聚焦抑郁症治疗药物

抗抑郁药市场潜藏着巨大商机。全世界约有3.5 亿人患有抑郁症,该疾病为全球范围内致残的第一大诱因。在美国,9.1% 的人患有抑郁症。在世界范围内,接受抑郁症治疗的患者不到实际患病人数的一半,在一些国家甚至还不到十分之一。较高的发病率,再加上较低的市场渗透率,抗抑郁药市场的前景非常广阔。但开发抗抑郁药的公司同样面临许多挑战。心理治疗仍然是优于药物治疗的一线疗法。在药物治疗方面,近年来大量上市的仿制药使品牌抗抑郁药的市场价值缩水一半。由于儿童、青少年和青壮年用药患者的自杀率有所增加,现在要求所有抗抑郁药必须在说明书中加入黑框警告,这直接影响了药物在这些人群中的使用,成为抗抑郁新药面临的又一困难。许多患者在开始接受治疗的第一年内都会更换最初使用的药物,这对于药企而言,既是机遇也是挑战。目前抑郁症的发病机制尚未充分阐明,虽然这有利于开发具有全新作用机制的新药,但也使该治疗领域面临重重困难。     

Thermodynamics of ribonuclease T1 denaturation.

Differential scanning calorimetry has been used to investigate the thermodynamics of denaturation of ribonuclease T1 as a function of pH over the pH range 2-10, and as a function of NaCl and MgCl2 concentration. At pH 7 in 30 mM PIPES buffer, the thermodynamic parameters are as follows: melting temperature, T1/2 = 48.9 +/- 0.1 degrees C; enthalpy change, delta H = 95.5 +/- 0.9 kcal mol-1; heat capacity change, delta Cp = 1.59 kcal mol-1 K-1; free energy change at 25 degrees C, delta G degrees (25 degrees C) = 5.6 kcal mol-1. Both T1/2 = 56.5 degrees C and delta H = 106.1 kcal mol-1 are maximal near pH 5. The conformational stability of ribonuclease T1 is increased by 3.0 kcal/mol in the presence of 0.6 M NaCl or 0.3 M MgCl2. This stabilization results mainly from the preferential binding of cations to the folded conformation of the protein. The estimates of the conformational stability of ribonuclease T1 from differential scanning calorimetry are shown to be in remarkably good agreement with estimates derived from an analysis of urea denaturation curves.     

Magnetic-circular-dichroism studies of haem a and its derivatives.

1. The Thy-1 membrane glycoproteins from rat thymus and brain bound deoxycholate to 24% of their own weight as measured by equilibrium dialysis. The binding occurred co-operatively at the critical micelle concentration of deoxycholate, suggesting that the glycoproteins bind to a micelle, and not to the detergent monomer. 2. From sedimentation-equilibrium and deoxycholate-binding data the molecular weights of the glycoprotein monomers were calculated to be 18700 and 17500 for thymus and brain Thy-1 glycoprotein monomers were calculated to be 18700 and 17500 for thymus and brain Thy-1 glycoproteins respectively. The molecular weight of the polypeptide part of the glycoprotein is thus 12500. 3. In the absence of deoxycholate, brain or thymus Thy-1 glycoprotein formed large homogeneous complexes of mol. wt. 270000 or 300000 respectively. The sedimentation coefficient of these was 12.8 S. The complex was only partially dissociated by 4M-guanidinium chloride. 4. After cleavage of brain or thymus Thy-1 glycoprotein with CNBr, two peptides were clearly identified. They were linked by disulphide bonds and both contained carbohydrate. This cleavage suggests there is only one methionine residue per molecule, which is consistent with the above molecular weights and the known amino acid composition.     

Seasonal variation in hydrochloric acid, malic acid, and calciumions secreted by the trichomes of chickpea (Cicer arietinum)

A novel experimental set-up and method of recording of electrical potential differences in plants have been developed which enable continuous, 8-channel monitoring of electrical activity over extended periods of time using inserted, extracellular electrodes. The investigations were carried out on 21- to 23-day-old Helianthus annuus plants, and spontaneously-generated action potentials were recorded during monitoring sessions lasting for 3 days and nights. Characteristics of these spontaneous action potentials were elaborated, adopting as parameters their typical form, amplitude, duration, velocity, direction, and distance of propagation and frequency of occurrence in morphologically different parts of the plant, Variability, similarities, and interdependence of the above parameters in individual plants and in a group of 15 plants were determined. A hypothesis concerning propagation of action potentials in plants along specific impulse-propagating 'columns' is discussed. The frequency of generated impulses is highest at night and lowest in the day and also displays an apparent 24-h rhythm. Presumably this mechanism is under both endogenous and exogenous control and may be partly dependent on a biological clock.     

