Perfect Resonant Absorption of Guided Water Waves by Autler-Townes Splitting

The control of guided water wave propagation based on the Autler-Townes splitting resonance concept is demonstrated experimentally, numerically, and theoretically. Complete wave absorption is achieved using an asymmetric pointlike scatterer made of two closely spaced resonant side channels connected to a guide and designed so that its energy leakage is in perfect balance with the inherent viscous losses in the system. We demonstrate that the nature of the resonators and guide junction completely controls the positions of the wave numbers at the reflection and transmission zeros on the real axis; the asymmetry of the resonators completely controls their positions on the imaginary axis. Thus, by adjusting these two independent parameters, we obtain a zero reflection and transmission.

A stable, unified model for resonant Faraday cages

We study some effective transmission conditions able to reproduce the effect of a periodic array of Dirichlet wires on wave propagation, in particular when the array delimits an acoustic Faraday cage able to resonate. In the study of Hewett & Hewitt (2016 Proc. R. Soc. A 472, 20160062 (doi:10.1098/rspa.2016.0062)) different transmission conditions emerge from the asymptotic analysis whose validity depends on the frequency, specifically the distance to a resonance frequency of the cage. In practice, dealing with such conditions is difficult, especially if the problem is set in the time domain. In the present study, we demonstrate the validity of a simpler unified model derived in Marigo & Maurel (2016 Proc. R. Soc. A 472, 20160068 (doi:10.1098/rspa.2016.0068)), where unified means valid whatever the distance to the resonance frequencies. The effectiveness of the model is discussed in the harmonic regime owing to explicit solutions. It is also exemplified in the time domain, where a formulation guaranteeing the stability of the numerical scheme has been implemented.

Enhanced resonance of sparse arrays of Helmholtz resonators-Application to perfect absorption

The influence of the spacing on the resonance of a periodic arrangement of Helmholtz resonators is inspected. An effective problem is used which accurately captures the properties of the resonant array within a large range of frequencies, and whose simplified version leaves an impedance condition. It is shown that the strength of the resonance is enhanced when the array becomes sparser. This degree of freedom on the radiative damping is of particular interest since it does not affect the resonance frequency nor the damping due to losses within each resonator; in addition, it does not affect the total thickness of the array. It is shown that it can be used for the design of a perfect absorbing wall.

Classical homogenization to analyse the dispersion relations of spoof plasmons with geometrical and compositional effects

We show that the classical homogenization is able to describe the dispersion relation of spoof plasmons in structured thick interfaces with periodic unit cell being at the subwavelength scale. This is because the interface in the real problem is replaced by a slab of an homogeneous birefringent medium, with an effective mass density tensor and an effective bulk modulus. Thus, explicit dispersion relation can be derived, corresponding to guided waves in the homogenized problem. Contrary to previous effective medium theories or retrieval methods, the homogenization gives effective parameters depending only on the properties of the material and on the geometry of the microstructure. Although resonances in the unit cell cannot be accounted for within this low-frequency homogenization, it is able to account for resonances occurring because of the thickness of the interface and thus, to capture the behaviour of the spoof plasmons. Beyond the case of simple grooves in a hard material, we inspect the influence of tilting the grooves and the influence of the material properties.

Generalized method for retrieving effective parameters of anisotropic metamaterials

Electromagnetic or acoustic metamaterials can be described in terms of equivalent effective, in general anisotropic, media and several techniques exist to determine the effective permeability and permittivity (or effective mass density and bulk modulus in the context of acoustics). Among these techniques, retrieval methods use the measured reflection and transmission coefficients (or scattering coefficients) for waves incident on a metamaterial slab containing few unit cells. Until now, anisotropic effective slabs have been considered in the literature but they are limited to the case where one of the axes of anisotropy is aligned with the slab interface. We propose an extension to arbitrary orientations of the principal axes of anisotropy and oblique incidence. The retrieval method is illustrated in the electromagnetic case for layered media, and in the acoustic case for array of tilted elliptical particles.

Characteristics and management of congenital esophageal stenosis: findings from a multicenter study

BACKGROUND

Congenital esophageal stenosis (CES) is a rare condition frequently associated with esophageal atresia (EA). There are limited data from small series about the presentation, treatment, and outcomes of CES.

METHODS

Medical records of all patients with CES included in the French Network on Esophageal Malformations and Congenital Diseases were reviewed retrospectively with regard to diagnosis, treatment, and outcome.

