Biomedical subjects

Philippe Durand

Publications and source records attributed to Philippe Durand.

At least 19 recordsLinked to original sources

PubMed2007

beta-Nerve growth factor participates in an auto/paracrine pathway of regulation of the meiotic differentiation of rat spermatocytes.

NGF appears to be involved in spermatogenesis. However, mice lacking NGF or TrkA genes do not survive more than a few days whereas p75(NTR) knockout mice are viable and fertile. Therefore, we addressed the effect of betaNGF on spermatogenesis by using the systems of rat germ cell culture we established previously. betaNGF did not modify the number of Sertoli cells, pachytene spermatocytes, secondary spermatocytes nor the half-life of round spermatids, but increased the number of secondary meiotic metaphases and decreased the number of round spermatids formed in vitro. These effects of betaNGF were reversible and maximal at about 4 x 10(-11) M. Conversely, K252a, a Trk-specific kinase inhibitor, enhanced the number of round spermatids above that of control cultures. The presence of betaNGF and its receptors TrkA and p75(NTR) was investigated in testis sections, in Sertoli cell and germ cell fractions, and in germ cell and Sertoli cell co-cultures. betaNGF was detected only in germ cells from pachytene spermatocytes of stages VII up to spermatids of stages IX-X. TrkA and p75(NTR) were detected in Sertoli cells and in these germ cells. Taken together, these results indicate that betaNGF should participate in an auto/paracrine pathway of regulation of the second meiotic division of rat spermatocytes in vivo.

Animals↗

PubMed2006

Decrease of both stem cell factor and clusterin mRNA levels in testicular biopsies of azoospermic patients with constitutive or idiopathic but not acquired spermatogenic failure.

BACKGROUND: Sertoli cells nurse germ cells during spermatogenesis, and alterations of Sertoli cell functions have been suggested in cases of spermatogenic failures. METHODS: In this work, we measured stem cell factor (SCF) and clusterin mRNA levels, by quantitative RT-PCR, in RNA extracted from testicular biopsies of 49 azoospermic patients classified according to testicular histology as having normal spermatogenesis or spermatogenic failure. RESULTS: When related to the percentage of Sertoli cells counted on a histological section of a neighbouring tissue sample, SCF and clusterin mRNA levels were significantly lower in the 'spermatogenic failure' group compared with the control group (P = 0.0297 and P = 0.0043, respectively). These levels were also significantly lower in the cases of 'constitutive' (cryptorchidism and Yq microdeletion) and 'idiopathic' spermatogenic failures when compared with the control group; conversely, they were not significantly decreased in the group with 'acquired spermatogenic failure' (orchitis, testicular traumatism, chemoradiotherapy and varicocele). CONCLUSIONS: These data further demonstrate an alteration of Sertoli cell functions in some human spermatogenic failures and suggest that a lack of Sertoli cell maturation may be involved in cases of constitutive or idiopathic spermatogenic failures.

Adult↗

PubMed2006

Long-term moderate magnesium-deficient diet shows relationships between blood pressure, inflammation and oxidant stress defense in aging rats.

Epidemiological and experimental studies have indicated a relationship among aging, dietary Mg, inflammatory stress, and cardiovascular disease. Our aim in the present study was to investigate possible links between dietary Mg, oxidant stress parameters, and inflammatory status with aging in rats. We designed a long-term study in which rats were fed for 22 months with moderately deficient (150 mg/kg), standard (800 mg/kg), or supplemented (3200 mg/kg) Mg diets. Comparisons were made with young rats fed with the same diets for 1 month. Compared to the standard and supplemented diets, the Mg-deficient diet significantly increased blood pressure, plasma interleukin-6, fibrinogen, and erythrocyte lysophosphatidylcholine, particularly in aging rats, it decreased plasma albumin. The impairment of redox status was indicated by increases in plasma thiobarbituric acid reactive substances and oxysterols and an increased blood susceptibility to in vitro free-radical-induced hemolysis. We concluded that Mg deficiency induced a chronic impairment of redox status associated with inflammation which could significantly contribute to increased oxidized lipids and promote hypertension and vascular disorders with aging. Extrapolating to the human situation and given that Mg deficiency has been reported to be surprisingly common, particularly in the elderly, Mg supplementation might be useful as an adjuvant therapy in preventing cardiovascular disease.

