Efficacy of micafungin in combination with other drugs in a murine model of disseminated trichosporonosis

Using a murine model of disseminated infection caused by Trichosporon asahii, we have evaluated the efficacies of amphotericin B (AMB; 1 mg/kg of body weight/day), fluconazole (FLC; 20 mg/kg/twice a day), and micafungin (MFG; 5 mg/kg/twice a day). We tested these drugs alone and in combination (MFG with AMB and MFG with FLC). MFG with AMB showed a synergistic effect and demonstrated a higher degree of efficacy in prolonging survival and reducing the kidney fungal burden than either agent alone. The combination MFG with FLC was able to reduce significantly the kidney fungal burden in comparison to that achieved with either drug administered alone.     

Pharmacokinetics of oral doxycycline during combination treatment of severe falciparum malaria

The pharmacokinetics of oral doxycycline administered at 200 mg every 24 h were investigated in 17 patients recovering from severe Plasmodium falciparum malaria. The data suggest that the doses of doxycycline currently recommended (circa 3.5 mg/kg of body weight daily) may not be optimal.     

Activity of trovafloxacin in combination with other drugs for treatment of acute murine toxoplasmosis.

Current therapy for toxoplasmosis with a synergistic combination of pyrimethamine plus sulfadiazine or pyrimethamine plus clindamycin is not always efficacious and is frequently discontinued due to intolerable toxic effects in immunocompromised individuals, particularly those with AIDS. Trovafloxacin, a new fluoroquinolone with potent activity against Toxoplasma gondii, was examined for potential synergistic activity when combined with other drugs used for treatment of human toxoplasmosis. Combinations of trovafloxacin with clarithromycin, pyrimethamine, or sulfadiazine demonstrated significantly enhanced activities compared to those observed with each drug alone. Our results suggest that combinations of trovafloxacin and other anti-toxoplasma drugs should be further explored for treatment of toxoplasmosis in humans.     

Assessment of azithromycin in combination with other antimalarial drugs against Plasmodium falciparum in vitro

Initial field malaria prophylaxis trials with azithromycin revealed insufficient efficacy against falciparum malaria to develop azithromycin as a single agent. The objective of this in vitro study was to determine the best drug combination(s) to evaluate for future malaria treatment and prophylaxis field trials. In vitro, azithromycin was tested in combination with chloroquine against 10 representative Plasmodium falciparum isolates. Azithromycin was also assessed in combination with eight additional antimalarial agents against two or three multidrug-resistant P. falciparum isolates. Parasite susceptibility testing was carried out with a modification of the semiautomated microdilution technique. The incubation period was extended from the usual 48 h to 68 h. Fifty percent inhibitory concentrations (IC(50)s) were calculated for each drug alone and for drugs in fixed combinations of their respective IC(50)s (1:1, 3:1, 1:3, 4:1, 1:4, and 5:1). These data were used to calculate fractional inhibitory concentrations and isobolograms. Chloroquine-azithromycin studies revealed a range of activity from additive to synergistic interactions for the eight chloroquine-resistant isolates tested, while an additive response was seen for the two chloroquine-sensitive isolates. Quinine, tafenoquine, and primaquine were additive to synergistic with azithromycin, while dihydroartemisinin was additive with a trend toward antagonism. The remaining interactions appeared to be additive. These results suggest that a chloroquine-azithromycin combination should be evaluated for malaria prophylaxis and that a quinine-azithromycin combination should be evaluated for malaria treatment in areas of drug resistance.     

Potencies of human immunodeficiency virus protease inhibitors in vitro against Plasmodium falciparum and in vivo against murine malaria

Parasite resistance to antimalarial drugs is a serious threat to human health, and novel agents that act on enzymes essential for parasite metabolism, such as proteases, are attractive targets for drug development. Recent studies have shown that clinically utilized human immunodeficiency virus (HIV) protease inhibitors can inhibit the in vitro growth of Plasmodium falciparum at or below concentrations found in human plasma after oral drug administration. The most potent in vitro antimalarial effects have been obtained for parasites treated with saquinavir, ritonavir, or lopinavir, findings confirmed in this study for a genetically distinct P. falciparum line (3D7). To investigate the potential in vivo activity of antiretroviral protease inhibitors (ARPIs) against malaria, we examined the effect of ARPI combinations in a murine model of malaria. In mice infected with Plasmodium chabaudi AS and treated orally with ritonavir-saquinavir or ritonavir-lopinavir, a delay in patency and a significant attenuation of parasitemia were observed. Using modeling and ligand docking studies we examined putative ligand binding sites of ARPIs in aspartyl proteases of P. falciparum (plasmepsins II and IV) and P. chabaudi (plasmepsin) and found that these in silico analyses support the antimalarial activity hypothesized to be mediated through inhibition of these enzymes. In addition, in vitro enzyme assays demonstrated that P. falciparum plasmepsins II and IV are both inhibited by the ARPIs saquinavir, ritonavir, and lopinavir. The combined results suggest that ARPIs have useful antimalarial activity that may be especially relevant in geographical regions where HIV and P. falciparum infections are both endemic.     

