Comparison of short tandem repeat and variable number tandem repeat genetic markers for quantitative determination of allogeneic bone marrow transplant engraftment.

Variable number tandem repeats (VNTRs) were among the first genetic markers used to quantitate bone marrow transplant engraftment. The limitations of PCR-based VNTR markers in distinguishing some donor/recipient pairs has shown the need for additional genetic markers to analyze engraftment. Short tandem repeats (STRs) provide an excellent tool for this purpose because of their high degree of polymorphism and relatively short length. We compared STR analysis results with previous VNTR results for 16 post-transplantation samples from four allogeneic bone marrow transplant patients. Previously analyzed patient samples were chosen to cover the full range of engraftment. DNA samples from each patient were analyzed in a blinded fashion. Good quantitative correlation was found between STR and VNTR results in samples from all four patients. STR markers were informative in one patient for whom PCR-based VNTR markers were not available. Correlation of VNTR and STR methods helps to validate the use of STRs for the quantitative analysis of bone marrow transplant engraftment. This study demonstrates that STR-based human identity testing kits are well suited for engraftment analysis.

Left ventricular mechanics and geometry in patients with congenital complete atrioventricular block.

BACKGROUND: Radiographic evidence of cardiomegaly is common in patients with congenital complete atrioventricular block (CCAVB). It has been speculated that left ventricular (LV) remodeling and increased stroke volume counteract the bradycardia, but the effects of slow heart rate and atrioventricular asynchrony on LV dimensions, geometry, wall stress, and function have not been examined in detail. METHODS AND RESULTS: Thirty patients with CCAVB without associated congenital heart disease (mean age, 8.5+/-5.3 years; range, 0.2 to 20 years) were included in a cross-sectional two-institution study. Thirty-five echocardiograms were performed using standard techniques. ECG and 24-hour ECG recordings were reviewed. Seven patients did not receive a pacemaker, whereas 23 patients underwent pacemaker implantation after the echocardiogram. Compared with normal control subjects, LV volume (Z score=1.5+/-1.3) and LV mass (Z=1.2+/-1.5) were significantly increased, whereas LV mass-to-volume ratio (1.1+/-0.3) and geometry (short-axis diameter/length ratio=0.65+/-0.09) were normal. LV end-systolic stress (ESS) (a measure of afterload) was normal (Z score=0.2+/-2.3), whereas shortening fraction (Z=3+/-2.9) and velocity of circumferential fiber shortening (VCF) (Z=3+/-3.1) were increased. The relationship between VCF and ESS (a preload-insensitive and afterload-adjusted index of contractility) was increased (Z=2.2+/-2) with only small increase in preload (Z=1.02+/-1.1). Regression analyses showed no significant change over age in LV mass, volume, geometry, loading conditions, or systolic function. Patients who ultimately met criteria for pacemaker implantation did not differ from those who did not in terms of heart rate or LV function but did have increased LV volume (Z score=1.8+/-1.4 versus 0.4+/-0.9, P=.03) and LV mass (Z score=1.7+/-1.2 versus 0.2+/-1.7, P=.001) compared to the unpaced group. CONCLUSIONS: In most patients with CCAVB, the LV was enlarged with normal geometry and enhanced systolic function during the first two decades of life. The degree of LV dilation and enhanced function did not significantly change with age. In patients who ultimately underwent pacemaker implantation LV function did not differ from those who remained unpaced, but evidence of a slightly increased load manifested as increased end-diastolic volume and mass.

Rise time and center-frequency effects on auditory brainstem responses to high-frequency tone bursts.

The effects of rise time and center frequency on the auditory brainstem response (ABR) elicited by high-frequency tone bursts were examined in six normal-hearing adults. Tone bursts with rise times of 0.1, 0.25, 0.5, and 1.0 msec, duration of 2 msec, and center frequencies of 8, 10, and 12 kHz were used in this study. The absolute latencies of waves I, III, and V were obtained in all subjects, and interpeak intervals of I-III, III-V, and I-V were calculated. As would be expected, rise time significantly affected the absolute latencies of waves I, III, and V, i.e., faster rise times shortened the absolute latencies, but did not affect the interpeak latencies. The tone-burst frequency significantly affected the latency of wave I but not the later waves. No significant differences were found in reliability of the response at different rise times or frequencies, within or across sessions. An estimate of the effective bandwidth of the stimulus suggests that frequency specificity of the response is maintained with fast rise time tone-burst stimuli.

Americans with Disabilities Act: overview of the employment provisions.

The Americans with Disabilities Act, when fully implemented, will affect almost every person in this country. The Act covers employment, public accommodations, transportation, and telecommunications. It will affect the employment, training, promotion, compensation, and termination policies of every employer having 15 or more employees. It also will affect the provision of goods and services by both private and public entities. This article examines the requirements included in Titles I and V of the Act pertaining to employment.

Chromosomal aberrations induced by Dispersion Yellow 3 in Rana clamitans larvae during tail regeneration.

Azo dyes have been shown to be mutagenic and toxic in a variety of organisms. The azo dye, Dispersion Yellow 3 is a pollutant in the river water supply of Northern Georgia. Preliminary and definitive studies have indicated that it is mutagenic in micro-organisms and causes several malformations in chicken embryos. The present study revealed that when larvae are exposed to the dye during tail regeneration, several aberrations are seen in the squash preparations from regenerates. Included are gaps (the most frequent abnormality), dicentrics, rings and breaks. The data suggest that this azo dye deserves more detailed study to determine its mutagenicity.