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S Quessy

Publications and source records attributed to S Quessy.

31 records · Page 2Linked to original sources
PubMed1997

Description of an albumin binding activity for Streptococcus suis serotype 2.

This study was undertaken to investigate the binding activity of Streptococcus suis serotype 2 to albumin. Using flow cytometry we observed a binding activity of S. suis to albumin for virulent as well as for avirulent isolates. Western immunoblots analysis revealed that a 39-kDa S. suis protein was responsible, at least in part, for this binding activity. This protein showed high N-terminal homology (95.6% for the first 23 residues) with a group A Streptococcus glyceraldehyde-3-phosphate dehydrogenase. Furthermore, the addition of albumin to the culture broth resulted in an increase in the virulence of S. suis strains in mice. These results suggest that an interaction with albumin could play a role in the pathogenesis of S. suis serotype 2 infections.

Albumins↗
PubMed1997

Immunization of pigs against Streptococcus suis serotype 2 infection using a live avirulent strain.

Streptococcus suis capsular type 2 is still an important cause of economic losses in the swine industry. At the present time, vaccination of pigs against this infection is generally carried out with autogenous bacterins and results are equivocal. In this study, the protective effect of a live avirulent S. suis type 2 strain (#1330) which had induced a good protection in mice, was evaluated in swine. The experiment was performed in triplicate using 4 week-old piglets. A total of 15 piglets were vaccinated 3 times, 15 others were vaccinated 2 times, and 15 piglets were injected 3 times with sterile Todd-Hewitt broth. Using an indirect ELISA, an increase in the IgG response to S. suis antigens was noted in 27 of the 30 vaccinated piglets. On day 21 post-vaccination, all animals were challenged intravenously with a virulent S. suis type 2 strain (#999). In the 2 vaccinated groups, 26 animals were fully protected. Only 1 out of the 15 piglets vaccinated 3 times developed mild clinical signs. In the group vaccinated twice, 3 piglets showed clinical signs and 1 of them died after the challenge. In the control group, 7 animals died out of the 11 with clinical signs of infection. In conclusion, a protective immunity was observed in swine when using strain 1330. However, more studies are needed to assess the use of a live S. suis strain in a vaccine for pigs.

Animals↗
PubMed1995

The cardiovascular effects and histamine-releasing properties of 51W89 in patients receiving nitrous oxide/opioid/barbiturate anesthesia.

BACKGROUND: Atracurium consists of a mixture of ten stereoisomers. One of these isomers, 51W89, is a potent intermediate-acting nondepolarizing neuromuscular blocking agent. Its ED95 is 0.05 mg.kg-1 in patients receiving nitrous oxide/opioid anesthesia. In preclinical trials, 51W89 did not show evidence of histamine release in cats at doses up to 80 times the human ED95. This study was undertaken to determine the cardiovascular effects and histamine-releasing properties of 51W89 in patients undergoing elective surgical procedures. METHODS: Sixty patients, ASA physical status 1 or 2, anesthetized with nitrous oxide/fentanyl/thiopental were studied. Patients received either 2 times the ED95 of atracurium or 51W89 or 4 or 8 times the ED95 of 51W89 as a rapid intravenous bolus under stable anesthesia, before surgical stimulation. Blood pressure and heart rate were measured by oscillometry and the electrocardiogram in patients receiving 2 times the ED95 of 51W89 or atracurium and by an intraarterial catheter and a tachograph triggered by the arterial pulse waveform in patients receiving 4 or 8 times the ED95 of 51W89. Maximal blood pressure and heart rate changes during the 5 min after administration of the muscle relaxant were recorded. Venous blood samples were obtained before the administration of relaxant and at 2 and 5 min after the administration of relaxant for determination of plasma histamine concentrations by radioenzymatic assay. RESULTS: Maximal blood pressure and heart rate changes in all groups of patients receiving 51W89 were small and similar to those observed in patients receiving 2 times the ED95 of atracurium. The mean maximum percent changes (+/- SE) in heart rate and mean arterial pressure were -0.6 +/- 1.5 and 0.4 +/- 2.5, respectively, in the group receiving 2 times the ED95 atracurium; -1.3 +/- 3.3 and 2.3 +/- 4.4, respectively, in the group receiving 2 times the ED95 51W89; -2.6 +/- 1.0 and 2.6 +/- 1.5, respectively, in the group receiving 4 times the ED95 51W89; and -2.4 +/- 1.5 and -1.0 +/- 1.3, respectively, in the group receiving 8 times the ED95 51W89. No patient developed a decrease in blood pressure > or = 20% or an increase in heart rate > or = 20% that was attributable to muscle relaxant administration. There was no dose-related change in plasma histamine concentration associated with the administration of 51W89. One patient in the study developed transient facial flushing after the administration of atracurium. CONCLUSIONS: 51W89 is a benzylisoquinolinium-type, nondepolarizing muscle relaxant that does not affect plasma histamine concentrations. No cutaneous flushing or clinically important cardiovascular effects were noted after rapid injection of doses up to and including 8 times its ED95 (0.4 mg.kg-1) in healthy patients undergoing elective surgical procedures.