RESULTS

Over 18 years, 61 patients (30 boys) had CES, and 29 (47%) of these patients also had EA. The mean age at diagnosis was 24 months (1 day to 14 years) and was younger in patients with CES and EA than in those with isolated CES (7 vs. 126 months, p < 0.05). Twenty-one of the 61 patients with CES had no clinical symptoms: in three patients, the findings were incidental, and in 18 of the 29 patients with associated EA, CES was diagnosed at the time of surgical repair of EA or during a postoperative systematic esophageal barium study. In the 40 other patients, at diagnosis, 50% presented with dysphasia, 40% with vomiting, 50% with food impaction, and 42% with respiratory symptoms. Diagnosis of CES was confirmed by esophageal barium study (56/61) and/or esophageal endoscopy (50/61). Sixteen patients had tracheobronchial remnants (TBR), 40 had fibromuscular stenosis (FMS), and five had membrane stenosis (MS). Thirty-four patients (56%) were treated by dilation only (13/34 remained asymptomatic at follow-up); 15 patients were treated by dilation but required later surgery because of failure (4/15 remained asymptomatic at follow-up); and nine patients had a primary surgical intervention (4/9 were asymptomatic at follow-up). Dilation was complicated by esophageal perforation in two patients (3.4%). At follow-up, dysphagia remained in 36% (21/58) of patients, but the incidence did not differ between the EA and the isolated CS groups (10/29 vs. 7/32, p = 0.27).

CONCLUSIONS

CS diagnosis can be delayed when associated with EA. Dilation may be effective for treating patients with FMS and MS, but surgical repair is often required for those with TBR. Our results show clearly that, regardless of the therapeutic option, dysphagia occurs frequently, and patients with CES should be followed over the long term.

Experimental realization of a water-wave metamaterial shifter

We demonstrate by quantitative experimental measurements that metamaterials with anisotropic properties can be used in the context of water waves to produce a reflectionless bent waveguide. The anisotropic medium consists in a bathymetry with subwavelength layered structure that shifts the wave in the direction of the waveguide bending (10°, 20°, and 30°). The waveguide filled with such metamaterial is tested experimentally and compared to a reference empty bent waveguide. The experimental method used to characterize the wave field allows for space-time resolved measurements of water elevation. Results show the efficiency of the shifter. Modal treatment of the experimental data confirms that the metamaterial prevents higher modes from being excited in the waveguide.

Time reversal of water waves

We present time reversal experiments demonstrating refocusing of gravity-capillary waves in a water tank cavity. Owing to the reverberating effect of the cavity, only a few channels are sufficient to reconstruct the surface wave at the point source, even if the absorption is not negligible. Space-time-resolved measurements of the waves during the refocusing allow us to quantitatively demonstrate that the quality of the refocusing increases linearly with the number of reemitting channels. Numerical simulations corresponding to water waves at larger scales, with negligible damping, indicate the possibility of very high quality refocusing.

Different regimes for water wave turbulence

We present an experimental study on gravity capillary wave turbulence in water. By using space-time resolved Fourier transform profilometry, the behavior of the wave energy density |η(k,ω)|(2) in the 3D (k,ω) space is inspected for various forcing frequency bandwidths and forcing amplitudes. Depending on the bandwidth, the gravity spectral slope is found to be either forcing dependent, as classically observed in laboratory experiments, or forcing independent. In the latter case, the wave spectrum is consistent with the Zakharov-Filonenko cascade predicted within wave turbulence theory.

Choosing a technique for severe hypospadias

INTRODUCTION

We participate in humanitarian missions in Madagascar during which we treat severe hypospadias. We report our experience and results with these patients, in these conditions, and discuss our choice of technique in this particular setting.

MATERIALS AND METHODS

We retrospectively reviewed the data of 27 patients operated for severe hypospadias during our humanitarian missions in Madagascar between November 2006 and September 2009. Twenty one patients underwent a modified Koyanagi procedure, three underwent a Duckett urethroplasty, two an onlay island flap, one an augmented Duckett and one a tubularised plate urethroplasty. Two patients who underwent a modified Koyanagi repair also had a Nesbitt dorsal plication.