Efficacy of micafungin alone or in combination against systemic murine aspergillosis

We tested the efficacy of micafungin (FK) alone or in combination with other antifungals against systemic murine aspergillosis. FK alone at 10 mg/kg of body weight/dose prolonged survival (P = 0.01) and reduced CFU in the brain and kidney. Combination therapy that used suboptimal FK with amphotericin B or itraconazole prolonged survival. Although no survivors were free of infection, no antagonism was seen. Nikkomycin Z with FK showed significantly greater potency (P < 0.01) than either alone.     

Activity of clarithromycin alone or in combination with other drugs for treatment of murine toxoplasmosis.

The activity of the macrolide antibiotic clarithromycin was examined alone or in combination with other drugs for the treatment of acute or chronic infections with Toxoplasma gondii in mice. A dose of 300 mg of clarithromycin per kg per day administered alone for 10 days, beginning 24 hours after infection, protected 10 to 30% of mice infected with lethal inocula of tachyzoites or tissue cysts of different strains of T. gondii, including some strains isolated from patients with both AIDS and toxoplasmosis. Although clarithromycin was protective, a wide variation in its activity against different strains was observed. Survival of infected mice was increased significantly by treatment with clarithromycin in combination with pyrimethamine or with sulfadiazine. Treatment of chronically infected mice with clarithromycin at 300 mg/kg/day administered alone for 8 weeks resulted in significant reduction in the numbers of T. gondii cysts in their brains. The combination of clarithromycin and minocycline resulted in an activity against T. gondii cysts that was significantly greater than the activity of clarithromycin or minocycline administered alone. These results indicate a role for clarithromycin in the treatment of human toxoplasmosis, particularly when this antibiotic is used in combination with other drugs with activity against T. gondii.     

A combination of sulfamonomethoxine and pyrimethamine versus other drugs for the treatment of malaria

Sixty-eight cases of vivax and 30 cases of falciparum malaria patients were treated with a combination of sulfamonomethoxine-pyrimethamine (MP tablet with 500 mg of sulfamonomethoxine and 25 mg of pyrimethamine) and the results were compared with those with chloroquine, Fansidar and quinine. Vivax malaria: Fever and parasites were cleared by the 4th day of treatment in 94 and 92% of the patients, respectively. Chloroquine was the most effective drug and Fansidar and MP tablets shared the next position. Falciparum malaria: Fever and asexual parasites were cleared by the 4th day of treatment in 67 and 78% of the patients, respectively. MP tablets were effective in chloroquine-resistant falciparum malaria contracted in Kalimantan (Indonesia) and Oceanian countries (Vanuatu etc.). Fever and parasite clearance times were shorter with chloroquine or with Fansidar than with MP tablets. Defective preschizonts used to appear following administration of MP tablets both in vivax and falciparum malarias. They were the premonitory laboratory indications that the asexual parasites will be soon eradicated.     

Activity of various drugs alone or in combination against Mycobacterium fortuitum

Interest in Mycobacterium fortuitum has increased since it was recognized as an emergent pathogen. The objective of this study was to screen a large number of drug combinations in order to evaluate the activity of classical and new potentially useful antibiotics against M. fortuitum. Twenty M. fortuitum clinical isolates were studied with 51 combinations of two drugs and 47 combinations of three drugs belonging to different families: fluoroquinolones, linezolid, macrolides, rifamycins, aminoglycosides, and carbapenems. Activity was determined in Mueller Hinton broth by seeing whether the cultures were negative after 4 days of incubation with the combination of antibiotics. The most active drugs were moxifloxacin and gatifloxacin, which were active against 15 of the 20 strains studied, followed by amikacin (14 of the 20). The combinations of gatifloxacin with rifampicin or rifabutin, moxifloxacin with rifampicin or amikacin, and ciprofloxacin with amikacin were the most useful against M. fortuitum, as they showed activity in 18 of the 20 strains studied. Linezolid, imipenem, and ertapenem showed poor activity in this experimental model when they were used on their own. Larger studies, both in vitro and in vivo, should be done to confirm the true usefulness of the new fluoroquinolones, alone or in combination, in the treatment of M. fortuitum.     

