Prevalence of Equine Hepacivirus Infections in France and Evidence for Two Viral Subtypes Circulating Worldwide

Like hepatitis C virus (HCV) in humans, the newly identified equine hepacivirus (NPHV) displays a predominating liver tropism that may evolve into chronic infections. The genomes of the two viruses share several organizational and functional features and are phylogenetically closest amongst the Hepacivirus genus. A limited amount of data is available regarding the spread of hepacivirus infections in horses. In this study, we asked whether in a more representative sample the prevalence and distribution of NPHV infections in France would resemble that reported so far in other countries. A total of 1033 horses sera from stud farms throughout France were analysed by qRT-PCR to determine the prevalence of ongoing NPHV infections and viral loads; in positive samples, partial sequences of NPHV's genome (5'UTR, NS3 and NS5B genes) were determined. Serum concentrations of biliary acids, glutamate dehydrogenase (GLDH) and L-gamma-glutamyl transferase (γ-GT) were measured for most horses. We detected NPHV infections in 6.2% of the horses, a prevalence that reached 8.3% in thoroughbreds and was significantly higher than in other breeds. The presence of circulating virus was neither significantly associated with biological disturbances nor with clinical hepatic impairment. Our phylogenetic analysis was based on both neighbour-joining and maximum-likelihood approaches. Its result shows that, like almost everywhere else in the world so far, two major groups of NPHV strains infect French domestic horses. Based on genetic distances, we propose a classification into two separate NPHV subtypes. Viral loads in the serum of horses infected by the main subtype were, in average, four times higher than in those infected by the second subtype. We hypothesize that amino acid substitutions in the palm domain of NS5B between NPHV subtypes could underlie viral phenotypes that explain this result.

New Bioartificial Polymeric Material: Poly(ethylene glycol) Cross-Linked with Albumin. I. Synthesis and Swelling Properties

A new family of translucide hydrogels obtained by cross-linking of bifunctionalized poly(ethylene glycol) (PEG) of various molecular masses (M, 2,000 to 35,000) with an albumin protein, namely bovine serum albumin (BSA), is described. The composition and the structure of these hydrogels have been investigated on the basis of the molar ratio of reagents, and through measurements of PEG and BSA released during washing and swelling steps. It appears that an excess of activated PEG is required in the reaction mixture to allow the gel formation with PEG of molecular mass ranging from 3,350 to 10,000. Above these Mr of PEG, smaller amounts of PEG are needed to carry out the gel formation. Experimental results suggest that the cross-link density decreases when the molecular mass of PEG increases. These hydrogels are characterized by a very high swelling ability with equilibrium water contents (EWC) ranging from 96.6 to 97.5% in distilled water containing NaN3 at 0.02% (w/v). The swelling factors (SF) ranged from 14 to 40 according to the incuba tion medium and to the PEG molecular mass involved. The swelling rates increased with increasing PEG molecular mass used to synthesize the hy drogel. This family of hydrogels possesses a good porosity since diffusion of bovine serum albumin out of the hydrogel network was observed in a long-term period.

Bioartificial Polymeric Material: Poly(Ethylene Glycol) Crosslinked with Albumin. II: Mechanical and Thermal Properties

A family of hydrogels based on the crosslinking of bovine serum albumin (BSA) and activated poly(ethylene glycol) (PEG), were characterized. The swelling process was found to be dependent on the molecular weight of the PEG used and on the OH/NH2 molar ratio of the reagents. These hydrogels performed a volume expansion from 266 to 554% when PEG with molecular weights from 3,350 to 20,000 were used. The volume expansion was greater when the OH/NH2 molar ratio increased. Some anisotropy occurred during swelling since thinner devices swelled more than thicker ones, due to the difference of constraints in the hydrogels structure. Mechanical studies showed that these hydrogels were highly deformable and presented good elastic behavior since they broke only after 80% deformation. At this point, they needed a compression force ranging from 165 to 456 g/cm2 to break. The differentiation of two kinds of water in these highly swollen hydrogels was performed using DSC studies at low temperature. Free water (i.e., bulk water) was found to be the predominant form which filled the network, .and bound water (i.e., water engaged in interactions with PEG) tended to form a trihydrate complex (three molecules of water per ethylene oxide repeated unit). Three forms of water with different evaporating rates were detected by DSC studies at high temperature. This other form of water may be important for maintaining the hydrogen's form.

