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Biomedical subjects

G Fortier

Publications and source records attributed to G Fortier.

At least 19 recordsLinked to original sources
PubMed2003

Reactivity against Sarcocystis neurona and Neospora by serum antibodies in healthy French horses from two farms with previous equine protozoal myeloencephalitis-like cases.

Sarcocystis neurona is considered a leading cause of equine protozoal myeloencephalitis (EPM), a common infectious neurological disease in horses in the Americas. EPM-like cases associated with S. neurona peptide reactive antibodies in Western blots were recently described in Normandy, France. In this report, antibodies reacting with S. neurona merozoites were detected using an agglutination assay at titers ranging from 50 to 500 in sera from 18/50 healthy horses from two farms with a previous EPM-like case. Higher values were found in older animals. Four out of six horses which traveled or stayed in the US exhibited titers over 50, a higher figure than in the group which did not travel out of France or stayed in an other European country. No correlation was found between anti-S. neurona and anti-Neospora sp. antibody titers. Data prompt further study of significance of anti-S. neurona antibodies in clinically healthy or diseased European horses, and identification of putative immunizing parasite(s) and their host(s).

Animals↗
PubMed2002

Physiological measurements and upper and lower respiratory tract evaluation in French Standardbred Trotters during a standardised exercise test on the treadmill.

There are a variety of reasons for poor performance in racehorses. Exercise intolerance has often been associated with subclinical respiratory abnormalities, and diagnostic aids are therefore used to enhance clinical detection. Physiological variables can also be measured in order to evaluate the metabolic reponse to exercise. This study evaluated the relationship between physiological measurements and upper airway videoendoscopy during a standardised treadmill exercise test and bronchoalveolar lavage (BAL) cytology in control horses (good racing performance, n = 14) and poor performers (n = 27). The poor performers were divided into 2 groups: Group 1 = both upper and lower respiratory airway abnormal findings (n = 10); Group 2 = lower respiratory airway abnormal findings (n = 17). Horses in Group 2 were divided into 3 categories: Group 2A = exercise-induced pulmonary haemorrhage (EIPH ; n = 5); Group 2B = small airway inflammation (SAI +/- EIPH; n = 7) and Group 2C = other (n = 5). During exercise, the poor performers had significantly lower arterial PaO2 and higher HR and blood lactate concentrations compared to controls. Total nucleated cell count of BAL fluid collected from poor racing performers was significantly higher than in controls; also, epithelial cells and haemosiderophage percentage collected from poor racing performers were significantly higher than in controls. Eight horses with dorsal displacement of the soft palate also had cytological evidence of lower respiratory airway disease. The results of this study suggest that there is a significantly different metabolic response (HR, blood lactate, PaO2) to exercise in poor compared to good performers. As both upper and/or lower respiratory problems can be associated with poor racing performance, a detailed examination of the upper and lower respiratory tracts at rest, during and after exercise is advised.

Animals↗
PubMed2001

Neosporosis in bovine dairy herds from the west of France: detection of Neospora caninum DNA in aborted fetuses, seroepidemiology of N. caninum in cattle and dogs.

Neospora caninum is considered one of the major causes of abortion in cattle in most parts of the world. In this study, the role of N. caninum was investigated in groups of aborted cattle and dairy herds from the west of France. Good correlation was found between parasite DNA detection in fetuses and serologic statuses of dams. In groups with documented abortion status and no antibodies to other pathogens, 17-45% of aborted animals were seropositive for N. caninum, and significant relationship between prevalence of Neospora antibodies and frequency of abortions was found. Neospora-associated abortions were observed all the year round, with a peak in summer. Higher ratios of seropositive abortions were found before the 6th month of gestation. In 12 herds studied in the field, serologic prevalence ranged 6-47%. No difference in age was found between seropositive and seronegative cows. Results indicate that N. caninum is an important and stable cause of abortion in cattle in France.

Abortion, Veterinary↗
PubMed2001

New landmarks improve the positioning of the left Broncho-Cath double-lumen tube-comparison with the classic technique.

