoprim. Marked resistance was also observed for levofloxacin and tetracyclines. Resistance was not present for macrolides and rare for clindamycin. C. jejuni (and C. coli) exhibited high swimming motility and possessed a unique end-side (cup-like) structure at both ends, in contrast to Helicobacter pylori and Vibrio cholerae O1 and O139. The morphology of C. jejuni (and C. coli) changed drastically after exposure to imipenem (coccoid formation), meropenem (bulking and slight elongation), and sitafloxacin (marked elongation), and exhibited reduced motility. In the HEp-2 cell adherence model, unusually elongated bacteria were also observed for sitafloxacin. The data suggest that although resistance to antimicrobial agents (e.g., levofloxacin) has continuously been noted, carbapenems, sitafloxacin, and others such as β-lactamase inhibitors alone showed good in vitro activity and that C. jejuni (and C. coli) demonstrated a unique ultrastructural nature related to high swimming motility and drug action.     

Development of interpretive criteria for tebipenem disk diffusion susceptibility testing with <Emphasis Type="Italic">Staphylococcus</Emphasis> spp. and <Emphasis Type="Italic">Haemophilus influenzae</Emphasis>

Disk diffusion susceptibility interpretive criteria for tebipenem against Staphylococcus spp. and Haemophilus influenzae were developed using the Clinical and Laboratory Standards Institute (CLSI) guidelines. Tebipenem was tested by disk diffusion and broth microdilution methods against 119 clinical isolates of Staphylococcus spp. and 102 clinical isolates of H. influenzae. The zone diameters of 5-, 10-, and 30-μg disks were compared with broth microdilution minimum inhibitory concentration (MIC) results by scattergram and regression analysis. When the MIC breakpoint of 1 μg/ml was applied to the scattergrams, the 10-μg disk showed good correlation between the zone diameters and the MIC values. The corresponding disk diffusion zone diameter breakpoints with the 10-μg disk for Staphylococcus spp. were ≧22 mm (MIC ≦1 μg/ml) for susceptible, 20–21 mm (MIC = 2 μg/ml) for intermediate, and ≦19 mm (MIC ≧4 μg/ml) for resistant. We also proposed the breakpoint zone diameter of H. influenzae: ≧22 mm (MIC ≦1 μg/ml) for susceptible. These criteria demonstrated that the categorical agreements between disk diffusion and broth microdilution methods for Staphylococcus spp. and H. influenzae were 95.0% and 99.0%, respectively. The discrepancy rates of these criteria were acceptable to the CLSI guidelines.     

茶多酚联合顺铂对人卵巢癌细胞SKOV3生长的影响及机制

目的观察茶多酚(TP)、顺铂(DDP)及二者联合对人卵巢癌细胞SKOV3增殖及凋亡的影响,初步探讨二者联合对SKOV3细胞生长影响的机制。方法人卵巢癌细胞SKOV3经低毒剂量TP、DDP单独或联合作用后,MTT法检测细胞增殖情况,DAPI核染色法荧光显微镜观察细胞凋亡形态变化,AnnexinV-FITC双染流式细胞术分析细胞凋亡,Westernblot方法检测细胞中Akt及p-Akt的表达。结果低毒剂量TP单药组、DDP单药组与联合用药组对细胞的增殖抑制率分别为(11.47±2.07)%、(32.26±4.85)%、(52.62±3.23)%,联合用药组的细胞增殖抑制率明显高于DDP单药组,差异有统计学意义(P=0.000);荧光显微镜下可见低毒剂量TP单药组的细胞核形态及染色与阴性对照组无明显差异,联合用药组细胞核比DDP单药组着色更重,核浓缩、核碎裂现象更加明显,呈现典型的细胞凋亡征象;低毒剂量的TP对细胞的凋亡无明显影响,联合用药组的凋亡率明显高于DDP单药组,差异有统计学意义(P=0.000);各用药组细胞中总的Akt蛋白表达无明显变化,p-Akt蛋白表达降低,其中联合用药组细胞中p-Akt蛋白表达降低最明显,与对照组及单药组比较,差异均有统计学意义(P<0.001)。结论 TP与DDP联合后可显著增强DDP的抑制细胞增殖、促细胞凋亡效应,可能是通过抑制Akt蛋白的磷酸化来实现的。     

Comparative trial of two intravenous doses of granisetron (1 versus 3?mg) in the prevention of chemotherapy-induced acute emesis: a double-blind, randomized, non-inferiority trial

Purpose  

A single 3 mg or 40 μg/kg intravenous dose of granisetron combined with dexamethasone is routinely used in several countries, although the antiemetic guidelines have recommended granisetron at the dose of 1 mg or 10 μg/kg. A randomized, multicenter trial was conducted to determine the optimal intravenous granisetron dose, 1 or 3 mg, in cancer patients receiving emetogenic chemotherapy.     