Efficacy of azithromycin as a causal prophylactic agent against murine malaria.

The efficacy of the newly marketed azalide azithromycin was compared with that of the clinical agent doxycycline in a murine model of sporozoite-induced malaria. Drug was administered once; Plasmodium yoelii sporozoites were administered 2 h later; survival at day 60 was determined. For parenterally administered drug, 160 mg of azithromycin or doxycycline per kg of body weight was 100% effective; 40 mg of azithromycin per kg was 80% effective, but 40 mg of doxycycline per kg was 40% effective. Orally administered azithromycin was somewhat less effective than parenterally administered drug, consistent with the 37% clinical oral bioavailability of this agent. For orally administered azithromycin, 160 mg/kg was 100% effective and 40 mg/kg was 40% effective. The efficacy of azithromycin in comparison with that of doxycycline and the known prolonged levels of azithromycin in the livers of humans suggest that azithromycin has potential as a clinical causal prophylactic agent for malaria.     

Activity of KRM-1648 in combination with isoniazid against Mycobacterium tuberculosis in a murine model.

The activity of KRM-1648, alone and in combination with isoniazid, was compared with those of isoniazid, rifampin, and the combination of rifampin plus isoniazid in a murine model of tuberculosis. Four-week-old female CD-1 mice were infected intravenously with approximately 10(7) viable Mycobacterium tuberculosis ATCC 35801 organisms. Treatment was started 1 week postinfection and was given by gavage 5 days per week. The duration of the treatment phase was 12 weeks, with groups of mice sacrificed at 2, 4, 6, 8, and 12 weeks. For the observation phase, additional groups of treated mice were sacrificed at 4, 8, 16, and 24 weeks after the cessation of treatment. Viable cell counts were determined from homogenates of the spleens and the right lungs. KRM-1648 was the most active single agent evaluated and resulted in no detectable CFUs in the spleens and lungs by the end of 6 weeks of treatment. Neither rifampin nor isoniazid reduced cell counts to undetectable levels, even after 12 weeks of treatment. The combination of KRM-1648 plus isoniazid was much more active than rifampin plus isoniazid. KRM-1648 plus isoniazid resulted in the apparent sterilization of organs at 6 months following the cessation of treatment. The promising activity of KRM-1648 may allow for ultrashort-course therapy of tuberculosis, i.e., treatment regimens of 4 months or less.     

Gemfibrozil in combination with other drugs for severe hyperlipidemia. Preliminary study comprising four cases

In this very early report, Dr Nash shares his insights into a newly developing approach to hyperlipidemia therapy. Four severely hyperlipidemic patients in whom maximum dietary therapy had proved ineffective showed a dramatic reduction in cholesterol and triglyceride levels when treated with multiple drugs, including gemfibrozil. These cases demonstrate that maximally effective polypharmacy can have striking results in selected patients. These provocative findings should encourage other investigators to verify or refute them.     

Sontochin as a guide to the development of drugs against chloroquine-resistant malaria

Sontochin was the original chloroquine replacement drug, arising from research by Hans Andersag 2 years after chloroquine (known as "resochin" at the time) had been shelved due to the mistaken perception that it was too toxic for human use. We were surprised to find that sontochin, i.e., 3-methyl-chloroquine, retains significant activity against chloroquine-resistant strains of Plasmodium falciparum in vitro. We prepared derivatives of sontochin, "pharmachins," with alkyl or aryl substituents at the 3 position and with alterations to the 4-position side chain to enhance activity against drug-resistant strains. Modified with an aryl substituent in the 3 position of the 7-chloro-quinoline ring, Pharmachin 203 (PH-203) exhibits low-nanomolar 50% inhibitory concentrations (IC(50)s) against drug-sensitive and multidrug-resistant strains and in vivo efficacy against patent infections of Plasmodium yoelii in mice that is superior to chloroquine. Our findings suggest that novel 3-position aryl pharmachin derivatives have the potential for use in treating drug resistant malaria.     

Ultrasound-enhanced effects of adriamycin against murine tumors.

