The Effects of a Third Generation Combined Oral Contraceptive Pill on the Classical Singing Voice

The success of professional operatic singers depends upon the quality of their vocal mechanism. This is known to be sensitive to changes in the endocrine environment. Despite a widespread belief among singers that vocal quality changes according to the stage of the menstrual cycle, this has received little attention. In particular, the possibility that use of the contraceptive pill might stabilize vocal quality by "dampening" hormonal fluctuations has not previously been studied systematically. Here, we show that drospirenone containing oral contraceptive pill (Yasmin, Schering AG, West Sussex, UK) with antiandrogenic and antimineralocorticoid properties demonstrates a significant reduction in the irregularity of the pattern of vibration of the vocal folds during the performance of highly trained classical singers. This study constitutes the first double blind, randomized placebo controlled trial to assess the effects of the contraceptive pill on the patterns of vibration of the vocal folds during the performance of Western classical singing repertoire.     

高效液相色谱法测定化妆品中5种性激素

应用高效液相色谱法测定化妆品中5种性激素的含量。化妆品样品以甲醇提取,采用Kromasil 100-5C18色谱柱为分离柱,以乙腈-水(65+35)溶液为流动相,在检测波长242nm和290nm处进行测定。5种性激素的质量浓度均在0.100~10.0mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.552~1.01 mg·kg-1之间,测定下限(10S/N)在1.10~5.04mg·kg-1之间。加标回收率在96.2%~110%之间,测定值的相对标准偏差(n=9)在均小于10%。     

Identification and composition of cuticular hydrocarbons of the major Afrotropical malaria vector Anopheles gambiae s.s. (Diptera: Culicidae): analysis of sexual dimorphism and age-related changes

Forty-eight cuticular hydrocarbons (CHCs) were characterized by gas chromatography-mass spectrometry from the epicuticular surface of the major Afrotropical malaria vector Anopheles gambiae. The hydrocarbons identified were 14 n-alkanes, 16 monomethyl alkanes, 13 dimethyl alkanes, 5 alkenes, with main-chain lengths ranging from C(17) to C(47), and the results are consistent with those from other Culicidae species. Qualitative differences were not observed between laboratory pools of three females and males, between different age-groups (0-16 days) and between single field specimens, whereas quantitative differences in CHC profiles were observed. Differences between sexes were more marked in individuals aged 0-2 days than in older ones. Both sexes undergo strong CHC profile changes with age, and individuals aged 0-2 days differ remarkably from the older ones. The possibility of exploiting these changes for estimating the age of mosquito was explored through multivariate analyses of the relative abundance of the compounds, using either the whole CHC profile or a subset of CHCs. Such a method allows us to assign more than 85% of females and 75% of males to the correct age-group. Although preliminary, these results show that the method is promising, as it has already been shown in Aedes aegypti and An. stephensi. The correct determination of the vector age (particularly in the case of the An. gambiae complex of sibling species) provides valuable information in malaria epidemiology and in evaluation of the effectiveness of vector control strategies. Further efforts will be made to validate this method on single specimens reared in seminatural conditions before being proposed to medical entomologists working in the Afrotropical region.     

Developmental gametophyte morphology of seven species of Thelypteris subg. Cyclosorus (Thelypteridaceae)

The morphogenesis of the sexual phase of seven species of Thelypteris subg. Cyclosorus (Thelypteridaceae) is described and compared. Spores of all species are monolete, ellipsoid and have positive photoblastism. They have Vittaria-type germination, germinal filaments are short and uniseriate, and Aspidium-type development. Adult gametophytes are spatulate-cordiform, and have wide wings with numerous glandular, marginal and superficial hairs. Antheridia have a narrow or widened basal cell, an undivided annular cell, and an opercular cell; antherozoids are liberated through three mechanisms. Archegonia have short necks and four triangular cells on the neck's mouth. The sporophyte's first leaf is lobed, with open dichotomous veins, glandular hairs similar to those of the gametophyte, and anomocytic stomata. Differences observed between the studied species are: spore size; ornamentation of the perispore; germination and emergence periods; size of hairs; developmental period of gametangia; and antherozoid liberation mechanisms through total detachment of the operculum, partial detachment of the operculum, and development of an apical pore through tearing of the operculum. These taxonomically valuable characters, combined with the sporophyte characteristics, can be useful tools in the identification of the species studied to the subg. Cyclosorus.     

Development,standardization and refinement of procedures for evaluating effects of endocrine active compounds on development and sexual differentiation of <Emphasis Type="Italic">Xenopus laevis</Emphasis>

Xenopus laevis has been introduced as a model to study effects of endocrine-active compounds (EAC) on development and sexual differentiation. However, variable and inconsistent data have raised questions about the reliability of the test methods applied. The current study was conducted in two laboratories to develop, refine, and standardize procedures and protocols. Larvae were exposed in flow-through systems to 17β-estradiol (E2), at concentrations from 0.2 to 6.0 μg E2 L⁻¹ in Experiment 1A, and 0.015 to 2.0 μg E2 L⁻¹ in Experiment 1B. In both studies survival (92%, 99%) and percentage of animals that completed metamorphosis (97%, 99%) indicated reproducible biological performance. Furthermore, minor variations in husbandry led to significant differences in snout-to-vent length, weight, and gonad size. In Experiment 1A, almost complete feminization occurred in all E2 treatment groups whereas a concentration response was observed in Experiment 1B resulting in an EC₅₀ of 0.12 μg E2 L⁻¹. The final verified protocol is suitable for determining effects of EAC on development and sexual differentiation in X. laevis.     

