Chromosome microarray proficiency testing and analysis of quality metric data trends through an external quality assessment program for Australasian laboratories.

Chromosome microarrays are an essential tool for investigation of copy number changes in children with congenital anomalies and intellectual deficit. Attempts to standardise microarray testing have focused on establishing technical and clinical quality criteria, however external quality assessment programs are still needed. We report on a microarray proficiency testing program for Australasian laboratories. Quality metrics evaluated included analytical accuracy, result interpretation, report completeness, and laboratory performance data: sample numbers, success and abnormality rate and reporting times. Between 2009 and 2014 nine samples were dispatched with variable results for analytical accuracy (30-100%), correct interpretation (32-96%), and report completeness (30-92%). Laboratory performance data (2007-2014) showed an overall mean success rate of 99.2% and abnormality rate of 23.6%. Reporting times decreased from >90 days to <30 days for normal results and from >102 days to <35 days for abnormal results. Data trends showed a positive correlation with improvement for all these quality metrics, however only 'report completeness' and reporting times reached statistical significance. Whether the overall improvement in laboratory performance was due to participation in this program, or from accumulated laboratory experience over time, is not clear. Either way, the outcome is likely to assist referring clinicians and improve patient care.

Physical Characteristics of Farm Equipment Crash Locations on Public Roads in Tennessee.

Safety of farm equipment on public roadways has been the topic of much research for several years. With more farm equipment traveling on roadways, it will continue to be an important topic. The objective of this research project was to locate areas with high crash rates involving farm equipment (excluding other slow-moving vehicles) and to identify similarities, if any, among those locations. Data collected from public crash report records obtained from the Tennessee Highway Patrol were entered into a geographic information system (GIS) database, so locations with high crash rates could be identified. Physical data, including number of lanes, presence and width of shoulders, presence of farm equipment warning signs, and other roadway information, were gathered for each location. Information contained within the public accident records was also considered, including time of day, weather conditions, and severity of the accident. This research revealed that most collisions involving farm equipment in Tennessee occur during the months of May, June, and October. More crashes occur on Mondays than other days of the week, with Sundays.having the fewest reported crashes. Typically, most collisions occur between 14:00 and 16:00 and when the weather is clear. Of 16 accident sites at locations with high crash frequencies in northwest Tennessee, 88% had grass shoulders that were 1.8 m wide or less. No sites had farm equipment warning signs posted, and 81% had no posted speed limits. Farm equipment collisions could be reduced through better driver education, proper sign posting, and wider shoulders.

Sporadic chromosome abnormalities in human lymphocytes and previous exposure to chemicals.

Sporadic abnormalities in lymphocyte cultures are often attributed to in vitro culture variations of no clinical significance. The data presented here compare the findings from 11,873 cells of 230 patients referred with histories of previous chemical exposure (usually to mixtures of solvents and/or pesticides) with 27,050 cells from 855 patients referred for other reasons. Detection of 0.38% or more, structural abnormalities (approximately 1 in 30 cells) was 27.2 times more likely in exposed persons than in controls and the finding of a single autosomal trisomic cell was 14.4 times more likely in exposed persons. These highly statistically significant findings were similar to the frequencies of abnormalities reported in other studies of persons exposed to benzene, pesticides, herbicides and irradiation. It is recommended that findings of sporadic abnormalities in lymphocytes be routinely recorded, and patients with positive findings followed up to discover whether there are past histories of significant exposures.

A 13-year cytogenetic study of spontaneous abortion: clinical applications of testing.

Chromosome analysis was performed on 1,543 specimens of first trimester miscarriage received between 1982 and 1994. Comparisons with earlier studies show that some findings are absolutely consistent between different years and populations, but some major differences are also found. The results are considered in the light of several recent genetic, environmental and physiological studies. Trisomy 16, and probably trisomy 22, is entirely dependent on maternal age; other trisomies show both maternal age and other environmental or genetic effects. Monosomy X and mosaic aneuploidy arise postzygotically by chromosome loss, a normal control mechanism. Some trisomy, dipaternal triploidy and tetraploidy probably occur because of pre- or postovulatory 'overripeness'; either due to transient or chronic maternal conditions or delayed fertilization. Unbalanced structural abnormalities, most apparently of de novo origin, are markedly increased compared to earlier studies and are possibly due to paternal environmental exposures. It is concluded that when considering histories of abortion, studies of the chromosomes of the aborted products are much more informative and cost-effective than studies of parental bloods. Where available, studies of products should be undertaken for preference, but only by experienced and committed laboratories.

Free radical yields from the homolysis of peroxynitrous acid.

A recent study reports discordant results for maximal free-radical yields from the decomposition of peroxynitrous acid using different assay reagents and a puzzling decrease (to zero) of the radical yields with increasing pH. An assay method using 2,2,'azino-bis(3-ethyl-benzthiazoline sulphonate) (ABTS) has been tested using stopped-flow kinetic studies, and the results imply that the assay is satisfactory when [HOONO] much greater than [-OONO] but that reactions involving peroxynitrite anion interfere at higher pH. Evidence is presented that peroxynitrite was an interfering species in the earlier studies.