RESULTS

Patient age at the time of surgery ranged from 22 to 198 months with a median age of 54.1 months. Mean follow-up was 16 months. Of the 21 patients who underwent a modified Koyanagi procedure, 16 presented at least one complication (76%): A fistula developed in 12 patients (57%), meatal regression developed in 7 (33%) and 2 showed complete wound dehiscence (9.5%). None developed stenosis or urethrocoele.

CONCLUSION

In this particular setting, the postoperative complication rate is high. Nevertheless, the Koyanagi technique is appropriate, because its complications are easy to treat and there is always sufficient ventral tissue for the secondary operation, if necessary.

Estimating the dynamic effective mass density of random composites

The effective mass density of an inhomogeneous medium is discussed. Random configurations of circular cylindrical scatterers are considered, in various physical contexts: fluid cylinders in another fluid, elastic cylinders in a fluid or in another solid, and movable rigid cylinders in a fluid. In each case, time-harmonic waves are scattered, and an expression for the effective wavenumber due to Linton and Martin [J. Acoust. Soc. Am. 117, 3413-3423 (2005)] is used to derive the effective density in the low frequency limit, correct to second order in the area fraction occupied by the scatterers. Expressions are recovered that agree with either the Ament formula or the effective static mass density, depending upon the physical context.

One-step management of apple-peel atresia

PURPOSE

Apple-peel atresia is a rare form of bowel atresia associating proximal jejunal atresia with a typical coil-shaped distal small bowel. Many of the children suffering from this condition are still managed with initial enterostomy followed by delayed anastomosis.

PATIENTS AND METHOD

Between 2000 and 2007, we managed four patients with apple-peel atresia. Three by primary anastomosis and one by initial enterostomy with delayed anastomosis.

RESULTS

Total duration of total parenteral nutrition (TPN) was an average 109 days. Survival rate was 100% with an average follow-up of 4.3 years.

CONCLUSION

Nowadays, the prognosis of apple-peel atresia depends mainly on prolonged TPN-related morbidity rather than immediate postoperative complications. We therefore recommend that those infants affected be managed by primary anastomosis in order to reduce the duration of parenteral nutrition, followed by careful nutrition by teams experienced in neonatal TPN and short bowel syndrome.

Multicenter assessment of ultrasound of the spermatic cord in children with acute scrotum

PURPOSE

Intravaginal or extravaginal spermatic cord torsion is a diagnostic challenge for the surgeon and radiologist. Color Doppler sonography can be inaccurate, leading to dangerous false-negative results. To date, no single reliable test has been able to provide 100% diagnostic accuracy. The direct visualization of the twisted cord during emergency high resolution ultrasonography has been proposed to avoid systematic and abusive surgical exploration. The aim of this multicenter study was to assess the validity and reproducibility of high resolution ultrasonography based management of acute scrotum in children.

MATERIALS AND METHODS

A total of 919 patients from 11 European university hospitals underwent color Doppler sonography and high resolution ultrasonography for acute scrotum between 1992 and 2005. The spermatic cord was studied along its complete length to detect a spiral twist. The surgical findings were correlated with the preoperative results.

RESULTS

A total of 208 patients had spermatic cord torsion proved at surgery. Intratesticular vascularization was absent in the affected testis in only 158 cases (76%). In contrast, high resolution ultrasonography detected the twist as a snail shell-shaped mass, measuring 7 to 33 mm, in 199 patients (96%). High resolution ultrasonography revealed a linear cord for all other causes of acute scrotum (711 patients) with a specificity of 99%. The radiologist training level was the best predictive factor of high resolution ultrasonography reliability (p <0.05).

CONCLUSIONS

High resolution ultrasonography based management of acute scrotum is reliable and reproducible. Thanks to its high sensitivity and specificity for the diagnosis of spermatic cord torsion, high resolution ultrasonography can significantly improve the management of acute scrotum in children.

A nonuniformly stretched vortex

A stretched vortex model is proposed which includes a nonuniform stretching in the radial direction that is clearly present in real flows, as well as a slow variation of velocity profiles along the vortex axis. Both features of this boundary layer approximation depart from the classical Burgers solution. This model is shown to be in very good agreement with experimental velocity measurements.

Determination of Lamb mode eigenvalues

An original method is presented to determine the complex Lamb wave spectrum by using a numerical spectral method applied to the elasticity equations. This method presents the advantage to directly determine complex wave numbers for a given frequency via a classical matricial eigenvalue problem, and allows the wave numbers to be determined at relatively high frequencies (i.e., corresponding to many propagating modes). It does not need initial guess values for the wave numbers, contrary to the usual method of root finding of the Rayleigh-Lamb frequency equations (dispersion relation) in the complex plane. Results are presented and the method is discussed.