Cytokine concentrations in bronchoalveolar lavage fluid from horses with neutrophilic inflammatory airway disease

Background

Multiple cytological patterns occur in bronchoalveolar lavage fluid (BALF) of horses with inflammatory airway disease (IAD). Only few data on BALF cytokine profiles are available for horses with IAD, and are limited to mRNA expression.

Hypothesis/Objective

Cytological profiles of IAD are associated with different BALF immunological pathways. To investigate BALF cytokine concentrations in a large number of horses with neutrophilic IAD.

Animals

One hundred and thirty‐eight client‐owned Standardbred racehorses in active training.

Methods

Prospective observational study. BALF samples were obtained from left and right lungs. Interleukin (IL)‐4, interferon (IFN)‐γ, and tumor necrosis factor (TNF)‐α concentrations were determined by ELISA.

Results

Fourteen horses had normal BALF cytological profiles and 56 exhibited evidence of bilateral neutrophilic IAD. Twenty‐four horses showed BALF with, respectively, IAD‐ and CTL consistent cytology and were excluded; as were 44 horses because of evidence of pulmonary hemorrhage. TNF‐α (56 ± 115 pg/mL; P = .034) and IFN‐γ concentrations (104 ± 247 pg/mL; P = .044) were significantly higher for IAD horses, compared with controls (respectively 19 ± 41 and 80 ± 116 pg/mL). Horses with ‘neutrophil’ subtype had significantly higher IFN‐γ concentrations (110 ± 154 pg/mL), than ‘neutrophil/metachromatic’ (56 ± 54 pg/mL; P = .028) and ‘neutrophil/metachromatic/eosinophil’ subtypes (44 ± 23 pg/mL; P = .012).

Conclusions and Clinical Importance

Cytokine concentrations in BALF suggested that neutrophilic IAD is associated with activation of the innate immune system and a possible T‐helper (Th)‐1 polarized response. This study also suggested that immunological pathways vary according to cytological IAD subtypes.

Outbreak of equine herpesvirus myeloencephalopathy in France: a clinical and molecular investigation

Equid herpesvirus 1 (EHV-1)-associated myeloencephalopathy (EHM) is a disease affecting the central nervous system of horses. Despite the constantly increasing interest about this syndrome, epidemiological data are limited especially when related to the description of large outbreaks. The aim of this article is to describe clinical, virological and molecular data obtained throughout a severe outbreak of EHM, with emphasis on laboratory diagnostic methods. The epidemic disease concerned a riding school in France where 7/66 horses aged 12-22 years developed signs of neurological disease in July 2009. Diagnosis of EHM was supported by EHV-1 detection using both real-time PCR and virus culture, and SNP-PCR test for viral strain characterization. EHM morbidity was 10.6% (7/66), mortality was 7.5% (5/66) and case fatality rate was 71.4% (5/7). Clinical presentation of the disease was characterized by the fact that fever was systematically present within 2 days before the severe neurological signs were noted. EHV-1 was detected by PCR in each available blood and nasal swab samples. Neuropathogenic strain only (G(2254) ) was isolated during the current outbreak; C(t) values, used as an indicative level of the viral load, ranged 26.0-37.0 among the six sampled horses. The amount of virus in biological samples was not systematically related to the intensity of the clinical signs being observed. In conclusion, this article described a severe outbreak of EHM while limited in time and restricted to one premise. Molecular data strongly suggested taking into account any low viral load as being a potential risk factor for neurological manifestations.

Physiological measurements and prevalence of lower airway diseases in Trotters with dorsal displacement of the soft palate

REASONS FOR PERFORMING STUDY

Dorsal displacement of the soft palate (DDSP) is one of the most common obstructive conditions of the upper respiratory tract in the racehorse. This condition has a complex aetiology which may be caused or exacerbated by pharyngeal inflammation. Additionally, lower respiratory airway diseases may be associated with DDSP thereby contributing to exercise intolerance in these horses.