PURPOSE: To compare a new technique (NT) for positioning the left modified Broncho-Cath double-lumen tube (LM- DLT) by fibreoptic bronchoscopy (FOB) to the classic technique (CT). METHODS: Sixty-one adult patients undergoing elective thoracic surgery with LM-DLT were randomly assigned to the NT or to the CT group. For the NT, the endoscopist confirms the left mainstem endobronchial intubation. The proximal edge of the blue bronchial cuff should not be visualized at the carina. Then, through the left bronchial lumen, by transparency across the wall of the tube, the position of the tube is adjusted so that the carina lies midway between the black radiopaque line and the top of the bronchial cuff. After this, the orifice of the left upper lobe (LUL) bronchus should be clearly seen. For the CT, the endoscopist uses the technique described by Benumof and Slinger. After lateral positioning of the patient, the LM-DLT was repositioned if the top of the endobronchial cuff was above the carina or when the LUL bronchus was obstructed. RESULTS: The incidence of proximal repositioning was significantly less in the NT compared to the CT (16% vs 43%, P=0.007). CONCLUSION: Using this new technique, the LM-DLT is inserted deeper in the left mainstem bronchus. This new landmark augments the range of movement that can be tolerated without requiring repositioning of the LM-DLT. This NT to position and to assess LM-DLT, by transparency across the wall of the tube with FOB, is better adapted to the LM-DLT and its recent modifications.

Bronchi↗
PubMed2001

Immobilization of native and poly(ethylene glycol)-treated ('PEGylated') bovine serum amine oxidase into a biocompatible hydrogel.

Native bovine serum amine oxidase (BSAO) and poly(ethylene glycol) (PEG)-treated ('PEGylated') BSAO were immobilized into a hydrogel during its synthesis. The hydrogel was obtained by cross-linking of BSA with PEG di-nitrophenyl carbonates with a molecular mass of 10 kDa. Approx. 60% of the amino groups at the surface of BSAO were modified by monomethoxy-PEG with a molecular mass of 5 kDa when the reaction was carried out for 5 h in borate buffer, pH 9. The number of anchorage points of BSAO in the matrix, which was determined as minimal when PEGylated BSAO was used or maximal when native BSAO was used, did not influence the apparent K(m) and V(max) values of the different preparations. The apparent K(m) values of both forms of the enzyme were decreased due to preconcentration of benzylamine substrate by the negatively charged hydrogel. V(max) values were generally lower upon immobilization. We can therefore conclude that the hydrogel swelling has no significant effect on the enzyme's structure. The operational stability, evaluated in the presence of substrate, was generally increased upon enzyme immobilization into the hydrogel. Enzymic hydrogels were very stable during storage in solution at 4 degrees C, maintaining a high activity even after several weeks. The immobilization of both forms of BSAO did not improve their thermostability at 65 degrees C. The BSA-PEG hydrogel is a good matrix for immobilization of enzymes with therapeutic potential such as BSAO.

Amine Oxidase (Copper-Containing)↗
PubMed2000

[Severe hyponatremic encephalopathy after pediatric surgery: report of seven cases and recommendations for management and prevention].

BACKGROUND: The infusion of hypotonic solutions in the perioperative period can lead to the development of hyponatraemic encephalopathy which is a severe, life threatening but preventable complication. CLINICAL PRESENTATION: Seven children aged 3-6 yr, ASA 1 or 2, operated on for a scheduled surgical procedure, presented at the 11th postoperative hour with seizures or status epilepticus, associated with vomiting (5/7), and a constant loss of consciousness (median Glasgow Coma Scale at 7), while one child presented with a respiratory arrest. At arrival in ICU, serum sodium was 120 mmol.L-1. All children had received in the perioperative period an hypotonic solution infusion (mainly dextrose 5%), at a high rate for most of them. Management included mechanical ventilation (3/7), antiepileptic drugs (7/7), fluid restriction (7/7), sodium chloride infusion (5/7), and diuretics (6/7). Serum sodium increased to a mean of 135 mmol.L-1 in 12 hours. Six children had a good neurologic outcome while one child died from brain death. CONCLUSION: The use of hypotonic solute in the perioperative period can lead to hyponatremic encephalopathy, a severe neurologic complication of acute hyponatremia. It must be prevented by the use of appropriate solutions i-e isotonic fluids in regards of the low free water elimination capacities of the surgical patient.

Brain Diseases↗
PubMed1999

Restriction fragment length polymorphisms of virulence plasmids in Rhodococcus equi.