[Preoperative prognostic factors for squamous cell carcinomas of the thoracic esophagus]

AIM OF THE STUDY

To identify preoperative survival prognostic factors in patients with resectable squamous cell carcinoma of the thoracic esophagus.

POPULATION

From January 1982 to September 1999, 868 patients underwent surgery for esophageal carcinoma in our department, including 493 for squamous cell carcinoma of the thoracic esophagus. The following parameters were retrospectively included in univariate and multivariate analysis: age, sex, undernutrition, dysphagia, tumor diameter and nodal involvement on the CT-scan, preoperative treatment, surgical technique, curative resection, pTNM classification, histologic type and postoperative complications. The actuarial survival was determined.

RESULTS

Survival prognostic factors were dysphagia, nodal involvement on CT-scan and depth of tumor invasion at pathological examination. Three groups of patients were identified on the two preoperative variables: group 1: patients without dysphagia (n=102), group 2: patients with dysphagia but without nodal involvement on the CT- scan (n=244), group 3: patients with dysphagia and with nodal involvement on the CT- scan (n=147). The median survivals were 62.4, 19.1 and 14.4 months in groups 1, 2 and 3, respectively, and 5-year actuarial survivals were 50%, 21% and 11% (P<0.009).

CONCLUSION

Our study confirms that dysphagia and nodal involvement on the CT-scan are simple preoperative prognostic factors in patients with resectable squamous cell carcinoma of the thoracic esophagus.

Scattering of sound by a vorticity filament: an experimental and numerical investigation

A vorticity filament is investigated experimentally using the transmission of an ultrasonic wave through the flow. The analysis of the wave-front distortion provides noninvasive measurements of the vortex circulation and size. The latter is estimated by analytical calculations of the scattering of a plane wave by a vorticity filament. The case of a cylindrical wave incident on a vortex leads to similar experimental results which are successfully compared to a parabolic equation simulation. Finally, a finite-difference code based on linear acoustics is presented, in order to investigate the structure of the scattered wave numerically.

Irregular scattering of acoustic rays by vortices

The scattering of high-frequency sound wave, under geometrical acoustic approximation, by three stationary vortices in two dimensions is investigated. For a sufficiently high Mach number of the vortex flow, the scattering of sound rays becomes irregular, displaying a new example of chaotic scattering for a time-reversal breaking system. The fractal dimension, as well as the unstable and stable manifolds of the scattering dynamics, is presented.

A placebo-controlled study of the effects of intravenous Buflomedil on foot skin microcirculation in patients with severe intermittent claudication

Buflomedil hydrochloride (Buflomedil), a vasoactive drug, has been proven to improve pain-free walking distance in patients with peripheral arterial occlusive disease stage II of the lower extremities. In the present double-blind, randomized study, resting skin flux motion activity and skin flux response to a local heat stress at the hallux were assessed by laser Doppler fluxmetry (LDF) in claudicants. Twenty of 39 enrolled patients with severe intermittent claudication received a daily intravenous dose of 400 mg Buflomedil, and the other 19 patients received 0.9% NaCl as placebo over a 5-day period. Before treatment mean LDF skin resting flux, flux frequency, and flux amplitude were 2 +/- 0.8 Arbitrary Units (AU), 8.4 +/- 0.5 cycles per minute (c/min), and 0.12 +/- 0.01 AU, respectively in the Buflomedil group, and 2.3 +/- 0.3 AU, 8.7 +/- 0.7 c/min, and 0.13 +/- 0.02 AU in the placebo group (NS). Also the response to heat stress was identical in both groups: a slow initial increase of skin flux, followed by a reflex reduction, with a maximal initial flux increase to 138 +/- 12% of the resting value in the Buflomedil group, and 155 +/- 16% in the placebo group (NS). After 5 days of treatment the mean LDF skin resting flux, flux frequency, and flux amplitude were unchanged in both patient groups. The response to heating on the contrary was dramatically enhanced in the Buflomedil group (226 +/- 33%), against that in the placebo group, which remained unchanged (144 +/- 13%) after 3 minutes (P < 0.05), while after reflex reduction the flux in the Buflomedil group remained stable at 200% of resting value during further heating and was only approximately 140% in the placebo group (P < 0.05). It is concluded that Buflomedil, administered in a daily intravenous dose of 400 mg, does not alter the mean LDF skin flux and flux motion at the hallux in claudicants in resting conditions. Local skin heating on the contrary provokes a significant LDF-monitored skin flux increase, suggesting an improved capacity of cutaneous microvessel perfusion in stressed conditions.

