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A Raynaud

Publications and source records attributed to A Raynaud.

At least 37 records · Page 2Linked to original sources
PubMed1997

There is no highly conserved embryonic stage in the vertebrates: implications for current theories of evolution and development.

Embryos of different species of vertebrate share a common organisation and often look similar. Adult differences among species become more apparent through divergence at later stages. Some authors have suggested that members of most or all vertebrate clades pass through a virtually identical, conserved stage. This idea was promoted by Haeckel, and has recently been revived in the context of claims regarding the universality of developmental mechanisms. Thus embryonic resemblance at the tailbud stage has been linked with a conserved pattern of developmental gene expression - the zootype. Haeckel's drawings of the external morphology of various vertebrates remain the most comprehensive comparative data purporting to show a conserved stage. However, their accuracy has been questioned and only a narrow range of species was illustrated. In view of the current widespread interest in evolutionary developmental biology, and especially in the conservation of developmental mechanisms, re-examination of the extent of variation in vertebrate embryos is long overdue. We present here the first review of the external morphology of tailbud embryos, illustrated with original specimens from a wide range of vertebrate groups. We find that embryos at the tailbud stage - thought to correspond to a conserved stage - show variations in form due to allometry, heterochrony, and differences in body plan and somite number. These variations foreshadow important differences in adult body form. Contrary to recent claims that all vertebrate embryos pass through a stage when they are the same size, we find a greater than 10-fold variation in greatest length at the tailbud stage. Our survey seriously undermines the credibility of Haeckel's drawings, which depict not a conserved stage for vertebrates, but a stylised amniote embryo. In fact, the taxonomic level of greatest resemblance among vertebrate embryos is below the subphylum. The wide variation in morphology among vertebrate embryos is difficult to reconcile with the idea of a phyogenetically-conserved tailbud stage, and suggests that at least some developmental mechanisms are not highly constrained by the zootype. Our study also highlights the dangers of drawing general conclusions about vertebrate development from studies of gene expression in a small number of laboratory species.

Amphibians↗
PubMed1997

Value of Doppler ultrasound for the diagnosis of renal artery stenosis in children.

To evaluate the reliability of Doppler ultrasonography (US) in identifying children with renal artery stenosis (RAS) among those with hypertension, we compared Doppler US results in 22 hypertensive children (mean age 8.9 +/- 4.3 years), with (13 cases) and without RAS at angiography, and in 33 normotensive children (mean age 8.8 +/- 4.7 years). We observed 2 false-negatives and 2 false-positives with Doppler US. Of the 2 false-negative diagnoses, I had RAS on an accessory renal artery located behind a normal upper polar artery and the other was observed in a patient with bilateral multiple stenosis of the very distal segments of renal arteries. The 2 false-positive diagnoses were due to sinuous left renal artery and to technical reasons, respectively. In another patient, Doppler US showed a tight RAS, while arteriography was normal. RAS was subsequently confirmed by a second arteriography. Peak systolic velocity values of Doppler US were significantly higher in patients with proven angiographic RAS (3.44 +/- 0.66 m/s) than in hypertensive patients with normal renal arteries at angiography (0.99 +/- 0.35 m/s, P < 0.0001) and normotensive healthy children (1.04 +/- 0.23 m/s, P < 0.0001). With the use of multiple views, and the experience acquired with practice, false-negatives or false-positives due to the geometry of the renal artery can be avoided. Nevertheless, very distal stenosis can be missed by Doppler US.

Angiography↗
PubMed1997

[Renal stenosis in hypertensive children. Doppler/arteriographic correlation].

To evaluate the reliability of Doppler-ultrasonography in identifying children with renal artery stenosis among those with hypertension, we compared Doppler ultrasonography results in 29 hypertensive children (mean age: 8.3 +/- 4.7 years) with angiography. Doppler-ultrasonography and arteriography were performed within a period less than two months. First, we established normal values in 40 normotensive children (mean age: 8.4 +/- 4.5 years). The diagnosis of renal artery stenosis was settled when maximal systolic velocities where > or = to 1.70 m.s-1. Peak systolic velocities values of Doppler-ultrasonography were significantly higher in patients with proven angiographic renal artery stenosis (3.56 +/- 0.70 m.s-1) than in hypertensive patients with normal renal arteries at angiography (1.02 +/- 0.29 m.s-1, p < 0.0001), and than in normotensive healthy children (1.05 +/- 0.33 m.s-1, p < 0.0001). We observed 3 false negative and 2 false positive diagnoses with Doppler-ultrasonography. Of the 3 false negatives, one had a stenosis on a right and posterior segmental artery and the other had bilateral and multiply intra-renal artery stenosis with few hemodynamic significance. The 2 false positives were due to a sinuous main renal artery and to a technical mistake, respectively. In another patient, Doppler-ultrasonography revealed a tight main renal artery stenosis, not detected by arteriography. Renal artery stenosis was subsequently confirmed by a second arteriography. Our results showed a sensitivity of 88%, a specificity of 93%, a positive predictive value of 92% and a negative predictive value of 89%, demonstrating the reliability of Doppler-ultrasonography for the diagnosis of renal artery stenosis in hypertensive children. With the use of a rigorous methodology and the increasing experience of the operators, diagnostic errors of renal artery stenosis are currently avoidable. Nevertheless, it is not excluded that intra-renal artery stenosis with few hemodynamic significance might be missed by Doppler-ultrasonography.

