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Biomedical subjects

C Bernard

Publications and source records attributed to C Bernard.

At least 73 records · Page 4Linked to original sources
PubMed2000

Kawasaki disease complicated by renal artery stenosis.

We report the case of a child who developed severe renovascular hypertension six months after acute Kawasaki disease. The hypertension was well controlled with enalapril, but there was a gradual decrease in function of the affected kidney. The lesion, an ostial stenosis of the right main renal artery, was not amenable to percutaneous balloon angioplasty, so was treated with bypass surgery. Vasculitis is an important cause of renovascular hypertension in children. This case highlights the importance of regular blood pressure monitoring in children with a history of systemic vasculitis.

Angioplasty↗
PubMed2000

Correlation between pancreatic islet uncoupling protein-2 (UCP2) mRNA concentration and insulin status in rats.

Hypothesizing that UCP2 may influence insulin secretion by modifying the ATP/ADP ratio within pancreatic islets, we have investigated the expression of intraislet UCP2 gene in rats showing insulin oversecretion (non-diabetic Zucker fa/fa obese rats, glucose-infused Wistar rats) or insulin undersecretion (fasting and mildly diabetic rats). We found that in Zucker fa/fa obese rats, hyperinsulinemia (1222+/-98 pmol/l vs. 128+/-22 pmol/l in lean Zucker rats) was accompanied by a significant increase in UCP2 mRNA levels. In rat submitted to a 5 day infusion with glucose, hyperinsulinemia (1126+/-101 pmol/l vs. 215+/-25 pmol/l in Wistar control rats), coincided with an enhanced intraislet UCP2 gene expression, whereas a 8h or a 2 day-infusion did not induce significant changes in UCP2 mRNA expression. In rats made hypoinsulinemic and mildly diabetic by the injection of a low dose of streptozotocin, and in 4-day-fasting rats (plasma insulin 28+/-5 pmol/l) UCP2 gene expression was sharply decreased. A 3-day-fast was ineffective. The data show the existence of a time-dependent correlation between islet mRNA UCP2 and insulin that may be interpreted as an adaptative response to prolonged insulin excess.

Analysis of Variance↗
PubMed2000

[Arachnoid cysts of the middle fossa and associated subdural hematoma. Three case reports and review of the literature].

BACKGROUND AND PURPOSE: We report 3 cases of subdural hematoma associated with arachnoid cyst of the middle fossa, and discuss the treatment. METHODS: Three males aged 33, 63 and 68 were treated in our institution. Before this event the cyst was asymptomatic and unknown. Magnetic resonance imaging was the most contributive radiologic exam. Surgical procedure was limited to subdural hematoma evacuation. The internal wall of subdural hematoma was opened in all cases. RESULTS: The clinical outcome was good for all patients. The CT or MRI scan follow-up 3 months later revealed nearly total disappearance of subdural hematoma for 2 out of 3 cases. For one patient the volume of arachnoid cyst decreased. CONCLUSIONS: We propose subdural hematoma drainage without any specific treatment (shunt or fenestration) of the arachnoid cyst, for this category of patient.

Adult↗
PubMed2000

Pancreatic secretory response to feeding in the calf: CCK-A receptors, but not CCK-B/gastrin receptors are involved.

In bovine species, as in human, the pancreas predominantly expresses cholecystokinin-B (CCK-B)/gastrin receptors. However, the role of this receptor in the regulation of meal-stimulated pancreatic enzyme release has not been determined. In milk-fed calves, we previously described prandial patterns of exocrine pancreatic secretion and a long prefeeding phase was observed. The present study was aimed at determining both the role of external stimuli in the outset of the prefeeding phase and the implication of pancreatic CCK-A and CCK-B/gastrin receptors in the mediation of pancreatic response to feeding. The first objective was studied by suppressing external stimuli associated with food intake (unexpected meal) and the second by infusing highly specific and potent antagonists of CCK-A (SR 27897) and CCK-B/gastrin (PD 135158) receptors during the prandial period. When calves were given an unexpected meal, the long prefeeding increase in pancreatic secretion was absent. SR 27897 (but not PD 135158) inhibited the preprandial phase and greatly reduced postprandial pancreatic juice and enzyme outflows. The expectancy of a meal seemed to elicit an increased pancreatic response right before a meal and CCK-A receptors may mediate this information via neural pathways. The implication of CCK and CCK-A receptors in mediating the postfeeding pancreatic response was also demonstrated. The participation of CCK-B/gastrin receptors in this regulation was not demonstrated.

Animals↗
PubMed2000

[Cochlear implants].

A cochlear implant is a technologically advanced medical device that simulates sound in the cochlea by electrically stimulating the hearing nerve. Cochlear implants are designed to help severely or totally deaf individuals who gain little or no benefit from hearing aids. Hearing aids and assistive listening devices amplify sounds. The sounds produced by even the most sophisticated hearing aids may not offer much benefit to people with a severe-to-profound or profound hearing loss in both ears. A cochlear implant is an electronic device that provides the function of the damaged or absent hair cells by providing electrical stimulation to the remaining nerve fibers. The implant provides useful hearing and improved communication abilities to the implant user.

