Pertinent parameters in photo-generation of electrons: Comparative study of anatase-based nano-TiO2 suspensions.

In the field of solar fuel cells, the development of efficient photo-converting semiconductors remains a major challenge. A rational analysis of experimental photocatalytic results obtained with material in colloïdal suspensions is needed to access fundamental knowledge required to improve the design and properties of new materials. In this study, a simple system electron donor/nano-TiO2 is considered and examined via spin scavenging electron paramagnetic resonance as well as a panel of analytical techniques (composition, optical spectroscopy and dynamic light scattering) for selected type of nano-TiO2. Independent variables (pH, electron donor concentration and TiO2 amount) have been varied and interdependent variables (aggregate size, aggregate surface vs. volume and acid/base groups distribution) are discussed. This work shows that reliable understanding involves thoughtful combination of interdependent parameters, whereas the specific surface area seems not a pertinent parameter. The conclusion emphasizes the difficulty to identify the key features of the mechanisms governing photocatalytic properties in nano-TiO2.

The need for epididymovasostomy at vasectomy reversal plateaus in older vasectomies: a study of 1229 cases.

Vasectomy reversal involves either vasovasostomy (VV) or epididymovasostomy (EV), and rates of epididymal obstruction and EV increase with time after vasectomy. However, as older vasectomies may not require EV for successful reversal, we hypothesized that sperm production falls after vasectomy and can protect the system from epididymal blowout. Our objective was to define how the need for EV at reversal changes with time after vasectomy through a retrospective review of consecutive reversals performed by three surgeons over a 10-year period. Vasovasotomy was performed with Silber score 1-3 vasal fluid. EVs were performed with Silber score 4 (sperm fragments; creamy fluid) or 5 (sperm absence) fluid. Reversal procedure type was correlated with vasectomy and patient age. Post-operative patency rates, total spermatozoa and motile sperm counts in younger (<15 years) and older (>15 years) vasectomies were assessed. Simple descriptive statistics determined outcome relevance. Among 1229 patients, 406 had either unilateral (n = 252) or bilateral EV's (n = 154) constituting 33% (406/1229) of reversals. Mean patient age was 41.4±7 years (range 22-72). Median vasectomy interval was 10 years (range 1-38). Overall sperm patency rate after reversal was 84%. The rate of unilateral (EV/VV) or bilateral EV increased linearly in vasectomy intervals of 1-22 years at 3% per year, but plateaued at 72% in vasectomy intervals of 24-38 years. Sperm counts were maintained with increasing time after vasectomy, but motile sperm counts decreased significantly (p < 0.001). Pregnancy, secondary azoospermia, varicocoele and sperm granuloma were not assessed. In conclusion, and contrary to conventional thinking, the need for EV at reversal increases with time after vasectomy, but this relationship is not linear. EV rates plateau 22 years after vasectomy, suggesting that protective mechanisms ameliorate epididymal 'blowout'. Upon reversal, sperm output is maintained with time after vasectomy, but motile sperm counts decrease linearly, suggesting epididymal dysfunction influences semen quality after reversal.

High-temperature ferromagnetism in Co-doped CeO2 synthesized by the coprecipitation technique.

The aim of the present study is to check the influence of annealing under vacuum and a mixture of N(2)-H(2) atmosphere on the magnetic properties of polycrystalline Co-doped CeO(2) diluted magnetic oxides (DMOs) with Co concentrations of 5 at% synthesized using the coprecipitation technique. X-Ray diffraction (XRD) patterns and transmission electron microscopy (TEM) showed for all samples the expected CeO(2) cubic fluorite-type structure and that Co ions are uniformly distributed inside the samples. Room-temperature Raman and photoluminescence (PL) spectroscopies indicate an increase in the concentration of oxygen vacancies upon Co doping and further annealing. Field dependent magnetization measurements revealed a paramagnetic behavior for as-prepared Co-doped CeO(2), while a ferromagnetic behavior appears when the same samples are annealed under vacuum or N(2)-H(2) atmosphere. Temperature dependent magnetization measurements suggest that the observed ferromagnetism is due to the presence of metallic Co clusters with nanometric size and broad size distribution. These results are supported by electron paramagnetic resonance studies.

Costs related to medical treatment for common cardiovascular risk factors.