Virulent Rhodococcus equi, which is a well-known cause of pyogranulomatous pneumonia in foals, possesses a large plasmid encoding virulence-associated 15- to 17-kDa antigens. Foal and soil isolates from five countries-Argentina, Australia, Canada, France, and Japan-were investigated for the presence of 15- to 17-kDa antigens by colony blotting, using the monoclonal antibody 10G5, and the gene coding for 15- to 17-kDa antigens by PCR. Plasmid DNAs extracted from positive isolates were digested with restriction endonucleases BamHI, EcoRI, EcoT22I, and HindIII, and the digestion patterns that resulted divided the plasmids of virulent isolates into five closely related types. Three of the five types had already been reported in Canadian and Japanese isolates, and the two new types had been found in French and Japanese isolates. Therefore, we tentatively designated these five types 85-kb type I (pREAT701), 85-kb type II (a new type), 87-kb type I (EcoRI and BamHI type 2 [V. M. Nicholson and J. F. Prescott, J. Clin. Microbiol. 35:738-740, 1997]), 87-kb type II (a new type), and 90-kb (pREL1) plasmids. The 85-kb type I plasmid was found in isolates from Argentina, Australia, Canada, and France. Plasmid 87-kb type I was isolated in specimens from Argentina, Canada, and France. The 85-kb type II plasmid appeared in isolates from France. On the other hand, plasmids 87-kb type II and 90-kb were found only in isolates from Japan. These results revealed geographic differences in the distribution of the virulence plasmids found in the five countries and suggested that the restriction fragment length polymorphism of virulence plasmids might be useful to elucidate the molecular epidemiology of virulent R. equi in the world.

Plasmids↗
PubMed1998

[Kasabach-Merritt syndrome on a congenital tufted angioma].

INTRODUCTION: Kasabach-Merritt syndrome is a very rare disease of infancy, with profound thrombocytopenia and a mild to severe consumption coagulopathy; this biological phenomenon is difficult to control. CASE REPORT: A 1-month old boy had a congenital plaque-like lesion in the calf. It was a biopsy-proven tufted angioma. Five weeks later, Kasabach-Merritt syndrome developed. After failure of ticlopidine + aspirin, and oral betamethasone treatment, thrombocytopenia was cured with vincristine treatment, then the leg lesion slowly continued to shrink after cessation of the treatment. It had disappeared before the age of 1 year. DISCUSSION: We highlighted two points: 1) Kasabach Merritt does not appear as a complication of a classic hemangioma (infantile, "cellular", "capillary", involuting-type), as it has long been thought. In our experience, it develops on a different endothelial cell proliferation, in this case a congenital tufted angioma, but it can also engraft on a kaposiform hemangioendothelioma. 2) These patients are difficult to treat because, up to now, no single treatment has given constant by good results. Vincristine was recently introduced in the treatment of Kasabach-Merritt syndrome, with excellent, rapid outcome. CONCLUSION: What seems a therapeutic progress in a difficult field needs further control.

Antineoplastic Agents, Phytogenic↗
PubMed1997

Immobilization of L-asparaginase into a biocompatible poly(ethylene glycol)-albumin hydrogel: evaluation of performance in vivo.

The L-asparaginase of Escherichia coli (ASNase) is currently used in combination with antineoplastic drugs to treat various lymphoblastic leukaemias. However, its use is limited by severe immunological reactions and the short serum half-life associated with the enzyme. Immobilization of ASNase into a biocompatible matrix can greatly decrease the immunogenicity of the enzyme, increase its half-life in vivo and its therapeutic index. Thus the E. coli ASNase was immobilized in a biocompatible hydrogel made of rat serum albumin and poly(ethylene glycol) (PEG; molecular mass 10 kDa). The effectiveness of this enzymic bioreactor to deplete serum L-asparagine was evaluated after its peritoneal implantation in rats. Seven units of immobilized ASNase/rat depleted serum asparagine to an undetectable level (< 1 microM) during 6 days, while 5 units of immobilized ASNase/rat decreased the level of serum asparagine by 85-90% during at least 2 days. Under both conditions asparagine levels returned to normal about 10 days after surgery, and hydrogels still retained 80% of their enzymic activity when assayed in vitro. After 10-14 days in vivo, hydrogels became opaque and surrounded by a fibrotic capsule with a few inflammatory sites. Nevertheless, the enzymic hydrogel showed great stability in vivo, and, after 4 months of implantation, 12% of the initial ASNase activity was still present. At 6 months, histological analysis showed stabilization of the fibrotic capsule thickness. Assays on the levels of ASNase and asparagine synthetase indicated an induction of the latter activity, mainly in the pancreas when compared with the level observed in spleen or liver. ELISA tests at 28 days and 120 days showed the presence of anti-ASNase (and, in lower amounts, anti-PEG) antibodies in sera of implanted rats. As observed with other enzyme-immobilization systems used in vivo, the formation of fibroblast-like cell layers around the implant, which block the translocation of the substrate into the enzymic matrix, is the major factor affecting the performance and longevity of the bioreactor.

