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Biomedical subjects

A Nasr

Publications and source records attributed to A Nasr.

At least 19 recordsLinked to original sources
PubMed2005

Developing an independent, generic, phosphorus modelling component for use with grid-oriented, physically based distributed catchment models.

Grid-oriented, physically based catchment models calculate fields of various hydrological variables relevant to phosphorus detachment and transport. These include (i) for surface transport: overland flow depth and flow in the coordinate directions, sediment load, and sediment concentration and (ii) for subsurface transport: soil moisture and hydraulic head at various depths in the soil. These variables can be considered as decoupled from any chemical phosphorus model since phosphorus concentrations, either as dissolved or particulate, do not influence the model calculations of the hydrological fields. Thus the phosphorus concentration calculations can be carried out independently from and after the hydrological calculations. This makes it possible to produce a separate phosphorus modelling component which takes as input the hydrological fields produced by the catchment model and which calculates, at each simulation time step, the phosphorus concentrations in the flows. This paper summarises the equations and structure of such a Grid Oriented Phosphorus Component (GOPC) developed by the authors for simulating phosphorus concentrations and loads using the outputs of a fully distributed physical based hydrological model. The GOPC performance is illustrated by an example of a simplified hypothetical catchment subjected to some ideal conditions.

Fertilizers↗
PubMed2000

Association of a balanced chromosomal translocation (4; 12)(q21.3; q15), affective disorder and autism.

This case report describes a set of monozygotic twins with severe intellectual disability, autism and affective disorder with a balanced translocation between chromosomes 4 and 12. Their mother, who carries the same balanced translocation, had severe postnatal depression. The association between autism affective disorder and these chromosome break points has not been reported previously. The implications are discussed.

Adult↗
PubMed1998

Safety and pharmacokinetics of a single oral dose of amisulpride in healthy elderly volunteers.

OBJECTIVE: Amisulpride is a substituted benzamide neuroleptic, which binds selectively to dopamine D2 and D3 receptors, mainly in the limbic structures. States of delusion and agitation occur frequently in the population aged more than 65 years, especially in demented patients and this sometimes requires the use of neuroleptics. The objectives of this study were to determine the safety and the pharmacokinetic profile of 50 mg of amisulpride administered orally as a single dose to elderly volunteers. METHODS: Twenty healthy volunteers (10 men and 10 women) aged 65 79 years were included in this open trial. Frequent measurements of blood pressure and heart rate were made and ECG and blood samples were performed up to 72 h after drug intake. RESULTS: The overall clinical and cardiovascular safety was satisfactory. The mean Cmax of the racemate amisulpride in elderly people was 64.1+/-6.7 ng ml(-1), and was not different from the value of 56+/-4.1 ng ml(-1) in young subjects. As with the Cmax, the mean values of t1/2 and AUC in elderly people (15.6+/-1.3 h and 667+/-51 ng. ml(-1).h, respectively) were not different to values observed in young subject (respectively 11.7+/-0.5 h and 603+/-25 ng m1(-1) h). CONCLUSION: A single oral dose of amisulpride was well tolerated and showed a similar pharmacokinetic profile in healthy elderly and young subjects. However, these findings should be confirmed after multiple dosing in a larger population in order to establish the lack of need of dosage adjustment in this elderly population.

Administration, Oral↗
PubMed1998

Pregnancy and delivery after annular detachment of the uterine cervix.

Spontaneous annular detachment of the uterine cervix during labour is a rarely encountered obstetric complication that may pass unrecognized. The aetiological factors involved in its development remain incompletely understood. In this report, a case of a 40-year-old multiparous woman in whom annular detachment of the cervix passed completely unnoticed in the course of a spontaneous vaginal delivery to become evident, for the first time, during subsequent delivery is presented. Intriguingly, pelvic examination revealed an absent portio vaginalis of the cervix; the external cervical os was replaced by a small fibrosed opening. Fertility was well preserved, despite marked cervical fibrosis. A transverse lower segment caesarean section with tubal sterilization was carried out. The postoperative course was uneventful and likewise, the course of the puerperium was benign.

Adult↗
PubMed1998

Estrogen replacement therapy and cardiovascular protection: lipid mechanisms are the tip of an iceberg.