Adult↗
PubMed1995

The clinical neuromuscular pharmacology of 51W89 in patients receiving nitrous oxide/opioid/barbiturate anesthesia.

BACKGROUND: Atracurium is a mixture of ten stereoisomers. 51W89, one of these isomers, is a potent nondepolarizing intermediate-duration neuromuscular blocking agent. Preclinical studies have shown 51W89 to be significantly more potent than atracurium but with a similar neuromuscular blocking profile. This study was undertaken to establish the neuromuscular blocking potency and pharmacodynamics of 51W89 in patients undergoing elective surgical procedures. METHODS: Ninety-nine ASA physical status 1 or 2 patients undergoing elective surgical procedures under nitrous oxide/opioid/barbiturate anesthesia were studied. The neuromuscular blocking effect of 51W89 was assessed after administration of bolus doses from 0.015 to 0.4 mg/kg, as well as during and after continuous infusions from 11 to 249 min in length. RESULTS: The calculated ED95 for inhibition of adductor pollicis twitch evoked at 0.15 Hz was 0.048 mg/kg. At 0.10 mg/kg, maximum block developed within 5.2 +/- 0.3 min, and recovery to 95% twitch height occurred 64.4 +/- 3.9 min after injection. At 0.4 mg/kg, onset was 1.9 +/- 0.1 min, and 95% recovery developed within 121.0 +/- 5.9 min. Comparative recovery indexes from 5% to 95% or from 25% to 75% twitch heights did not differ significantly among all dosage groups from 0.1 to 0.4 mg/kg (means ranged from 29.6 to 32.3 min and from 12.6 to 14.3 min, respectively). The average infusion rate necessary to maintain approximately 95% twitch suppression was 1.35 micrograms/kg/min. Recovery indexes from infusions were 5-95% 33.2 +/- 1.8 min and 25-75% 15.0 +/- 0.6 min, not differing significantly from recovery indexes from single bolus doses. Twenty-five patients received neostigmine (0.06 mg/kg) with atropine (0.03 mg/kg) at twitch height recovery of between 6% and 21%. Antagonism to 95% control twitch height developed within 6.8 +/- 0.3 min, and the neostigmine-accelerated 25-75% recovery index was 2.8 +/- 0.2 min. CONCLUSIONS: 51W89 is a potent nondepolarizing neuromuscular blocking agent that shows noncumulative intermediate-duration neuromuscular blocking pharmacodynamics.

Adult↗
PubMed1995

Discrimination of virulent and avirulent Streptococcus suis capsular type 2 isolates from different geographical origins.