Animals↗

PubMed2006

Nonketotic hyperglycemic coma in toddlers after unintentional methadone ingestion.

Methadone overdoses are increasing in parallel with the increased frequency of opiate substitution therapy in adults. Although unintentional methadone intoxication in children is rare, it is becoming more frequently recognized. We report 3 cases of unintentional methadone overdose in toddlers who initially displayed central nervous system depression associated with severe nonketotic hyperglycemia and discuss the possible pathophysiologic mechanisms of an underrecognized symptom of opiate intoxication in young children.

Accidents, Home↗

PubMed2006

Monitoring enzyme-catalyzed production of glucosamine-6P by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: a new enzymatic assay for glucosamine-6P synthase.

A matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) method for quantification of D-glucosamine-6P (GlcN-6P) that allows the kinetic study of glucosamine-6P synthase (Glms) is presented. The present report describes the optimization of the different steps of a new enzymatic assay for Glms based on in situ N-acetylation of GlcN-6P and MALDI-TOFMS analysis using N-(13C2)acetylglucosamine-6P as internal standard. Since no isotopically substituted GlcN-6P was available, the N-(13C2)acetyl derivative, easily obtained from (13C4)-acetic anhydride, was used as internal standard. Validation of the assay was achieved by measuring the fructose-6P Michaelis constant, in full agreement with reported values, and by studying the inhibition properties of arabinose-5P oxime.

Calibration↗

PubMed2006

Noninvasive positive pressure ventilation: five years of experience in a pediatric intensive care unit.

OBJECTIVES: To evaluate the feasibility and outcome of noninvasive positive pressure ventilation (NPPV) in daily clinical practice. DESIGN: Observational retrospective cohort study. SETTING: Pediatric intensive care unit in a university hospital. PATIENTS: : Patients treated by NPPV, regardless of the indication, during five consecutive years (2000-2004). MEASUREMENTS AND RESULTS: A total of 114 patients were included, and 83 of the 114 patients (77%) were successfully treated by NPPV without intubation (NPPV success group). The success rate of NPPV was significantly lower (22%) in the patients with acute respiratory distress syndrome (p < .05) than in the other patients. The Pediatric Risk of Mortality II (p = .003) and Pediatric Logistic Organ Dysfunction scores (p = .002) at admission were significantly higher in patients who were unsuccessfully treated with NPPV (NPPV failure group). Baseline values of Pco2, pulse oximetry, and respiratory rate did not differ between the two groups. A significant decrease in Pco2 and respiratory rate within the first 2 hrs of NPPV was observed in the NPPV success group. Multivariate analysis showed that a diagnosis of acute respiratory distress syndrome (odds ratio, 76.8; 95% confidence interval, 4.4-1342; p = .003) and a high Pediatric Logistic Organ Dysfunction score (odds ratio, 1.09; 95% confidence interval, 1.01-1.17; p = .01) were independent predictive factors for NPPV failure. A total of 11 patients (9.6%), all belonging to the NPPV failure group, died during the study. CONCLUSIONS: This study demonstrates the feasibility and efficacy of NPPV in the daily practice of a pediatric intensive care unit. This ventilatory support could be proposed as a first-line treatment in children with acute respiratory distress, except in those with a diagnosis of acute respiratory distress syndrome.

Adolescent↗

PubMed2006

Glial cell-line-derived neurotropic factor and its receptors are expressed by germinal and somatic cells of the rat testis.

Glial cell-line-derived neurotropic factor (GDNF) and its receptors glial cell-line-derived neurotropic factor alpha (GFR1alpha) and rearranged during transformation (RET) have been localized in the rat testis during postnatal development. The three mRNAs, and GDNF and GFR1alpha proteins were detected in testis extracts from 1- to 90-day-old rats by reverse transcriptase PCR and Western blotting respectively. The three mRNAs were present in Sertoli cells from 20- and 55-day-old rats, pachytene spermatocytes (PS), and round spermatids (RS). The GDNF and GFR1alpha proteins were detected in PS, RS, and Sertoli cells. GDNF and GFR1alpha were also detected using flow cytometry in spermatogonia and preleptotene spermatocytes, and in secondary spermatocytes. The localization of GDNF and GFR1alpha in germ and Sertoli cells was confirmed by immunocytochemistry. The hypothesis that GDNF may control DNA synthesis of Sertoli cells and/or spermatogonia in the immature rat was addressed using cultures of seminiferous tubules from 7- to 8-day-old rats. Addition of GDNF for 48 h resulted in a twofold decrease in the percentage of spermatogonia able to duplicate DNA, whereas Sertoli cells were not affected. These results are consistent with a role of GDNF in inhibiting the S-phase entrance of a large subset of differentiated type A spermatogonia, together with an enhancing effect of the factor on a small population of undifferentiated (stem cells) spermatogonia. Moreover, the wide temporal and spatial expression of GDNF and its receptors in the rat testis suggest that it might act at several stages of spermatogenesis.

