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Biomedical subjects

N David

Publications and source records attributed to N David.

At least 37 records · Page 2Linked to original sources
PubMed1998

Clinical and scintigraphic comparison of silicone and polyvinylpyrrolidone coated silicone perforated plugs.

BACKGROUND/AIM: Isolated stenosis of the lacrimal punctum is a frequent cause of epiphora. Treatment relies on surgical opening or dilatation with bi- or monocanalicular prosthesis. Recently, silicone perforated punctum plugs (PPP) were proposed. The drawback with these silicone PPP was that secretions accumulate in the central orifice blocking the spontaneous flow of tears. A modification of the surface of the PPP using polyvinylpyrrolidone (PVP) was thus proposed. The aim was to compare silicone PPP with new PVP surface treated PPP. METHODS: A prospective study was conducted of 20 patients with dilatable stenosis of the lacrimal puncta who developed epiphora. Epiphora, tolerance, implantation of the PPP, and lacrimal drainage were evaluated using scintigraphy of the lacrimal ducts. RESULTS: The raw data and statistical analysis showed evidence of a superior performance of PVP surface treated PPP. CONCLUSION: Long term evaluation of the advantages or risks of PVP plugs and comparison with microsurgical punctoplasty are warranted.

Drainage↗
PubMed1997

[Disproportion in diameter of the cardiac chambers and great arteries in the fetus. Contribution to the prenatal diagnosis of coarctation of the aorta].

The aim of this study was to identify simple echocardiographic criteria suggesting the presence of coarctation of the aorta in the antenatal period. This was a retrospective cooperative study of 43 cases of foetal echocardiography referred to a paediatric cardiologist for abnormal dimensions of the left cardiac chambers and vessels compared with 102 control foetus. Eighteen (41.8%) had abnormalities of the aortic arch at birth. Thirteen of the 18 (72%) neonates had aortic arch abnormalities when disequilibrium with a small left heart was observed before 25 weeks amenorrhea. The ratio between the right and left ventricular dimensions was abnormally high in foetus with functional disequilibrium similar to the foetus with coarctation: the difference between the two groups was not significant. The ratio of pulmonary artery to aortic dimension was higher in the foetus with coarctation of the aorta than with functional disequilibrium. The difference was significant: p < 0.0001. The diameter of the aortic arch in foetus with a future coarctation was much smaller than the mean of the controls, except in 4 cases. The majority of the foetus without left-sided obstacles at birth had normal aortic arches. An early disequilibrium, a high pulmonary artery/aortic ratio and the small size of the aortic ischmus were the main elements suggestive of abnormalities of the aortic arch, especially in the early prenatal period.

Aorta, Thoracic↗
PubMed1996

[Late supraventricular arrhythmia complicating Fontan or cavopulmonary type procedures. Apropos of 7 cases].

The authors report 7 cases of late arrhythmias after atriopulmonary (5 cases) or total cavopulmonary (2 cases) bypass procedures. There were 6 cases of atrial flutter and one case of atrial tachycardia. The condition presented with cardiac failure in 5 cases. In 2 patients, atrial flutter caused syncope or dizziness. The arrhythmia was reduced by atrial stimulation (3 cases) or by cardioversion (1 case). Prevention of recurrence with oral amiodarone was effective in all cases but was responsible for secondary effects in 4 cases. In one patient, recurrence of atrial flutter was complicated by right atrial thrombosis with cerebral embolism. Five patients were reoperated after cardiac catheterisation and angiography. Surgery consisted of resection of a stenosis of the anastomosis in one case, and the transformation of atriopulmonary anastomosis into a total cavopulmonary bypass because of a very dilated right atrium without stenosis in 4 patients. The immediate postoperative period was complicated by a recurrence of the arrhythmia in 3 children not treated by antiarrhythmic therapy. At long-term, one patient died 6 months after withdrawal of amiodarone therapy of recurrence of atrial flutter. Five of the 6 survivors are treated with amiodarone or a betablocker; 3 have had pacemaker implantation for severe bradycardia. Late atrial arrhythmias complicating atrio- and cavopulmonary bypass procedures carry a risk of cardiac failure and sudden death. When diagnosed, the patient should be investigated for stenosis of the anastomosis but severe dilatation of the right atrium is often the only finding. After restoration of sinus rhythm, maintenance antiarrhythmic therapy should be continued indefinitely.

