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Biomedical subjects

A Kamoun

Publications and source records attributed to A Kamoun.

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

[Primary hyperoxaluria: Tunisian experience apropos of 24 pediatric cases].

We report on 24 children (10 girls) presenting with primary hyperoxaluria. The mean age at diagnosis was 6.3 years (range: 3 months-14.8 years). The mean interval between initial symptom and diagnosis was 1.3 year. The average follow-up period was 22 months (range: 1-60 months). At the time of diagnosis the renal function was normal in 6 children, moderately altered in 1 and severely in 17. During the follow-up the renal function remained stable in 6 patients, improved in 2, deteriorated in 4. The 12 patients with end-stage renal disease at diagnosis remained unchanged. Urolithiasis were present in all patients older than 2 years, and in 1 among the 5 infants. Medullary nephrocalcinosis was observed in 3 patients in whom the renal function was preserved. Diffuse nephrocalcinosis was present in all patients with end-stage renal failure. Improvement of renal function was secondary to stone removal in 2 patients. Extracorporeal shock wave lithotripsy performed in 7 patients was efficient only in 3. In 10 patients oxalate bone disease was correlated with both renal function and dialysis duration, whereas retinal involvement noted in 6 patients was not.

Adolescent↗
PubMed1996

End-stage renal disease of the Tunisian child: epidemiology, etiologies, and outcome.

From December 1989 to December 1993, 90 children under 15 years were admitted to our department for end-stage renal disease; 9 children were less than 5 years and 28 were aged between 5 and 10 years. The sex ratio (M/F) of the children was 2.1. The estimated incidence of pediatric end-stage renal disease in Tunisia is 7 new cases per year and per million child population under 15 years. The chief etiologies of end-stage renal disease are glomerulonephritis (19%), hereditary nephropathies (29%), and malformative uropathies (13%); 26% of the end-stage renal diseases are of unknown etiologies. Our findings, compared with the European data, show a particularly high frequency of primary hyperoxaluria (13.5%) and an unusual proportion of male subjects.

Adolescent↗
PubMed1996

[Infantile forms of primary hyperoxaluria type I: apropos of 4 cases].

BACKGROUND: Approximately 10% of the cases with primary hyperoxaluria type I present before age 1 and are usually classified as neonatal primary oxaluria. CASE REPORTS: Four unrelated infants, aged 3 to 9 months, were admitted for severe renal failure due to primary hyperoxaluria type I. Other affected members were known in two of these four families but the disease was not present at the same age in each family. Echogenicity of kidneys was increased in all the patients and calcium oxalate crystals were seen in the collecting system and within the renal parenchyma. Urolithiasis was not present. Treatment of renal failure, ie, peritoneal dialysis, was uneffective in one patient and was interrupted in two others because organ transplantation was impossible. CONCLUSIONS: The infantile forms of primary hyperoxaluria type I may be rapidly complicated by severe renal failure in the absence of urolithiasis.

Female↗
PubMed1996

Cortico-adrenal function under simulated weightlessness during gestation in the rat--effects on fetal development.

To examine the effects of simulated weightlessness on cortico-adrenal function and on fetal development, we suspended pregnant rats for 20 days. The levels of adrenal and plasma corticosterone were examined in mothers and in fetuses. The animal control group was kept single in standard cages. Growth of the suspended animals was repressed for the first 8 days of the experiment, but thereafter it increased greatly, as did the daily food intake. By the 18th day of the experiment, the body masses and food intake of the two groups were equal. No modification in circulating corticosterone was found. It appears that there is no stress in pregnant rats submitted to simulated weightlessness.

Adaptation, Physiological↗
PubMed1996

[Possible implication of TRH and dopamine in postnatal lactotropic hypoactivity in rats].

Our results show that pituitary glands of young rats (6 days) incubated in vitro, increase their PRL secretion in presence of TRH, this responses is greater than that in adult glands. Indeed, in presence of TRH 10(-7) M, PRL basal secretion of immature glands passes from 478.70 +/- 67.25 to 952.78 +/- 67.02, versus 5333.29 +/- 75.456 and 6347.15 +/- 75.246 ng/mg protein at mature glands. The same dose of dopamine (DA), weakens the TRH stimulating effect by 60% and 40% respectively by young and adult pituitary glands. These results suggest that lactotroph insensitiveness to TRH injection observed during the first days of postnatal life at the rat, would not be explained by lactotroph failure, but by intervention of central and peripheral multiple modulator factors affecting lactotrophs reactivity, in particular the importance of dopaminergic control.

Animals↗
PubMed1996

[Postnatal lactotropic hypoactivity in rats: possible implication of VIP, endogenous opioids, dopamine and glucocorticoids].

