The antihypertensive drug carvedilol inhibits the activity of mitochondrial NADH-ubiquinone oxidoreductase

A study is presented on the interaction of carvedilol with mitochondria isolated from several rat organs. It is shown that carvedilol causes a moderate uncoupling effect under non phosphorylating succinate supported respiration of intact mitochondria, as well as a marked inhibition of coupled respiration with NAD-dependent substrates. The inhibitory effect was also found in the bovine heart purified Complex I as well as in experiments with mitochondrial particles, where the individual redox segments of the respiratory chain were analysed. It is also shown that carvedilol, though exhibiting an intrinsic scavenger activity, caused reactive oxygen species to be produced as a consequence of its inhibitory effect on the steady-state respiration. Under these conditions the pro-oxidant activity of carvedilol appears to prevail over its scavenging activity, and a net generation of ROS is promoted.     

Analysis of the nonsteroidal anti-inflammatory drug literature for potential developmental toxicity in rats and rabbits

BACKGROUND: Nonsteroidal anti‐inflammatory drugs (NSAIDs) are among the most commonly prescribed to pregnant women. Some case‐control studies have linked the NSAIDs aspirin and indomethacin with a risk of congenital abnormalities and low birthweight. High doses of aspirin produce developmental toxicity in rats (e.g., gastroschisis/umbilical hernia, diaphragmatic hernia [DH]) when administered during sensitive windows of development. Unlike other NSAIDs, aspirin irreversibly inhibits cyclooxygenases (COXs) 1 and 2. Hence, the developmental toxicity seen in rats after exposure to aspirin may be due to the irreversible inhibition of COX‐1 and/or COX‐2. If so, other NSAIDs, which act through a reversible inhibition of COX, may produce a weak developmental toxicity signal or no developmental toxicity signal when tested in preclinical models. To investigate this relationship, a comprehensive analysis of the NSAID developmental toxicity literature was undertaken to determine whether NSAIDs other than aspirin induce developmental anomalies similar to those elicited by aspirin. METHODS: Developmental toxicity studies were identified through literature searches of PubMed and TOXNET, and pregnancy outcome data were extracted and tabulated. By using a set of defined criteria, each study was evaluated for quality and assigned to one of five tiers. The relation between certain malformations and NSAID treatment was analyzed for the best studies (tiers 1–4) by using concurrent control data (Mantel–Haenszel and permutation tests) and by combining the concurrent control data with historical control data (χ² test and permutation tests). RESULTS: A qualitative analysis of these data led to a focus on three types of malformations: DH, ventricular septal defects (VSDs), and midline defects (MDs). In rats, the incidences of VSD and MD were increased among fetuses treated with NSAIDs when compared with the concurrent controls. The extent of the increase was attenuated when the data from the aspirin studies were excluded from the analysis. There were no qualifying (i.e., tiers 1–4) aspirin studies conducted in rabbits, but the incidences of the three defects were increased over control incidences among non‐aspirin NSAID‐treated animals. Statistical analysis of these data was subsequently conducted. When tiers 1–4 were combined and compared with concurrent controls plus the most appropriate historical control database, the strongest associations were between NSAID treatment and VSD in rats, VSD in rabbits, and MD in rabbits. There also was some suggestion of an association between NSAID treatment and DH in rabbits. CONCLUSIONS: This analysis of the non‐clinical NSAID literature demonstrated a possible association between exposure to NSAIDs and developmental anomalies. The anomalies were similar for aspirin and for other NSAIDs, but effects occurred at a much lower incidence with non‐aspirin NSAIDs than previously reported with aspirin. Such a finding is consistent with the concept that reversible inhibition of COX‐1 and/or COX‐2 by other NSAIDs would produce weaker developmental toxicity signals than aspirin. However, there were limitations of the evaluated studies: (1) there were very few robust International Conference on Harmonization–compliant studies conducted with NSAIDs in the published literature; (2) many of the studies were conducted at doses well below the maximum tolerated dose (MTD), where effects are rarely seen; and (3) numerous studies were conducted above the MTD, where reduced numbers of fetuses hampered detection of low‐incidence findings. Although weak associations were observed, these limitations prevented us from definitively determining the presence or absence of a developmental toxicity signal from the existing body of NSAID data. Further exploration of this hypothesis will require assessing the potential association in animal models by using dose levels centered around the MTD. Birth Defects Research (Part B) 68:5–26, 2003. © 2003 Wiley‐Liss, Inc.     

