Randomised controlled trial of antibiotics in patients with cough and purulent sputum.

Two hundred and twelve adults with cough and purulent sputum of up to one week''s duration were allocated randomly to treatment with doxycycline or placebo capsules for up to 10 days. Cough, purulent sputum, feeling "off colour," and time off work lasted as long in treatment and control groups, but running nose persisted for a shorter time in the doxycycline group. The number of new episodes of lower respiratory tract infections, vaginal infections, gastrointestinal upsets, and otitis media over the next six months were the same in both groups, but fewer new upper respiratory infections were experienced by the doxycycline-treated patients. There is no consensus among doctors about using antibiotics in patients with cough and purulent sputum, and these results indicate that otherwise healthy people with these symptoms will usually get better without antibiotic treatment.     

Comparative evaluation of methacycline hydrochloride capsules and tablets according to their dissolubility and rate of solution]

Desintegration and dissolution of capsules and tablets of methacycline hydrochloride were studied. The study on solubility of methacycline hydrochliride capsules filled with methacycline granulate or powder according to the same formula showed that the rate of the antibiotic liberation from the capsules filled with the powder decreased during storage while that from the capsules filled with the granulate did not change. Investigation of the effect of the mass packing value in a drop on the antibiotic liberation from the capsules showed that an increase in the packing coefficient above 1.38 resulted in a marked decrease in the rate of methacycline liberation from the capsules filled with the granulate. No correlation between desintegration and dissolution of methacycline capsules and tablets was found.     

Soluplus-Solubilized Citrated Camptothecin—A Potential Drug Delivery Strategy in Colon Cancer

Camptothecin (CPT), a potent antitumor drug, exhibits poor aqueous solubility and rapid conversion from the pharmacologically active lactone form to inactive carboxylate form at physiological pH. Solid dispersion of CPT in Soluplus®, an amphiphilic polymeric solubilizer, was prepared to increase the aqueous solubility of CPT and the resultant solid dispersion along with citric acid was formulated as hard gelatin capsules that were subsequently coated with Eudragit S100 polymer for colonic delivery. FTIR spectrum of the solid dispersion confirmed the presence of CPT. PXRD and DSC revealed the semicrystalline nature of solid dispersion. The solubility of the drug was found to increase ~40 times in the presence of Soluplus and ~75 times in solid dispersion. The capsules showed no drug release in 0.01 N HCl but released 86.4% drug in lactone form in phosphate buffer (pH 7.4) and the result appears to be due to citric acid-induced lowering of pH of buffer from 7.4 to 6.0. Thus the presence of citric acid in the formulation led to stabilization of the drug in its pharmacologically active lactone form. Cytotoxicity studies conducted with the formulation of solid dispersion with citric acid, utilizing cell cytotoxicity test (MTT test) on Caco-2 cells, confirmed cytotoxic nature of the formulation.     

Solid Self-Microemulsifying Formulation for Candesartan Cilexetil

Sparingly, water-soluble drugs such as candesartan cilexetil offer challenges in developing a drug product with adequate bioavailability. The objective of the present study was to develop and characterize self-microemulsifying drug delivery system (SMEDDS) of candesartan cilexetil for filling into hard gelatin capsules. Solubility of candesartan cilexetil was evaluated in various nonaqueous careers that included oils, surfactants, and cosurfactants. Pseudoternary phase diagrams were constructed to identify the self-microemulsification region. Four self-microemulsifying formulations were prepared using mixtures of oils, surfactants, and cosurfactants in various proportions. The self-microemulsification properties, droplet size, and zeta potential of these formulations were studied upon dilution with water. The optimized liquid SMEDDS formulation was converted into free flowing powder by adsorbing onto a solid carrier for encapsulation. The dissolution characteristics of solid intermediates of SMEDDS filled into hard gelatin capsules was investigated and compared with liquid formulation and commercial formulation to ascertain the impact on self-emulsifying properties following conversion. The results indicated that solid intermediates showed comparable rate and extent of drug dissolution in a discriminating dissolution medium as liquid SMEDDS indicating that the self-emulsifying properties of SMEDDS were unaffected following conversion. Also, the rate and extent of drug dissolution for solid intermediates was significantly higher than commercial tablet formulation. The results from this study demonstrate the potential use of SMEDDS as a means of improving solubility, dissolution, and concomitantly the bioavailability.     

