[Substitution of prenatal karyotyping with targeted QFPCR--cytogenetic residual risk assessment]. / Stanovení reziduálního cytogenetického rizika v prenatální diagnostice pri nahrazení tradicního karyotypování cílenými molekulárními testy urcenými k rychlé detekci aneuploidií--retrospektivní studie.

OBJECTIVE: Molecular techniques focused on detection of common aneuploidies--FISH and QFPCR--provide a quick result in prenatal diagnosis. There is a trend to apply these rapid tests as 'stand-alone' tests which would lead to substantial economical savings. The purpose of the retrospective study is to determine the frequency of chromosomal aberrations (CA) which would be missed by this tool in particular indication groups--residual cytogenetic risk. DESIGN: Retrospective study. SETTING: Department of Medical Genetics and Foetal Medicine University Hospital Olomouc. METHOD: 5305 prenatal samples were examined and the frequency of QFPCR undetected CA (structural and rare aneuploidies) was observed. RESULTS: The residual risk in patients referred for abnormal results of current prenatal screening programs for Down syndrome or for maternal age, without any ultrasound (US) pathological findings, was 0.9%. It was 6.9% in the group where US pathological findings or family history of CA were present. CONCLUSION: The rapid test can replace karyotyping if there is a risk for CA based exclusively on abnormal results of current screening programes for Down syndrome or age related risk, providing that US is normal.

Preparation and characterization of photoactive composite kaolinite/TiO(2).

Preparation of nanocomposite kaolinite/TiO(2), using hydrolysis of titanyl sulfate in the presence of kaolin was addressed. A variable (kaolin)/(titanyl sulfate) ratio has been used in order to achieve the desired TiO(2) content in prepared nanocomposites. Calcination of the composites at 600 °C led to the transformation of the kaolinite to metakaolinite and to origination of metakaolinite/TiO(2) composites. The prepared samples were investigated using X-ray fluorescence spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry and diffuse reflectance spectroscopy in the UV-VIS region. Structural ordering of TiO(2) on the kaolinite particle surface was modeled using empirical force field atomistic simulations in the Material Studio modeling environment. Photodegradation activity of the composites prepared was evaluated by the discoloration of Acid Orange 7 aqueous solution.

Fluorescence of reduced charge montmorillonite complexes with methylene blue: Experiments and molecular modeling.

The intensity of fluorescence of montmorillonites fully saturated by methylene blue (MB) is very poor due to energy dissipation in MB aggregates. A series of reduced charge montmorillonites (RCM) were prepared from Na-homoionic SWy and Ca homoionic SAz with the aim to decrease the MB aggregation. Fine tuning MB adsorption degree by charge reduction and MB concentration enabled controlled production of different dye species from aggregates via dimers to monomers. It was shown that the intensity of the fluorescence of low-loaded MB-RCM complexes is enhanced by several orders of magnitude with respect to dye-saturated original montmorillonites. XRD analyses, molecular modeling, and diffuse reflectance spectroscopy revealed that low MB-loaded RCMs are very probably adsorbed mainly on the external montmorillonite surface as isolated dye molecules. Such a state cannot be achieved in the solid state without very careful tailoring of the host-guest interaction.

Molecular modeling of layered double hydroxide intercalated with benzoate, modeling and experiment.

The structure of Zn4Al2 Layered Double Hydroxide intercalated with benzencarboxylate (C6H5COO-) was solved using molecular modeling combined with experiment (X-ray powder diffraction, IR spectroscopy, TG measurements). Molecular modeling revealed the arrangement of guest molecules, layer stacking, water content and water location in the interlayer space of the host structure. Molecular modeling using empirical force field was carried out in Cerius(2) modeling environment. Results of modeling were confronted with experiment that means comparing the calculated and measured diffraction pattern and comparing the calculated water content with the thermogravimetric value. Good agreement has been achieved between calculated and measured basal spacing: d(calc) = 15.3 A and d(exp) = 15.5 A. The number of water molecules per formula unit (6H2O per Zn4Al2(OH)12) obtained by modeling (i.e., corresponding to the energy minimum) agrees with the water content estimated by thermogravimetry. The long axis of guest molecules are almost perpendicular to the LDH layers, anchored to the host layers via COO- groups. Mutual orientation of benzoate ring planes in the interlayer space keeps the parquet arrangement. Water molecules are roughly arranged in planes adjacent to host layers together with COO- groups.

Composition, structure, and luminescence of montmorillonites saturated with different aggregates of methylene blue.