In an effort to relate the protein profile to virulence, proteins from the cellular fractions and from culture supernatants of Streptococcus suis capsular type 2 strains from different geographical origins were compared by using Western blots (immunoblots). The protein profiles of the cellular fractions were similar for the majority of virulent and avirulent isolates studied, with the exception of three virulent Canadian strains for which a 135-kDa protein was not detected. Examination of the culture supernatants revealed the presence of a 135-kDa protein in all strains except the same three virulent Canadian isolates. In addition, a 110-kDa protein was present in 14 of 16 virulent strains and not in avirulent isolates. When injected into mice, the 110-kDa protein induced an immunoglobulin G response and protected against infection with homologous and heterologous virulent strains. Four strains (1330, 0891, TD10, and R75/S2) that were avirulent in the mouse model of infection and four other strains (1591, 999, JL590, and AAH4) that were virulent in the mouse model were injected into pigs. All virulent strains reproduced the disease, and all avirulent strains failed to reproduce the disease (with the exception of transient lameness in one case and fever in another case). The 110-kDa protein therefore appears to be a reliable virulence marker and a good candidate for a subunit vaccine.

Animals↗
PubMed1995

Binocular interactions and visual acuity loss in esotropic cats.

Visual acuity was measured behaviorally in various groups of cats by using a two-choice discrimination procedure. Cats in group 1 were rendered strabismic soon after birth by sectioning the tendon of the lateral rectus muscle (unilateral esotropia); at adulthood, their visual acuity (VA) was evaluated, after which the optic chiasm was sectioned and VA reassessed. Cats in group 2 were not only tenotomized but also chiasmatomized neonatally, while cats in group 3 underwent a neonatal section of the optic chiasm only. VA was measured at adulthood in the two latter groups. Group 4 consisted of adult cats whose VA was evaluated before and after an optic chiasm section. Stimuli consisted of square-wave gratings of various spatial frequencies. Results showed that in normal cats, the average threshold values under monocular viewing were identical for each eye (4.76 cycles/degree); however, following optic chiasm section, monocular VA was reduced to 1.23 cycles/degree. VA in early optic chiasm section cats was lower than that of the normal cats but higher than that of late-lesioned animals (2.33 cycles/degree). In strabismic cats, mean VA was 1.25 cycles/degree for the deviated eye and 2.8 cycles/degree for the normal eye. Following the optic chiasm section at adulthood, VA was lower not only for the deviated eye (< 0.17 cycles/degree) but also for the normal eye (1.14 cycles/degree). Similar results were found when both the deviation and chiasmatomy were performed neonatally. The elimination of interocular interactions through chiasm transection failed to improve VA in the strabismic eye.

Animals↗
PubMed1995

Receptive field properties of areas 17-18 neurons in strabismic cats with the early section of the optic chiasm.

In cats raised with surgically induced esotropia and early section of the optic chiasm visually responsive neurons were recorded from areas 17-18 ipsilaterally and contralaterally to the deviated eye. In these animals both cortices were monocularly activated only through the ipsilateral eye. In addition, unlike to that occurring in otherwise intact strabismic animals, the esotropic eye drove a number of neurons equivalent to that driven by the non-deviated eye. We suggest that an inhibitory influence exterted over the ipsilateral afferents of the deviated eye is removed by the early section of the crossed retinal projections.

Animals↗
PubMed1994

Increase of capsular material thickness following in vivo growth of virulent Streptococcus suis serotype 2 strains.

Protein profile and capsular material thickness of Streptococcus suis serotype 2 strains were compared after in vitro and in vivo growth. Three virulent and one avirulent strains were used. These strains were grown in Brain Heart Infusion (BHI) broth, cells were collected by centrifugation, resuspended in a sterile saline solution and injected in diffusion chambers. The devices were then inserted in rat abdomens for 17 h. In vitro grown strains were also inoculated into fresh BHI broth and cultivated for 17 h at 37 degrees C. In vivo as well as in vitro grown bacteria were harvested by centrifugation, processed in a French pressure cell, treated with lysozyme and centrifuged to collect cell proteins for SDS-PAGE analysis. Transmission electron microscopy using polycationic ferritin labeling to stabilize capsular material was also carried out. No significant modification was noted in the protein profile for any strain after in vivo growth except for a 39 kDa protein of one virulent strain. On the other hand, an increase in thickness of capsular material was noted for the three in vivo grown virulent strains while no change was noted for the avirulent strain. This increase in capsular material thickness of virulent strains was accompanied by an increased resistance to killing by pig polymorphonuclear leukocytes. The capacity to produce more capsular material in vivo seems to be an attribute of some virulent S. suis serotype 2 strains.