Effects of doxycycline on articular cartilage GAG release and mechanical properties following impact

The effects of doxycycline were examined on articular cartilage glycosaminoglycan (GAG) release and biphasic mechanical properties following two levels of impact loading at 1 and 2 weeks post-injury. Further, treatment for two continuous weeks was compared to treatment for only the 1st week of a 2-week culture period. Following impact at two levels, articular cartilage explants were cultured for 1 or 2 weeks with 0, 50, or 100 microM doxycycline. Histology, GAG release to the media, and creep indentation biomechanical properties were examined. The "High" (2.8 J) impact level had gross surface damage, whereas "Low" (1.1 J) impact was indiscernible from non-impacted controls. GAG staining decreased after High impact, but doxycycline did not visibly affect staining. High impact resulted in decreased aggregate moduli at both 1 and 2 weeks and increased permeability at 2 weeks, but tissue mechanical properties were not affected by doxycycline treatment. At 1 week, High impact resulted in more GAG release compared to non-impacted controls. However, following High impact, 100 microM doxycycline reduced cumulative GAG release at 1 and 2 weeks by 30% and 38%, respectively, compared to no treatment. Interestingly, there was no difference in GAG release comparing 2 weeks continuous treatment with 1 week on, 1 week off. These results support the hypothesis that doxycycline can mitigate GAG release from articular cartilage following impact loads. However, doxycycline was unable to prevent the loss of tissue stiffness observed post-impact, presumably due to initial matrix damage resulting solely from mechanical trauma.     

Oral formulation of a novel antiviral agent,PG301029, in a mixture of Gelucire 44/14 and DMA (2∶1, wt/wt)

To develop an oral formulation for PG301029, a novel potent agent for the treatment of Hepatitis C virus infection, that not only has very low aqueous solubility but also degrades rapidly in water. The solubility of PG301029 was determined in water, various aqueous media, and several neat organic solvents. The stability of PG301029 was monitored at room temperature in buffess for 4 days, and in several neat organic solvents for up to 8 mo. Drug concentrations were measured by high-performance liquid chromatography (HPLC). Based on solubility and stability data, Gelucire 44/14 and DMA (N,N-dimethylacetamide) at a weight ratio of 2 to 1 were chosen as the formulation vehicle. After the vehicle was prepared, it was maintained in liquid form at ∼40°C until the PG301029 was dissolved. The final formulation product was a semisolid at room temperature. The bioavailability of the formulation was tested on 4 female BALB/c mice. PG301029 is insoluble in all tested aqueous media, while its solubility is promising in DMA. This compound is unstable in aqueous media and some organic solvents; however, it is stable in DMA. This proposed formulation is able to hold up to 10 mg/mL of drug and is stable at 4°C. The shelf life for this formulation stored at 4°C is extrapolated to be greater than 4 years. This formulation dramatically increases the bioavailability of PG301029. This nonaqueous formulation solves the stability, solubility, and bioavailability problems for PG301029. This semisolid formulation can easily be incorporated into soft elastic capsules.     

Protective effects of doxycycline in ischemia/reperfusion injury on kidney

Renal ischemia and reperfusion injury is the major cause of acute renal failure and may also be involved in the development and progression of some forms of chronic kidney disease. The aim of this study was to evaluate whether doxycycline, a member of the tetracycline family of antibiotics, protects kidney tissue or not. 36 Sprague-Dawley rats (200–250 g) were used. The animals were divided into three groups: control, ischemia/reperfusion and ischemia/reperfusion+doxycycline group. Rats were subjected to renal ischemia by clamping the left pedicle for 1 h, and then reperfused for 1 h. The ischemia/reperfusion+doxycycline group were pretreated intraperitoneally with doxycycline suspension (10 mg/kg) 2 h before the induction of ischemia. Our results indicate that malondialdehyde, matrix-metalloproteinase-2, interleukin-2, interleukin-6, interleukin-10, interleukin 1-beta and tumor necrosis factor-alpha levels were significantly higher in the ischemia/reperfusion group than those in the control group. Doxycycline administration significantly decreased these parameters. Tissue inhibitor of metalloproteinases-1 levels also increased after ischemia/reperfusion and decreased with doxycycline pretreatment, but these changes were not significantly different. Glutathione levels significantly decreased after ischemia/reperfusion injury when compared with the control group and doxycycline pretreatment significantly increased glutathione levels when compared with the ischemia/reperfusion group. Apoptotic cells and p53 positive cells were significantly decreased in doxycycline treated group. These results suggest that doxycycline reduces renal oxidative injury and facilitates repair. Doxycycline may play a role in a renoprotective therapeutic regimen.     