Albumins↗
PubMed1996

Immobilization of L-asparaginase into a biocompatible poly(ethylene glycol)-albumin hydrogel: I: Preparation and in vitro characterization.

The feasibility of the immobilization of Escherichia coli L-asparaginase into a hydrogel matrix made of poly-(ethylene glycol) (PEG) and BSA was demonstrated. After immobilization a 200-fold increase in the Km value was observed. The use of an L-aspartic acid analogue, carbobenzoxy-L-aspartic acid and surface modification by methoxy-PEG of molecular mass 5 kDa cause a only a slight gain in affinity of the enzyme for its natural substrate. The immobilized L-asparaginase has an optimal activity over a larger range of pH than the native enzyme, owing to the effect of the matrix. At a physiological pH of 7.3, the immobilized enzyme retained 90% of its activity compared with only 43% for the native form. The immobilized enzyme retained a high proportion of its initial activity, more than 90% after 50 days of incubation at 37 degrees C, even in the presence of its substrate. This may be compared with a half-life of 2 days observed for native enzyme incubated under the same conditions. These results suggest that the BSA-PEG matrix can be very useful for enzyme immobilization and, taking into account the good biocompatibility of the matrix, one can expect that this matrix will provide a functional bioreactor for use in vivo.

Animals↗
PubMed1995

Poly(ethylene glycol)-serum albumin hydrogel as matrix for enzyme immobilization: biomedical applications.

Poly(ethylene glycol)-albumin hydrogels were implanted in mice in subcutaneous position to study their biocompatibility. After one month of implantation, the fibrous capsule formed around the implant was thin and the inflammatory tissue was limited. Acid phosphatase (AP) was selected to evaluate the hydrogel as matrix for enzyme immobilization. AP-hydrogels were prepared using activated PEG (PEGa) of different molecular weights (M.W. 4,600 to 20,000) to evaluate the effect of the matrix composition on the activity of AP. The apparent Km of the immobilized AP was 16 to 20 times higher than the Km of the soluble enzyme. The apparent Km value decreases with the increase of the chain length of the PEGa used. This can be correlated to an increase in the hydrogel porosity. The operational stability of the AP was markedly improved after immobilization by 110 to 160 times according to the PEGa molecular weight involved. Also, asparaginase (ASNase) was immobilized in PEGa (M.W. 10,000)-albumin-hydrogel as a model for in vivo bioreactor. ASNase hydrogels were implanted in the peritoneal cavity of rats; 7 days later, 75% of the initial enzyme activity were retrieved.

Acid Phosphatase↗
PubMed1995

Drug release from new bioartificial hydrogel.

The use of high water content (> 96%) hydrogels obtained from copolymerisation of bovine serum albumin and poly(ethylene glycol) as a controlled release system has been investigated. Such hydrogels allowed release of soluble and hydrophobic substances, even proteins. Release is shown to occur by a diffusion controlled mechanism, leading to half-life times of release ranging between 0.8 hour for theophylline and 4.2 hours for lysozyme, when a 2.4 mm thick disc of BSA-PEG (MW of 10000) was used. The effect of the porosity of the hydrogel on the diffusive properties of theophylline and hydrocortisone has been evaluated by varying the molecular weight of the poly(ethylene glycol). It was shown that poly(ethylene glycol) of high molecular weight leads to more porous hydrogels in which the diffusion is faster.

Acetaminophen↗