Protein-protein interactions as a target for drugs in proteomics

Protein-protein interactions play a central role in numerous processes in the cell and are one of the main fields of functional proteomics. This review highlights the methods of bioinformatics and functional proteomics of protein-protein interaction investigation. The structures and properties of contact surfaces, forces involved in protein-protein interactions, kinetic and thermodynamic parameters of these reactions were considered. The properties of protein contact surfaces depend on their functions. The contact surfaces of permanent complexes resemble domain contacts or the protein core and it is reasonable to consider such complex formation as a continuation of protein folding. Characteristics of contact surfaces of temporary protein complexes share some similarities with active sites of enzymes. The contact surfaces of the temporary protein complexes have unique structure and properties and they are more conservative in comparison with active site of enzymes. So they represent prospective targets for a new generation of drugs. During the last decade, numerous investigations were undertaken to find or design small molecules that block protein dimerization or protein(peptide)-receptor interaction, or, on the contrary, to induce protein dimerization.     

Stereoselective pharmacokinetics and metabolism of flobufen in guinea pigs

Stereoselective aspects of pharmacokinetics and metabolism of a chiral nonsteroidal antiinflammatory drug, flobufen, 4-(2', 4'-difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic acid, were studied in male guinea pigs after p.o. administration of racemic flobufen (rac-flobufen) at a dose of 10 mg/kg. Blood samples were collected at intervals over 16 h after the administration of rac-flobufen for the quantification of flobufen enantiomers and their respective metabolites in plasma by chiral high-performance liquid chromatography (HPLC). Compartmental pharmacokinetic analysis was used to determine pharmacokinetic parameters of R- and S-flobufen. The plasma concentrations of the S- and R-enantiomers differed significantly during the experimental period. The S/R-enantiomeric ratio in 7plasma reached a maximum value of 10.1 at 240 min postdose. The oral clearance value of R-flobufen was five times higher than S-flobufen. The other pharmacokinetic parameters (K(e), T(1/2), V(SS)/F, MRT) of the enantiomers also differed substantially. All four stereoisomers of the dihydrometabolite of flobufen were detected in plasma with varying concentrations. Metabolite 17203 [4-(2,4-difluorophenyl)-phenylacetic acid] exhibited a relatively longer residence time compared to that noted for the enantiomers of the parent compound. Pharmacokinetics of the flobufen enantiomers were stereoselective in guinea pigs. The metabolism of flobufen was complex. However, metabolite 17203 seemed to be the main metabolite of flobufen that may be responsible for its relatively long-lasting antiphlogistic and immunomodulatory effects.     

New insights into the kinetic resistance to anticancer agents

Kinetic resistance plays a major role in the failure of chemotherapy towards many solid tumors. Kinetic resistance to cytotoxic drugs can be reproduced in vitro by growing the cells as multicellular spheroids (Multicellular Resistance) or as hyperconfluent cultures (Confluence-Dependent Resistance). Recent findings on the cell cycle regulation have permitted a better understanding why cancer cells which arrest in long quiescent phases are poorly sensitive to cell-cycle specific anticancer drugs. Two cyclin-dependent kinase inhibitors (CDKI) seem particularly involved in the cell cycle arrest at the G1 to S transition checkpoint: the p53-dependent p21^cip1 protein which is activated by DNA damage and the p27^kip1 which is a mediator of the contact inhibition signal. Cell quiescence could alter drug-induced apoptosis which is partly dependent on an active progression in the cell cycle and which is facilitated by overexpression of oncogenes such as c-Myc or cyclins. Investigations are yet necessary to determine the influence of the cell cycle on the balance between antagonizing (bcl-2, bcl-X_L...) or stimulating (Bax, Bcl-X_S, Fas...) factors in chemotherapy-induced apoptosis. Quiescent cells could also be protected from toxic agents by an enhanced expression of stress proteins, such as HSP27 which is induced by confluence. New strategies are required to circumvent kinetic resistance of solid tumors: adequate choice of anticancer agents whose activity is not altered by quiescence (radiation, cisplatin), recruitment from G1 to S/G2 phases by cell pretreatment with alkylating drugs or attenuation of CDKI activity by specific inhibitors. This revised version was published online in August 2006 with corrections to the Cover Date.     

肽核酸的分子生物学效应及应用

肽核酸(PNA)是一类以酰胺键连接骨架替代核酸中核糖磷酸二酯键骨架构成的核酸类似物,其中N-乙基甘氨酸骨架PNA与核酸链以Waston-Crick碱基配对形式稳定互补结合,具有广泛生物学效应,包括调节DNA识别蛋白质的功能以及调节转录和翻译.在分子生物学研究中PNA作为新的工具在多方面得到应用.除它的DNA(RNA)结合特性外PNA在生物稳定性、细胞摄取、结构修饰多方面的研究进展显示出作为基因调节药物具有良好前景.     