Amiodarone↗
PubMed1995

[Hypoplasia of abdominal aorta, rare cause of hypertension in childhood].

BACKGROUND: The majority of children with secondary hypertension have a renal abnormality or renovascular lesions. Coarctation of the aorta is also a classical cause, rarely located to the abdominal aorta. CASE REPORTS: Two girls, 11 and 12 years-old, were suspected of having recent sustained hypertension. Pulsed-wave doppler ultrasonography and angiography showed abdominal aortic hypoplasia associated with renal artery stenosis, unilateral in one patient and bilateral in the other. Both patients became normotensive 10 and 18 months, respectively, after corrective vascular surgery. CONCLUSION: Examination of the abdominal part of the aorta is mandatory in all patients with hypertension.

Aorta, Abdominal↗
PubMed1994

A comparison of flushing solutions for liver procurement using an isolated perfused porcine model.

There is no agreement on the best technique of in situ flushing of livers prior to storage. In order to study this, porcine livers were stored in the University of Wisconsin (UW) solution for 18 h and then assessed using an isolated perfused porcine model. Livers flushed in situ with UW solution were compared to livers flushed with a non-preservation solution (Hartmann's solution). No statistically significant differences could be found in bile production (18.7 +/- 4.4 vs 17.9 +/- 3.8mL/1000 g per 2 h), aspartate amino-transferase (AST) levels in the perfusate after 2 h of isolated perfusion (687 +/- 101 vs 724 +/- 114 U/L), potassium levels in the perfusate after 2 h on the circuit (5.4 +/- 1.5 vs 5.5 +/- 2.3 mmol/L), weight gain (15.2 +/- 3.7 vs 17.1 +/- 4.0%) or platelet sequestration (41.6 +/- 11.7 vs 37.4 +/- 9.8%) between livers flushed with UW solution as opposed to those flushed with Hartmann's solution, respectively. Of overriding importance was the solution in which the liver was stored, reconfirming the superiority of UW solution over an extracellular solution for preservation. If extrapolated to the clinical situation, these findings would have substantial cost-saving implications.

Adenosine↗
PubMed1990

Distinct sequence elements control the specificity of G protein activation by muscarinic acetylcholine receptor subtypes.

Relatively little is understood concerning the mechanisms by which subtypes of receptors, G proteins and effector enzymes interact to transduce specific signals. Through expression of normal, hybrid and deletion mutant receptors in Xenopus oocytes, we determined the G protein coupling characteristics of the functionally distinct m2 and m3 muscarinic acetylcholine receptor (mAChR) subtypes and identified the critical receptor sequences responsible for G protein specificity. Activation of a pertussis toxin insensitive G protein pathway, leading to a rapid and transient release of intracellular Ca2+ characteristic of the m3 receptor, could be specified by the transfer of as few as nine amino acids from the m3 to the m2 receptor. In a reciprocal manner, transfer of no more than 21 residues from the m2 to the m3 receptor was sufficient to specify activation of a pertussis toxin sensitive G protein coupled to a slow and oscillatory Ca2+ release pathway typical of the m2 subtype. Notably, these critical residues occur within the same region of the third cytoplasmic domain of functionally distinct mAChR subtypes.

Amino Acid Sequence↗
PubMed1990

Double-blind, placebo-controlled, multi-centre trial of the efficacy and tolerance of niflumic acid ('Nifluril') capsules in the treatment of tonsillitis in adults.

