血小板生成素与白介素-11治疗胃癌术后辅助化疗后血小板减少症时效及安全性的比较

目的:比较血小板生成素与白介素-11治疗胃癌患者术后化疗血小板减少症的时效和安全性。方法:术后辅助化疗出现血小板计数低于75×109/L的进展期胃癌患者68例,将其分为TPO组与IL-11组,分别为35例和33例。分别皮下注射rhTPO 15000U,每日1次;rhIL-11 1.5 mg,每日1次,当血小板计数125×109/L或比用药前上升50×109/L,即停止给药,疗程最长为14天。每3天抽取外周静脉血2 m L,通过全自动血液分析仪测定血小板计数,密切观察出现的不良反应并记录。比较两组患者不同临床病理资料、血小板计数、血小板计数升至75×109/L和125×109/L的时程、药物不良反应。结果:两组患者年龄、性别、化疗方案、血小板最低值出现的化疗周期及临床病理分期的比较均没有统计学差异(P值均0.05)。TPO组与IL-11组血小板动态值的比较,第9天出现显著差异(P=0.032)。TPO组与IL-11组血小板计数恢复至75×109/L和125×109/L所需的时间,有显著差异(P=0.041,P=0.013)。TPO组中,有3例(8.6%)患者发生不良反应,IL-11组中,有13例(39.4%)患者发生不良反应,TPO组患者出现的不良反应少且较轻微(P=0.006)。结论:rhTPO治疗胃癌患者术后化疗血小板减少症时效快,安全性好。     

Insulin stimulates GDP release from G proteins in the rat and human liver plasma membranes

Plasma membranes (1–2 mg protein) prepared from the livers of adult male rats and human organ donors were incubated with 0.6 μM [α-³²P] guanosine triphosphate (GTP) in an adenosine triphosphate (ATP)-regenerating buffer at 37°C for 1 h; during this incubation, the [³²P]GTP is hydrolyzed and the nucleotide that is predominantly bound to the membranes is [³²P] guanosine diphosphate (GDP). [³²P]GDP release from the liver membranes was proportional to the protein concentration and increased as a function of time. At 5 mM, Ca²⁺, Mg²⁺, Mn²⁺, and Zn²⁺ maximally inhibited GDP release by 80–90%, whereas, 5 mM Cu²⁺ maximally stimulated the reaction by 100%. Therefore, cations were not included in the buffer used in the GDP release step. One μM Gpp(NH)p (5′-guanylylimidodiphosphate), a nonhydrolyzable analog of GTP, maximally stimulated [³²P]GDP release in the liver membranes by up to 30%. Although 10 nM Gpp(NH)p had no effect on GDP release, it appeared to stabilize the hormonal effect by blocking further GDP/GTP exchange. In the rat membranes, 1–100 nM glucagon (used as a positive control) stimulated [³²P]GDP release by about 17% (P < .05); similarly, 0.1–100 nM insulin stimulated [³²P]GDP release by 10–13% (P < .05). In the human membranes, 10 pM to 100 nM insulin stimulated [³²P]GDP release by 7–10%. In the rat membranes, 10 nM insulin stimulated [³²P]GDP release by 17 and 24% at 2 and 4 min, respectively (P < .05); in the human membranes, 10 nM insulin stimulated [³²P]GDP release by about 9% at 2 and 4 min. Normal rabbit IgG (used as a control for insulin receptor antibody) by itself stimulated the GDP release by rat and human membranes. However, the stimulation of the GDP release by insulin receptor antibody was consistently higher than that observed with normal rabbit IgG. Four to 15 μg of insulin receptor antibody stimulated [³²P]GDP release by 12–22% (P < .05) and 7–14% in rat and human membranes, respectively. These results indicate that ligand binding to the insulin receptor results in a functional interaction of the receptor with a guanine nucleotide-binding transducer protein (G protein) and activation of GTP/GDP exchange.     