Differential Effector Engagement by Oncogenic KRAS

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Feeding rats a diet enriched with saturated fatty acids prevents the inhibitory effects of acute and chronic ethanol exposure on the in vitro uptake of hexoses and lipids

Chow-fed rats were given 15% ethanol in their drinking water for 4 weeks, and then for the next 2 weeks of ethanol exposure they were fed isocaloric semisynthetic diets enriched in either saturated (S) or polyunsaturated (P, linoleic acid) fats. Food intake was lower in ethanol-fed (ETH) than in control (C) rats, but the average body weight gain was similar in ETH and C fed S or P. Intestinal dry weight and the percentage of the intestinal wall comprised of mucosa were more than 2-fold higher in ETH than C fed P, whereas these values were 50% lower in ETH than C fed S. The in vitro jejunal uptake of glucose and galactose was higher in ETH than C fed S, whereas the converse was true when feeding P. These effects were due to differences in the values of the maximal transport rate (Vmax), the Michaelis constant (Km), and the contribution of passive permeation. The relative permeability of the intestine to lipids was unchanged by giving ethanol or by feeding S or P, but the individual rates of uptake of most medium- and long-chain fatty acids and cholesterol were lower in ETH fed P as compared with S. In a second series of studies the acute effect of ethanol exposure was examined: animals were fed S or P for 2 weeks and the intestine was then removed: when 5% ethanol was added directly to the test solutions, there was lower in vitro jejunal and ileal uptake of glucose and higher jejunal uptake of 18:2 when rats were previously fed P, but not in those fed S. In summary; (1) feeding an isocaloric polyunsaturated fatty acid diet has a trophic effect on the intestinal mucosa of animals chronically drinking ethanol; and (2) feeding rats a diet enriched with saturated fatty acids prevents the inhibitory effects of acute and chronic ethanol exposure on the in vitro jejunal uptake of glucose, galactose and lipids observed in animals fed a polyunsaturated diet. Thus, the effect of chronic consumption of ethanol on the active and passive jejunal uptake of nutrients is influenced by the type of lipids in the animal's diet.     

A primary assembly of a bovine haplotype block map based on a 15,036-single-nucleotide polymorphism panel genotyped in holstein-friesian cattle

Analysis of data on 1000 Holstein-Friesian bulls genotyped for 15,036 single-nucleotide polymorphisms (SNPs) has enabled genomewide identification of haplotype blocks and tag SNPs. A final subset of 9195 SNPs in Hardy-Weinberg equilibrium and mapped on autosomes on the bovine sequence assembly (release Btau 3.1) was used in this study. The average intermarker spacing was 251.8 kb. The average minor allele frequency (MAF) was 0.29 (0.05-0.5). Following recent precedents in human HapMap studies, a haplotype block was defined where 95% of combinations of SNPs within a region are in very high linkage disequilibrium. A total of 727 haplotype blocks consisting of > or =3 SNPs were identified. The average block length was 69.7 +/- 7.7 kb, which is approximately 5-10 times larger than in humans. These blocks comprised a total of 2964 SNPs and covered 50,638 kb of the sequence map, which constitutes 2.18% of the length of all autosomes. A set of tag SNPs, which will be useful for further fine-mapping studies, has been identified. Overall, the results suggest that as many as 75,000-100,000 tag SNPs would be needed to track all important haplotype blocks in the bovine genome. This would require approximately 250,000 SNPs in the discovery phase.     

Cloning, nucleotide sequencing, and expression of tetanus toxin fragment C in Escherichia coli.

The amino acid sequence of the first 30 residues of fragment C of tetanus toxin was determined, and a mixture of 32 complementary oligonucleotides, each 17 bases long, was synthesized. A 2-kilobase (kb) EcoI fragment of Clostridium tetani DNA was identified by Southern blotting and was cloned into the Escherichia coli plasmid vector pAT153 with the 32P-labeled oligonucleotide mixture as a probe. A second 3.2-kb Bg/II fragment was identified and cloned with the 2-kb EcoRI fragment as a probe. The nucleotide sequence of 1.8 kb of this DNA was determined and was shown to encode the entire fragment C and a portion of fragment B of tetanus toxin. The tetanus DNA was expressed in E. coli with pWRL507, a plasmid vector containing the trp promoter and a portion of the trpE gene. The trpE-tetanus fusion proteins were visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and were shown to react with anti-fragment C antibody.     

Effects of sieving, drying and rewetting upon soil bacterial community structure and respiration rates

Soil microcosm studies often require some form of soil homogenisation, such as sieving, to provide a representative sample. Frequently, soils are also homogenised following drying and are then rewetted, yet little research has been done to understand how these methods impact upon microbial communities. Here we compared the molecular diversity and functional responses of intact cores from a Scottish grassland soil with homogenised samples prepared by drying, sieving and rewetting or freshly sieving wet soils. Results showed that there was no significant difference in total soil CO₂-C efflux between the freshly sieved and intact core treatments, however, respiration was significantly higher in the dried and rewetted microcosms. Molecular fingerprinting (T-RFLP) of bacterial communities at two different time-points showed that both homogenisation methods significantly altered bacterial community structure with the largest differences being observed after drying and rewetting. Assessments of responsive taxa in each treatment showed that intact cores were dominated by Acidobacterial peaks whereas an increased relative abundance of Alphaproteobacterial terminal restriction fragments were apparent in both homogenised treatments. However, the shift in community structure was not as large in the freshly sieved soil. Our findings suggest that if soil homogenisation must be performed, then fresh sieving of wet soil is preferable to drying and rewetting in approximating the bacterial diversity and functioning of intact cores.