The distribution of various aggregates (dimers, trimers, and tetramers) of methylene blue (MB) formed in aqueous solution at various concentrations of dye has been calculated using the equilibrium aggregation constants betaq. Two montmorillonite samples with different cation exchange capacities, surface areas, and interlayer distances d001, Na-SWy, and Ca-Cheto, were saturated with methylene blue (MB) solutions with various ratios between monomers and higher aggregates of dye. The total amount of MB in the intercalated montmorillonite samples (MB-SWy and MB-Cheto) increases with increasing concentration of dye in water solutions, i.e., with increasing aggregates/monomers ratio of MB in water solution. In all intercalated montmorillonite samples with methylene blue except guest qth aggregate cations [MBqq+] low contents of Na+ (in MB-SWy) and Ca2+ (in MB-Cheto) cations were also determined. A very good positive correlation between the basal spacing d001 and the MB/montmorillonite molar ratio was revealed for saturated MB-montmorillonite samples. Structural analysis using a combination of diffraction data with molecular modeling revealed the differences in the interlayer arrangement of MB guests in MB-SWy and MB-Cheto intercalates. Also, fluorescence measurements showed the strong effect of the silicate layer charge on the spectroscopic behavior of MB guests intercalated in montmorillonite. Methylene blue exhibits a certain luminescence in MB-SWy samples with cation exchange capacity 0.80 meq g-1 and almost no luminescence in MB-Cheto samples with higher cation exchange capacity 1.50 meq g-1.

Structure of montmorillonite cointercalated with stearic acid and octadecylamine: modeling, diffraction, IR spectroscopy.

Structural analysis of Na-montmorillonite co-intercalated with octadecylamine and stearic acid was carried out using combination of experiment: X-ray powder diffraction and IR spectroscopy with molecular modeling (force field calculations) in Cerius(2) modeling environment. Results of structure analysis revealed the chemical reaction of guest compounds leading to the formation of octadecylammonium stearate. This reaction may occur even before the intercalation out of the interlayer space of montmorillonite. The presence of octadecylammonium stearate in the samples was clearly confirmed by IR spectroscopy and X-ray diffraction. Present results also showed that: (1) Stearic acid itself does not intercalate into Na-montmorillonite; (2) cointercalation with octadecylamine led to the formation of octadecylammonium stearate, which was successfully intercalated into the interlayer space of montmorillonite, and (3) Na-montmorillonite intercalated with octadecylammonium stearate does not create a stable structure. Intercalated samples in ambient conditions undergo gradual decomposition, accompanied by the release of octadecylammonium stearate from the interlayer space and rearrangement of the interlayer structure. Co-intercalation of STA and ODA to lower the octadecylamine content and consequently to suppress the unfavorable effect of amine groups on the polymer matrix in nanocomposite, was investigated.

Structure analysis of intercalated layer silicates: combination of molecular simulations and experiment.

Na(+)-montmorillonite type Wyoming, cloisite Na(+) from Southern Clay Products, Inc., was intercalated (i) with octadecylammonium cations and subsequently intercalated with octadecylamine molecules, (ii) with dodecylamine molecules, and (iii) with octylamine molecules to determine the applicability of these intercalates for nanocomposite materials on the base of polymer/clay. The structures were determined on the basis of a combination of results from X-ray diffraction and molecular simulations. The calculated values of basal spacings are in good agreement with experimental basal spacings when experimental samples were prepared. The interlayer space of intercalated montmorillonite shows a monolayer or bilayer arrangement of alkyl chains in dependence on the concentration of the intercalation solution. The values of the total sublimation energy, interaction energy, and exfoliation energy were calculated for all investigated samples. Low values of exfoliation energies lead to better exfoliation of intercalated silicate layers and this material appears suitable for use as a precursor for polymer/clay nanocomposites. The values of exfoliation energy for the investigated samples show that montmorillonite intercalated with dodecylamine or octadecylamine molecules is suitable for exfoliation of silicate layers.

The rhodamine B intercalation of montmorillonite.

Using photometric methods the dissociation constants and weight fractions of rhodamine B dimer in water solutions at different concentrations were determined. The montmorillonite (SWy) samples were fully intercalated with rhodamine B (RhB) solutions at various monomer/dimer ratios. The amount of rhodamine B in fully intercalated montmorillonite (RhB-SWy) increases with increasing concentration of dye in water solutions, i.e., with increasing dimer/monomer ratio. The sum of exchangeable guest cations in RhB-SWy is approximately constant (0.900 meq g(-1)) for all samples, because RhB-SWy samples with prevailing dye monomer also contain higher amounts of non-exchanged alkali elements. The experimental data are supported by calculated structure models that illustrate the changes in RhB-SWy structure depending on monomeric and/or dimeric arrangement of guests. The analysis of the calculated structure models confirmed the existence of two phases with different basal spacings, d approximately 1.8 and approximately 2.3 nm, revealed by X-ray diffraction.

[Importance of genetic testing in couples with reproductive disorders]. / Význam genetického vysetrení u páru s poruchami reprodukce.