Exploration of optimal teicoplanin dosage based on pharmacokinetic parameters for the treatment of intensive care unit patients infected with methicillin-resistant Staphylococcus aureus

Severely ill intensive care unit (ICU) patients are frequently at risk of developing methicillin-resistant Staphylococcus aureus (MRSA) infections. It is generally accepted that a trough level of >10 μg/mL teicoplanin (TEC) is appropriate for most such infections. The present study was designed to determine how TEC exposure and patient characteristics affect microbiological response in the treatment of MRSA infections. All patients studied were admitted to Aichi Medical University Hospital ICU between May 2005 and April 2010. Fifty-nine patients were prescribed TEC and 33 of those patients used to treat MRSA infection. Outcome was classified as either cure or failure, and logistic regression analysis was performed to determine which covariates, including severity, significantly influenced the microbiological response. Satisfactory outcomes were obtained in 19 of the 33 patients. Although the cured and failed groups showed adequate trough concentrations, the area under the serum concentration curve (AUC_0–24) on the third day was significantly higher for the cured group (897.6 ± 71.7) than for the failed group (652.9 ± 83.4) (p < 0.05). The results suggested that at least 800 μg h/mL TEC AUC_0–24 were required to obtain microbiological cure. The higher AUC_0–24, the better the outcome. In our study, higher initial AUC_0–24 was associated with a better microbiological outcome, which demonstrates the importance of the loading dose of TEC, especially for ICU patients. Moreover, the present findings are useful for optimizing the individual dose of TEC using AUC_0–24 in the treatment of MRSA-infected patients.     

Glycopeptide susceptibility profiles of nosocomial multiresistant Staphylococcus haemolyticus isolates

We investigated 48 Staphylococcus haemolyticus isolates from patients and medical staff in terms of susceptibility to and in-vitro selection for vancomycin and teicoplanin in regard to their antibiotypes. On comparison of multiresistant S. haemolyticus isolates with non-multiresistant isolates, the geometric mean minimum inhibitory concentration (MIC) of vancomycin for multiresistant S. haemolyticus was 2.9 μg/ml, and that of teicoplanin was 18.0 μg/ml, both of which values were significantly greater than the corresponding mean MICs of vancomycin (2.0 μg/ml) and teicoplanin (4.7 μg/ml) for nonmultiresistant isolates. After agar selection, the mean of the highest teicoplanin concentration of selected plates for multiresistant S. haemolyticus was 97.1 μg/ml, which was significantly higher than that for nonmultiresistant isolates (57.8 μg/ml). However, the means' of the highest vancomycin concentrations after agar selection for multiresistant and nonmulti-resistant isolates were the same, at 7.4 μg/ml, with no colonies capable of growing in 32 μg/ml of vancomycin. There was no significant difference in glycopeptide susceptibility between oxacillin-resistant and oxacillin-susceptible isolates among nonmultiresistant S. haemolyticus. The geometric mean MICs of vancomycin for oxacillin-resistant and oxacillin-susceptible isolates were 2.1 μg/ml and 1.6 μg/ml, and those of teicoplanin were 4.4 μg/ml and 5.6 μg/ml, while the means of the highest concentrations of the selected plates of vancomycin were 8.6 μg/ml and 3.3 μg/ml, and those of teicoplanin were 52.8 μg/ml and 74.7 μg/ml, respectively. Multiresistant isolates showed significantly greater mean MICs of vancomycin and teicoplanin and higher teicoplanin concentration of the selected plates than nonmultiresistant isolates, irrespective of oxacillin resistance. These results indicate that methicillin resistance may not be related to reduced susceptibility to glycopeptide in S. haemolyticus, and that a multiresistant profile is associated more with a decreasing susceptibility to glycopeptides then with resistance to oxacillin. In this study, antibiotypes showed good concordance with pulsed-field gel electrophoresis typing results, with a sufficiently high discriminatory ability index, of 0.912. We consider that primary screening with antimicrobial susceptibility testing and antibiotyping, with attention to the multiresistant profile, would be useful for monitoring nosocomial S. haemolyticus colonization and infection. Received: August 9, 2000 / Accepted: February 5, 2001     