Adolescent↗
PubMed1996

[Non-surgical treatments of renal artery stenoses].

Management of patients with renal artery stenoses is aimed at normalizing or reducing blood pressure and correcting or preventing reduced glomerular filtration. The results of renal revascularization have been documented mainly in retrospective, uncontrolled reports in which blood pressure improvement was overestimated due to the placebo effect and optimization of drug treatment, the latter being frequently required despite adequate revascularization. In an overview of 10 series reporting blood pressure outcome following percutaneous angioplasty, cure rates were 50% in patients with fibrodysplastic stenosis but only 19% in those with atherosclerotic stenosis. The literature on revascularization of atherosclerotic stenosis with progressive renal failure shows that 55% of patients have improved renal function following surgery and 41% following angioplasty. Mortality is 6 and 5% respectively. The first controlled trials comparing revascularization to medical treatment in renal artery stenosis have recently been published. In a prospective randomized trial, Weibull et al. compared percutaneous angioplasty and surgery in 58 patients with unilateral atherosclerotic stenosis. Although 17% of the patients initially treated with angioplasty required subsequent surgery, blood pressure, renal function and renal artery patency rate did not differ between angioplasty and surgery 24 months after treatment. A Scottish group reported a prospective randomized trial of percutaneous angioplasty vs. medical therapy in patients with bilateral or unilateral atherosclerotic stenosis. In the bilateral group (n = 28), the drop in systolic pressure was significantly larger following angioplasty than following medical therapy, but diastolic pressure and creatinine did not differ after 24 months. In the unilateral group (n = 27), there were no differences in blood pressure or creatinine levels following angioplasty or medical therapy. Several randomized trials comparing angioplasty and conservative treatment or angioplasty and stent placement in patients with renal artery stenosis and normal or reduced renal function are currently underway. They should provide additional information regarding the risk/benefit ratio of these procedures.

Angioplasty, Balloon↗
PubMed1996

Percutaneous treatment of acute iliac artery injury after intraaortic balloon counterpulsation.

We report on a novel approach to correcting iliac artery occlusions caused by aortic counterpulsation. Two patients who had leg ischemia after retrieval of an intraaortic balloon pump underwent angiograms that showed occlusion of the right external iliac artery because of dissection (one case) or thrombosis (one case). Percutaneous self-expandable stents were implanted in the occluded vessels, and they fully restored normal iliac patency with no complications and satisfactory midterm follow-up results. We conclude that iliac artery occlusion induced by aortic counterpulsation can be safely treated by implanting self-expandable stents in cases of acute iatrogenic dissection.

Acute Disease↗
PubMed1996

[Spontaneous spinal epidural hematoma: 2 cases].

The authors report on two cases of spontaneous spinal epidural hematomas with atypical subacute clinical presentation and good recovery after surgical treatment. Etiologies, physiopathology, early diagnosis and treatment are considered through a brief review of the literature.

Adult↗
PubMed1995

[Fibroblast growth factors (FGF-2) and delayed involution of the posterior limbs of the slow-worm embryo (Anguis fragilis, L.)].

Administration at doses of 1,800 ng to 6,200 ng of basic fibroblast growth factor (bFGF), around the posterior limb buds of young slow-worm (Anguis fragilis, L.) embryos developing in cultured eggs has, after 4 to 6 days, in several embryos (10 among 15, treated at stage of allantoic bud, from 3 to 9 mm long), delayed the involution of these posterior limbs: their anlagen are larger than the control ones and histological examination shows an increase, between 20% and 30%, of cell density in the mesodermal component of the limb bud. These results bring into light the possibility to control, to some degree, the regressive evolution of the limbs.