Adult↗
PubMed2000

A para-testicular primitive neuroectodermal tumor in an adult: a case report and literature review.

OBJECTIVE: The authors describe the salient clinical, radiologic and histopathologic features of an extremely rare para-testicular primitive neuroectodermal tumor in a 25 year-old man. INTERVENTION: Excisional biopsy of the tumor en bloc was performed. Adjuvant VAdriaC-based chemotherapy (Vincristine, Doxorubicin, and Cyclophosphamide) was given post-operatively. MAIN OUTCOME MEASURES: Histopathologic examination and immunohistochemical studies were performed on formaldehyde-fixed, paraffin-embedded tumor tissue. RESULTS: Histologic examination showed an undifferentiated small cell tumor. The tumor cells stained positively with MIC-2, a marker specific for primitive neuroectodermal tumors. The patient is 12 months post surgery and has completed adjuvant chemotherapy with no evidence of recurrent disease. CONCLUSIONS: This highly unusual, peripheral primitive neuroectodermal tumor should be considered in the differential diagnosis of undifferentiated small cell neoplasms of the genitourinary system in adults, from the kidney to the testicle. We present a patient with a PNET treated based on a Ewing's family of tumors protocol.

Adult↗
PubMed2000

Solution structure of hpTX2, a toxin from Heteropoda venatoria spider that blocks Kv4.2 potassium channel.

HpTX2 is a toxin from the venom of Heteropoda venatoria spider that has been demonstrated to bind on Kv4.2 potassium channel. We have determined the solution structure of recombinant HpTX2 by use of conventional two-dimensional NMR techniques followed by distance-geometry and molecular dynamics. The calculated structure belongs to the Inhibitory Cystin Knot structural family that consists in a compact disulfide-bonded core, from which four loops emerge. A poorly defined two-stranded antiparallel beta-sheet (residues 20-23 and 25-28) is detected. Analysis of the electrostatic charge anisotropy allows us to propose a functional map of HpTX2 different from the one described for kappa-conotoxin PVIIA, but strongly related to the one of charybdotoxin. The orientation of the dipole moment of HpTX2 emerges through K27 which could therefore be the critical lysine residue. Close to this lysine are a second basic residue, R23, an aromatic cluster (F7, W25, W30) and an hydrophobic side chain (L24). The high density in aromatic side chains of the putative functional surface as well as the lack of an asparagine is proposed to be the structural basis of the specificity of HpTX2 toward Kv4.2 channel.

Amino Acid Sequence↗
PubMed2000

[Clinical application of functional MRI: a strategic tool for neurosurgery].

The purpose was to incorporate preoperative functional imaging data into anatomic data of operative microscope for neurosurgical procedures of patients suffering from lesions contiguous to eloquent brain areas. The day before surgery, patients bearing scalp markers underwent fMRI, just before anatomical contrast-enhanced MR images. FMRI data analysis were realised using a t test (p<0.0001). The resulting functional-anatomical images were downloaded onto a surgical neuronavigation computer in order to outline tumoral target and functional areas. At surgery, cortical stimulation has been used to confirm functional data. Functional image-guided surgery of lesions abutting functional cortex can be safely performed.

Adult↗
PubMed1999

Newly formed excitatory pathways provide a substrate for hyperexcitability in experimental temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) in humans and animals is associated with axonal sprouting of glutamatergic neurons and neosynaptogenesis in the hippocampal formation. We examined whether this plasticity of excitatory pathways contributes to an increased level of glutamatergic excitation in the CA1 region of rats experiencing chronic spontaneous limbic seizures following kainic acid or pilocarpine treatment. In chronic cases, we report an extensive axonal sprouting of CA1 pyramidal neurons, with many axonal branches entering the pyramidal cell layer and stratum radiatum, regions that are not innervated by axonal collaterals of CA1 pyramidal neurons in control animals. Concurrently with this anatomical reorganization, a large increase of the spontaneous glutamatergic drive is observed in the dendrites and somata of CA1 pyramidal cells. Furthermore, electrical activation of the reorganized CA1 associational pathway evokes epileptiform bursts in CA1 pyramidal cells. These findings suggest that reactive plasticity could contribute to the hyperexcitability of CA1 pyramidal neurons and to the propagation of seizures in these two models of TLE.

Animals↗
PubMed1999

Exogenous CCK and gastrin stimulate pancreatic exocrine secretion via CCK-A but also via CCK-B/gastrin receptors in the calf.