Comparison between gamma and beta irradiation effects on hydroxypropylmethylcellulose and gelatin hard capsules

The effects of electron beam or λ-irradiation on technological performances (capsule hardness, expressed as deforming work and dissolution time) of empty 2-shell capsules made of gelatin or hydroxypropylmethylcellulose (HPMC) were studied. Capsule structural changes induced by radiation treatment were investigated by capillary viscometry and atomic force microscopy (AFM). The capsules were irradiated in the air at 5, 15, and 25 kGy. The deforming work of nonirradiated HPMC capsules (0.06±0.01 J) was lower than that of gelatin capsules (0.10±0.01 J). The dissolution time of the HPMC capsules (414±33 seconds) was slightly higher than that determined for gelatin hard capsules (288±19 seconds). The hardness and dissolution time of gelatin and HPMC capsules were not significantly influenced by the irradiation type and the applied irradiation dose. As the viscometry analyses are concerned, irradiation caused a reduction of the intrinsic viscosity and water and dimethyl sulfoxide solvent power in both the cases. AFM analysis showed that the radiation treatment did not appreciably affect the surface roughness of the samples nor induce structural changes on capsule surface. However, measurements of force-distance curves pointed out a qualitative parameter for the identification of the irradiated capsules. On the bases of these preliminary results, empty gelatin or HPMC hard capsules can be sanitized/sterilized by ionizing radiation. Published: December 1, 2005     

Improvement of Dissolution and Hypoglycemic Efficacy of Glimepiride by Different Carriers

Effects of tromethamine (Tris), polyvinylpyrrolidone (PVP-K25), and low molecular weight chitosan (LM-CH) on dissolution and therapeutic efficacy of glimepiride (Gmp) were investigated using physical mixtures (PMs), coground mixtures, coprecipitates (Coppts) or kneaded mixtures (KMs), and compared with drug alone. Fourier transform infrared spectroscopy, differential scanning colorimetry, and X-ray diffractometry were performed to identify any physicochemical interaction with Gmp. Surface morphology was examined via scanning electron microscopy. The results of Gmp in vitro dissolution revealed that it was greatly enhanced by Coppt with Tris or PVP-K25 and KM with LM-CH at a drug to carrier ratio of 1:8. Gmp amorphization by PVP-K25 and LM-CH was a major factor in increasing Gmp dissolution. Being basic, Tris might increase the pH of the microdiffusion layer around Gmp particles improving its dissolution. Formation of water-soluble complexes suggested by solubility study may also explain the enhanced dissolution. Capsules were prepared from Coppts and KM 1:8 drug to carrier binary systems and also with Tris PMs. In vivo, the hypoglycemic efficacy of Gmp capsules in rabbits increased by 1.63-, 1.50-, and 1.46-fold for 1:8 Coppts with Tris or PVP-K25 and KM with LM-CH respectively, compared with Gmp alone. Surprisingly, the response to Tris PM 1:20 capsules was 1.52-fold revealing statistically insignificant difference to that of Tris Coppt 1:8 (1.63 fold). As a conclusion, dissolution enhancement and hypoglycemic potentiation by 1:20 PM of Gmp/Tris, being simple and easy to prepare, may enable development of a reduced-dose and fast-release oral dosage form of Gmp.     

Doxycycline in the treatment of human onchocerciasis: Kinetics of Wolbachia endobacteria reduction and of inhibition of embryogenesis in female Onchocerca worms