OBJECTIVE: To determine the prevalence of chromosomal aberrations in infertile couples undergoing in vitro fertilization (IVF). DESIGN: Cytogenetic analysis of peripheral blood lymphocytes in the group of patients undergoing IVF. Detection of chromosomal aberrations in the fetuses after IVF. SETTING: Department of Medical Genetics and Fetal Medicine, Medical Faculty, Palacký University and the University Hospital, Olomouc. METHODS: Cultivation of peripheral blood lymphocytes or fibroblasts of amniotic fluid. Using fluorescent in situ hybridization in cases of mosaicism. RESULTS: Out of 638 patients undergoing treatment for male or female infertility, 595 had normal karyotype and 43 (6.8%) had abnormal karyotype. There were detected 9 (1.4%) cases of balanced chromosomal rearrangements, 2 (0.31%) cases of deletion of Y chromosome, 2 (0.31%) cases of inversion, 2 (0.31%) cases of marker chromosome, 5 (0.78%) cases of gonosomal aneuploidy (47,XXY) and 23 (3.65%) cases of gonosomal mosaicism--out of the 22 (3.5%) cases of low-level mosaicism. In the small group of pregnant patients after IVF investigated for the risk of genetic disorders included in our study (n = 60) the frequency of chromosomal abnormalities was 9 (15%). CONCLUSIONS: Our data show that a high number of infertile couples is affected by chromosomal aberrations which occur more frequently in females than in males. It is caused by high frequency of low-level gonosomal mosaicism in the group of infertile women. Chromosomal analyses are highly recommended before each IVF procedure.

[Microdeletion of the azoospermia factor as one of the causes of male infertility]. / Mikrodelece faktoru azoospermie jako jedna z prícin muzské infertility.

One of the possible causes of male infertility is microdeletion of the Y chromosome in the Yq11.23 region--named the azoospermia factor. These deletions are associated with azoospermia or severe oligozoospermia. In these cases, testicular histopathological findings comprise a wide spectrum, from total absence of germ cells, through arrest of their maturation to decreased sperm production. Most Y-chromosome microdeletions arise de novo but transmission from the father is also possible, either by the natural way or by assisted reproduction. In relation to the assisted reproduction, the relationship between the Y-deletions and presence of spermatozoa in testis, fertilization capability and embryo quality were examined. Heredity of the deleted Y chromosome is holandric and therefore all sons of males with deletions will carry the same defect and will probably have fertility problems. Another negative influence of deletions on a man's health has not yet been identified.

Molecular simulations of smectites intercalated with a zirconium complex ion.

Molecular mechanics simulations using the Cerius2 modeling environment have been applied to study the structures of dioctahedral smectites intercalated with the zirconium cation [Zr4(OH)12(H2O)12]4+. The substitutions in the silicate layers influence the sublimation energy in these types of intercalated layer structures. Charge distribution in the smectite layer was analyzed in relation to the interlayer structure. Tetrahedral substitutions in the smectite layer create preferential interlayer positions of the [Zr4(OH)12(H2O)12]4+ ion. A regular distribution of the tetrahedral substitutions in the smectite layer results in a better intercalant ordering in the interlayer space. Such a more homogeneous intercalant distribution results in a better interlayer pore size control.

Intercalation of octadecylamine into montmorillonite: molecular simulations and XRD analysis.

Intercalation of octadecylamine (ODAMIN) into Na montmorillonite based on the ion-dipole interaction was investigated using molecular mechanics and molecular dynamics simulations combined with X-ray powder diffraction. Molecular modeling revealed the interlayer structure of the ODAMIN-montmorillonite intercalate, the charge distribution on the host layer and guest species, and the energy characteristics, i.e., the total sublimation energy and it's individual contributions (electrostatic and Van der Waals). The present study showed the development of the interlayer structure, basal spacing, and exfoliation energy in dependence on the ODAMIN content.

Influence of aromatic sulfonation on the geometry of [2.2]paracyclophane: crystal structures of one sulfonate, one disulfonic anhydride and five disulfonimides.

The crystal structures of potassium [2.2]paracyclophane-4-sulfonate (1), [2.2]paracyclophane-4,15-disulfonic anhydride (2), [2.2]paracyclophane-4,15-disulfonimide (3), N-n-propyl-[2.2]paracyclophane-4,15-disulfonimide (4), N-isopropyl-[2.2]paracyclophane-4,15-disulfonimide (5), N-cyclopropyl-[2.2]paracyclophane-4,15-disulfonimide (6) and N-phenyl-[2.2]paracyclophane-4,15-disulfonimide (7) were established by single-crystal X-ray diffraction. The structural changes caused by sulfonation are discussed with respect to the parent [2.2]paracyclophane (tricyclo[8.2.2.2(4,7)]hexadeca-4,6,10,12,13,15-hexaene). The main features are a change in the non-bonding distances between the para-phenylene rings and a rotation of these rings with respect to the molecular symmetry plane. The rings are rotated away from each other in the case of monosulfonation (1), but are rotated in the opposite way in the case of the disulfonic anhydride (2) or the disulfonimide compounds (3)-(7). The results are also discussed in terms of the parameters proposed by Keehn [(1983), Organic Chemistry, A Series of Monographs 45, edited by P. H. Keehn & S. M. Rosenfeld, Vol. 1, pp. 69-238. New York: Academic Press] showing that (bonded and non-bonded) angles involving the para-phenylene rings are mainly affected.

