Determination of amino acids in saliva using capillary electrophoresis with fluorimetric detection

In the present study a sensitive method for the quantification of main free amino acids in saliva using capillary electrophoresis with laser induced fluorescence detection was developed. As background electrolyte 20 mM borate buffer pH 9.5 was used. Amino acids were separated after derivatization were optimized. The main amino acids occurring in saliva (Pro, Ser, Gly and Glu) were separated in less than 7 min. The parameters of validation such as linearity of response, precision and detection limits were determined. The detection limits were obtained in the range from 0.1 to 2.4 nM. The developed method was employed for determination of amino acids in real saliva samples.     

Novel DNA-binding element within the C-terminal extension of the nuclear receptor DNA-binding domain

The heterodimer of the ecdysone receptor (EcR) and ultraspiracle (Usp), members of the nuclear receptors superfamily, is considered as the functional receptor for ecdysteroids initiating molting and metamorphosis in insects. Here we report the 1.95Å structure of the complex formed by the DNA-binding domains (DBDs) the EcR and the Usp, bound to the natural pseudopalindromic response element. Comparison of the structure with that obtained previously, using an idealized response element, shows how the EcRDBD, which has been previously reported to possess extraordinary flexibility, accommodates DNA-induced structural changes. Part of the C-terminal extension (CTE) of the EcRDBD folds into an α-helix whose location in the minor groove does not match any of the locations previously observed for nuclear receptors. Mutational analyses suggest that the α-helix is a component of EcR-box, a novel element indispensable for DNA-binding and located within the nuclear receptor CTE. This element seems to be a general feature of all known EcRs.     

Triadin is a critical determinant of cellular Ca cycling and contractility in the heart

Triadin is involved in the regulation of cardiac excitation-contraction coupling. However, the extent of its contribution to the regulation of sarcoplasmic reticulum (SR) Ca release remains unclear, because overexpression of triadin in single-transgenic mice was associated with the downregulation of its homologous protein, junctin. In the present study, this problem was circumvented by cross-breeding of mice with heart-directed overexpression of triadin and junctin (JxT). This resulted in a stable approximately threefold expression of total triadin but unchanged junctin protein. Transgenic mice exhibited cardiac hypertrophy and structural abnormalities of myofibrils. Measurement of cardiac function by echocardiography and edge detection in myocytes revealed an impaired relaxation in JxT mice. The stimulation of beta-adrenergic receptors resulted in a depressed contractility and an impaired relaxation in catheterized hearts and myocytes of JxT mice. The use of a maximum stimulation frequency (5 Hz) was associated with both a lower shortening and relengthening in isolated myocytes of JxT mice. The contractile effects in JxT myocytes were paralleled by similar changes of the intracellular Ca concentration ([Ca](i)) peak amplitude and Ca transient decay kinetics at basal conditions, under administration of isoproterenol, and with high-frequency stimulation. Finally, we found a higher caffeine-induced [Ca](i) peak amplitude in JxT myocytes. Our data show that the stable expression of triadin, independent of junctin expression, resulted in cardiac hypertrophy, prolonged basal relaxation, a depressed response to beta-adrenergic agonists, and altered Ca transients. Thus the maintenance of triadin expression is essential for normal SR Ca cycling and contractile function.     

Specific Bacillus anthracis identification by a plcR-targeted restriction site insertion-PCR (RSI-PCR) assay

A RSI-PCR assay was developed for the detection of a Bacillus anthracis-specific nonsense mutation in the plcR gene. The assay specificity was tested using 170 Bacillus spp. strains including 47 strains of B. anthracis. The plcR RSI-PCR distinguished Bacillus cereus group strains closely related to B. anthracis from the anthrax agent. The assay was found to be a robust, simple and cost effective tool for B. anthracis identification. In contrast to previously developed real time PCR-based methods, the RSI-PCR needs basic molecular biology equipment only, and thus may be easily introduced in developing countries, where anthrax is endemic.     

Some problems with testosterone determination

Testosterone is the main male sex hormone which determination is useful for assessment of androgen status. It seems that serum levels of testosterone, when assayed by commonly used methods, do not correlate with clinical parameters. One of the causes may be that these assays are suitable for determination of total testosterone, but not for measurement of biologically active forms of this hormone. The aim of this review is to present usefulness of testosterone measurement and its bioactive forms determination as well as factors influencing on their levels.     

Features of impaired seminiferous tubule differentiation are associated with germ cell neoplasia in adult men surgically treated in childhood because of cryptorchidism

