Menstrual bleeding patterns and prevalence of bleeding disorders in a multidisciplinary adolescent haematology clinic.

Heavy menstrual bleeding (HMB) is a frequent complaint in adolescence. Although HMB is often caused by immaturity of the hypothalamic-pituitary-ovarian axis, bleeding disorders are another common yet often unidentified cause. The aim of this study was to examine the bleeding patterns and prevalence of inherited bleeding disorders among females referred for HMB to a multidisciplinary adolescent haematology clinic. We retrospectively reviewed the first 105 patients (ages 8-18 years) referred to this specialty clinic from February 2009 to December 2011. Using menstrual bleeding questionnaires and medical records, data were extracted regarding demographics, bleeding patterns, frequency and types of bleeding disorders identified, and prescribed interventions. Sixty-two per cent of patients were diagnosed with a bleeding disorder, including platelet storage pool deficiency (36%), von Willebrand's disease (9%), other platelet function defect (8%), Ehlers-Danlos syndrome (7%) and combined bleeding disorders (2%). Comparison of the bleeding profiles for females with and without a bleeding disorder revealed only three factors that were significantly different, including the reported regularity of patients' periods (P = 0.02), description of period flow (P = 0.04) and number of days of each period that the bleeding was described as 'heavy' (P = 0.007). Bleeding disorders are prevalent in adolescent females presenting to a specialty clinic. Specifically, a relatively high proportion of adolescents were diagnosed with platelet storage pool deficiency. In our small population, menstrual bleeding profiles, as examined by a standardized questionnaire, could not identify females with an underlying bleeding disorder, demonstrating the important role of haemostasis testing in the evaluation of adolescents with HMB.

Carbon disulfide neurotoxicity in rats: VI. Electrophysiological examination of caudal tail nerve compound action potentials and nerve conduction velocity.

The effects of subchronic exposure to carbon disulfide (CS2) on ventral caudal tail nerve compound nerve action potential (CNAP) amplitudes and latencies, and nerve conduction velocity (NCV) in rats were examined. Male and female Fischer 344 rats were exposed to 0, 50, 500, or 800 ppm CS2 for 6 hrs/day, 5 days/week. Using separate groups, exposure duration was 2, 4, 8, or 13 weeks. Exposure to 500 or 800 ppm CS2 for 13 weeks decreased NCV compared to the 50 ppm CS2 group. CNAP amplitudes were increased, and peak P1P2 interpeak latency decreased, after exposure to 500 or 800 ppm CS2 for 13 weeks. Most of the changes in NCV and CNAPs were not attributable to differences in tail or colonic temperature. However, the increases in peak P1 amplitude may relate to the proximity of the electrodes to the tail nerves. Assessment of tail nerve morphology after 13 weeks exposure to 800 ppm CS2 revealed only minor changes compared to the extent of axonal swelling and degeneration observed in the muscular branch of the tibial nerve and axonal swelling in the spinal cord. As anticipated, in older animals the NCV increased, the CNAP amplitudes increased, and the CNAP latencies decreased. The biological basis for the changes in CNAPs produced by CS2 is under investigation. Future studies will focus on electrophysiological evaluation of spinal nerve function, to allow better correlation with pathological and behavioral endpoints.

Recombination-mediated PCR-directed plasmid construction in vivo in yeast.

We have extended the technique of PCR-directed recombination in Saccharomyces cerevisiae to develop a simple method for plasmid or gene construction in the absence of suitable restriction sites. The DNA to be cloned is PCR-amplified with 30-40 bp of homology to a linearized yeast plasmid. Co-transformation into yeast results in homologous recombination at a position directed by the PCR oligonucleotides.

Possible confounding effects of strobe "clicks" on flash evoked potentials in rats.

Flash evoked potentials (FEPs) undergo within- and between-session changes and are modified by auditory white noise (26). We examined whether an auditory potential produced by the "click" associated with the strobe discharge could be recorded, and if alterations in an auditory response could explain the within- and between-session changes in FEPs. We also examined differences between a frontal cortex or a nasal reference electrode location on FEPs and auditory potentials. An auditory potential associated with the strobe discharge could be clearly recorded. This response was eliminated by the presence of 80 dB SPL masking white noise. However, the within- and between-session changes in FEPs could not be explained by modifications of the auditory potential. Animals whose ear drums were ruptured did not exhibit an auditory response, and their FEPs were similar to those of controls tested in the presence of masking white noise. A nasal reference electrode decreased the impact of auditory potentials on FEPs, but allow visual potentials (electroretinogram and optic tract activity) to influence FEPs. The data show that auditory potentials associated with the strobe discharge can be recorded from the visual cortex of rats, and that these auditory responses represent a possible confounding factor in the interpretation of toxicological studies employing FEPs.

Iontophoretic delivery of oligonucleotides across full thickness hairless mouse skin.

In recent years there has been an increased interest in the use of oligonucleotides as therapeutic agents. Oligonucleotide therapeutics may have significant potential over traditional drugs due to their high degree of specificity and increased affinity. The major drawbacks to the use of oligonucleotide therapeutics are the problems associated with their delivery and their relative instability in serum. The serum instability problem has been partially overcome through the use of oligonucleotides with modified backbones. Transdermal electrotransport may be used to overcome the problems associated with delivery. Here we report the use of transdermal electrotransport in the delivery of oligonucleotides across hairless mouse skin. The effects of pH, salt concentration, current density, and oligonucleotide concentration, structure, and length have been investigated.