Treatment of uncomplicated gonococcal urethritis by double-dosing of 200 mg cefixime at a 6-h interval

 The efficacy of antimicrobial regimens for the treatment of uncomplicated gonococcal urethritis depends partially upon the period of time (therapeutic time) during which the drug concentration in the blood after the concentration peak is greater than four times the minimum inhibitory concentration for 90% of clinical isolates of Neisseria gonorrhoeae (MIC₉₀). A therapeutic time of at least 10 h is suggested as an important determinant for elimination of 95% or more of the infection. In this study, therapeutic times for a single 400-mg dose of cefixime at various MIC₉₀s were calculated, and pharmacokinetic profiles of double-dosing of 200 mg cefixime at various intervals were simulated. Subsequently, a dosing interval of 6 h was tested in 6 healthy Japanese men, and then 93 Japanese men with gonococcal urethritis were treated with a regimen of two 200-mg doses of cefixime given at a 6-h interval. For a single dose of 400 mg cefixime, therapeutic times were calculated to be 12.8, 9.1, 5.4, and 1.7 h for MIC₉₀s of 0.06, 0.125, 0.25, and 0.5 μg/ml, respectively. In the simulation study of double-dosing of 200 mg cefixime at a 6-h interval, the therapeutic times for the MIC₉₀s of ≤0.125 μg/ml were longer than 10 h. Of the 93 patients, 68 were evaluated for microbiological outcome, and N. gonorrhoeae was eradicated in 60 (88.2%). The MIC₉₀ of cefixime for the 61 isolates tested was 0.125 μg/ml. All strains with MICs of ≤0.06 μg/ml were eradicated, whereas 8 of 16 strains with MICs of ≥0.125 μg/ml persisted after treatment. This regimen would not be effective against infection by strains exhibiting cefixime MIC₉₀s of ≥0.125 μg/ml. For such strains, a different regimen with a higher dose of cefixime would be required. Received: July 10, 2002 / Accepted: September 21, 2002 Acknowledgments We thank Kohji Ishibashi and Kohji Takeshita, at Fujisawa Pharmaceutical Co., Ltd., for pharmacokinetic analyses.     

In vitro antifungal activity of luliconazole against clinical isolates from patients with dermatomycoses

The in vitro antifungal activity of luliconazole, a novel topical imidazole, against pathogenic fungi implicated in dermatomycoses was studied. A total of 91 clinical isolates, consisting of 59 Trichophyton rubrum isolates, 26 T. mentagrophytes isolates, 1 Epidermophyton floccosum isolate, and 5 Candida albicans isolates were tested by the broth microdilution method, employing lanoconazole, terbinafine, and bifonazole as reference drugs. The minimum inhibitory concentrations (MICs) of luliconazole against T. rubrum and T. mentagrophytes were in the range of 0.00012–0.004 μg/ml and 0.00024–0.002 μg/ml, respectively. The MIC₉₀ of luliconazole for these two species of dermatophytes was the same, at 0.001 μg/ml, and these values were 4 times, 30 times, and more than 1000 times lower than those of lanoconazole, terbinafine, and bifonazole, respectively. Similarly, the 1 isolate of E. floccosum tested was inhibited by luliconazole with an MIC of 0.001 μg/ml. Luliconazole also proved to be very potent against C. albicans (MIC range, 0.031–0.25 μg/ml), nearly on par, in terms of efficacy, with lanoconazole (0.063–0.25 μg/ml) and more potent than terbinafine (2–>64 μg/ml) and bifonazole (0.5–4 μg/ml). These results showed that luliconazole was very potent in vitro against pathogenic fungi isolated from patients with dermatomycoses, and these findings emphasized the utility of luliconazole for the topical management of this condition.     

Experimental verification of the efficacy of optimized two-step infusion therapy with meropenem using an in vitro pharmacodynamic model and Monte Carlo simulation