Cardiovascular disease remains a major cause of mortality among postmenopausal women. After menopause, atherogenesis is promoted by a number of metabolic and vascular changes. A multitude of observational clinical studies have come to the conclusion that estrogen replacement therapy (ERT) reduces cardiovascular risk by approximately 50% and that estrogen's favorable effects on the lipid profile can explain only 25-50% of the overall observed reduction. Estrogens are now known to have potent anti-atherogenic properties through lipid and non-lipid mechanisms; both will be highlighted in view of the recent literature. Estrogens induce favorable changes on lipids and lipoproteins, partly by increasing HDL-cholesterol and decreasing both LDL-cholesterol and lipoprotein (a). Non-lipid mechanisms of estrogen action include decreasing insulin resistance, serum fibrinogen, factor VII and plasminogen activator inhibitor-1 (PAI-1). Moreover, estrogens maintain endothelial cell integrity, decrease expression of adhesion molecules, lower systemic blood pressure, promote vasodilatation, decrease platelet aggregability, inhibit vascular smooth muscle cell proliferation, possess potent antioxidant and calcium antagonist activities, inhibit adrenergic responses and downregulate platelet and monocyte reactivity. Also mentioned are recent reports linking estrogen to the renin-angiotensin system, relaxin, serotonin and homocysteine. What was once thought of as a simple action is now being increasingly appreciated as a complex, multifaceted mechanism, which serves to prove that estrogen is a powerful cardiovascular agent.

Aged↗
PubMed1997

A surprisingly ameliorating effect of high doses of estradiol in primary osteomyelofibrosis: a case report.

OBJECTIVES: To report a case of a postmenopausal woman with primary (idiopathic) osteomyelofibrosis who showed a considerable improvement under the effect of high doses of estradiol given for the control of severe intractable menopausal symptoms. METHODS: This study was carried out by a case report. RESULTS: Astonishingly, under the effect of high doses of estradiol, both clinical and laboratory indices of the disease were not only kept stable but also showed a noticeable improvement. Hemoglobin increased from a value of 8.4 gm/dl in 1989 to 10.7 gm/dl in 1996. Blood transfusion was no longer necessary, the patient had had no infections whatsoever and was only afraid of not being allowed to continue using these high estrogen doses, which seemed indispensable and central to her well-being. CONCLUSIONS: High doses of estrogens could possibly be given the credit for ameliorating the natural sinister course of primary osteomyelofibrosis.

Climacteric↗
PubMed1996

Growth hormone therapy in elderly people: an age-delaying drug?

The aims of this review are to present a brief overview of growth hormone (GH) physiology and to summarize the studies of GH treatment in adults. Special attention has been paid to randomized controlled trials. Studies have revealed a partial deficiency of GH secretion in the elderly. GH secretion on the average declines by 14% with each decade in normal adults after 20 years of age. Aging has a central effect on the GH secretion and peripheric effect on insulin-like growth factor 1 (IGF-1) through changes in the body composition. GH administration may attenuate several important decrements in body composition and in function associated with aging. GH may also have very potent anabolic effects in surgical situations. Short-term side-effects of GH therapy include edema, carpal tunnel syndrome and arthralgia. A number of agents such as oral GH-releasing peptides (GHRPs) increase GH secretion; they may be an alternative to GH treatment in the future. Further studies of GH replacement are needed, examining issues such as dosage, tolerance and efficacy before the widespread use of GH in the elderly is advocated.

Adult↗
PubMed1995

[Atrial natriuretic factor and brain natriuretic peptide. Variations in elderly subjects with heart failure].

Atrial natriuretic factor (ANF) is a peptide hormone secreted by the atria in response to increased transmural pressure. This peptide is the first of a series of natriuretic hormones which also includes brain natriuretic peptide (BNP). It is destroyed mainly by an ubiquitous enzyme, neutral endopeptidase (NEP). Its main actions are vasodilatation and natriuresis. It is the main physiological agonist of the renin/angiotensin/aldosterone system. In elderly subjects free of cardiovascular disease, baseline concentrations are higher than in younger subjects. In patients with congestive heart disease (CHD), the level of ANF rises due to permanent increased filling pressures. Both atrial and ventricular secretion increase ANF levels which loose their day/night rhythm. ANF is a risk factor independent of mortality, rhythm disorders and acute heart failure in patients with heart failure. BNP is also raised in CHD. There is an inverse correlation between concentration and severity of left ventricule dysfunction. There has been little work on ANF in elderly subjects with CHD. ANF is elevated in these patients and is an independent risk factor for cardiac decompensation. In addition, in very elderly subjects where the diagnosis of CHD is difficult and echocardiography not always possible, assay of BNP could be an interesting diagnostic tool. Currently work on therapeutic possibilities (administration of exogenous ANF, combinations with NEP inhibitor/conversion enzyme inhibitor, ANF/diuretics) have revealed certain problems (short half life of ANF, transient effects, non-specific activity of NEP). The usefulness of ANF and BNP in heart failure in elderly subjects will undoubtedly lie in its capacity to mark disease severity and as a diagnostic tool, particularly in case of acute dyspnoea.