Recently, experts have warned that mass treatment with ivermectin alone may not interrupt the transmission of Onchocerca. Hence, additional drugs are needed, such as antibiotics acting on symbiotic endobacteria of the filariae, the causative agents of onchocerciasis. Based on animal experiments, human onchocerciasis was treated with doxycycline, and preliminary observations published in 2001 in The Lancet showed sterility in female worms by depletion and marked reduction in symbiotic Wolbachia endobacteria from the filariae. Here, a detailed kinetic analysis of the features of the worms, following administration or not of doxycycline to the patients is reported. Sixty-three onchocerciasis patients in Ghana were treated with 100 mg doxycycline daily for 6 weeks and 2 or 6 months later with ivermectin. Onchocercomas were extirpated 2, 6, 11 and 18 months after the onset of treatment and the filariae were examined by immunohistology and PCR. The analysis showed: (i) progressive depletion of Wolbachia from adult worms and microfilariae by doxycycline over a period of 6 months; (ii) inhibition of embryogenesis by doxycycline after 6 months with respect to all embryo stages followed by decline in microfilariae after 11 months; (iii) reduction in spermatozoa in the female genital tract by doxycycline, whereas spermiogenesis was only partly reduced after 11 and 18 months; (iv) no relevant macro- or microfilaricidal activity; (v) depletion/marked reduction in endobacteria and inhibition of embryogenesis were sustained until 18 months after doxycycline and 12 months after co-administration of ivermectin; (vi) no severe adverse side effects were seen. Due to its long-lasting inhibition of embryogenesis, doxycycline presents an additional strategy for the treatment of onchocerciasis and control of Onchocerca microfilariae transmission. Extension of the existing registration will not require much time or high cost. Treatment of individual patients can be considered immediately.     

Effect of Rheology and Poloxamers Properties on Release of Drugs from Silicon Dioxide Gel-Filled Hard Gelatin Capsules—A Further Enhancement of Viability of Liquid Semisolid Matrix Technology

The liquid and semisolid matrix technology, filling liquids, semi-solids and gels in hard gelatin capsule are promising, thus, there is a need of enhanced research interest in the technology. Therefore, the present study was aimed to investigate isoniazid (freely soluble) and metronidazole (slightly soluble) gels filled in hard gelatin capsules for the effect of poloxamers of different viscosities on release of the drugs. Gel of each drug (10% w/w, particle size 180–250 μm), prepared by mixing poloxamer and 8% w/w hydrophilic silicon dioxide (Aerosil® A200), was assessed for rheology, dispersion stability and release profile. Both the drugs remained dispersed in majority of gels for more than 30 days, and dispersions were depended on gels’ viscosity, which was further depended on viscosity of poloxamers. A small change in viscosity was noted in gels on storage. FTIR spectra indicated no interactions between components of the gels. The gels exhibited thixotropic and shear-thinning behaviour, which were suitable for filling in hard gelatin capsules without any leakage from the capsules. The release of both drugs from the phase-stable gels for 30 days followed first-order kinetics and was found to be correlated to drugs’ solubility, poloxamers’ viscosity, polyoxyethylene contents and proportion of block copolymer (poloxamers) in the gels. The findings of the present study indicated that release of drugs of different solubilities (isoniazid and metronidazole) might be modified from gels using different poloxamers and Aerosil® A200.     

Pharmacokinetics of saquinavir after intravenous and oral dosing of saquinavir: hydroxybutenyl-beta-cyclodextrin formulations

The current research evaluated the ability of hydroxybutenyl-beta-cyclodextrin (HBenBCD) to enhance saquinavir in vitro solubility and in vivo oral bioavailability; both the base and mesylate salt forms of saquinavir were investigated. HBenBCD was effective and significantly improved saquinavir solubility in aqueous media. In the presence of 10 wt % HBenBCD, saquinavir base solubility in water was increased to ca. 5.5 +/- 0.4 mg/mL and represents a 27-fold increase from that observed in water (207 +/- 5 microg/mL) in the absence of HBenBCD. Saquinavir-HBenBCD formulations were found to have rapid dissolution over a wide pH range (1.2-6.8), and saquinavir solubility in these media was maintained throughout the experiments. When saquinavir-HBenBCD formulations were administered to Wistar-Hannover rats, saquinavir was rapidly absorbed and rapidly eliminated. Rapid saquinavir elimination was particularly pronounced when saquinavir-HBenBCD formulations were given as an oral aqueous gavage. Saquinavir oral bioavailability in rats obtained from saquinavir mesylate capsules (2.0% +/- 0.7%) was increased (9 +/- 4)-fold (18.6% +/- 7.3%) when dosed with saquinavir base-HBenBCD capsules. Clearly, HBenBCD can significantly improve the solubility and oral bioavailability of saquinavir; however, further formulation studies are required to optimize saquinavir oral delivery using this technology.     