Structure determination of two intercalated compounds VOPO4.(CH2)4O and VOPO4.OH-(CH2)2-O-(CH2)2-OH; synchrotron powder diffraction and molecular modelling.

The crystal structures of two intercalated compounds have been determined using a combination of synchrotron powder diffraction and molecular mechanics simulations: (1) vanadyl phosphate intercalated with tetrahydrofuran, VOPO(4).(CH(2))(4)O, and (2) vanadyl phosphate intercalated with diethylene glycol, VOPO(4).HO(CH(2))(2)O(CH(2))(2)OH. Both intercalates preserve the tetragonal space group P4/n, as found in the host structure VOPO(4).2H(2)O. (1): a = 6.208, c = 8.930 A, Z = 2, D(x) = 2.51 g cm(-3); (2): a = 6.223, c = 11.417 A, Z = 2, D(x) = 2.66 g cm(-3). Both intercalates exhibit the same type of orientational disorder in the arrangement of guest molecules, as observed in the same host compound intercalated with water. These two intercalates also exhibit, rather surprisingly, perfect ordering in layer stacking without the displacement disorder, characteristic of many intercalated layered structures. Thanks to this regularity in the arrangement of guests and layers, synchrotron powder diffraction could be used in the present structure determination. The present results also enabled the analysis of the effect of geometrical parameters characterizing the mutual host-guest complementarity and the effect of host-guest and guest-guest interaction on the crystal packing of intercalates.

[Early fetal karyotyping and its role in prenatal diagnosis]. / Vcasná karyotypizace fetu a její prínos pro prenatální diagnostiku.

OBJECTIVE: Shift of indicated invasive examination in prenatal diagnostics towards the earlier phases of pregnancy with preservation of quality of cytogenetic detection. DESIGN: Cytogenetic and molecular-cytogenetic analysis of the chorionic villi after long term culture. SETTING: Department of Medical Genetics and Foetal Medicine, Faculty of Medicine, Palacky University Olomouc, Faculty Hospital in Olomouc. METHODS: Cultivation of fibroblasts developing from chorionic villi after enzymatic or mechanical disintegration and their karyotyping. Using fluorescent in situ hybridisation to identify the most common chromosomal aneuploidies and to determine gonosomes in indicated cases. RESULTS: Testing and optimisation of long term culture method and its routine use. Method was utilised so far in 12 patients and successfulness was 83%. Additional fluorescent in situ hybridisation was performed in 6 cases. CONCLUSION: Using long term culture method of chorionic villi as reliable and routine tool in prenatal diagnostics.

[The importance of ultrasonography in the 1st and 2nd trimester of pregnancy in prenatal diagnosis of chromosome aberrations]. / Význam ultrazvuku v I. a II. trimestru gravidity pro prenatální diagnostiku chromosomálních aberací.

Indications for examination of the foetal karyotype on the basis of ultrasonic atypies or detection of specific US minor-markers is an important screening method for prenatal detection of chromosomal aneuploidies of the foetus. It is associated with possible detailed evaluation of certain factors by more perfect ultrasonographic equipment. In the group investigated by the authors this indication was of greatest importance for detection of chromosomal aneuploidies in-8.52%. Isada et al. [18] reports 16%; Donner et al. [11] found chromosomal aberrations in 9.5% abnormal sonograms. The highest sensitivity is obtained by assessment of the "nuchal translucency" (NT) which can be investigated during the first and second trimester of pregnancy. In the author's group it was recorded in 47% foetuses with Down's syndrome. Risk assessment of chromosomal trisomies based on the assessed NT during the first trimester was done by means of the Fetal Database programme. The assessment calls for special training. A reduced length of the femur is a significant marker of chromosomal aberrations if the disproportion with BPD between the 15th and 22nd week of gestation is 10 days or more. The importance of other ultrasonographic markers such as a reduced femur, hyperechogenity of the gut, pyelectasia etc. requires further studies. In the author's investigation the risk of chromosomal aberrations increases significantly only after detection of two or more of these atypical features. Chorionic and amniotic atypies in the first trimester and placental dysmorphias (partial moles) in the second trimester of gestation are frequently associated with chromosomal triploidy. The prenatal diagnosis of these abnormalities is possible by the vaginal and transabdominal route. It calls for considerable enlargement of the picture similarly as investigations of "NT".