Animals↗
PubMed1995

[Drug thrombolysis and mechanical recanalization in recent femoro-popliteal arterial occlusions].

Acute femoro-popliteal occlusions (native arteries or bypass grafts) were treated by medical and surgical treatment. Despite improvement in surgical technique, patient mortality was high and limb loss remained frequent. Percutaneous endoluminal treatment of such lesions is feasible using in situ fibrinolysis and/or thromboaspiration singly or in association with balloon angioplasty. Those techniques are effective and are currently the first intention treatment of many of those acute femoro-popliteal occlusion. The advantages and disadvantages of those techniques are discussed, as well as their respective indications, and particularly their place compared to surgical techniques. New devices such as mechanical thrombectomy may increase effectivity and indications of endovascular treatment however such devices need to be better evaluated.

Arterial Occlusive Diseases↗
PubMed1995

[Fibroblast growth factor (FGF-2) and delayed involution of the posterior limbs of the slow-worm embryo (Anguis fragilis, L.)].

Administration at doses of 1,800 ng to 6,200 ng of basic fibroblast growth factor (bFGF), around the posterior limb buds of young slow-worm (Anguis fragilis, L.) embryos developing in cultured eggs has, after 4 to 6 days, in several embryos (10 among 15, treated at stage of allantoic bud, from 3 to 9 mm long), delayed the involution of these posterior limbs: their anlagen are larger than the control ones and histological examination shows an increase, between 20% and 30%, of cell density in the mesodermal component of the limb bud. These results bring into light the possibility to control, to some degree, the regressive evolution of the limbs.

Animals↗
PubMed1994

[Calcitonin gene-related peptide (CGRP)].

Calcitonin gene-related peptide (CGRP), a 37 amino acid peptide resulting from the specific maturation processes of calcitonin gene products, was discovered in 1982. Its messenger RNA was isolated from a calcitonin cancer in rats similar to the human thyroid medullary carcinoma. CGRP is closely related to calcitonin and amylin, and to a lesser extent, to the region coding for the alpha chains of relaxins, insulin and insulin growth factors. In thyroid C cells, calcitonin itself is the major gene product, but CGRP is predominant in the central and peripheral nervous system. CGRP is found in most all tissues and is considered to be a neuromediator of particular importance in the cardiovascular system. CGRP is a powerful endogenous vasodilator in man; plasma concentrations of 56 pmol/l (slightly above physiological levels) provoke flush, hypotension and secondary catecholamine release and subsequent tachycardia. Intravenous injections lead to systemic vasodilatation and redistribution of blood flow to the skin, the brain, and probably the splanchnic territory. It has been suggested that CGRP plays a role in blood pressure modulation in certain pathological conditions. CGRP level is decreased in hypertension and increased in septic shock. In patients with terminal renal failure, CGRP is correlated with excess volaemia. It could affect blood pressure by redistributing blood flow, interacting with the renin-angiotensin system or by inhibiting aldosterone secretion. CGRP may also play a role in modulating cutaneous vascular constriction in Raynaud's syndrome and cerebral vascularization in patients with migraine or meningeal hemorrhage subsequent to rupture of cerebral aneurisms. CGRP increases arterial flow in the cavernous body. Coronarian vascular tone and cardiac performance (positive chronotrope and inotrope effects) are improved. CGRP has also been studied in connection with glucose metabolism and may have other endocrine effects. Finally, CGRP increases electrolyte and water flow in the colon and its bronchoconstrictor effect could be implicated in asthma. The clinical significance of plasma CGRP is not yet known although it may be a marker of poor prognosis in thyroid medullary cancer. Recent studies suggest that CGRP could be a useful therapeutic agent in severe Raynaud syndrome, impotency, ischaemic neurological lesions due to ruptured aneurisms and in severe heart failure.

Amyloid↗
PubMed1994

Evidence for the effect of antibodies to TSH receptors on the thyroid ultrasonographic volume in patients with Graves' disease.