In this study we compared the efficacy of a theoretically optimized two-step infusion therapy (OTIT; rapid first-step infusion and slow second-step infusion) to the efficacies of prolonged infusion therapy (PIT) and traditional 0.5 h infusion therapy (TIT) with meropenem against Pseudomonas aeruginosa using an in vitro pharmacodynamic model and a Monte Carlo simulation. In the in vitro pharmacodynamic model, the bactericidal effect against P. aeruginosa was evaluated for 8 h, which is the usual dosing interval of meropenem. It was confirmed that the durability of the bactericidal effect of OTIT (0.25–1 g/0.5 h + 0.25–1 g/4 h t.i.d.) was almost equal to that of PIT and superior to that of TIT (0.5–2 g/0.5–4 h t.i.d.). In addition, the initial bactericidal effects of OTIT were superior to those of the prolonged 4 h infusion. In the Monte Carlo simulation study, the probability of target attainments (PTAs) of all dosing regimens of OTIT at MICs of 2–8 μg/ml were apparently superior to those of TIT and 4- and 6 h-PIT, when the target therapeutic condition for serious life-threatening infections was the achievement of both the percentage of the dosing interval at which the drug concentration exceeds the MIC (%T _>MIC) ≥ 50% and the peak level divided by the MIC (C _max/MIC) ≥ 4. Especially, the PTAs of the dosing regimens of 0.25–1 g/0.5 h + 0.25–1 g/4–6 h were excellent at MICs of 2–8 μg/ml. Against recent clinical isolates of P. aeruginosa in Japan, the dosing regimens of OTIT provided higher PTAs compared with those of TIT and 4- and 6 h-PIT. These results suggested that OTIT with sufficient pharmacokinetic conditions could be useful for enhancing the therapeutic efficacy of meropenem against serious life-threatening infections.     

THP与ADM对乳腺癌的体外生长抑制及诱导凋亡研究

目的比较吡柔比星(THP)和阿霉素(ADM)对乳腺癌细胞的体外抑制及凋亡诱导作用。方法采用ATP生物荧光肿瘤体外药敏检测技术(ATP-TCA)及AnnexinV凋亡检测技术比较吡柔比星和阿霉素对人乳腺癌细胞株MCF-7的体外生长抑制及细胞凋亡诱导作用。结果吡柔比星对MCF-7细胞株生长抑制作用明显高于阿霉素,其IC50仅相当于阿霉素的1/3-1/6,差异具有显著意义(P0.01);吡柔比星和阿霉素对MCF-7细胞抑制作用均有剂量依赖性,并均能在低浓度下诱导MCF-7细胞凋亡,吡柔比星处理组的细胞凋亡比例高于阿霉素组(P0.01)。结论吡柔比星较阿霉素对乳腺癌细胞MCF-7具有更好的体外生长抑制和诱导细胞凋亡作用。     

Influence of colloidal bismuth subcitrate on enzyme secretion from isolated rat pancreatic acinar cells

Bismuth salts are currently used as monotherapy or in combination with antibiotics for the treatment ofHelicobacter pylori-associated peptic ulcer disease. Besides encouraging clinical results with colloidal bismuth subcitrate (CBS), there is an ongoing fear of organ toxicity with the use of bismuth salts. To study potential toxic effects of CBS under short-term exposure, we tested the influence of CBS on amylase secretion from isolated rat pancreatic acinar cells under basal conditions and following carbachol (CCh) and ceruletide (CRT) stimulation. Basal secretion was reduced by 8.9±9.6% (n=10) (mean±SEM) (P<0.05), 5.2±9.2% (P<0.05), 9.4±6.4% (P<0.01), and 6.2±12.2% (P<0.05) with 0.001, 0.01, 0.1, and 1 μg/ml CBS, respectively. With 10 μg/ml and 100 μg/ml CBS, basal amylase secretion was increased in a dose-dependent manner, by 13.7±11.7% (P<0.05) and 24.5±12.8% (P<0.01). CCh (10⁻⁵ M)-and CRT (3×10⁻¹⁰ M)-stimulated secretory responses were not altered significantly by any of the CBS doses used. In concentrations above 1 μg/ml, CBS increased pancreatic amylase secretion. Amylase secretion in response to secretagogues was not affected by CBS. These findings are unlikely to be associated with a toxic effect of CBS on exocrine pancreatic acinar cell function.     

Superior in vitro activity of carbapenems over anti-methicillin-resistant Staphylococcus aureus (MRSA) and some related antimicrobial agents for community-acquired MRSA but not for hospital-acquired MRSA

Eighty-eight strains of Panton-Valentine leukocidin (PVL)-positive and -negative community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) and 152 strains of hospital-acquired MRSA (HA-MRSA) were examined for susceptibility to carbapenems, oxacillin, and other antimicrobial agents. CA-MRSA strains were more susceptible to carbapenems (MIC₉₀, 1–4 μg/ml) than HA-MRSA strains (MIC₉₀, 32–64 μg/ml). Among the carbapenems examined, CA-MRSA strains were most susceptible to imipenem (MIC₅₀, 0.12 μg/ml; MIC₉₀, 1 μg/ml). A similar tendency was observed with oxacillin, but less markedly (MIC₉₀: 32 μg/ml for CA-MRSA and ≥256 μg/ml for HA-MRSA). This difference was also observed between CA-MRSA and HA-MRSA in susceptibility levels to cephems, erythromycin, clindamycin, and levofloxacin, but not to ampicillin, vancomycin, teicoplanin, linezolid, and arbekacin. The data indicate that, in terms of MIC₅₀ or MIC₉₀ values, CA-MRSA is 64–256 times more susceptible to imipenem than HA-MRSA, and for CA-MRSA, some carbapenems, e.g., imipenem, show better in vitro activity than anti-MRSA or some related agents.     