OBJECTIVE

The aim of this study was to measure physiological variables during a standardised exercise test and to assess the prevalence and consequences of lower respiratory airway disease in horses with DDSP.

METHODS

A total of 46 horses were included in this study: 22 in the control and 24 in the DDSP groups. All horses performed a SET with measurement of heart rate (HR) and blood lactate concentration. One hour post exercise, respiratory samples were collected for cytological and bacteriological analysis.

RESULTS

During exercise, the DDSP group had higher blood lactate concentration than the control group. According to BAL results, 50 and 63% of control and DDSP group horses, respectively, had evidence of inflammatory airway disease (IAD). In the DDSP group, 42% of horses had a syndrome of tracheal inflammation (STI) with 71% of this group having bacteria isolated at >10(5) CFU/ml.

CONCLUSIONS

Horses with DDSP showed evidence of a high prevalence of IAD and STI with an associated positive bacteriology in 55% of the cases. Even if DDSP is treated by surgery, the authors' recommendation would be to investigate the possibility of lower respiratory airway problems which may also be impacting the horse's performance and/or surgery efficiency.

Serum concentration of surfactant protein D in horses with lower airway inflammation

REASONS FOR PERFORMING STUDY

Surfactant protein D (SP-D), mainly synthesised by alveolar type II cells and nonciliated bronchiolar cells, is one important component of innate pulmonary immunity. In man, circulating concentrations of SP-D are routinely used as biomarkers for pulmonary injury. To date, serum SP-D levels have only been investigated in horses in an experimental model of bacterial airway infection.

OBJECTIVES

To compare serum SP-D concentrations at rest and after exercise in horses with and without inflammatory airway disease (IAD).

METHODS

Venous blood samples were collected from 42 Standardbred racehorses at rest and 60 min after performing a standardised treadmill exercise test. Tracheal wash and bronchoalveolar lavage fluid (BALF) samples were collected after exercise. Based on BALF cytology, 22 horses were defined as IAD-affected and 20 classified as controls. Serum SP-D concentrations were assessed using a commercially available ELISA kit and statistically compared between groups of horses and sampling times.

RESULTS

Serum concentrations of SP-D in IAD-affected horses were significantly higher than those of control horses, both at rest and after exercise. Within the IAD-affected group, no significant correlation was found between serum SP-D concentrations and BALF cytology. Within each group of horses (IAD and control), no significant influence of exercise was found on serum SP-D levels.

CONCLUSIONS

This is the first study determining serum SP-D concentrations in a noninfectious, naturally occurring form of lower airway inflammation in horses. The results highlight that IAD is associated with a detectable, though moderate, increase of circulating SP-D levels.

POTENTIAL RELEVANCE

Serum concentration of surfactant protein D could represent a potentially valuable and readily accessible blood biomarker of equine lower airway inflammation.

Detection of equine herpesviruses in aborted foetuses by consensus PCR

The major role of EHV-1 in equine abortion is widely reported in the literature but the contribution of EHV-2, EHV-3, EHV-4 or EHV-5 remains less well documented. The objective of this study is to evaluate the contribution of these five different EHVs to equine abortion in a variety of biological tissues using a consensus polymerase chain reaction (PCR). The test was validated for specificity and sensitivity in horses before screening specimens from 407 foetuses, stillbirths and premature foals collected over a 2.5-year interval. Positive results obtained with this assay were compared to other EHV type-specific PCR or by sequencing. EHV-1 was identified as the major cause of abortion in French mares (59/407 cases). However, there was evidence to suggest some variation in the potential of EHV-1 strains to induce abortion. Indeed, DNA samples from EHV-2 (in three cases) and EHV-5 (in one case) inferred a role of these viruses in abortion. The presence of viral DNA from EHV-3 or EHV-4 strains was not detected in the specimens studied. The data obtained suggest that the consensus herpesvirus PCR is an efficient screening tool. In association with a specific PCR, the test provides a rapid identification of the type of herpesvirus involved in abortion and is useful for routine diagnostic tests as it allows the identification of herpesviruses other than the EHV-1 strain.