A double-blind, placebo-controlled study was carried out in 231 adult patients suffering from acute diffuse pharyngitis or acute tonsillitis with fever and dysphagia to assess the effectiveness of niflumic acid combined with standard antibiotic therapy in relieving pain and inflammation. Patients were allocated at random to receive either 4 capsules of 250 mg niflumic acid or placebo daily in addition to 1.5 million units phenoxymethyl penicillin for 4 to 5 days. Clinical assessments before and after 2 and 4 days of treatment showed that there was faster resolution of fever, pain, adenopathy, pharyngeal congestion and dysphagia, and improved patient comfort in the niflumic acid group. Few side-effects were recorded and there were only 4 drop-outs due to side-effects in patients receiving niflumic acid.

Adolescent↗
PubMed1990

[Aneurysm of the membranous ventricular septum. Apropos of 4 cases surgically treated].

Four patients with aneurysms of the membranous ventricular septum were operated either because of complications or for associated malformations. The authors describe the anatomical, radiological and, above all, the echocardiographic and angiographic features of this malformation. Surgical management is necessary in complicated cases or when there are associated congenital malformations. The information provided by echocardiography in the diagnosis and follow-up of ventricular septal defects indicates that this malformation is not as rare as was previously thought.

Adolescent↗
PubMed1989

[Echocardiographic monitoring of the left ventricle in infants and children presenting the primary form of acute cardiac failure].

A retrospective multicenter study was based on influential echocardiograms performed in 34 children, the majority (29/34) being under 2 years of age, and presenting with a primary form of acute congestive heart failure. Four died early. The average duration of serial echocardiographic monitoring was 25 months (9-72 months) in the others. During the acute stage, the left cardiac cavities were extremely dilated and the shortening fraction was reduced to 15 +/- 4%. The 4 decreased children belonged to a group of 17 children who had a shortening fraction less than 13%. From the 8th day significant improvement of the left ventricular function was observed. Recovery was faster during the first 6 months of evolution and became very low after 1 year. The age at onset, the severity of the initial left ventricular changes, and the speed of recovery during the first 15 days were not predictive of the degree of eventual recovery of left ventricular function. At the end of the study 28 of the 30 surviving children had recovered a normal shortening fraction. However 16 of 30 still showed some dilatation, albeit moderate in most cases, of this ventricle. These data show that most children presenting with a primary form of acute congestive heart failure recover satisfactory heart function and that the initial echocardiographic features are not predictive of the subsequent course.

Acute Disease↗
PubMed1987

[Congenital aortic valve stenosis treated by dilatation. Apropos of a case with hemodynamic control 12 months later].

Intraluminal dilatation of congenital aortic valve stenosis was attempted in a 14-year old boy. Significant improvement was obtained, with a fall in transaortic gradient from 80 to 30 mmHg. A control haemodynamic examination performed 12 months later confirmed that the result was stable; there was no aortic leakage, and myocardial hypertrophy had begun to regress at echocardiography. This case is of interest in that dilatation is less costly than surgical commissurotomy. However, this technique cannot be widely used until satisfactory long-term results have been demonstrated in a large population of children.

Adolescent↗
PubMed1987

[Scimitar syndrome in infants. Physiopathology and therapeutic implications in 12 cases].

Twelve children, aged 6 days to 6 months (mean: 42 +/- 23 days) were diagnosed as presenting with the scimitar syndrome. In this syndrome, anomalous pulmonary venous drainage, hypoplasia of the right pulmonary artery and parenchyma, variety of "sequestrum" of the right pulmonary artery and parenchyma, variety of "sequestrum" of the right pulmonary base usually fed by subdiaphragmatic branches of the aorta are associated. Respiratory disorders were constant, severe in 8 cases. X-rays showed "dextro-cardia" and "hypoplasia of the right lung". Endocardiac investigation assessed the diagnosis and showed pulmonary arterial hypertension in 11 cases, with (5) or without (6) associated heart defect. One case with good tolerance remains under simple supervision; 4 were operated on from the associated lesions only and died; 7 took benefit of a simple surgical removal of the branches feeding the sequestrum, with one death and 6 successes. The poor prognostic significance of the sequestrum is thus indirectly demonstrated and the value of its devascularization is emphasized.

Cardiac Catheterization↗