Animals↗

PubMed2006

New management options for end-stage chronic liver disease and acute liver failure: potential for pediatric patients.

The management of children with end-stage chronic liver disease and acute liver failure mandates a multidisciplinary approach and intense monitoring. In recent years, considerable progress has been made in developing specific and supportive medical measures, but studies and publications have mainly concerned adult patients. Therapeutic approaches to complications of end-stage chronic liver disease and acute liver failure (e.g. refractory ascites, hepatorenal syndrome, encephalopathy, and cerebral edema) that may be applied to children are reviewed in this article.Mild-to-moderate ascites should be managed by modest salt restriction and oral diuretic therapy in the first instance. Large volume paracentesis associated with colloid volume expansion and diuretic therapy may be effective for acute relief. Treatment of hepatorenal syndrome type 1 with vasopressin analogs (terlipressin) is recommended prior to liver transplantation in order to improve renal function. Prevention and treatment of chronic hepatic encephalopathy are directed primarily at controlling the events that may precipitate hepatic encephalopathy and at reducing ammonia generation and increasing its detoxification or removal. In addition to reduction of gut ammonia production using non-absorbable disaccharides such as lactulose and/or antibacterials such as neomycin, sodium benzoate may be used on a long-term basis to prevent, stabilize, or improve hepatic encephalopathy. The management of hepatic encephalopathy in acute liver failure is considerably more unsatisfactory; treatment is aimed at preventing brain edema and intracranial hypertension. Extracorporeal liver support devices are now used commonly in critically ill children with acute renal failure, advanced hepatic encephalopathy, cerebral edema, intracranial hypertension, and severe coagulopathy. Continuous renal replacement therapy could potentially help support patients until liver transplantation is performed or liver regeneration occurs. The Molecular Adsorbent Recirculating System (MARS or albumin dialysis) is the liver support system most frequently used worldwide in adults and appears to offer distinct advantages over hepatocyte-based systems. There are no specific medical therapies or devices that can correct all of the functions of the liver. Apart from a few metabolic diseases presenting with severe liver dysfunction for which specific medical therapies may preclude the need for liver transplantation, liver transplantation still remains the only definitive therapy in most instances of end-stage chronic liver disease and acute liver failure. Future research should focus on gaining a better understanding of the mechanisms responsible for liver cell death and liver regeneration, as well as developments in hepatocyte transplantation and liver-directed gene therapy.

Ascites↗

PubMed2005

Phosphatidylserine externalization in human sperm induced by calcium ionophore A23187: relationship with apoptosis, membrane scrambling and the acrosome reaction.

BACKGROUND: Translocation of phosphatidylserine (PS) from the inner to the outer leaflet of the plasma membrane is a modification of the lipid architecture occurring in sperm. This is one of the earliest signs of apoptosis that can be monitored by the calcium-dependent binding of annexin V. METHODS AND RESULTS: Flow cytometric analysis of annexin V binding was performed. Calcium ionophore A23187 led to a significant increase in the proportion of living sperm with PS exposure: 7.3 3.2% of cells in the untreated ejaculate versus 47.5 5.6% of cells after 1 h of incubation with A23187. Conversely, diminution of mitochondrial membrane potential [DiOC6(3)/propidium iodide (PI) assay], caspase activation [fluorescein isothiocyanate (FITC)-Val-Ala-Asp-fluoromethylketone (VAD-FMK)/PI assay], increased plasma membrane permeability (Yo-Pro-1/PI assay) and increased DNA fragmentation [TdT (terminal deoxynucleotidyl transferase)-mediated dUDP nick-end labelling assay], which are among the main signs of apoptosis, were not observed in sperm, even after 4 h of incubation with A23187. However, A23187 significantly increased the proportion of sperm with plasma membrane scrambling and with a reacted acrosome, as detected with the merocyanine 540 probe (M540) and the monoclonal anti-human CD46-PE antibody respectively. CONCLUSIONS: Our results suggest that PS exposure in human sperm, as induced by A23187, is mainly related to the acrosome reaction rather than to apoptosis.