A predominance of the pancreatic cholecystokinin (CCK) receptor of the B/gastrin subtype (CCK-B/G) was reported in calves older than 1 month. Specific CCK-A and CCK-B/G receptor antagonists (SR 27897 and PD 135158, respectively) were used to identify the CCK receptor subtype involved in exogenous CCK- and gastrin-induced exocrine pancreatic responses. Conscious calves (2 months old) with catheterized pancreas, jugular vein and duodenum were used; the pancreatic juice was continuously reinfused. CCK (30 pmol kg-1 min-1, 40 min) evoked an increase in pancreatic juice flow and enzyme secretion, while the same dose of gastrin increased enzyme secretion alone. CCK-induced pancreatic secretion was abolished by SR 27897 (15 nmol kg-1 min-1, 55 min) and reduced by PD 135158 (0.15 nmol kg-1 min-1, 55 min). Gastrin-induced enzyme secretion was reduced by PD 135158 (50% to 90%) and to a lesser extent by SR 27897 (50% to 60%). These results demonstrate that CCK and gastrin in the physiological range stimulate pancreatic exocrine secretion in calves and that these effects are partly mediated by CCK-B/G receptors. Although CCK-A receptors are not predominantly expressed, they seem to play a major role in the response of pancreatic exocrine secretion to CCK.

Animals↗
PubMed1999

Quantitative variation and selection of esterase gene amplification in Culex pipiens.

Although descriptions of evolutionary mechanisms are common in the literature, very few studies focus on the possible evolution of the adaptive genes themselves, i.e. their quantitative and qualitative changes. Evolution of insecticide resistance in Culex pipiens is a suitable model for studying such processes. In this species, organophosphorous insecticide resistance can be achieved through the overproduction of esterases that sequester the insecticide, and this overproduction can be caused by gene amplification. It is generally assumed, but never verified, that esterase activity, and therefore resistance, is monotonically related to gene amplification. We have analysed resistance, esterase activity and gene amplification in different laboratory strains and natural populations in order to detect variability and to infer effects of selection on these factors. We have shown that resistance, esterase activity and amplification covary, that insecticide selection is able to increase amplification levels, and that a fitness cost is probably attached to the amplification in laboratory strains, related to the level of amplification. The importance of variation in gene amplification level is discussed and some evolutionary implications are proposed.

Animals↗
PubMed1999

Effect of mild hypothermia on the vascular actions of phenylephrine in rat aortic rings.

Intraoperative mild hypothermia is common. We have investigated the effects of mild hypothermia (34 vs 38 degrees C) on phenylephrine--(10(-8) to 10(-5) mol litre-1) induced contractions of rat aortic rings mounted for isometric tension recordings. A marked decrease in Emax (maximal tension) (P < 0.05) and significant increase in EC50 (phenylephrine concentration producing 50% of maximal tension) were observed at the lower temperature in endothelium intact rings, but there was no effect of temperature when the endothelium had been removed. The decreased contraction with hypothermia in the endothelium intact vessels was restored to 84% by administration of the nitric oxide synthase inhibitor L-NNA and a small additional amount of tone was restored in the presence of the cyclooxygenase inhibitor, indomethacin. We conclude that mild hypothermia markedly decreased phenylephrine-induced rat aortic contraction in vitro by endothelium dependent mechanisms, largely related to increased nitric oxide production or action.

Animals↗
PubMed1999

A new mechanism conferring unprecedented high resistance to chlorpyrifos in Culex pipiens (Diptera: Culicidae).

The cause of high resistance to chlorpyrifos observed in Tunisian Culex pipiens (L.) was investigated by comparing a Tunisian strain G (> 10,000-fold resistance), a French strain T (approximately 50-fold resistance), and a susceptible reference strain S. Strains G and T had the same level of propoxur resistance (approximately 1,000-fold) and were homozygous for an autosomal propoux-insensitive acetylcholinesterase (AChE-1). In G and T strains, as well as in the offspring of different F1s and backcrosses using these F1s and the S strain, the effect of DEF and Pb synergists on chlorpyrifos resistance was low or absent, indicating that increased detoxification by enzymes inhibited by these chemicals had a minor role. Chlorpyrifos resistance in the G strain was caused by a major gene (or group of genes) tightly linked to the Ace-1 gene (coding AChE-1 enzyme). The possibility of allelism between this gene and the Ace-1R allele present in the T strain was rejected by showing that AChE-1 inhibition by chlorpyrifos-oxon was not different between G and T mosquitoes.

Acetylcholinesterase↗
PubMed1999

Neogenesis vs. apoptosis As main components of pancreatic beta cell ass changes in glucose-infused normal and mildly diabetic adult rats.

We have investigated in adult rats made mildly diabetic by a low dose of streptozotocin (35 mg/kg; STZ rats) and in nondiabetic rats (ND rats) the mechanisms leading to adaptive changes in the beta cell mass, during glucose infusion and several days after stopping infusion. As early as 24 h of glucose infusion, the beta cell mass was maximally increased in ND and STZ rats. In both groups, this increase was due mainly to a rapid activation of neogenesis of new endocrine cells rather than to an increase in beta cell proliferation. Seven days after stopping glucose infusion, the beta cell mass returned to basal values in both groups as a result of stimulation of beta cell apoptosis and a decrease in beta cell replication rate. In glucose-infused ND rats, changes in the beta cell mass were correlated to insulin secretion, whereas in STZ rats, insulin secretion in response to glucose was still impaired whatever the beta cell mass. In conclusion, the data stress the impressive plasticity of the endocrine pancreas of adult rats. They also show that changes in beta cell mass in ND and STZ rats resulted from a disruption in the balance between neogenesis and apoptosis.

Animals↗