Genetic variation and phylogenetic analysis of 22 French isolates of equine arteritis virus

Genetic variation and phylogenetic relationships among 22 French isolates of equine arteritis virus (EAV) obtained over four breeding seasons (2001-2004) were determined by sequencing open reading frames (ORFs) 2a-7. The ORFs 2a-7 of 22 isolates differed from the prototype virulent Bucyrus strain of EAV by between 14 (99.5% identity) and 328 (88.7% identity) nucleotides, and differed from each other by between 0 (100% identity) and 346 (88.1% identity) nucleotides, confirming genetic diversity among EAV strains circulating in France. Phylogenetic analysis based on the partial ORF5 sequences (nucleotides 11296-11813) of 22 French isolates and 216 additional EAV strains available in GenBank clustered the global isolates of EAV into two distinct groups: North American and European. The latter could be further divided into two large subgroups: European subgroup 1 (EU-1) and European subgroup 2 (EU-2). Phylogenetic analysis based on 100 EAV ORF3 sequences yielded similar results. Of the 22 French EAV isolates, the 11 isolates obtained before January 28, 2003 clustered with either the EU-1 (9 isolates) or EU-2 (2 isolates) subgroup. In contrast, by the criteria used in this study, the 11 isolates obtained after January 30, 2003 belong to the North American group, strongly suggesting that these strains were recently introduced into France.

[An epidemiological survey of equine anaplasmosis (Anaplasma phagocytophilum) in southern France]

Anaplasmosis is caused by the bacterium Anaplasma phagocytophilum and transmitted by Ixodes spp. ticks. According to some reports the disease can be introduced into disease-free zones by migrating birds. The purpose of this study was to evaluate the seroprevalence of A. phagocytophilum in horses in the Camargue. Data concerning 424 horses were gathered and the sera were tested for A. phagocytophilum and for piroplasmoses using an enzyme-linked immunosorbent assay and a complement fixation test, respectively. The seroprevalence rates were 11.3 % for A. phagocytophilum, 64.4 % for Theileria equi and 19.7% for Babesia caballi. Stallions were less likely to produce antibodies against A. phagocytophilumthan were females or geldings (odds ratio [OR] = 0.3; p = 0.021). The presence of swallows increased the risk of infections in stables (OR = 5.18; p = 0.011). Spatial analysis showed the existence of groups of infected stables along canals and rivers (p = 0.008). These results suggest an emergence of A. phagocytophilum in the Camargue.

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).

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.

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.

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.

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.

[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.

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.

[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.

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.

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.

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.

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.

Significance of CT-scan-detected seminal vesicle enlargement in prostate cancer. A pilot study

The significance of CT-scan-detected seminal vesicle enlargement was investigated by correlating preoperative CT scans and pathologic findings for 25 patients undergoing radical prostatectomy. Seminal vesicle size was found to be a poor predictor of pathologic involvement when compared with tumor differentiation and obliteration of seminal vesicle angle.

Kinetic study of nucleophile specificity in dipeptide synthesis catalyzed by clostridiopeptidase B

The kinetic parameters of Clostridiopeptidase B-catalyzed aminolysis of carbobenzoxyarginyl methyl ester leading to the formation of various dipeptides are investigated. The deacylation rates of the acylenzyme were evaluated by direct product analysis using high-performance liquid chromatography on a reversed-phase column. On the basis of the partitioning ratio and the first-order and second-order rate constants for the deacylation step, large differences in the nucleophile reactivities, which appear to be related to a S'1-P'1 interaction, were observed. The order of specificity was established as Leu much greater than Ser greater than Phe greater than Val greater than Ala = Gly much greater than Pro with second-order rate constants ranging from 578,614 M-1 s-1 for leucinamide to 5132 M-1 s-1 in the case of prolinamide. All of the amino acid amides had a nucleophilic strength at least 10 times higher than that of water during the deacylation step. The data reported here represent the first experimental evidence for the existence of a S'1 site engaged in the recognition of the amino acid side chain residue for this enzyme. The recognition site showed an increase in the affinity along with an increase in the hydrophobicity of the amino acid amide side chains.