In this study, the possible intervention of VIP (Vasoactive Intestinal Peptide), beta-endorphine, glycocorticoids and dopamine, in postnatal lactotrophs hypoactivity at the rat, was investigated. Our results show that the injection of VIP (40 micrograms/kg), beta-endorphine (125 micrograms/kg) or its antagonist, naloxone (2 mg/kg), does not provide a change in serum PRL before or after ether stress at 6-day-old rats. However, after adrenalectomy, 6 day-old neonates became sensitive to ether stress as do adults, while acute treatment with dexamethasone (2 mg/kg) or dopamine (1 mg/kg), abolished this response completely. Sulpiride injection (1 mg/kg), on the contrary potentialized response. This lactotroph insensitiveness to ether stress, TRH, VIP, and beta-endorphine, during the beginning of postnatal life in the rat, might be explained, partially, by the failure of stimulatory factors "PRF" (Prolactin Releasing Factors), together with strength of inhibitory factors "PIF" (Prolactin Inhibitory Factors), such as dopamine and glycocorticoids.

Animals↗
PubMed1995

[Value of extracorporeal shockwave lithotripsy in primary hyperoxaluria type I].

BACKGROUND: Application of extracoporal shock wave lithotripsy (ESWL) has revolutionized the management of many types of urolithiasis, including that observed in primary hyperoxaluria where surgical attempts to remove calculi sometimes result in worsening of renal function. CASE REPORTS: Three unrelated patients aged 8, 10 and 11 years, respectively, with type I primary hyperoxaluria, suffered from recurrent bouts of abdominal pain (two patients) or anemia (one patient). Two patients had chronic renal failure. Plain abdominal films and ultrasonography showed several large bilateral stones. ESWL was applied to the three patients permitting complete removal of stones following three sessions in one patient and partial removal following four sessions in the second patient who developed infection after the first session with transitory increase in creatinemia. Several sessions of ESWL failed to fragment stones in the third patient. CONCLUSION: ESWL may represent a safe procedure for attempting stone removal in patients with primary hyperoxaluria.

Child↗
PubMed1995

Growth stimulation of human skin fibroblasts by elastin-derived peptides.

Elastin-derived peptides (kappa-elastin: kappa E, mean molecular mass: 75 kDa), either coated onto plastic dishes or added to culture media (0.26 to 1.33 nM) stimulated the growth of human skin fibroblasts (HSF) strains obtained from different donors and tested at different cell passages (4 to 12). Coated 44.4 micrograms/cm2 insoluble elastin (iE) exhibited the same action; coated iE or kappa E significantly modifies the HSF morphology: after 5-6 days of culture, HSF are more elongated, and at preconfluence state, formation of HSF clusters surrounding iE were observed. Increased 3H thymidine incorporation and proliferative effect of HSF by kappa E (1.3 to 2.2 fold as compared to control cells) was observed after a lag phase period which raised with initial HSF density. Optimal proliferative effect was obtained at kappa E 8.5 10(-10) M, a value close to the dissociation constant (kD = 2.7 10(-10) M) of kappa E to HSF. Valine-glycine-valine-alanine-proline-glycine (VGVAPG), but not valine-glycine-valine (VGV) or Valine-glycine-valine-valine-glycine-alanine (VGVVGA) also significantly stimulated, optimally at 7.0 10(-10) M, HSF proliferation. It was concluded that the stimulatory influence of elastin derived peptides on HSF proliferation was mediated through a binding to plasmalemmal receptor of HSF.

Adult↗
PubMed1995

[Radiological signs of type I primary hyperoxaluria].

The authors report the radiological signs observed in 14 patients between the ages of 3 months and 16 years, suffering from type I primary hyperoxaluria. Four of these patients were being treated conservatively for renal failure and ten had reached end-stage renal failure. Stones were demonstrated in 9 patients. Nephrocalcinosis was present on the plain abdominal x-ray in 6 patients before dialysis, and in all patients dialysed for more than 3 months. Bone signs characteristic of type I primary hyperoxaluria were only observed in children with end-stage renal failure. Metaphyseal dense bands were revealed in 5 patients. Metaphyseal clear bands, observed in 4 patients, occurred later and appeared to replace dense bands which moved towards the diaphysis. The other signs detected were osteosclerosis of the vertebrae and ilium (4 patients) and epiphyseal subchondral clear bands (one patient).

Adolescent↗
PubMed1995

[Etiologic factors of urinary lithiasis in Tunisian children].

Fifty-five Tunisian children with urinary stones, between the ages of 8 months and 15 years, underwent morphological and infrared spectrophotometric analysis of their stones. This study provides an approach to the aetiological profile of urinary stones in Tunisian children. The nucleus of the stones was composed of acidic ammonium urate in 48% of cases with a morphology suggestive of phosphorus deficiency associated with a history of diarrhoea. In 24% of cases, the nucleus contained struvite indicating the presence of urinary tract infection by urease-positive bacteria. The main growth factors of urinary stones were hyperoxaluria and urinary tract infection. In 5 cases, the stones were due to a hereditary lithogenic metabolic disease : cystinuria in 1 case and primary hyperoxaluria in 4 cases.