How to make tetracycline-regulated transgene expression go on and off

Tetracycline-regulated gene expression systems are widely used to allow temporal and quantitative control of transgene expression in cultured cells and transgenic animals. While working with the Tet-Off system, where tetracycline or the analogue doxycycline suppresses expression, we noted a considerable variability in induced transgene expression after removal of doxycycline. Variable expression of the transgene could not be explained by clonal variation since it was noted when working with clonal cell lines. Instead we found that doxycycline bound nonspecifically to cells and extracellular matrix and was slowly released after it had been removed from tissue culture media. The released doxycycline reached sufficiently high levels to completely suppress transgene expression. The effect was not dependent on cell type or the nature of the transgene. However, robust and rapid transgene expression could be induced if released doxycycline were removed by washing cells 3h after the initial removal of doxycycline. The use of different vector systems, harboring the tetracycline-regulatable components, yielded similar results. These results not only help explain why tetracycline-regulatable transgene expression systems sometimes are variable but also provide simple ways to substantially improve the efficiency, utility, and reliability of these widely used expression systems.     

Klucel? EF and ELF polymers for immediate-release oral dosage forms prepared by melt extrusion technology

The objective of this research work was to evaluate Klucel™ hydroxypropylcellulose (HPC) EF and ELF polymers, for solubility enhancement as well as to address some of the disadvantages associated with solid dispersions. Ketoprofen (KPR), a Biopharmaceutics Classification System class II drug with poor solubility, was utilized as a model compound. Preliminary thermal studies were performed to confirm formation of a solid solution/dispersion of KPR in HPC matrix and also to establish processing conditions for hot-melt extrusion. Extrudates pelletized and filled into capsules exhibited a carrier-dependent release with ELF polymer exhibiting a faster release. Tablets compressed from milled extrudates exhibited rapid release owing to the increased surface area of the milled extrudate. Addition of mannitol (MNT) further enhanced the release by forming micro-pores and increasing the porosity of the extrudates. An optimized tablet formulation constituting KPR, MNT, and ELF in a 1:1:1 ratio exhibited 90% release in 15 min similar to a commercial capsule formulation. HPC polymers are non-ionic hydrophilic polymers that undergo polymer-chain-length-dependent solubilization and can be used to enhance solubility or dissolution rate of poorly soluble drugs. Dissolution/release rate could be tailored for rapid-release applications by selecting a suitable HPC polymer and altering the final dosage form. The release obtained from pellets was carrier-dependent and not drug-dependent, and hence, such a system can be effectively utilized to address solubility or precipitation issues with poorly soluble drugs in the gastrointestinal environment.Key words: hot-melt extrusion, Klucel™ EF/ELF, solid solutions/dispersions, solubility enhancement, thermal miscibility evaluation     

Histidine-capped copper nanoclusters for in situ amplified fluorescence monitoring of doxycycline through inner filter effect

There is a significant need to accurately measure doxycycline concentrations in view of the adverse effects of an overdose on human health. A fluorescence (FL) detection method was adopted and copper nanoclusters (CuNCs) were synthesized using chemical reduction technology. Based on FL quenching with doxycycline, the prepared CuNCs were used to explore a fluorescent nanoprobe for doxycycline detection. In an optimal sensing environment, this FL nanosensor was sensitive and selective in doxycycline sensing and displayed a linear relationship in the range 0.5–200 μM with a detection limit of 0.092 μΜ. A characterization test demonstrated that CuNCs offered active functional groups for identifying doxycycline using electrostatic interaction and hydrogen bonds. Static quenching and the inner filter effect (IFE) resulted in weakness in the FL of His@CuNCs with doxycycline with great efficiency. This suggested nanosensor was revealed to be a functional model for simple and rapid detection of doxycycline in real samples with very pleasing accuracy.     

The Improvement of the Dissolution Rate of Ziprasidone Free Base from Solid Oral Formulations

This work aims at increasing solubility and dissolution rate of ziprasidone free base—Biopharmaceutics Classifaction System (BCS) class II compound. The authors describe a practical approach to amorphization and highlight problems that may occur during the development of formulations containing amorphous ziprasidone, which was obtained by grinding in high-energy planetary ball mills or cryogenic mills. The release of ziprasidone free base from the developed formulations was compared to the reference drug product containing crystalline ziprasidone hydrochloride—Zeldox® hard gelatin capsules. All preparations were investigated using compendial tests (USP apparatuses II and IV) as well as novel, biorelevant dissolution tests. The novel test methods simulate additional elements of mechanical and hydrodynamic stresses, which have an impact on solid oral dosage forms, especially during gastric emptying. This step may prove to be particularly important for many formulations of BCS class II drugs that are often characterized by narrow absorption window, such as ziprasidone. The dissolution rate of the developed ziprasidone free base preparations was found to be comparable or even higher than in the case of the reference formulation containing ziprasidone hydrochloride, whose water solubility is about 400 times higher than its free base.KEY WORDS: amorphization, dissolution stress test device, enhanced dissolution, solubility improvement, ziprasidone free base formulations     