OBJECTIVE: It has been demonstrated that antibodies (Ab) to thyroid-stimulating hormone receptors (R), which stimulate the thyroid gland, induce hyperthyroidism in patients with Graves' disease. Furthermore, it has been shown in thyroid cells in culture that thyroid-stimulating hormone receptor Ab acts through the adenosine 3', 5'-monophosphate pathway which stimulates both thyroid hormonogenesis and growth. We investigated the relations between thyroid autoimmunity expression and thyroid ultrasonographic parameters or thyroid hormonal status in patients with Graves' disease. PATIENTS: A prospective study of 53 consecutive patients referred with untreated Graves' disease. MEASUREMENTS: Measurements were made of serum TSH-R, peroxidase (TPO) and thyroglobulin (Tg) Ab and basal plasma free T4 (FT4), free T3 (FT3) and TSH. Thyroid morphological characteristics (number and total volume of nodule(s), total volume of lobes and total thyroid volume) were determined by ultrasonography. RESULTS: There were significant correlations (P < 0.001) between TSH-RAb levels and FT4 values (r = 0.48) or FT3 levels (r = 0.46). Likewise, significant correlations were found between TSH-RAb levels and total lobe volume values (r = 0.56, P < 0.001), total nodular volume values (r = 0.59, P < 0.01) or total thyroid volume values (r = 0.63, P < 0.001). By contrast, no correlation was found between TSH-RAb levels and the number of nodules or between any of the ultrasonographic parameters and TPOAb levels or TgAB values. CONCLUSIONS: This study demonstrates, in vivo, that TSH receptor antibodies modulate the thyroid ultrasonographic extranodular and nodular volumes in patients with Graves' disease.

Adult↗
PubMed1994

Stenoses of renal branch arteries in fibromuscular dysplasia: results of percutaneous transluminal angioplasty.

PURPOSE: To evaluate percutaneous transluminal renal angioplasty (PTRA) in the treatment of renal branch artery stenoses caused by fibromuscular dysplasia. MATERIALS AND METHODS: The authors retrospectively studied the files of 20 consecutive hypertensive patients with 25 branch artery stenoses associated with 10 main renal artery lesions. Results at clinical and angiographic follow-up were assessed by means of life-table analysis. RESULTS: PTRA was technically successful in 21 of the 25 renal branch artery stenoses (84%). One of the technical failures was treated by means of selective embolization. Nine of the 10 associated main renal artery lesions were successfully dilated, and the 10th was improved. Immediately after PTRA, at 6-month follow-up, and at long-term follow-up, 70%, 76%, and 68% of the patients, respectively, were cured and 25%, 24%, and 16% were improved. Stenosis recurred in 9% of the branch arteries and was associated with clinical relapse; these arteries were redilated, and all patients were considered cured at the second 6-month follow-up. CONCLUSION: PTRA should be considered the first-line treatment for hypertension due to renal branch artery stenosis in fibromuscular disease.

Adolescent↗
PubMed1994

[Percutaneous endoluminal angioplasty of the transplanted kidney. Long-term follow-up].

A hundred and ninety five percutaneous transluminal angioplasty (PTA) of a renal transplant artery were attempted before january 1st, 1990 in 151 patients. Analysis of the series was essentially based on follow-up after PTA. PTA was initially successful in 85% of the patients. Restenoses occurred in 30% of the patient. They were usually amenable to repeat PTA. Restenosis rate after repeat PTA was of 26%. The five year secondary patency rate of the renal artery was over 85%. After a successful PTA, the blood pressure, the number of antihypertensive drug per patient and serum creatinine returned to a level close to their basal value within few days and remained stable long. After an immediate failure of PTA, secondary patency rate of the renal transplant artery was over 80% at one year. Blood pressure returned to a level close to its basal value. But, that improvement was slower (1 to 6 months) and antihypertensive drug regimen and serum creatinine remained stable. We conclude that PTA is an effective treatment at long term of hypertension and of decline in renal function due to stenoses of renal transplant arteries. However PTA carried some risks and should be attempted only stenoses of renal transplants arteries cause, severe hypertension resisting to medical therapy or decline in renal function.

Adult↗
PubMed1994

[Ostial stenosis of the renal arteries: treatment by angioplasty].

In a series of 50 patients (22 females, 28 males); 52 ostial renal artery stenoses were treated by transluminal balloon angioplasty. The mean age of patients was 66 years (range 36-81); mean arterial pressures were 181 mmHg for the systolic pressure and 87 mmHg for the diastolic pressure. The mean level of serum creatinine was 179 mumol/l +/- 128. An immediate success was obtained in 86.5% (residual stenosis of 26%). There were 7.6% of immediate failures and 13.5% of residual stenosis above 50%. Mortality within 1 month was observed in 2 patients. Morbidity included one aortic dissection and 5 cholesterol embolisms. After a mean follow-up of 10 months, 78% of the series were controlled: 66.6% exhibited a residual stenosis below 50%, 25.9% had restenosis and 7.4% had an occlusion of the renal artery. Since patients with ostial renal artery stenosis constitute a high surgical risk group, transluminal balloon angioplasty might be considered as an acceptable and safe alternative treatment.

Adult↗