Prediction of Post-interventional Outcome in Great Saphenous Vein Incompetence: The Role of Venous Plethysmography with Selective Superficial Vein Occlusion.

OBJECTIVE/BACKGROUND: To evaluate whether the outcome of radiofrequency ablation (RFA) treatment of great saphenous vein (GSV) incompetence may be predicted using strain-gauge plethysmography (SGP) with selective occlusion of the superficial venous system. METHODS: Seventeen patients (20 limbs) underwent endovenous RFA treatment for GSV incompetence (Clinical Etiology Anatomy Pathophysiology classification C2-C5; "C-group"). Duplex ultrasound (DUS) and SGP were performed with selective occlusion of superficial veins before and after RFA. Selective superficial occlusion was validated, in a control group (C-group) of 12 patients (14 legs), by ascending phlebography. In the RFA group, the time taken to reach 50% and 90% (T50, T90) of maximum venous volume was measured, as well as relative maximal reflux rates (%EV/min). The methodological error and coefficient of variation (CV) were assessed. RESULTS: Nineteen of 20 legs had complete post-operative GSV obliteration using DUS, and refilling times were improved after RFA (T50 11 ± 3 vs. 19 ± 3 s; p < .001; T90 27 ± 5 vs. 47 ± 6 s; p < .001). With SGP, the methodological error and CV for T50 were 4 s and 16%, respectively. Equivalence between pre-operative superficial occlusion and post-operative baseline measurements was achieved in 15 of 17 legs for T50, and 12 of 17 for T90 (three of the 20 legs were excluded due to treatment failure [n = 1], and untreated perforating veins [n = 2]). Mean differences (95% confidence interval) were within the equivalence ranges (T50 1 [-1 to 3] seconds; T90 -3 [-11 to 4] seconds). In the C-group superficial vein occlusion was possible in 12 of 14 legs. The remaining patient (two legs) showed incomplete superficial vein occlusion at ankle level (lipodermatosclerosis) and complete superficial vein occlusion at calf level. CONCLUSION: SGP with standardized superficial venous occlusion seems to be a reliable method for identifying venous reflux and may be useful in predicting the results of successful RFA treatment.

Dependence of jaw opening on pitch and vowel in singers.

In singing, F0 sometimes is much higher than the typical frequency value of F1. According to previous investigations, sopranos raise F1 to a frequency near F0 by widening the jaw opening in such cases. In the present study, the jaw opening was measured in 10 professional singers of different categorizations whose task was to sing an ascending two-octave scale on different vowels. Their normal F1 values for these vowels were determined at a low F0. Only for the vowels /a/ and /a/ did the singers widen the jaw opening when F0 approached the F1 value measured at a low pitch. For the other vowels, jaw opening was widened, beginning at a higher F0. It is assumed that for these vowels the singers used other articulatory means to increase F1.

Relief of triple-helix-mediated promoter inhibition by elongating RNA polymerases.

We have characterized triple-helix-mediated inhibition of an artificial bacteriophage promoter with respect to relief of inhibition by incoming RNA polymerases that initiate upstream or downstream from the operator sequence. Whereas oligonucleotide-directed triple-helix formation inhibits the test promoter, promoter activity is restored when the triple-helical complexes are disrupted by transcription of either strand of the homopurine operator sequence. The degree of relief from inhibition is related to the frequency of operator transcription. These observations demonstrate that this artificial repressor-operator complex is subject to antagonism by cis elements (other promoters) acting at a distance. Such antagonism might also arise between certain natural transcriptional control regions. Our results suggest that the efficiency of artificial repressors based on triple-helix formation may be limited by transcriptional activity in the gene control region.

Repression of bacteriophage promoters by DNA and RNA oligonucleotides.

We are interested in creating artificial gene repressors based on duplex DNA recognition by nucleic acids rather than polypeptides. An in vitro model system involving repression of bacteriophage T7 RNA polymerase initiation has been employed to demonstrate that certain DNA oligonucleotides can repress transcription by site-specific triple-helix formation at two kinds of homopurine operator sequences [Maher, L. J., III, (1992) Biochemistry 31, 7587-7594]. Recognition in the purine motif is based on antiparallel oligonucleotide binding (G.G.C and T.A.T triplets). Recognition in the pyrimidine motif is based on parallel oligonucleotide binding (C+.G.C and T.A.T base triplets). Using this system, we report that the concentration-dependence of repression by DNA oligonucleotides provides triple-helix inhibition constant (Ki) estimates of approximately 2 x 10(-7) M for both purine motif and pyrimidine motif DNA complexes. RNA oligonucleotides are shown to repress promoters overlapping pyrimidine motif operators (Ki = 6 x 10(-7) M), but not purine motif operators. Although competent to hybridize to complementary single strands, RNA oligonucleotides fail to bind the purine motif operator. Partial substitution of deoxyribose residues tends to rescue repressor activity by RNA oligonucleotides in the purine motif. These results suggest prospects for, and constraints on, natural and artificial RNA-based repressors.