Stimulation of HeLa cell growth by physiological concentrations of 4-hydroxynonenal

The aim of this study was to analyze the growth response of HeLa cells over a prolonged period of time to a single exposure of physiological and supraphysiological concentrations of 4-hydroxynonenal (HNE), a peroxidation product of omega-6-polyunsaturated fatty acids. Furthermore, the growth modulating effect of serum factors, particularly albumin, on the growth pattern was examined. The effects of HNE on the growth rate and viability of the cells, as well as on the incorporation of labelled amino acids were monitored daily over a period of four days. Fetal calf serum not only had a growth stimualting effect but also modulated the action of HNE. In neither respect was albumin able to substitute for serum indicating that the influence of serum was not exerted via an albumin–HNE conjugate. HNE had a clear dose-dependent effect and a distinction could be made between a supraphysiological concentration (100 μM), which was primarily cytotoxic and a physiological range (below 10 μM) which showed growth modulatory effects. These effects consisted of a transient inhibition in the initial phase of the cell growth, which under optimal conditions (in presence of serum) was followed by a period of increased proliferation, compared to untreated control cultures, until confluence was attained. It is suggested that HNE is not only a toxic product of lipid peroxidation, but a physiological growth regulating factor as well.     

N-phenyl ureidobenzenesulfonates,a novel class of promising human dihydroorotate dehydrogenase inhibitors

N-phenyl ureidobenzenesulfonates (PUB-SOs) is a new class of promising anticancer agents inducing replication stresses and cell cycle arrest in S-phase. However, the pharmacological target of PUB-SOs was still unidentified. Consequently, the objective of the present study was to identify and confirm the pharmacological target of the prototypical PUB-SO named 2-ethylphenyl 4-(3-ethylureido)benzenesulfonate (SFOM-0046) leading to the cell cycle arrest in S-phase. The antiproliferative and the cytotoxic activities of SFOM-0046 were characterized using the NCI-60 screening program and its fingerprint was analyzed by COMPARE algorithm. Then, human dihydroorotate dehydrogenase (hDHODH) colorimetric assay, uridine rescuing cell proliferation and molecular docking in the brequinar-binding site were performed. As a result, SFOM-0046 exhibited a mean antiproliferative activity of 3.5 μM in the NCI-60 screening program and evidenced that leukemia and colon cancer cell panels were more sensitive to SFOM-0046. COMPARE algorithm showed that the SFOM-0046 cytotoxic profile is equivalent to the ones of brequinar and dichloroallyl lawsone, two inhibitors of hDHODH. SFOM-0046 inhibited the hDHODH in the low nanomolar range (IC₅₀ = 72 nM) and uridine rescued the cell proliferation of HT-29, HT-1080, M21 and MCF-7 cancer cell lines in the presence of SFOM-0046. Finally, molecular docking showed a binding pose of SFOM-0046 interacting with Met43 and Phe62 present in the brequinar-binding site. In conclusion, PUB-SOs and notably SFOM-0046 are new small molecules hDHODH inhibitors triggering replication stresses and S-phase arrest.     

Analysis of ECs and related compounds in plasma: artifactual isomerization and ex vivo enzymatic generation of 2-MGs

The analysis of peripheral endocannabinoids (ECs) is a good biomarker of the EC system. Their concentrations, from clinical studies, strongly depend on sample collection and time processing conditions taking place in clinical and laboratory settings. The analysis of 2-monoacylglycerols (MGs) (i.e., 2-arachidonoylglycerol or 2-oleoylglycerol) is a particularly challenging issue because of their ex vivo formation and chemical isomerization that occur after blood sample collection. We provide evidence that their ex vivo formation can be minimized by adding Orlistat, an enzymatic lipase inhibitor, to plasma. Taking into consideration the low cost of Orlistat, we recommend its addition to plasma collecting tubes while maintaining sample cold chain until storage. We have validated a method for the determination of the EC profile of a range of MGs and N-acylethanolamides in plasma that preserves the original isomer ratio of MGs. Nevertheless, the chemical isomerization of 2-MGs can only be avoided by an immediate processing and analysis of samples due to their instability during conservation. We believe that this new methodology can aid in the harmonization of the measurement of ECs and related compounds in clinical samples.     