Suppression of fertility in female hamsters with polyvinylpyrrolidone — Silicone rubber (PSR) implants containing prostaglandin F2α

Fertility has been suppressed in female hamsters by premating implantation of polyvinylpyrrolidone-silicone rubber (PSR) capsules containing PGF_2α. When tubular PSR capsules (0.5 cm diameter, 1 cm length) with 4 mg PGF_2α (tham salt) were implanted subcutaneously 3 days before mating, no pregnancies occurred among the treated animals. Removal of the capsules was associated with a recovery of fertility. Administration of PGF_2α by subcutaneous bi-daily injections, 2 mg/day on days 3 and 2 prior to mating, and by implantation of PSR capsules, whose exposed surfaces were sealed, produced no obvious effect on either the rate of pregnancy or upon the number of fetuses/pregnancy. From the present results, PSR capsules provide an effective means of implanting prostaglandin and appear to be suitable for their long term administration.     

Effect of ethylenediaminetetraacetic acid disodium salt and doxycycline on drug resistant bacteria]

Effect of Na2EDTA and doxycycline applied alone and in combination in the treatment of experimentally induced dermatitis in rabbits with Staphylococcus aureus resistant to tetracyclines was studied. The rabbits were divided into three groups. The animals of group I were treated locally with the ointment containing 1% doxycycline or 1% Na2EDTA. In group II topical treatment was applied by means of injections of Na2EDTA solution in doses of 12.5 and 6.25 mg Na2EDTA per 1 kg/body weight. Group III was also treated locally with Na2EDTA solution like in group II, but additionally doxycycline in a dose of 50 micrograms per 1 kg/body weight was given i.v. Favourable therapeutic results were observed in the case of local, simultaneous application of Na2EDTA and doxycycline, or local application of Na2EDTA, and intravenous administration of doxycycline. However, the best therapeutic effect was seen in the case of local, simultaneous application of the ointment containing Na2EDTA and doxycycline.     

薄层色谱法鉴定天麻胶囊中的天麻素

为了建立天麻胶囊中主要有效成分天麻素的快速鉴定方法,根据天麻素的理化特性,使用乙醇和甲醇提取天麻胶囊中的天麻素,使用薄层色谱法进行鉴定,并与高效液相色谱法的分析结果进行比较。结果表明,薄层色谱法的鉴定结果与高效液相色谱法的检测结果一致,能较准确地鉴别天麻胶囊的真伪。本研究结果表明薄层色谱法能快速简便、准确灵敏地检测天麻胶囊中的有效成分,可作为法定鉴定方法的补充,对天麻胶囊实施快速初筛。     

血小板生成素基因在NIH/3T3细胞中的表达与调控

应用 Tet- On基因表达系统 ,调控血小板生成素 (TPO)基因在 NIH/3T3细胞中的表达时间与水平 .籍脂质体介导的基因转移方法 ,p Tet- On质粒转染 NIH/3T3细胞株 ,得到稳定细胞株NIH/3T3- Tet- On.p TRE/TPO与 p TK- Hyg质粒共转染 NIH/3T3- Tet- On细胞株 ,得到双稳定细胞株 NIH/3T3- Tet- On- TPO.在培养基中加入或不加强力霉素 ,RT- PCR、Western印迹及 ELISA法检测培养上清 TPO表达 .结果表明 ,当培养基中不加强力霉素时 ,TPO无明显表达 (0 .1 μg/L) ;当培养基中加入 2 mg/L强力霉素时 ,TPO表达明显增高 (1 0 .8μg/L) .TPO表达水平与强力霉素浓度有关 ,随强力霉素浓度增高 ,TPO表达增加 .TPO表达水平还与强力霉素作用时间有关 ,加入强力霉素 6 h后 ,TPO表达明显增加 (1 .2μg/L) ,随培养时间延长 ,TPO表达增加 ,2 4 h达到峰值(1 0 .8μg/L) ,而且这种诱导作用是可逆的 .为进一步进行 TPO基因表达调控的体内研究奠定基础 ,有望为 TPO基因治疗提供一条可控的安全途径