Optimization of a polypyrrole glucose oxidase biosensor

An amperometric glucose biosensor was fabricated by the electrochemical polymerization of pyrrole onto a platinum electrode in the presence of the enzyme glucose oxidase in a KCl solution at a potential of +0.65 V versus SCE. The enzyme was entrapped into the polypyrrole film during the electropolymerization process. Glucose responses were measured by potentiostating the enzyme electrode at a potential of +0.7 V versus SCE in order to oxidize the hydrogen generated by the oxidation of glucose by the enzyme in the presence of oxygen. Experiments were performed to determine the optimal conditions of the polypyrrole glucose oxidase film preparation (pyrrole and glucose oxidase concentrations in the plating solution) and the response to glucose from such electrodes was evaluated as a function of film thickness, pH and temperature. It was found that a concentration of 0.3 M pyrrole in the presence of 65 U/ml of glucose oxidase in 0.01 M KCl were the optimal parameters for the fabrication of the biosensor. The optimal response was obtained for a film thickness of 0.17 microns (75 mC/cm2) at pH 6 and at a temperature of 313 K. The temperature dependence of the amperometric response indicated an activation energy of 41 kJ/mole. The linearity of the enzyme electrode response ranged from 1.0 mM to 7.5 mM glucose and kinetic parameters determined for the optimized biosensors were 33.4 mM for the Km and 7.2 microA for the Imax. It was demonstrated that the internal diffusion of hydrogen peroxide through the polypyrrole layer to the platinum surface was the main limiting factor controlling the magnitude of the response of the biosensor to glucose. The response was directly related to the enzyme loading in the polypyrrole film. The shelf life and the operational stability of the optimized biosensor exceed 500 days and 175 assays, respectively. The substrate specificity of the entrapped glucose oxidase was not altered by the immobilization procedure.

[Intestinal angiostrongyliasis caused by Angiostrongylus costaricencis. Apropos of a case in Martinique]

Intestinal angiostrongyliasis caused by Angiostrongylus costaricensis is a rare nematodiasis which is present mainly in Costa-Rica, and in some other countries in the northern part of South America, Central America, and in the southern part of Mexico. This is a report of the first case from Martinique involving a sixteen month old child, and proved by an intestinal pathologic study. The epidemiology of the disease, its clinical, parasitological, histopathologic and therapeutic aspects are emphasized.

Effect of magnesium on ATP labelling by kidney brush border membrane

1. Brush border membranes purified from rat kidney cortex were incubated in the presence of ATP and analysed by SDS polyacrylamide gel electrophoresis. 2. Quantitative analysis of phosphorylation was performed with a calibration curve obtained by autoradiography. 3. The presence of magnesium was required for the phosphorylation of membrane proteins. 4. EDTA completely inhibited the labelling of all bands, except for the alkaline phosphatase band. 5. In contrast, alkaline phosphatase was inhibited by 52, 65 and 85% in the presence of 1 mM bromotetramisole, 10 mM NaF and 10 mM Na arsenate respectively. 6. However these inhibitors had only minor effects on the labelling of other proteins. 7. High concentrations of magnesium caused a pronounced inhibition on the labelling of the alkaline phosphatase band but had no effect on the phosphorylation of other proteins.

Analysis of amino acids by gas-liquid chromatography as tert.-butyldimethylsilyl derivatives. Preparation of derivatives in a single reaction

The effect of temperature, solvent and reagents on the formation of the N(O)-dimethyl-tert.-butylsilyl derivatives of proteic amino acids has been studied. Quantitative silylation is achieved using dimethyl-tert.-butylsilyltrifluoroacetamide with 1% tert.-butyldimethylchlorosilane in dimethylformamide by heating at 75 degrees C for 30 min. Two peaks were obtained for arginine under these conditions. However, most of the standard proteic amino acids can be assayed. The N(O)-dimethyl-tert.-butylsilyl derivatives of the proteic amino acids have been analysed by gas chromatography-mass spectrometry using the methane chemical ionization mode. The spectral data are presented and have been used to confirm the structures of the amino acid derivatives.