Age Factors↗
PubMed1993

The histopathology and the mechanism of entropion in patients with trachoma.

BACKGROUND: Eyelids of patients with trachoma may be thickened. This thickening could be attributed to trachomatous changes in the conjunctiva and tarsus. METHODS: Biopsies of tarsal plates and palpebral conjunctivae were obtained from 17 upper eyelids of 11 patients with inactive trachoma who underwent posterior tarsotomy procedures for entropion repair. RESULTS: Light microscopy studies showed a thick and compact subepithelial fibrous membrane adherent to the tarsal plate. This membrane caused apparent thickening of the tarsus when measured intraoperatively (range, 1.25-2.00 mm). Other histopathologic findings include atrophy of the meibomian glands with thickening of the acinar basement membrane, loss of goblet cells, retention cysts, and hyaline degeneration of the tarsal plate with focal replacement by adipose tissue. CONCLUSION: The contraction of the subepithelial fibrous membrane formed by vertically oriented parallel collagen fibers is one of the main factors contributing to the entropion formation.

Adult↗
PubMed1992

Corticosteroids in the management of adnexal hemangiomas in infancy and childhood.

Adnexal hemangiomas are common in infancy and childhood. They can be interesting to the ophthalmologist for two reasons: cosmetic and functional (the second, the more important). By their natural history, they can produce serious visual consequences by producing refractive or stimulus-deprivation amblyopia. The management of adnexal hemangiomas is a challenge. The accepted method is most instances is corticosteroid therapy. This is administered either by local, intralesional, or systemic routes; the first is preferred. Steroid therapy can cause systemic and local side effects. Furthermore, a rebound effect can occur with this type of therapy. We present the cases of 12 patients with adnexal hemangiomas treated with steroids. These patients are reviewed, with emphasis on their responses and the complications of steroid therapy.

Betamethasone↗
PubMed1991

[Desmoid tumor and Gardner syndrome].

A desmoid tumor was found in a patient with Gardner's syndrome. The tumor was visualized by CT before and after contrast injection, by radiographic examination of the small bowel, and by sonography. CT demonstrated a heterogeneous mass in the left lower abdomen with attenuation values ranging from 23 to 72 HU on native scans, enhancing to 123 up to 172 HU after injection of contrast medium. This examination also demonstrated the extent of the tumor and its exact dimensions. The radiographic examination of the small bowel completed the diagnosis and showed no involvement of the small bowel. This diagnosis was confirmed by laparotomy.

Adult↗
PubMed1990

Perinatal renal vein thrombosis. Sonographic demonstration.

The use of ultrasound (US) in the diagnosis of renal vein thrombosis (RVT) remains ill defined because the classical features lack specificity. The authors report three cases of renal vein thrombosis with a common US pattern: hyperechoic streaks in the interlobulary spaces confirming previous reports with the same pattern. The pattern has been observed in neonates as well as in utero. Associated vena cava thrombosis was present in two cases. This sign might be a specific sign of RVT.

Female↗
PubMed1990

[Intravenous urography in acute pyelonephritis].

Intravenous urography, systematically performed in 50 consecutive acute pyelonephritis patients, revealed abnormalities in 17 of them: in 12 cases (24%), treatment and follow-up were modified; in the other 5 cases (10%), the anomalies were insignificant. The nephrogram was normal for 33 patients (66%). The frequency of significant abnormalities was higher in patients over 50 years of age (46.2%) than in those under 50 (16.2%) (p less than 0.05), and was also higher in patients remaining febrile for 3 days after the onset of an appropriate antibiotic therapy (66.6%) than in responsive patients (14.4%) (p less than 0.01). Among the significant lesions, 10 were detectable by echography and another by abdominal X-ray. Thus, a population of women under 50 years of age with acute pyelonephritis can be selected for urography, as shown by these results, however, they must be confirmed before changing the systematic practice of urography.

Acute Disease↗