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)

Chromosomal analysis of sperm from infertile men using sperm karyotyping and multi-colour fluorescence in situ hybridization

Bibliography: p. 86-99

Evaluation of Oral Neutrophil Levels as a Quantitative Measure of Periodontal Inflammatory Load in Patients with Special Needs

Purpose: To validate and assess the feasibility of using an assay of oral neutrophils to measure periodontal inflammation in uncooperative patients with special needs. Methods: Periodontal examination and neutrophil counts derived from oral swabs were performed on patients with special needs having comprehensive dental treatment under general anaesthesia (GA). The conventional periodontal measurements were compared to neutrophil levels while patients were under GA, and later at their recall examination. Results: Forty-nine patients were assessed under GA and 30 (61%) returned for recall examination. Spearman’s correlation allowed for comparisons between periodontal parameters and oral neutrophil counts. Despite limited cooperation, it was possible to acquire neutrophils (using swabs) for all patients that presented for recall examination in the ambulatory dental clinic. Conclusions: Oral neutrophil levels correlated significantly with conventional parameters of gingival inflammation and may serve as a standardized method for clinical assessment of periodontal diseases in the special needs population.MAS

Exploring the attempts of a grade V mathematics teacher towards improvement in mathematical tasks\u27 selection and implementation for developing students\u27 conceptual understanding in a private school of Karachi, Pakistan

Classroom experiences play a vital role in developing students\u27 conceptual understanding of mathematics. Therefore, it is essential to engage students in such mathematical tasks in the classroom which provide students opportunities for reasoning, conjecturing, pattern seeking and generlizing in a collaborative learning environment. The National Curriculum of Mathematics (2006) also emphasizes the changing role of teachers from knowledge transformers to facilitators in the student-directed learning process and this cannot be achieved unless teachers are provided professional development to choose and design mathematical tasks for their students which promotes students mathematical reasoning and conceptual understanding. This study explored the ways through which a primary mathematics teacher brought improvement in her selection and implementation of mathematical tasks for developing students\u27 mathematical understanding. The reported study used Collaborative Action Research which comprised four action research cycles using Lewin\u27s model of Action Research that aimed to explore progress in the participant teacher\u27s task selection and implementation. Data for the study were collected from a private school in Karachi Pakistan where I worked with one mathematics teacher for more than two months. Data collection tools included classroom observations, semi structured interviews, reflections/reflective sessions and students\u27 sample work. The findings of the study demonstrated that the factors resulting in improvement of teacher\u27s task selection and implementation includes the facilitation by the mentor teacher, enhancement in one\u27s own content and pedagogies knowledge and development of a teacher\u27s understanding of students\u27 cognitive level. The findings of the study also revealed that the common factors influencing the selection of mathematics tasks comprised shortage of time, obligation of syllabus coverage, level of students\u27 understanding, students\u27 prior knowledge and teacher\u27s belief about mathematics. This study also highlighted the residing factors influencing the implementation of rich mathematical task which include the nature of the selected task, its alignment with students\u27 prior knowledge, amount of time provided to students and mainly the role of the teacher in implementing the tasks. Based on the findings, this study recommends that classroom teachers should be provided some autonomy to make modifications in the syllabus. Moreover, the school management should work for teachers\u27 professional development by arranging in- service teacher training sessions for lifelong learning

VOMegaPlot: efficient plotting of large VOTable datasets

Most plotting tools tend to load all the data to be plotted into main memory and then use the in-memory data for the actual operations such as plotting. Our Analysis shows that in case of such interactive applications, as the memory usage grows, the response time increases in a significant fashion resulting in poor user interactivity. Further, in cases where the data size exceeds the limits imposed by the available physical memory, the entire data cannot be loaded in memory for performing any kind of operation

Nuclear organisation of sperm remains remarkably unaffected in the presence of defective spermatogenesis

Organisation of chromosome territories in interphase nuclei has been studied in many systems and positional alterations have been associated with disease phenotypes (e.g. laminopathies, cancer) in somatic cells. Altered nuclear organisation is also reported in developmental processes such as mammalian spermatogenesis where a "chromocentre" model is proposed with the centromeres and sex chromosomes repositioning to the nuclear centre. The purpose of this study was to test the hypothesis that alterations in nuclear organisation of human spermatozoa are associated with defects upstream in spermatogenesis (as manifest in certain infertility phenotypes). The nuclear address of (peri-) centromeric loci for 18 chromosomes (1-4, 6-12, 15-18, 20, X and Y) was assayed in 20 males using established algorithms for 3D extrapolations of 2D data. The control group comprised 10 fertile sperm donors while the test group was 10 patients with severely compromised semen parameters including high sperm aneuploidy. All loci examined in the control group adopted defined, interior positions thus providing supporting evidence for the presence of a chromocentre and interior sex chromosome territories. In the test group however there were subtle alterations in the nuclear address for certain centromeres in individual patients and, when all patient results were pooled, some different nuclear addresses were observed for chromosomes 3, 6, 12 and 18. Considering the extensive impairment of spermatogenesis in the test group (evidenced by compromised semen parameters and increased chromosome abnormalities), the observed differences in nuclear organisation for centromeric loci compared to the controls were modest. A defined pattern of nuclear reorganisation of centromeric loci in sperm heads therefore appears to be a remarkably robust process, even if spermatogenesis is severely compromised