Seminiferous tubule differentiation was related to the occurrence of germ cell neoplasia in 38 men, aged 17-47, treated surgically in childhood for cryptorchidism. Tissues from 46 testes obtained from biopsies taken as a neoplastic preventive procedure or whole testes removed because of GCT were evaluated quantitatively. Paraffin sections were treated with antibodies against placental like alkaline phosphatase (PLAP), a marker of germ cell neoplasia, and cytokeratin 18 (CK-18), a marker of immature Sertoli cells. Quality of spermatogenesis and number Leydig cells were assessed with a score count. Seminiferous tubules diameter, thickness of basal membrane and size of intertubular spaces were measured with image analysis software. In 17.4% of testes spermatogenesis was normal (9.9 points) (N) and neoplasia was not found there. In the other 38 specimens (83%) spermatogenesis was abnormal (A). When spermatogenesis was arrested or when germ cells were absent (3.7+/-1.8 points), neoplastic lesions were found in 13.1% of the specimens. In A group 5.1+/-7.1% of tubules contained immature Sertoli cells, while in N they were not found. Tubular diameter was significantly lower in A (161.5+/-31.8 microm) than in N (184.6+/-24.3 microm) and the percentage of seminiferous tubules with the thickening of tubular basal membrane was also greater in A. Intertubular spaces were significantly larger in A (49.9+/-18.6%) in comparison to N group (32.6+/-12.5%). Mean number of Leydig cells was similar in both groups. To conclude, in most of the formerly cryptorchid testes, despite surgical treatment, impaired seminiferous tubules differentiation is predominant. Germ cell neoplasia is present in testes with retarded seminiferous tubules differentiation. Retardation of seminiferous tubule differentiation consists of inhibited spermatogenesis, presence of tubules with immature Sertoli cells, decreased tubular diameter, increased thickness of basal membrane and enlarged intertubular spaces. Examination of testicular biopsy with respect to the state of seminiferous tubule differentiation may be helpful to predict the appearance of germ cell neoplasia in adult men with cryptorchidism in anamnesis. Orchiopexy of cryptorchid testes may not prevent the occurrence of features of testicular dysgenesis and the associated germ cell neoplasia.     

The differences in RCAS1 and DFF45 endometrial expression between late proliferative, early secretory, and mid-secretory cycle phases

RCAS1 expression is related to the regulation of activated immune cells and to connective tissue remodeling within the endometrium. DFF45 seems to play an important role in the apoptotic process, most likely by acting through the regulation of DNA fragmentation. Its expression changes within the endometrium seem to be related to the resistance of endometrial cells to apoptosis. The aim of the present study was to evaluate RCAS1 and DFF45 endometrial expressions during ovulation and the implantation period. RCAS1 and DFF45 expression was assessed by the Western-blot method in endometrial tissue samples obtained from 20 patients. The tissue samples were classified according to the menstrual cycle phases in which they were collected, with a division into three phases: late proliferative, early secretory, and mid-secretory. The lowest level of RCAS1 and the highest level of DFF45 endometrial expression was found during the early secretory cycle phase. Statistically significantly higher RCAS1 and statistically significantly lower DFF45 endometrial expression was identified in the endometrium during the late proliferative as compared to the early secretory cycle phase. Moreover, statistically significantly higher RCAS1 and statistically significantly lower DFF45 expression was found in the endometrium during the mid-secretory as compared to the early secretory cycle phase. The preparation for implantation process in the endometrium is preceded by dynamic changes in endometrial ECM and results from the proper interaction between endometrial and immune cells. The course of this process is conditioned by the immunomodulating activity of endometrial cells and their resistance to immune-mediated apoptosis. These dynamic changes are closely related to RCAS1 and DFF45 expression alterations.     

Algorithmic approaches to selecting control clones in DNA array hybridization experiments

We study the problem of selecting control clones in DNA array hybridization experiments. The problem arises in the OFRG method for analyzing microbial communities. The OFRG method performs classification of rRNA gene clones using binary fingerprints created from a series of hybridization experiments, where each experiment consists of hybridizing a collection of arrayed clones with a single oligonucleotide probe. This experiment produces analog signals, one for each clone, which then need to be classified, that is, converted into binary values 1 and 0 that represent hybridization and non-hybridization events. In addition to the sample rRNA gene clones, the array contains a number of control clones needed to calibrate the classification procedure of the hybridization signals. These control clones must be selected with care to optimize the classification process. We formulate this as a combinatorial optimization problem called Balanced Covering. We prove that the problem is NP-hard, and we show some results on hardness of approximation. We propose approximation algorithms based on randomized rounding, and we show that, with high probability, our algorithms approximate well the optimum solution. The experimental results confirm that the algorithms find high quality control clones. The algorithms have been implemented and are publicly available as part of the software package called CloneTools.     

Analysis of the role of the Rac/Cdc42 GTPases during planar cell polarity generation in Drosophila

Initial genetic studies in Drosophila suggested that several members of the Rho subfamily (RhoA, Rac1 and Cdc42) are involved in planar cell polarity (PCP) establishment. However, analyses of Rac1, Rac2 and Mtl loss-of-function (LOF) mutants have argued against their role in this process. Here, we investigate in detail the role of the Rho GTPases Mtl, Cdc42, Rac1 and Rac2 in PCP generation. These functional analyses were performed by overexpressing Mtl in eyes and wings, by performing genetic interaction assays and by using a combination of triple and quadruple mutant LOF clones. We found that Mtl overexpression caused PCP phenotypes and that it interacted genetically with other Rho GTPases, such as Rac1 and Cdc42 as well as with several PCP genes, such as stbm, pk and aos. However, Mtl was not found to interact with Rac2, RhoA and other members of the Fz/PCP pathway. Triple mutant clones of Rac1, Rac2 and Mtl were found to exhibit mild PCP defects which were enhanced by reduction of Cdc42 function with a hypomorphic Cdc42 allele. Taken together, these and previous results suggest that Rho GTPases may have partially overlapping functions during PCP generation. Alternatively, it is also possible that the mild PCP phenotypes observed could indicate that they are required at low levels in that process. However, since not all of them function upstream of a JNK cassette, we propose that they may act in at least two parallel pathways.