AIM: The aim of this study was to evaluate the direct and indirect costs of selected cardiovascular diseases, namely hypertension (HT), metabolic syndrome (MS) and diabetes mellitus (DM) in the Slovak Republic. METHODS AND RESULTS: This study analyzes the data of 1,000 patients, randomly selected from NEMESYS database (10,300 patients). Average direct pharmacotherapeutic costs of hypertension per year were 257 Euros in men and 264 Euros in women. Costs of metabolic syndrome were 334 Euros in men and 321 Euros in women. Finally, the costs of diabetes mellitus were 392 Euros in men and 384 Euros in women. The most expensive pharmacotherapy was used in patients with a combination of all three diagnoses (HT+MS+DM), namely 452 Euros in men and 455 Euros in women. Indirect costs represent an even more serious financial burden. The highest indirect costs were in patients with diabetes mellitus, namely 5,227 Euros in men and 5,365 Euros in women. CONCLUSIONS: The study proved the assumption of increasing the direct pharmacotherapeutic costs in correlation with the increased severity of disease. The gender differences on the other hand, were smaller in patients with more serious conditions. The indirect costs represented the greatest financial burden, and were 13 to 17 times higher than the direct pharmacotherapeutic costs (Tab. 4, Ref. 17).

Analysis of spermatogenesis in non-obstructive azoospermic and virtually azoospermic men with known testicular pathology.

It is widely thought that human testicles affected by unilateral pathology will have greater impairment of spermatogenesis than the otherwise unaffected testis. This study reviewed records of non-obstructive azoospermic (NOA) and virtually azoospermic (NOVA) men with associated testicular pathology who underwent testicular fine needle aspiration (FNA) mapping. Concentration of spermatozoa found in each testis was analysed to discern sperm-lateralization patterns in affected and unaffected testes. A total of 1098 FNA sites from 56 men (32 varicocele, 16 cryptorchidism, three epididymo-orchitis, two mumps orchitis, three torsion) were analysed. Overall, 38 patients (68%) had spermatozoa detected in at least one testis. Most men (68%) had equal proportions of FNA sites showing spermatozoa from both testes, 29% had more spermatozoa from the unaffected testis and 3% had more spermatozoa from the affected testis. Significantly fewer sperm-positive sites were observed on the affected (272 out of 752) than unaffected side (164 out of 346) (P < 0.0001, chi-squared test). When assessed by FNA mapping, most NOA and NOVA men with known unilateral testis pathology will have equal proportions of spermatozoa in both testes. However, when sperm production differs between sides, the unaffected side is much more likely to have spermatozoa. This information may be used to refine sperm-retrieval strategies in selected patients.

Reduced meiotic recombination on the XY bivalent is correlated with an increased incidence of sex chromosome aneuploidy in men with non-obstructive azoospermia.

Both aberrant meiotic recombination and an increased frequency of sperm aneuploidy have been observed in infertile men. However, this association has not been demonstrated within individual men. The purpose of this study was to determine the association between the frequency of recombination observed in pachytene spermatocytes and the frequency of aneuploidy in sperm from the same infertile men. Testicular tissue from seven men with non-obstructive azoospermia (NOA) and six men undergoing vasectomy reversal (controls) underwent meiotic analysis. Recombination sites were recorded for individual chromosomes. Testicular and ejaculated sperm from NOA patients and controls, respectively, were tested for aneuploidy frequencies for chromosomes 9, 21, X and Y. There was a significant increase in the frequency of pachytene cells with at least one achiasmate bivalent in infertile men (12.4%) compared with controls (4.2%, P = 0.02). Infertile men also had a significantly higher frequency of sperm disomy than controls for chromosomes 21 (1.0% versus 0.24%, P = 0.001), XX (0.16% versus 0.03%, P = 0.004) and YY (0.12% versus 0.03%, P = 0.04). There was a significant correlation between meiotic cells with zero MLH1 foci in the sex body and total sex chromosome disomy (XX + YY + XY) in sperm from men with NOA (r = 0.79, P = 0.036).

The relationship between meiotic recombination in human spermatocytes and aneuploidy in sperm.

BACKGROUND: We have previously demonstrated that a decreased recombination frequency between human X and Y chromosomes is associated with the production of aneuploid 24,XY sperm. This study's aim was to determine the relationship between recombination frequency in human pachytene spermatocytes and aneuploidy frequencies in individual chromosomes in sperm from the same men. METHODS: Six previously fertile vasectomy reversal patients donated testicular tissue for meiotic analysis of pachytene spermatocytes using immunocytogenetic techniques for visualization of the synaptonemal complex and recombination sites (MLH1). Individual meiotic chromosomes were identified with centromere-specific multicolor fluorescence in situ hybridization (FISH), and the number of MLH1 signals was recorded for individual chromosomes. An ejaculated sperm sample was obtained from each patient 2-26 months post-reversal for FISH analysis of sperm aneuploidy frequencies of chromosomes 1, 9, 13, 21, X and Y. RESULTS: There was no significant correlation between meiotic recombination frequency and sperm aneuploidy for any individual chromosome. Similarly, there was no correlation between aneuploid sperm and bivalents with no recombination. CONCLUSIONS: The study provides unique data on intra-individual human recombination and aneuploidy events. It also demonstrated for the first time that men do not have an increased frequency of sperm aneuploidy 5-9 years post-vasectomy.