Adolescent↗
PubMed1994

Effect of tianeptine on the hypothalamic somatotropic axis in the conscious sheep.

The action of serotonin on growth hormone (GH) secretion is controversial because of interspecies differences and lack of specificity of serotoninergic drugs. Serotonin (5-HT) appears to inhibit GH release in the sheep and in man. We have investigated the site of action of tianeptine, a 5-HT uptake enhancer, in sheep since it is possible to collect hypophysial portal blood for the simultaneous determination of growth hormone-releasing hormone (GHRH) and somatostatin in this species under conscious, unstressed conditions. Tianeptine injection (10 mg/kg i.v.) resulted in a significant, immediate and short-lasting (30 min) increase in peripheral GH (+750%; P < 0.01) and hypophysial portal GHRH (+180%; P < 0.01). No change in the secretion of somatostatin was recorded during the same time. These data suggest that serotoninergic inputs are inhibitory to GH secretion. Tianeptine acts centrally to stimulate GH secretion in the sheep and its effect is mediated through changes in GHRH but not somatostatin release into hypophysial portal blood.

Animals↗
PubMed1994

[Treatment of anemia in hemodialyzed children using recombinant human erythropoietin (Eprex). Results of a French multicenter clinical trial].

Intravenous recombinant human erythropoietin (Eprex Cilag) was used in 28 hemodialyzed children, treated in 3 French paediatric centers, from November 1989 to November 1990. Transfusion dependency disappeared in all cases: the number of transfusions decreased from 7.3 unit/patient/year to 0.6 unit/pt/year. The mean haemoglobin concentration for the whole group increased from 6.6 +/- 0.8 g/dl, to 9.2 +/- 1.2 at 6 months and 9.7 +/- 0.7 g/dl at 1 year. Twenty-two out of 28 children reached the target haemoglobin value of 9.6 g/dl (6 mmol/dL) within a mean time of 16.5 weeks. Poor responses were due to either a premature withdrawal of treatment because of renal transplantation, or too low a dosage for the age. The study showed indeed that the dose requirement was significantly dependent on physical development: the mean dosage required to maintain haemoglobin concentration at the target value was 300 U/kg/week in children weighing less than 20 kg, 222 U/kg/week in 20-30 kg children, and 135 U/kg/week in those weighing more than 30 kg (p = 0.02). The only complication was an increase in blood pressure, observed in 43% of cases. The increase of anti-hypertensive medication was always successful in controlling blood pressure, and hospitalization was required in only one case. The improvement in general condition was obvious, and in several cases, the cognitive abilities seemed to improve. The growth deficit remained unchanged.

Adolescent↗
PubMed1993

Novel bioactive compounds from actinomycetes.

Actinomycetes form an enormous reservoir of secondary metabolites and enzymes. The potential for exploiting rare actinomycetes is highlighted by the discovery of novel compounds from strains of Spirillospora and Nocardioides. Novel compounds of well known classes of antibiotics, such as polyenes, continue to be discovered. For compounds containing a chromophore, the analysis by high-performance liquid chromatography coupled with a diode-array detector enables the elimination of producers of known compounds and facilitates the discovery of novel compounds or derivatives. The complexity of the regulatory mechanisms is illustrated by glutamine synthetase. The characterization of thermostable amylolytic, lignolytic, peroxidase and neuramidase activities, and the isolation of novel cellulolytic actinomycetes clearly demonstrate the potential of Actinomycetes as producers of enzymes.

Actinomycetales↗
PubMed1992

Glucocorticoids, transmitters and stress.

Many kinds of stress stimulate the neuroendocrine systems controlling catecholamine and glucocorticoid secretion. Stress-induced stimulation of CRF-containing neurons appears to be mediated by serotonergic, noradrenergic, and possibly other neuronal pathways. Stress can alter various neurobiological and endocrine functions, two essential components of the neuroendocrine responses being release of adrenalin from chromaffin cells of the adrenal medulla and secretion of glucocorticoids from adrenocortical cells. Activation of adrenal steroid secretion is mainly by a reflex activation of hypothalamic neurons, which stimulate ACTH secretion from the anterior pituitary. While the neuropeptide CRF plays a major role in the neuroendocrine response to stress, the neuronal signals which are responsible for the regulation of CRF neurons have not been completely elucidated. A number of other regulatory substances may also participate, alone or with CRF, in the control of ACTH secretion by pituitary corticotrophs, and there is increasing evidence that classical neurotransmitters or neuropeptides may act directly on adrenocortical cells to modulate corticosteroid secretion. We review the neuronal, neuroendocrine, and humoral pathways which participate in the regulation of stress-induced corticosteroid secretion, and present preliminary data on the effect of the tricyclic antidepressant, tianeptine in the response of the HPA axis to stress.

Animals↗