Earlier studies from our and other laboratories have demonstrated that ultrasound (US) enhances the cytotoxicity in vitro of the antitumor agent Adriamycin (Adr) (Harrison et al. 1991; Loverock et al. 1990; Saad and Hahn 1987, 1989; Yang et al. 1991; Yumita et al. 1987, 1989). We have now tested the possibility that this additional cytotoxicity can be translated into antitumor activity in vivo. Mice, bearing either a fibrosarcoma (RIF-1) or a melanoma (B-16) on their thighs, were injected with a single dose of Adr (10-20 mg/kg). The tumors were then heated locally to 41 degrees -43 degrees C for 30 min, either by insonation with US or by immersion of the animals' limbs into hot water baths. Antitumor efficacy was scored two ways: by serial measurements of tumor volume to determine the time for the tumor to double in size, or by determining the X-ray dose required to sterilize 50% of the tumors (TCD50) after the Adr-hyperthermia treatment. Both assays gave similar results. Ultrasound-induced hyperthermia was substantially more effective in enhancing Adr activity than was hyperthermia induced by the water bath. The mean-doubling time was 13 days for tumors treated with the combination of Adr and US and 6 days for tumors heated with a water bath immediately after injection of Adr. The TCD50 was 21.2 +/- 0.8 Gy for the combination of US and Adr and 36.1 +/- 0.9 Gy for the water bath heating and Adr.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiac function in Ghanaian children with severe malaria

Purpose

The aim was to assess whether impaired cardiac function contributes to symptoms of severe malaria in general or to metabolic acidosis in particular in children living in endemic regions.

Methods

In a prospective observational investigation, 183 children with severe malaria were investigated for hemodynamic status and cardiac function upon admission (day 0) and after recovery (day 42). Cardiac function parameters were assessed by cardiac ultrasonography. Blood gas analyses and cardiac enzymes were measured at hospitalization and follow-up. Differences in subgroups with and without metabolic acidosis as well as other severe malaria-defining symptoms and conditions were assessed.

Results

Cardiac index (CI) was significantly increased on day 0 compared to day 42 (5.8?ml/m², SD?±?1.8?ml/m², versus 4.7?ml/m², SD?±?1.4?ml/m²; P?<?0.001). CI correlated negatively with hemoglobin levels but not with parameters indicating impaired tissue perfusion or metabolic acidosis. Parasite levels had a significant influence on metabolic acidosis but not on CI. Alterations related to cardiac function, hemoglobin levels and metabolic acidosis were most prominent in children younger than 2?years.

Conclusion

Increased CI reflecting high output status is associated with low hemoglobin levels while metabolic acidosis is linked to parasite levels.     

Pharmacokinetics of L-arginine in adults with moderately severe malaria

Severe malaria is associated with decreased nitric oxide (NO) production and low plasma concentrations of L-arginine, the substrate for NO synthase. Supplementation with L-arginine has the potential to improve NO bioavailability and outcomes. We developed a pharmacokinetic model for L-arginine in moderately severe malaria to explore the concentration-time profile and identify important covariates. In doses of 3, 6, or 12 g,L-arginine was infused over 30 min to 30 adults with moderately severe malaria, and plasma concentrations were measured at 8 to 11 time points. Patients who had not received L-arginine were also assessed and included in the model. The data were analyzed using a population approach with NONMEM software. A two-compartment linear model with first-order elimination best described the data, with a clearance of 44 liters/h (coefficient of variation [CV] = 52%) and a volume of distribution of 24 liters (CV = 19%). The natural time course of L-arginine recovery was described empirically by a second-order polynomial with a time to half recovery of 26 h. The half-life of exogenous L-arginine was reduced in patients with malaria compared with that for healthy adults. Weight and ethnicity were significant covariates for clearance. MATLAB simulations of dosing schedules for use in future studies predicted that 12 g given over 6, 8, or 12 h will provide concentrations above the K(m) of endothelial cell CAT-1 transporters in 90%, 75%, and 60% of patients, respectively.     

N-乙酰半胱氨酸对重症急性胰腺炎大鼠肾损伤保护作用的研究

目的 探讨N-乙酰半胱氨酸(NAC)对重症急性胰腺炎(SAP)大鼠肾损伤的保护作用及机制.方法 30只SD雄性大鼠,年龄7~8周,随机分为假手术(SO)组、SAP模型组、NAC组,每组10只.采用胰胆管逆行注射5%牛磺胆酸钠(0.1 Ml/100 g)诱导SAP模型,NAC组在造模后30 min腹腔注射5%NAC 2 Ml/kg,SO组和SAP组均在造模后30 min腹腔注射生理盐水2 Ml/kg.造模后12 h分批剖杀大鼠,心脏取血,取胰头及左肾组织冻存,测定血清淀粉酶(AMY)、肌酐(Cr)、尿素氮(BUN)、肿瘤坏死因子-α(TNF-α)水平及肾组织髓过氧化物酶(MPO)活性变化,行胰腺和肾脏病理学观察,Western blot法检测肾组织细胞间黏附分子1(ICAM-1)蛋白表达.结果 SAP组血清AMY、Cr、BUN、TNF-α、胰腺及肾组织病理损伤、肾组织MPO活性和ICAM-1蛋白表达与SO组比较差异有统计学意义(P<0.01),NAC组各指标与SAP组比较差异有统计学意义(P<0.01).结论 NAC可能通过减轻胰腺损伤、减少血清TNF-α等促炎因子产生、减少肾脏ICAM-1蛋白表达及白细胞聚集,对SAP大鼠肾损伤发挥保护和治疗作用.     