Analysis of non-crossover bivalents in pachytene cells from 10 normal men.

BACKGROUND: Bivalents with no recombination foci (possible achiasmates) are unable to orient properly on the metaphase plate or to segregate chromosomes to daughter cells. Non-crossover bivalents are known to cause meiotic arrest in various organisms. METHODS: Individual non-crossover bivalents were identified in 886 pachytene cells (19 492 bivalents) from testicular biopsies of 10 normal men. Fluorescence staining combined with centromere-specific multicolour fluorescence in situ hybridization (cenM-FISH) was used to identify mismatch repair gene mutation of human mutL homologue 1 (MLH1) recombination foci along each bivalent synaptonemal complex (SC). RESULTS: A total of 60 autosomal non-crossovers (SCs without an MLH1 focus) were found, and of these, chromosomes 21 (2.1%) and 22 (1.7%) had a significantly higher proportion than chromosomes 11, 12, 19 (each 0.1%), 13 (0.2%), 14 (0.6%), 16 (0.5%) and 15, 17, 18, 20 (each 0.3%) (P < 0.05). Sex chromosome univalents had a frequency of 27%, higher than that observed in any autosomal bivalent (P < 0.0001). CONCLUSIONS: These results suggest that G-group chromosomes and sex chromosomes are most susceptible to having no recombination foci and thus would be more susceptible to non-disjunction during spermatogenesis. This is consistent with previous observations from sperm karyotyping and FISH analysis, which demonstrate that chromosomes 21 and 22 and the sex chromosomes have a significantly increased frequency of aneuploidy compared with other autosomes.

A stable isotope-mass spectrometric method for measuring human spermatogenesis kinetics in vivo.

PURPOSE: Currently it is thought to take 60 to 70 days to produce and ejaculate human sperm. This estimate is derived mainly from a single older, descriptive, kinetic analysis of spermatogenesis. We developed a noninvasive method to assess germ cell turnover time accurately in vivo using stable isotope labeling and gas chromatography/mass spectrometry analyses. We confirmed the postulated length of a normal cycle of spermatogenesis. MATERIALS AND METHODS: A total of 11 men with normal sperm concentrations ingested (2)H(2)O daily for 3 weeks. Semen samples were collected every 2 weeks for up to 90 days. Label incorporation into sperm DNA was quantified by gas chromatography/mass spectrometry, allowing calculation of the percent of new cells present. A cycle of sperm production was determined as the lag time until labeled sperm appeared in the ejaculate. RESULTS: Labeled sperm were detected after a mean +/- SD of 64 +/- 8 days (range 42 to 76). In 1 subject the time lag was 42 days but it was at least 60 in all other subjects. In most subjects plateau labeling in sperm was not attained. In 2 subjects the rise and fall of the labeling curve was steep and reached greater than 85% new cells, suggesting rapid washout of old sperm in the epididymal reservoir. CONCLUSIONS: This direct kinetic assessment confirms a course of spermatogenesis that is on the shorter side of traditional estimates based on prior analyses. In addition, the variability observed in healthy men suggests that characteristics such as the epididymal reservoir effect may influence the modeling of in vivo spermatogenesis.

Immunofluorescent synaptonemal complex analysis in azoospermic men.

The molecular cause of germ cell meiotic defects in azoospermic men is rarely known. During meiotic prophase I, a proteinaceous structure called the synaptonemal complex (SC) appears along the pairing axis of homologous chromosomes and meiotic recombination takes place. Newly-developed immunofluorescence techniques for SC proteins (SCP1 and SCP3) and for a DNA mismatch repair protein (MLH1) present in late recombination nodules allow simultaneous analysis of synapsis, and of meiotic recombination, during the first meiotic prophase in spermatocytes. This immunofluorescent SC analysis enables accurate meiotic prophase substaging and the identification of asynaptic pachytene spermatocytes. Spermatogenic defects were examined in azoospermic men using immunofluorescent SC and MLH1 analysis. Five males with obstructive azoospermia, 18 males with nonobstructive azoospermia and 11 control males with normal spermatogenesis were recruited for the study. In males with obstructive azoospermia, the fidelity of chromosome pairing (determined by the percentage of cells with gaps [discontinuities]/splits [unpaired chromosome regions] in the SCs, and nonexchange SCs [bivalents with 0 MLH1 foci]) was similar to those in normal males. The recombination frequencies (determined by the mean number of MLH1 foci per cell at the pachytene stage) were significantly reduced in obstructive azoospermia compared to that in controls. In men with nonobstructive azoospermia, a marked heterogeneity in spermatogenesis was found: 45% had a complete absence of meiotic cells; 5% had germ cells arrested at the zygotene stage of meiotic prophase; the rest had impaired fidelity of chromosome synapsis and significantly reduced recombination in pachytene. In addition, significantly more cells were in the leptotene and zygotene meiotic prophase stages in nonobstructive azoospermic patients, compared to controls. Defects in chromosome pairing and decreased recombination during meiotic prophase may have led to spermatogenesis arrest and contributed in part to this unexplained infertility.