[Effect of smoking on blood rheology]

The aim of this study was to compare the effects of cigarette smoking on biologic and rheologic tests, chiefly on the red blood cells (RBC) in measuring the deformability by the Cell Transit Analyser (CTA) and their aggregation by using an ultrasonic interferometry method based on A-mode echography allowed for the measurement of the accumulation rate of particles in a solid plate which is related to their sedimentation rate (Echo-Cell). Nine male smoker subjects with a high nicotine addiction measured by Fagerström questionnaire (> 8) and level of carbon monoxide (CM) in the breathed out air (> 20 ppm), have been compared with ten healthy no-smoker volunteers (CM < 3 ppm). One smoker has been eliminated of statistic evaluations because his glucose level showed a diabetes (10.5 mmol/l). A nailfold capillaroscopy performed in all subjects has eliminated the patterns of latent vasculitis or scleroderma. RBC and platelets counts, hemoglobin, ionogram, gamma GT, ASAT, ALAT, uric acid, total cholesterol and glucose levels were not significantly different between the two groups. On the other hand, in the smoker group, white blood cells count, serum triglycerides and especially fibrinogen values were higher than in the non-smoker's group. RBC sedimentation rate was normal in the two groups but was higher in smoker's group too. Without consumption of alcohol, the mean RBC volume was more important in smokers (91.9 +/- 1.2 versus 87.5 +/- 0.4, p = 0.003). Rheologic tests were more pathologic in smokers. The transit time or RBC by CTA was longer than in control group (1.6 ms +/- 0.02 versus 1.2 +/- 0.05, p = 0.0003). Echo-Cell technic showed a number and size of RBC aggregates more important with a rate of speed of accumulation higher than in the control group. These results demonstrated the toxic effects of smoking alone on blood toward a propensity for thrombotic status.

The pathophysiological mechanism of fluid retention in advanced cancer patients treated with docetaxel, but not receiving corticosteroid comedication

AIMS

Fluid retention is a phenomenon associated with taxoids. The principal objective of this study was to investigate the pathophysiological mechanism of docetaxel-induced fluid retention in advanced cancer patients.

METHODS

Docetaxel was administered as a 1 h intravenous infusion every 3 weeks, for at least 4-6 consecutive cycles, to patients with advanced breast (n = 21) or ovarian (n = 3) carcinoma, who had received previous chemotherapy, 21 for advanced disease. Phase II clinical trials have shown that 5 day corticosteroid comedication, starting 1 day before docetaxel infusion, significantly reduces the incidence and severity of fluid retention. This prophylactic corticosteroid regimen is currently recommended for patients receiving docetaxel but was not permitted in this study because of its possible interference with the underlying pathophysiology of the fluid retention.

RESULTS

Fluid retention occurred in 21 of the 24 patients but was mainly mild to moderate, with only five patients experiencing severe fluid retention. Eighteen patients received symptomatic flavonoid treatment, commonly prescribed after the last cycle. Specific investigations for fluid retention confirmed a relationship between cumulative docetaxel dose and development of fluid retention. Capillary filtration test analysis showed a two-step process for fluid retention generation, with progressive congestion of the interstitial space by proteins and water starting between the second and the fourth cycle, followed by insufficient lymphatic drainage.

CONCLUSIONS

A vascular protector such as micronized diosmine hesperidine with recommended corticosteroid premedication and benzopyrones may be useful in preventing and treating docetaxel-induced fluid retention.

[Obstacles to stopping smoking among patients with vascular risk]

Despite the risk, smoking has only slightly decreased and the percentage of heavy smokers increases. The reason for the paradoxical situation has now been identified in more than 95% of the cases and is due to behaviour amplified by a pharmacological dependence on nicotine. The psycho-active effects of nicotine binding to nicotine receptors in the brain, produce a quasi constant physical dependence and a psychic dependence in certain smokers.