Why did heterospory evolve?

The primitive land plant life cycle featured the production of spores of unimodal size, a condition called homospory. The evolution of bimodal size distributions with small male spores and large female spores, known as heterospory, was an innovation that occurred repeatedly in the history of land plants. The importance of desiccation‐resistant spores for colonization of the land is well known, but the adaptive value of heterospory has never been well established. It was an addition to a sexual life cycle that already involved male and female gametes. Its role as a precursor to the evolution of seeds has received much attention, but this is an evolutionary consequence of heterospory that cannot explain the transition from homospory to heterospory (and the lack of evolutionary reversal from heterospory to homospory). Enforced outcrossing of gametophytes has often been mentioned in connection to heterospory, but we review the shortcomings of this argument as an explanation of the selective advantage of heterospory. Few alternative arguments concerning the selective forces favouring heterospory have been proposed, a paucity of attention that is surprising given the importance of this innovation in land plant evolution. In this review we highlight two ideas that may lead us to a better understanding of why heterospory evolved. First, models of optimal resource allocation – an approach that has been used for decades in evolutionary ecology to help understand parental investment and other life‐history patterns – suggest that an evolutionary increase in spore size could reach a threshold at which small spores yielding small, sperm‐producing gametophytes would return greater fitness per unit of resource investment than would large spores and bisexual gametophytes. With the advent of such microspores, megaspores would evolve under frequency‐dependent selection. This argument can account for the appearance of heterospory in the Devonian, when increasingly tall and complex vegetative communities presented competitive conditions that made large spore size advantageous. Second, heterospory is analogous in many ways to anisogamy. Indeed, heterospory is a kind of re‐invention of anisogamy within the context of a sporophyte‐dominant land plant life cycle. The evolution of anisogamy has been the subject of important theoretical and empirical investigation. Recent work in this area suggests that mate‐encounter dynamics set up selective forces that can drive the evolution of anisogamy. We suggest that similar dispersal and mating dynamics could have underlain spore size differentiation. The two approaches offer predictions that are consistent with currently available data but could be tested far more thoroughly. We hope to re‐establish attention on this neglected aspect of plant evolutionary biology and suggest some paths for empirical investigation.     

A testis‐specific gene within a widely expressed gene: Contrasting evolutionary patterns of two differentially expressed mammalian proteins encoded by a single gene,CAMK4

Understanding the patterns of genetic variations within fertility‐related genes and the evolutionary forces that shape such variations is crucial in predicting the fitness landscapes of subsequent generations. This study reports distinct evolutionary features of two differentially expressed mammalian proteins [CaMKIV (Ca²⁺/calmodulin‐dependent protein kinase IV) and CaS (calspermin)] that are encoded by a single gene, CAMK4. The multifunctional CaMKIV, which is expressed in multiple tissues including testis and ovary, is evolving at a relatively low rate (0.46–0.64 × 10^?9 nucleotide substitutions/site/year), whereas the testis‐specific CaS gene, which is predominantly expressed in post‐meiotic cells, evolves at least three to four times faster (1.48–1.98 × 10^?9 substitutions/site/year). Concomitantly, maximum‐likelihood‐based selection analyses revealed that the ubiquitously expressed CaMKIV is constrained by intense purifying selection and, therefore, remained functionally highly conserved throughout the mammalian evolution, whereas the testis‐specific CaS gene is under strong positive selection. The substitution rates of different mammalian lineages within both genes are positively correlated with GC content, indicating the possible influence of GC‐biased gene conversion on the estimated substitution rates. The observation of such unusually high GC content of the CaS gene (≈74%), particularly in the lineage that comprises the bovine species, suggests the possible role of GC‐biased gene conversion in the evolution of CaS that mimics positive selection.