The functional capability of the deep femoral artery (DFA) as a collateral channel is an important feature in patients suffering peripheral arterial occlusive disease (PAOD). A noninvasive method of indirect quantification of the DFA blood flow volume is presented. In normal lower limbs, it was found that the common femoral artery (CFA) mean blood flow volume was maintained at 59% of its resting value when the superficial femoral artery (SFA) was occluded by a pneumatic cuff placed around the thigh. The reduction of the mean flow volume is mainly due to an increase of the diastolic backward flow, while the maximum systolic flow remains constant. In a few patients with various degrees of stenosis of the DFA, we observed a much greater drop in mean CFA blood flow volume than in normal subjects. On the basis of this preliminary study, we conclude that: --When the normal SFA is occluded, pulsatile flow through the CFA is maintained. --Occlusion flow reflects the runoff and the compliance of the DFA bed. --Occlusion flow is diminished in patients with DFA stenosis. It is suggested that this non-invasive test might help the physician to assess the involvement of the DFA in PAOD. Further investigation is needed to establish the correlation between quantitative occlusion blood flow volume and the degree of DFA stenosis.

Quantitative blood flow measurements were performed on 37 normal lower limbs with a 128-channel digital pulsed Doppler (MDPD) system. The evolution of mean flow (QM), peak systolic flow (QS), diastolic flow (QD), and prograde stroke volume (PSV) was observed at rest, during postocclusive reactive hyperemia (PORH), and at 1-, 2-, and 3-min intervals. The QM at rest was 2.9 +/- 1.1 ml/s; PORH induced a four- to fivefold increase in QM and PSV secondary to a slight increase in QS and the disappearance of the reverse protodiastolic component of resting flow. Reverse flow was restored after 1 min. Both QS and QD returned to resting values after 2 min, whereas QM remained significantly higher after 3 min. To provide a better description of the hyperemic response, we also studied the evolution of the pulsatility index as as applied the flow curve (PIQ). Similarly, the systolic amplitude index (SAI) is presented. Our study demonstrates that pulsed Doppler techniques can be used for noninvasive quantitative assessment of blood flow at rest and during PORH. The values obtained on normal subjects provide base-line data for further investigation of pathological conditions.

In order to find the correlations existing between segmental and selective arterial blood flow volume, 20 healthy subjects have been submitted to calf venous occlusion plethysmography and Multichannel Digital Pulsed Doppler examination of the common femoral and popliteal arteries at rest. We found a linear correlation only between mean popliteal artery blood flow volume and plethysmographic calf blood flow volume (r = 0,41; p less than 0,01). We therefore suggest that venous occlusion plethysmography should not be used for the assessment of aorto-iliac and common femoral hemodynamics after direct arterial reconstructive surgery. Its use should be complementary to pulsed Doppler blood flow volume determination at the femoro-popliteal level, along with the usual pressure measurement.

Since Satomura first described an ultrasonic device using the Doppler effect to detect blood flow in 1959, more recent advances in medical engineer ing have met the need for non-invasive, quantitative measurement of blood flow in peripheral arteries.1 This goal can now be achieved with the use of a pulsed Doppler combined with an A-mode scan to estimate the angle of the ultrasound beam and the dimensions of the vessel. Although several authors have already published data concerning blood flow volume obtained by continuous wave or pulsed Doppler devices in human peripheral arteries2,3,4 or in animal experiments,5,6,7 the accuracy of their meas urements was only correlated with indirect blood flow determinations such as electromagnetic flowmetry or venous occlusion plethysmography. The present study compares the values of blood flow volume obtained by a Multichannel Digital Pulsed Doppler (MDPD) and by direct timed blood collec tion (DTBC) in the canine common femoral artery.

Many eukaryotes descend from polyploid ancestors that experienced massive duplicate gene loss. This genomic erosion is particularly strong for duplicated (meiotic) recombination genes that return to a single copy more rapidly than genome average following polyploidy. To better understand the evolutionary forces underlying duplicate loss, we analysed how varying copy numbers of MSH4, an essential meiotic recombination gene, influences crossover formation in allotetraploid Brassica napus. We show that faithful chromosome segregation and crossover frequencies between homologous chromosomes are unchanged with MSH4 duplicate loss; by contrast, crossovers between homoeologous chromosomes (which result in genomic rearrangements) decrease with reductions in MSH4 copy number. We also found that inter-homoeologue crossovers originate almost exclusively from the MSH4-dependent crossover pathway. Limiting the efficiency of this pathway by decreasing the copy number of key meiotic recombination genes could therefore contribute to adaptation to polyploidy, by promoting regular chromosome segregation and genomic stability. TextGene duplication and gene loss are two driving forces in evolution 1-3 . These two mechanisms are well illustrated by the evolution of the meiotic recombination machinery. At the outset, the emergence of meiosis required key evolutionary breakthroughs 4-6 that were all made possible through iterative gene duplications followed by acquisition of new functions. These include, among others, the formation of programmed DNA double-strand breaks by SPO11 proteins 7 , the promotion of double-strand break repair using homologous templates by DMC1, RAD51 and some other related proteins 8 or the resolution of recombination intermediates as crossovers by MSH and MLH proteins 9 . After this initial phase, genes involved in meiotic recombination (and DNA repair in general) have tended to return preferentially to single copy following subsequent duplications 10,11 , with some

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The recent development of a new multigate pulsed Doppler system used in conjunction with an A-mode scan allows real time display of the velocity profiles across the vessel and quantitative flow measurement. Experimental in-vitro and in-vivo studies showed an excellent correlation between flow measurements obtained by this noninvasive method and by direct timed collection. Preliminary results of the post-occlusive hyperaemic response in normals and in patients with iliac stenosis are presented. Although no statistical comparison is allowed, it appears that the hyperaemic response is diminished when an iliac stenosis is present. A non-invasive method of quantifying the haemodynamic significance of profunda femoris artery stenosis is described. Finally, the velocity profiles and the flow curves in PTFE grafts were studied and compared to the flow patterns of the normal superficial femoral artery. The differences observed between the two conditions might explain the low patency rate of the synthetic grafts. Other fields of application of the method are suggested. The future development of a Duplex scanner combining B-mode imaging and the multigate Doppler system will allow the exploration of vessels within the abdomen and thorax: portal vein, in situ or transplanted renal arteries, ascending and abdominal aorta.