Effect of buflomedil on the neutrophil-endothelial cell interaction under inflammatory and hypoxia conditions

In hypoxia/ischaemia and ischaemia/reperfusion, human neutrophils are likely to play an important role in the development of endothelial cell damage in the microcirculation. Buflomedil hypochloride improves the capillary perfusion in such related situations, evoking a possible effect upon neutrophils. Using in vitro models of cell adhesion, buflomedil decreased 100% of histamine related neutrophil adhesion (flow system) and partially inhibited adhesion after IL-1-4 hours (flow and stable systems). Hypoxia induced neutrophil adhesion (4 hours) was also reduced by buflomedil, which decreased the expression of P-selectin at the surface of endothelial cells. As adenosine (NECA) exhibited the same results in hypoxia and theophylline inhibited them, such results support an action of buflomedil presumably via the A2 receptor.

Dialysis clearance of buflomedil in hemodialysed patients

Buflomedil (CAS 55837-25-7, Fonzylane) is a peripherally vasoactive drug which improves nutritional blood flow in ischaemic tissue of patients with peripheral vascular disease by the way of an increase of perfusion in the microcirculation. Ten hemodialysed patients with chronic renal failure treated with intravenous infusion of 400 mg of buflomedil during 4 h of dialysis were included in the first study. This study was carried out to determine the dialysis plasma clearance and the amount of drug dialysed during the first intravenous administration of buflomedil. The dialysis clearance calculated from the amount recovered in dialysate was (mean +/- SD) 25.4 +/- 25.6 ml/min. The drug recovery resulting from hemodialysis represented a small fraction of the dose (< or = 5%). A second study was carried out to determine the accumulation of buflomedil in chronic hemodialysed patient. The drug concentration were measured before and at the end (4 h) of the infusion of buflomedil in six other patients maintained on intermittent hemodialysis (3 per week) for 4 weeks. The average Cmin and Cmax were stable during the 12 successive dialyses (mean +/- SD intervals were between 0.36 +/- 0.53 and 0.66 +/- 0.79 microgram/ml for Cmin and between 5.15 +/- 2.19 and 7.37 +/- 1.76 micrograms/ml for Cmax), showing no trend of accumulation of buflomedil. These results agree with the pharmacokinetics of the drug which is mainly metabolised in the liver and has a low renal clearance. Dialysis is unable to modify significantly the plasma concentration of the drug in regularly dialysed patients.

Improvement of microcirculation abnormalities in sickle cell patients upon buflomedil treatment

The efficacy of the vasoactive compound buflomedil on previously described microcirculation abnormalities observed in sickle cell disease (SCD) was investigated using bulbar conjunctival angioscopy (BCA) and laser doppler flux metering. Eleven sickle cell disease patients at steady state were studied in a double-blind randomized parallel-versus-placebo study (5 patients were given placebo and 6 patients received 600 mg buflomedil per day for 21 days after a washout period of 15 days). The blood flux score measured by BCA improved, indicating reduced entrapment of sickle red blood cells. There was a striking improvement of reactive alterations of vasomotion in the buflomedil group, particularly in postocclusive reactive hyperemia; the half return time was also significantly reduced. These results encourage further studies with buflomedil to investigate long-term effects of this compound in SCD, potential prevention of acute vaso-occlusive events, and degenerative complications.

Observations on experimental flow-through venous flaps

The aim of this work was to compare the survival of an arteriovenous island flap with the survival of an island flap with a flow-through venous supply. Our experimental studies were performed on 95 Wistar rats randomised into six groups: Group 1: Indian ink injection of flow-through venous flaps with capillary network; Group 2: control group deprived of vascularisation; Group 3: control group with arteriovenous supply; Group 4: flow-through venous flaps of group 1; Group 5: epigastric flow-through venous flaps with a main venous trunk; Group 6: histological examination of flow-through venous flaps. The survival of flaps was monitored by direct examination, histological examination, capillaroscopy, and laser Doppler. Three out of 50 flow-through venous flaps survived. There was a statistically significant difference in the delay of clinical necrosis between the composite non vascularised free grafts (2.8 +/- 1.2 days) and the flow-through venous flaps (4.1 +/- 1.3 to 4.9 +/- 1.1 days depending on the type of flap). A 20% decreased venous blood flow was observed in the flow-through venous flaps.