Animals↗
PubMed1994

Immunization of mice against Streptococcus suis serotype 2 infections using a live avirulent strain.

In this study, the IgG response of mice injected with two virulent strains and one avirulent Streptococcus suis capsular type 2 strain was compared by Western blotting. The serum from mice immunized against the avirulent strain could recognize most proteins of the various strains tested and similar results were obtained with serum from mice injected with virulent strains. The live avirulent strain was injected twice (days 0 and 10) to groups of five mice, and four virulent strains from different geographical origins were used to challenge the animals. All mice, except one in one group, survived the challenge. These results suggest that a live avirulent strain could be used for immunization of swine, the natural host.

Animals↗
PubMed1994

Comparison of pig, rabbit and mouse IgG response to Streptococcus suis serotype 2 proteins and active immunization of mice against the infection.

The aim of this study was to compare the IgG response of different animal species to Streptococcus suis serotype 2 proteins and to evaluate the immunogenic potential of these proteins in the mouse experimental model of infection. The protein profiles of ten different S. suis capsular type 2 isolates were compared by Western blotting using antisera produced in mice, rabbits and pigs against the reference strain. Strains were grown overnight in Todd-Hewitt broth, harvested by centrifugation, processed in a French press cell and digested with lysozyme. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was then performed and proteins transferred to nitrocellulose. The rabbit antiserum recognized seventeen common immunoreactive proteins, of which, proteins of 33, 44, 96, 122 kDa were present in all strains. Two, 128 and 136 kDa proteins were recognized by swine serum in many strains. An additional protein of 30 kDa was recognized by the mouse antiserum. These seven proteins, originating from the reference strain, were excised directly from polyacrylamide gels, mixed with incomplete Freund's adjuvant and given to groups of five mice on days 0 and 10. Immunoglobulin G response to each protein was monitored on day 20 using Western blots. Mice were then experimentally infected on day 21. Results indicated that vaccination with proteins of 33, 44, 128 and 136 kDa resulted in an IgG response and protection against the challenge with the reference strain, but gave only a partial protection against another virulent S. suis serotype 2 strain.

Animals↗
PubMed1992

Prevalence of Salmonella spp., Campylobacter spp. and Listeria spp. in ring-billed gulls (Larus delawarensis).

Cloacal swabs collected from 264 ring-billed gulls (Larus delawarensis) at four sites near Montréal, Canada were cultured for the presence of Salmonella spp., Campylobacter spp. and Listeria spp. All birds were apparently healthy when captured or killed. Of all birds examined, 8.7%, 15.9% and 9.5%, respectively, were infected with Salmonella spp., Campylobacter spp. and Listeria monocytogenes. Overall, 29.9% of gulls sampled harbored one or more of these bacteria. Gulls probably play only a minor role in the epizootiology of these bacteria.

Animals↗
PubMedDate not supplied

Focal dermatitis and cellulitis in broiler chickens: bacteriological and pathological findings.

Involvement of aerobic bacteria, especially Escherichia coli, in lesions of cellulitis in broiler chickens was investigated. Samples of subcutaneous caseous material for bacteriological examination were collected aseptically at the slaughterhouse from 109 broilers with lesions. Skin tissue was taken from five of these birds for histopathological examination. In 96 of the 109 (88.1%) broilers sampled, E. coli was isolated from the lesion, and in 60 of these birds it was the only bacterial species found. In 33 broilers, Streptococcus dysgalactiae was found along with E. coli. Although serotype O78 was isolated the most frequently, numerous other serotypes were found; no correlation could be established between the size of the lesions and the serotype isolated. The microscopic lesions were characterized by thickening of the dermis with a granulomatous inflammatory reaction. This study confirms the frequent association of E. coli with cellulitis lesions in broiler chickens and reports the frequent isolation of S. dysgalactiae from the lesion.

Animals↗