Acrosome↗

PubMed2005

A new supported reagent for the parallel synthesis of primary and secondary O-alkyl hydroxylamines through a base-catalyzed Mitsunobu reaction.

The growing field of applications of O-alkyl hydroxylamines in medicinal chemistry and chemical biology has motivated the search for a parallel synthesis. A solid-phase approach based on the alkylation by alcohols of a new supported N-hydroxyphthalimide reagent using a Mitsunobu reaction followed by methylaminolysis has been optimized. This study points out the importance of the linker and a specific base effect for the Mitsunobu reaction. A large variety of alcohols can be used to give with moderate to high yields diverse O-alkyl hydroxylamines in high purity.

Journal Article↗

PubMed2005

Transforming growth factor beta-1 decreases the yield of the second meiotic division of rat pachytene spermatocytes in vitro.

BACKGROUND: TGF beta and its receptors are present in both germ cells and somatic cells of the male gonad. However, knock-out strategies for studying spermatogenesis regulation by TGF beta have been disappointing since TGF beta-or TGF beta receptor-null mice do not survive longer than a few weeks. METHODS: In the present study, we addressed the role of TGF beta-1 on the completion of meiosis by rat pachytene spermatocytes (PS) cocultured with Sertoli cells. Identification and counting of meiotic cells were performed by cytology and cytometry. RESULTS: Under our culture conditions, some PS differentiated into round spermatids (RS). When TGF beta-1 was added to the culture medium, neither the number of PS or of secondary spermatocytes nor the half-life of RS was modified by the factor. By contrast, the number of RS and the amount of TP1 mRNA were lower in TGF beta-1-treated cultures than in control cultures. Very few metaphase I cells were ever observed both in control and TGF beta-1-treated wells. Higher numbers of metaphase II were present and their number was enhanced by TGF beta-1 treatment. A TGF beta-like bioactivity was detected in control culture media, the concentration of which increased with the time of culture. CONCLUSION: These results indicate that TGF beta-1 did not change greatly, if any, the yield of the first meiotic division but likely enhanced a bottleneck at the level of metaphase II. Taken together, our results suggest strongly that TGF beta participates in an auto/paracrine pathway of regulation of the meiotic differentiation of rat spermatocytes.

Animals↗

PubMed2005

Sustained inhibitory effect of Agouti Related Protein on the ACTH-induced cortisol production by bovine cultured adrenal cells.

The adrenal gland is the second tissue after hypothalamus exhibiting high expression level of Agouti Related Protein (Agrp) mRNA, which suggests that this peptide may control adrenal cell functions. However, its role in this tissue remained to be determined. In this report, we studied the effects of a long-term treatment (24 h) of cultured bovine adrenal cells by Agrp on the (Nle4, d-Phe7)-alphaMSH (NDP-alphaMSH)- or ACTH-induced cortisol release. We showed that Agrp inhibited, in a dose-dependent manner, the 10(-9) M NDP-alphaMSH-induced cortisol production through its antagonistic properties towards MSH at the level of MC4-R. Surprisingly, we found that Agrp in the same conditions of cell treatment also induced a strong inhibition of the ACTH-induced cortisol release. These effects were stronger using low concentrations of Agrp and disappeared for higher concentrations resulting in U-shaped curve data. There was no effect of SHU9119 in the same conditions of stimulation of the cells. Our data confirmed that Agrp is not an antagonist of ACTH at the level of MC2-R and that its sustained effect on ACTH-induced steroidogenesis did not involve its antagonistic properties at the level of MC4-R. The hypothesis would be that Agrp is acting on adrenal steroidogenesis through an alternate mechanism.

Adrenal Glands↗

PubMed2005

Long-term outcome of pediatric liver transplantation for biliary atresia: a 10-year follow-up in a single center.