Comparative evaluation of laser Doppler flux metering, bulbar conjunctival angioscopy, and nail fold capillaroscopy in sickle cell disease

Eleven adult patients with stable sickle cell disease (SCD) were investigated twice at a 15-day interval by nail fold capillaroscopy (NFC), bulbar conjunctival angioscopy (BCA), and laser Doppler flux metering (LDF). NFC and BCA are essentially descriptive. NFC revealed, in some patients, network patterns similar to those observed in vasculitis. BCA provides a reproducible method for the visual assessment of the microcirculation. When using a rating scale with five criteria it identified abnormalities related to both altered red blood cells and vascular morphology but failed to discriminate between patients. LDF, in contrast, is quantifiable and showed reproducible characteristic reactive alterations of vasomotion in response to ischemia after 3 min of occlusion. The SCD patients had a delayed response, best measured by the recovery half time, which was four to five times longer than that of normal subjects. In addition, the cold provocative test was always abnormal, as evidenced by a significant drop in the contralateral flux, and was often poorly tolerated. The observed trends suggest that BCA and LDF should be performed in a large cohort of patients, both in the steady state and during vasoocclusive crises. These methods seem to be useful complementary noninvasive procedures to cellular and clinical evaluation monitoring for therapeutic trials.

[Cutaneous microvascular flow studied by laser-Doppler. A study of 100 healthy volunteers]

Cutaneous capillary flow (tip of the 3rd right finger) was measured with a laser Doppler (Periflux, Perimed), in 100 healthy volunteers without any history of hypertensive or vasospatic diseases, 15 females smoke and were taking contraceptive drugs. Smokers (n = 16 M, 25 F) stopped smoking 3 hours before the study. Basal laser Doppler flux (BLDF), amplitude of vasomotion waves (AV), post-occlusive reactive hyperthermia peakflow (F Max), difference between BLDF and F Max (delta F Max), time to reach 50 percent of the initial value (t1/2 r) and total recovery (tr), t Max (peak of over-shoot) and t/2 over shoot were measured. F Max after heating stimulus (40 degrees) (f Max H), delta F Max H (difference between BLDF and F Max H) and t Max H time (mn) to reach F Max H were measured before a cold stimulus was applied. Results were expressed in arbitrary units (cvolts), BLDF showed inter-individual variation but was reproducible over months in the same subject. The basal flux was statistically different between males (352.7 +/- 21.7) and females (249.6 +/- 22.4). Spontaneous vasomotion waves and different times (in sec.) to reach the peak after three minutes of arterial occlusion could be measured with this technique. These normal range of values can allow comparison and assessment of variations in pathological conditions, mainly Raynaud's phenomenon, high blood pressure, diabetes, smokers, sickle-cell anemia. Acute pharmacological tests can be carried out with drugs showing specific action on microcirculation and spontaneous vasomotion.

In vitro studies of the effect of buflomedil on platelet responsiveness

The effect of buflomedil (Fonzylane; Laboratoire Lafon, Maisons-Alfort, France) on platelet function, a drug used clinically for the treatment of peripheral vascular diseases, was investigated in vitro. The compound significantly inhibits epinephrine-induced aggregation at the micromolar level. At higher doses (approximately 1 mM), a weak inhibition of ADP- and collagen-induced aggregation was observed; at these concentrations, buflomedil inhibits granular secretion and the interaction of fibrinogen with its receptor on platelet. Further investigations indicate that the drug affects calcium uptake at the membrane level and inhibits the binding of [3H]-yohimbine to the same extent as observed with phentolamine. The IC50 determined from competition binding assays was 1 +/- 0.5 microM. This value was consistent with the affinity constant approximated for the binding of [3H]-buflomedil to non-stimulated platelets. Taken-together, these results indicate that the vasoactive compound buflomedil is a weak antiaggregating agent which exhibits alpha 2-adrenergic antagonistic properties.

[Laser-Doppler velocimetry: a new technic for evaluating of microcirculation. A reproducibility study]

The recent introduction of the laser-Doppler technique to measure capillary flow velocity offers new prospects in clinical pharmacology. We used this technique in 45 healthy volunteers (23 women and 22 men) to study the capillary network at the distal end of the third finger of the non-dominant hand. Each subject was tested twice at one-week interval. The results showed that the data concerning flow velocity and amplitude were perfectly reproducible, under standard conditions, after one week in each subject. No correlation was found between the microcirculation parameters and the subjects age, weight and, paradoxically, blood pressure and heart rate. We would suggest that this innocuous, sensitive and reproducible technique be used more systematically to evaluate the haemodynamic effects of drugs on capillary blood flow.