Characteristic biological effects of itraconazole on L929 fibroblasts and their cell membrane

Itraconazole (ITCZ), a triazole antifungal agent, was studied for its effects on the morphology and function of L929 fibroblasts. L929 fibroblasts were cultured for 20 h with ITCZ or one of several other triazoles (fluconazole, ketoconazole, and hydroxy-itraconazole [ITCZ-OH]) at the concentration of 0.5 μg/ml. Among these agents, only ITCZ and its metabolite ITCZ-OH markedly elongated the cells bidirectionally. Scanning electron microscopy studies showed that the surface of the elongated cells was smoother than that of the untreated cells. The viability of L929 cells cultured with 0.5 μg/ml of ITCZ for 20 h was not lowered. However, after treatment with 0.0375% sodium deoxycholate (DOC) solution, the viability of the cells treated with ITCZ, as evaluated by the 3-(4,5-dimethyl-2thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) proliferation assay or the release of lactic dehydrogenase from cytoplasm, was decreased. When L929 cells were cultured in the presence of a combination of ITCZ and vincristine, their growth was synergistically inhibited. This synergism was also observed when ITCZ was replaced by ITCZ-OH, but not by the other azoles. These findings suggest that the exposure of L929 fibroblasts to low ITCZ concentrations affects the physiological nature of their cell membrane. Received: June 23, 1999 / Accepted: October 29, 1999     

Nanomedicine-based combination of gambogic acid and retinoic acid chlorochalcone for enhanced anticancer efficacy in osteosarcoma

In this study, gambogic acid (GA) and retinoic acid chlorochalcone (RACC) co-loaded glycol chitosan nanoparticle was successfully developed and studied for its therapeutic efficacy against osteosarcoma cancer cells. The GA/RACC loaded glycol chitosan nanoparticles (RGNP) was nanosized and exhibited a controlled release of drug in either pH 7.4 and pH 5.0. Owing to the strong positive charge on the RGNP surface, efficiency cellular uptake was observed in cancer cells. Moreover, a synergistic combination of GA and RACC were effectively suppressed the tumor growth progression. The half maximal inhibitory concentration (IC50) values in MG63 cells were 0.89 μg/ml and 0.35 μg/ml for GA and RGNP after 24 h. The results clearly suggest the synergist effect of GA and RACC in effectively inhibiting the cancer cell proliferation. The RGNP as expected induced a remarkably higher apoptosis of cancer cells with ∼28%. Overall, combination of GA and RACC encapsulated in a nanocarrier could be an effective strategy to treat osteosarcoma. Future studies will focus on the in vivo evaluation of GA/RACC-loaded polymeric nanoparticles.     

Antifungal spectrum and fungicidal mechanism of an N-terminal peptide of bovine lactoferrin

The antifungal spectrum and fungicidal mechanism of an N-terminal peptide of bovine lactoferrin (lactoferricin B), an antimicrobial peptide produced by gastric pepsin digestion of bovine lactoferrin, were investigated. The susceptibility of pathogenic yeasts and dermatophytes to the peptide varied in a species-dependent and strain-dependent manner. Dematiaceous fungi and dimorphic fungi were susceptible to the peptide (range of MIC values: 0.63 to 10 μg/mL). In the case of nonpigmented hyphomycetes and zygomycetes, most strains exhibited resistance to the peptide (MIC:>80 μg/ mL). This peptide killedCandida albicans dose dependently without inducing a change in cell wall stability against osmotic stress. The peptide at 10 μg/ml immediately induced the release of K⁺ fromC. albicans cells and pH increases in cell suspensions. These pharmacological activities were more potent than those for miconazole nitrate, a well-known antifungal agent that interferes with membrane synthesis and function. These in vitro findings suggest that the lactoferrin oligopeptide has potent membrane disrupting activity against this yeast and suggests that in vivo LF-B studies would be useful to further understand host defenses and to develop improved therapeutic agents against yeast infections.