In situ study of calcite-III dimorphism using dynamic diamond anvil cell

The phase transitions among the high-pressure polymorphic forms of CaCO₃ (cc-I, cc-II, cc-III, and cc-IIIb) are investigated by dynamic diamond anvil cell (dDAC) and in situ Raman spectroscopy. Experiments are carried out at room temperature and high pressures up to 12.8 GPa with the pressurizing rate varying from 0.006 GPa/s to 0.056 GPa/s. In situ observation shows that with the increase of pressure, calcite transforms from cc-I to cc-II at ～ 1.5 GPa and from cc-II to cc-III at ～ 2.5 GPa, and transitions are independent of the pressurizing rate. Further, as the pressure continues to increase, the cc-IIIb begins to appear and coexists with cc-III within a pressure range that is inversely proportional to the pressurizing rate. At the pressurizing rates of 0.006, 0.012, 0.021, and 0.056 GPa/s, the coexistence pressure ranges of cc-III and cc-IIIb are 2.8 GPa-9.8 GPa, 3.1 GPa-6.9 GPa, 2.7 GPa-6.0 GPa, and 2.8 GPa-4.5 GPa, respectively. The dependence of the coexistence on the pressurizing rate may result from the influence of pressurizing rate on the activation process of transition by reducing the energy barrier. The higher the pressurizing rate, the lower the energy barrier is, and the easier it is to pull the system out of the coexistence state. The results of this in situ study provide new insights into the understanding of the phase transition of calcite.     

Structural dimorphism of N-(3-hydroxysalicylidene)-2,4,6-trimethylaniline

The title compound N-(3-hydroxysalicylidene)-2,4,6-trimethylaniline exhibits dimorphism. The structure of (I) is orthorhombic Pbca with a = 22.222(3), b = 16.200(2), c = 7.596(2) Å, V = 2735(1) ų, and Z = 8. The structure of (II) is monoclinic P2₁/c with a = 11.734(1), b = 15.734(1), c = 7.432(2) Å, = 100.97(1)°, V = 1347.0(5)ų, and Z = 4. The two structures are analyzed in relation with the possibility of an equilibrium between two tautomeric phenol and quinone forms by rapid hydrogen transfer. The molecules associated by intermolecular hydrogen bonds form centrosymmetric dimers. The compounds are thermochromic. The results are compared with the photochromic analog N-(hydroxysalicylidene)-2,4,6-trimethylaniline (compound III) and with the thermochromic one N-(5-hydroxysalicylidene)-2,4,6-trimethylaniline (compound IV). It is concluded that the 3-hydroxyl substituent of the salicylidene moiety enables the intermolecular hydrogen transfer from oxygen to nitrogen.     

The Reserve/Maximum Capacity of Melatonin’s Synthetic Function for the Potential Dimorphism of Melatonin Production and Its Biological Significance in Mammals

In this article, we attempt to classify a potential dimorphism of melatonin production. Thus, a new concept of “reserve or maximum capacity of melatonin synthetic function” is introduced to explain the subtle dimorphism of melatonin production in mammals. Considering ASMT/ASMTL genes in the pseudoautosomal region of sex chromosomes with high prevalence of mutation in males, as well as the sex bias of the mitochondria in which melatonin is synthesized, we hypothesize the existence of a dimorphism in melatonin production to favor females, which are assumed to possess a higher reserve capacity for melatonin synthesis than males. Under physiological conditions, this subtle dimorphism is masked by the fact that cells or tissues only need baseline melatonin production, which can be accomplished without exploiting the full potential of melatonin’s synthetic capacity. This capacity is believed to exceed the already remarkable nocturnal increase as observed within the circadian cycle. However, during aging or under stressful conditions, the reserve capacity of melatonin’s synthetic function is required to be activated to produce sufficiently high levels of melatonin for protective purposes. Females seem to possess a higher reserve/maximum capacity for producing more melatonin than males. Thus, this dimorphism of melatonin production becomes manifest and detectable under these conditions. The biological significance of the reserve/maximum capacity of melatonin’s synthetic function is to improve the recovery rate of organisms from injury, to increase resistance to pathogen infection, and even to enhance their chances of survival by maximizing melatonin production under stressful conditions. The higher reserve/maximum capacity of melatonin synthesis in females may also contribute to the dimorphism in longevity, favoring females in mammals.     

Electrochemical Portable Method for on site Screening of Scopolamine in Beverage and Urine Samples

Scopolamine (SCP) is a psychoactive drug often added to beverages for recreational or abuse purposes (loss of memory and non‐consensual practices). In this work, a simple and portable method for fast in field screening of SCP in beverage (beer, coke, energy drink, sugarcane spirit, vodka, and whisky) and urine samples is presented. The proposed method is based on batch injection analysis with square wave voltammetric (BIA‐SWV) detection using boron‐doped diamond (BDD) as the working electrode. A voltammetric profile with accurate information on the presence or absence of SCP is obtained using a small sample volume (～50 μL) and a simple sample pretreatment step (dilution in supporting electrolyte). Around two hundred analyses are possible using the proposed system (injection of single sample plug – 120 μL) without the need of electrodes handling or supporting electrolyte exchange (friendly to point‐of‐care or on site screenings). The quantification of SCP in beverages is also possible using the proposed portable protocol, with a limit of detection of 0.18 μmol L^?1 and recovery values between 87 to 113 %.