Antimycobacterial spectrum of sparfloxacin and its activities alone and in association with other drugs against Mycobacterium avium complex growing extracellularly and intracellularly in murine and human macrophages.

The MICs and MBCs of the new difluorinated quinolone drug sparfloxacin against type strains belonging to 21 species of mycobacteria were screened. The MICs and MBCs were within the range of 0.1 to 2.0 and 0.1 to 4.0 micrograms/ml, respectively (with an MBC/MIC ratio of 1 to 2), and against 18 of the 21 species tested, the drug showed significant bactericidal activity (at least 99% killing or more of the initial inoculum added) at concentrations well within the reported peak concentrations in serum (Cmax) in humans. MICs of sparfloxacin for 7 of 10 Mycobacterium avium complex strains were below the Cmax, with MBC/MIC ratios within the range of 2 to 4. Enhancement of its activity by ethambutol, rifampin, amikacin, and clarithromycin (which were used at sublethal concentrations) assessed by using BACTEC radiometry revealed that its activity was further enhanced in 2 of 10 strains by rifampin and in 7 of 10 strains by ethambutol. The bactericidal effects of various drugs used alone as well as two-drug combinations used at Cmax levels were also screened against four strains of M. avium complex growing intracellularly in two different macrophage systems, namely, mouse bone marrow-derived macrophages and peripheral blood monocyte-derived human macrophages. Our results showed a satisfactory correlation between the extracellular and intracellular drug activity data.     

Inhibition of histamine-mediated signaling confers significant protection against severe malaria in mouse models of disease

From the inoculation of Plasmodium sporozoites via Anopheles mosquito bites to the development of blood-stage parasites, a hallmark of the host response is an inflammatory reaction characterized by elevated histamine levels in the serum and tissues. Given the proinflammatory and immunosuppressive activities associated with histamine, we postulated that this vasoactive amine participates in malaria pathogenesis. Combined genetic and pharmacologic approaches demonstrated that histamine binding to H1R and H2R but not H3R and H4R increases the susceptibility of mice to infection with Plasmodium. To further understand the role of histamine in malaria pathogenesis, we used histidine decarboxylase-deficient (HDC(-/-)) mice, which are free of histamine. HDC(-/-) mice were highly resistant to severe malaria whether infected by mosquito bites or via injection of infected erythrocytes. HDC(-/-) mice displayed resistance to two lethal strains: Plasmodium berghei (Pb) ANKA, which triggers cerebral malaria (CM), and Pb NK65, which causes death without neurological symptoms. The resistance of HDC(-/-) mice to CM was associated with preserved blood-brain barrier integrity, the absence of infected erythrocyte aggregation in the brain vessels, and a lack of sequestration of CD4 and CD8 T cells. We demonstrate that histamine-mediated signaling contributes to malaria pathogenesis. Understanding the basis for these biological effects of histamine during infection may lead to novel therapeutic strategies to alleviate the severity of malaria.     

The fluid management of adults with severe malaria

Fluid resuscitation has long been considered a key intervention in the treatment of adults with severe falciparum malaria. Profound hypovolemia is common in these patients and has the potential to exacerbate the acidosis and acute kidney injury that are independent predictors of death. However, new microvascular imaging techniques have shown that disease severity correlates more strongly with obstruction of the microcirculation by parasitized erythrocytes - a process termed sequestration. Fluid loading has little effect on sequestration and increases the risk of complications, particularly pulmonary edema, a condition that can develop suddenly and unpredictably and that is frequently fatal in this population. Accordingly, even if a patient is clinically hypovolemic, if there is an adequate blood pressure and urine output, there may be little advantage in infusing intravenous fluid beyond a maintenance rate of 1 to 2 mL/kg per hour. The optimal agent for fluid resuscitation remains uncertain; significant anemia requires blood transfusion, but colloid solutions may be associated with harm and should be avoided. The preferred crystalloid is unclear, although the use of balanced solutions requires investigation. There are fewer data to guide the fluid management of severe vivax and knowlesi malaria, although a similar conservative strategy would appear prudent.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0642-6) contains supplementary material, which is available to authorized users.