The aim of this study was to review our experience in orthotopic liver transplantation (OLT) for biliary atresia (BA) in children and analyze the survival and prognostic factors, and long-term outcome. We reviewed 332 OLTs performed in 280 children between the years 1986 and 2000. Univariate and multivariate analysis were performed on patient and graft survivals according to recipients' and donors' characteristics as well as intraoperative data. The long-term outcome among the 80 children living at 10 years after OLT was studied according to growth, immunosuppressive therapy, and liver and renal functions. Liver graft status was eventually documented by liver biopsy. Status of rehabilitation was assessed by reviewing school performance and employment. Overall patient survival rates at 1, 5, and 10 years were 85, 82, and 82%, respectively, and the corresponding overall graft survival rates were 77, 73, and 71%. In the multivariate analysis, we identified 4 independent prognostic factors: polysplenia syndrome (P = .03), United Network for Organ Sharing (UNOS) status (P = .05), donor's age (P = .01), and perioperative surgical complications (P = .03). At 10 years after transplant, 80 children were alive and had normal growth rates. Liver histology was abnormal in 73% of these long-term survivors, mainly due to chronic rejection and centrilobular fibrosis. A total of 63 of the 80 children attended normal school and in 55 children (69%) school performance was not delayed. In conclusion, we discovered that a good long-term survival could be achieved after liver transplantation for BA, with a 82% survival rate at 10 years with normal scholastic studies in the majority of recipients.

Adolescent↗

PubMed2005

Pneumococcal meningitis in a pediatric intensive care unit: prognostic factors in a series of 49 children.

BACKGROUND: Despite advances in antibiotic therapy strategies and in pediatric intensive care, prognosis of Streptococcus pneumoniae meningitis remains very poor. However, few prognostic studies have been published, especially in pediatric populations. METHODS: We conducted a prognostic study to determine the factors associated with hospital mortality of 49 children admitted in a single pediatric intensive care unit during a 12-yr period (1990-2002). RESULTS: Hospital mortality was 49% (24 of 49 patients), and neurologic sequels were observed in 47% of survivors. Among them, 90% had permanent sensory deafness. Based on univariable analyses, seven variables were associated with the outcome: Pediatric Risk of Mortality II score (p = .000005), Glasgow Coma Score of >8 (p = .001), use of mechanical ventilation (p = .001), platelet count (p = .007), white blood cells count (p = .002), cerebrospinal fluid glucose level (p = .02), and lack of corticosteroids use (p = .02). In multivariable analysis, only three factors were independently associated with in-hospital mortality: Pediatric Risk of Mortality II score (hazard ratio, 1.13; 95% confidence interval, 1.06-1.20; p = .0002), platelets count of >200 x 10/L (hazard ratio, 0.25; 95% confidence interval, 0.08-0.81; p = .021) and white blood cell count above 5 x 10/L (hazard ratio, 0.31; 95% confidence interval, 0.11-0.87; p = .026). CONCLUSIONS: S. pneumoniae meningitis remains a devastating childhood disease in developed countries. Three variables were independently associated with the in-hospital death in our series-high Pediatric Risk of Mortality II score, low white blood cells count, and low platelet count-reflecting the main importance of severe sepsis and neurologic presentation in establishing the prognosis of these patients.

Adrenal Cortex Hormones↗

PubMed2004

Synthesis and structure of symmetrical bicyclic hexapeptides bridged by metathesis reaction.

[structure: see text] Bicyclic hexapeptides 1a-c were synthesized via an intramolecular ring-closing metathesis reaction on solid phase followed by an N- to C-terminal cyclization in solution. Structural elucidation showed that these compounds assumed a C2-symmetrical structure with two beta-turns. The trans-ethylene plane was found to occupy two positions in rapid interconversion. One of the bicyclic hexapeptides crystallized with five water molecules, which made an arch above the ethylene group.

Cyclization↗

PubMed2004

BARD1 expression during spermatogenesis is associated with apoptosis and hormonally regulated.