Responsiveness to hormone, growth factor and drug treatment of a human breast cancer cell line: Comparison between early and late cultures

Summary Growth rate, morphology, and responsiveness to mitogenic stimuli and pharmacological treatments were evaluated in early and late cell passages derived from the same clone of the widely used MCF-7 human breast adenocarcinoma cell line. Our results indicate dissimilarities between early (E) and late (L) passages for some of the parameters analyzed. The cells that underwent many subcultivations grew faster than the others; both appeared homogeneous in size and shape. The E cells, subcultured for almost 1 yr, displayed higher sensitivity to the mitogenic action of both estradiol, according to the level of estrogen receptor, and insulin-like growth factor-I than did the L cells, kept in culture for more than 10 yr. Cell responsiveness to two drugs, a novel steroid antiestrogen and a polysulfonated distamycin A derivative, was more pronounced in the early cultures only at the longer time of exposure to the higher concentration of the estrogen antagonist. In addition, a drug-induced inhibition of insulin-like growth factor-I binding to its receptor was shown in both E and L cells, the latter being less sensitive than the former when exposed to the antiestrogen. Finally, MCF-7 E and L cells showed similar behavior when drug-induced apoptosis was tested.     

Detection of 4-hydroxycoumarin anticoagulants and their metabolites in urine as part of a systematic toxicological analysis procedure for acidic drugs and poisons by gas chromatography–mass spectrometry after extractive methylation

A gas chromatography–mass spectrometry (GC–MS) procedure was developed for the detection of 4-hydroxycoumarin anticoagulants and their metabolites in urine as part of a systematic toxicological analysis procedure for acidic drugs and poisons after extractive methylation. The part of the phase-transfer catalyst remaining in the organic phase was removed by solid-phase extraction on a diol phase. The compounds were separated by capillary GC and identified by computerized MS in the full scan mode. Using mass chromatography with the ions m/z 291, 294, 295, 309, 313, 322, 324, 336, 343 and 354, the possible presence of 4-hydroxycoumarin anticoagulants and/or their metabolites could be indicated. The identity of positive signals in such mass chromatograms was confirmed by comparison of the peaks underlying full mass spectra with the reference spectra recorded during this study. This method allowed the detection of therapeutic concentrations of phenprocoumon and warfarin in human urine samples. In absence of human urine, acenocoumarol, coumachlor, coumatetrayl, pyranocoumarin (cyclocumarol) could be detected only in rat urine.     

Chronopharmacology of cardiovascular medications

The cardiovascular system is well organized in time. Mechanisms of regulation and pathophysiological events are not evenly distributed over the 24-h scale. Moreover, certain diseases may even alter the physiological circadian pattern in the cardiovascular system. This observation bares implications for drug treatment, e.g. regarding drug formulations and dosing time intervals. Pitfalls may arise from neglecting circadian phase-dependency in pharmacokinetics and in the concentration-dependent effect relationship. Moreover, different types of drugs may be superior to others when circadian time-related symptoms are concerned. There is sound evidence that “time-of-day” has to be included in our diagnostic and therapeutic strategies.     

抗青光眼药物长期使用对眼表的影响

目的：研究长期使用青光眼药物对患者眼表结构的影响,为正确选择青光眼治疗药物提供依据。方法：将采用青光眼药物治 疗≥ 3 个月的青光眼患者40 例（62 只眼）设为病例组,以同期健康志愿者30 例（30 只眼）设为对照组,比较两组基础泪液分泌长 度(ST)、泪膜破裂时间(BUT)、角膜荧光染色评分（FB）及结膜印记细胞评级（IC）。结果：病例组ST、BUT 分别为（6.12± 3.63）mm、 （5.21± 2.13）s,均短于对照组的（10.72± 4.62）mm、（11.45± 5.12）s（P<0.01);病例组FB 评分为（2.19± 0.42）分,高于对照组（0.62± 0.04）分（P<0.01）;病例组IC 评级为Ⅱ~Ⅲ级比例为54.84%,高于对照组的5.00%（P<0.01)。结论：青光眼患者长期使用青光眼药物 会导致泪液分泌减少,泪膜稳定性下降,并加快结膜细胞鳞状上皮化进程,对泪膜、角膜及结膜均有损伤,应引起重视。