Temporal progression of recombination in human males.

To date, immunocytology has been used in humans to detect a limited number of meiotic proteins: components of the synaptonemal complex (SCP1 and SCP3) and some proteins known to participate in recombination events, such as MLH1 or RAD51. However, the colocalization or coexistence of proteins known to participate during the different stages of human meiosis remains largely unstudied, and these studies could provide important clues about the mechanics of recombination. This work reports the relative timing and localization of five different meiotic proteins that have previously been implicated in human homologous recombination [RAD51, replication protein A (RPA), MSH4, MLH1 and MLH3]. MSH4 foci appear concurrently with synapsis initiation at zygotene, shortly after the first RAD51 foci are detected. The presence of RPA in MSH4 foci was noted, suggesting that these two proteins may act co-operatively. Both RPA and MSH4 foci reach maximal numbers at the end of zygotene, when synapsis is concluding. From this point, RPA foci all but disappear by the end of pachytene, whereas MSH4 foci decline to a stable number at mid-pachytene, where they localize with MLH1/MLH3 recombination sites. We discuss a possible role for MSH4 in synapsis initiation and/or maintenance.

Meiotic studies in an azoospermic human translocation (Y;1) carrier.

A reciprocal translocation between the long arm of the Y chromosome and the long arm of chromosome 1 was observed in an infertile man with non-obstructive azoospermia. The study was performed using a combination of techniques: immunocytogenetic analysis, which allows the detection of synaptonemal complexes (SCs) and recombination sites (MLH1) simultaneously, and fluorescence in-situ hybridization analysis. Meiotic pairing analysis on 100 pachytene spreads showed the presence of a quadrivalent containing chromosomes 1 and Y. There were many abnormalities in chromosome pairing and recombination. These abnormalities included a great reduction of recombination events (as many as one fifth of the SCs had no MLH1 foci), and high proportions of unpaired regions and discontinuities in the SCs. We discuss the possibility that infertility in this patient may be due to transcriptional repression of part of chromosome 1 involved in the translocation, silencing some genes necessary for the progression of meiosis and causing defective meiotic pairing and recombination.

[Molecular study of type 2 von Willebrand disease]. / Molekulární studie von Willebrandovy choroby typu 2.

BACKGROUND: von Willebrand disease is an inherited bleeding disorders caused by mutations in the von Willebrand factor gene. We attempted to characterise the phenotype and the genotype in the first five families in Czech Republic affected by this heterogeneous disorder. METHODS AND RESULTS: The level of FVIII was measured by the one stage assay, the vWF:Ag by the immunoelectrophoresis, vWF:RiCo by aggregometry. For the vWF multimer analysis a western blot based technique was used. The vWF binding to FVIII was evaluated by the ELISA method. Two families were classified as the type 2A, one as the type 2B and two as the combined type 1/2N. Based on that knowledge, parts of the vWF gene were selected for genetic analysis. The previously described mutations Arg1374His and Gly1579Arg were identified in two families with the type 2A. In the family with type 2B a substitution Arg1308Cys was detected. In one family with the type 1/2N, two different previously described defects were found on the separate alleles of the vWF gene: a deletion of cytosine 2435 and a polymorphism Arg854Gln. Compound heterzygotes had the type 1/2N phenotype, while a carriers of the deletion had type 1 phenotype. In the second type 1/2N family, only the amino acid substitutions Thr791Me was found explaining the qualitative defect. A mutation underlying the quantitative deficiency needs to be searched for throughout the entire vWF gene. CONCLUSIONS: Based on the characterisation of the phenotype and genotype, five apparently unrelated families with the von Willebrand disease were diagnosed according to the revised classification. Our work represents laboratory basis for further studies into von Willebrand disease in Czech Republic.