The BRCA1-binding RING-finger domain protein BARD1 may act conjointly with BRCA1 in DNA repair and in ubiquitination, but it may also induce apoptosis in a BRCA1-independent manner. In this study, we have investigated BARD1 expression during spermatogenesis. In contrast with BRCA1, which is expressed only in meiotic spermatocytes and early round spermatids, BARD1 is expressed during all stages of spermatogenesis. However, while spermatogonia expressed full-length BARD1 mRNA, later stages of spermatocyte precursors express predominantly a novel, shorter splice form BARD1beta. BARD1beta lacks the BRCA1-interacting RING finger but maintains its proapoptotic activity. Consistently, BRCA1 can counteract the proapoptotic activity of full-length BARD1 but not of BARD1beta. Several lines of evidence suggest that BARD1 is involved in proapoptotic signaling in testis: i) both BARD1 isoforms are mostly found in cells that stain positive for TUNEL, Bax, and activated caspase 3; ii) BARD1beta, capable of inducing apoptosis even in the presence of BRCA1, is specifically expressed in BRCA1-positive later stages of spermatogenesis; iii) antiapoptotic hormonal stimulation leads to BARD1 downregulation; and iv) BARD1 expression is associated with human pathologies causing sterility due to increased germ cell death. Our data suggest that full-length BARD1 might be involved in apoptotic control in spermatogonia and primary spermatocytes, while a switch to the BRCA1-independent BARD1beta might be necessary to induce apoptosis in BRCA1-expressing meiotic spermatocytes and early round spermatids.

Amino Acid Sequence↗

PubMed2004

Bound ferulic acid from bran is more bioavailable than the free compound in rat.

Ferulic acid (FA) is reported as a good antioxidant absorbed by human or rat but only few data deal with the influence of the food matrix on its bioavailability and with its potential protection against cardiovascular diseases and cancer. Wheat bran is used as a source of ferulic acid, the compound being mainly bound to arabinoxylans of the plant cell walls. Pharmacokinetic profiles of FA and its metabolites are established in rats. Free and conjugated FA quickly appear in plasma, reach a plateau 1 h after intake and remain approximately constant at 1 microM up to 24 h. 2.3% of FA are eliminated in urine. Compared with results obtained after intake of free FA, the presence of FA-arabinoxylans bonds in the food matrix increases the occurrence time of FA in the organism and decreases the level of urinary excretion in 24 h. Nevertheless, sulfated FA is still the main plasmatic form. The antioxidant activity of plasmas of rats fed with a standard diet (containing no FA), pure ferulic acid (5.15 mg FA/kg bw) or bran (4.04 mg FA/kg bw) are measured in an ex vivo test using AAPH as free radical inducer. Plasmas of rats fed with bran show a better antioxidant activity than the control group and the pure FA supplemented group, increasing the resistance of erythrocytes to hemolysis by factors of 2 and 1.5, respectively. These results show the good bioavailability of FA from bran and its potential efficiency to protect organism against pathology involving radical steps of development.

Animals↗

PubMed2004

Cryopreservation induces an apoptosis-like mechanism in bull sperm.

Cryopreservation induces many changes in sperm cells, including membrane disorders and cell death. We tested the hypothesis that apoptosis, a form of programmed cell death, can contribute to the fatal effect of cryopreservation on sperm cells. A multiparametric study of apoptosis on bovine sperm is proposed, using flow cytometry, including mitochondrial membrane potential (DeltaPsi(m)), caspase activation, membrane permeability, nucleus condensation, DNA fragmentation, and phosphatidylserine (PS) externalization. The relevance of each test was first validated on a human somatic cell line, U937. Cryopreservation and/or thawing induced significant changes in all apoptotic markers in living bull sperm cells except those concerning the nucleus. After cryopreservation, 44.9% +/- 17% (vs. 11.3% +/- 10.6% before cryopreservation) of sperm cells showed low DeltaPsi(m), 12% +/- 6.3% (vs. 2.2% +/- 1.0% before) contained active caspases, and 10.8% +/- 5.8% (vs. 1.4% +/- 1.1% before) exhibited high membrane permeability. However, cryopreservation had no effect on DNA fragmentation (9.1% +/- 7.7% before vs. 11.1% +/- 5.7% after cryopreservation) or on nucleus condensation (46% +/- 12.7% before vs. 43.8% +/- 13.1% after). Cryopreservation acts as an apoptotic mechanism inducer in bovine sperm cells, where the earliest but not the latest features of cells undergoing apoptosis occur. We have named this abortive process an apoptosis-like phenomenon.

Animals↗