Robert Paquin

Submental endotracheal intubation : An alternative to tracheotomy in patients with Midfacial and panfacial fractures

BACKGROUND The submental route for endotracheal intubation has been proposed as an alternative to tracheotomy in the surgical management of patients with maxillofacial trauma. The purpose of this study was to review our experience with this procedure. METHODS Medical records of 25 patients who had surgical reduction of midfacial or panfacial fractures while securing their airway with submental intubation were reviewed. After standard orotracheal intubation, a passage was created by blunt dissection with a hemostat clamp through the floor of the mouth in the submental area. The proximal end of the orotracheal tube was pulled through the submental incision. Surgery was completed with minimal interference from the endotracheal tube. At the end of surgery, the tube was pulled back to the usual oral route. RESULTS Mean duration of surgery was 7.9 hours (range, 2-16 hours). Mean duration of postoperative mechanical ventilation was 5.2 days (range, 1-24 days). Fourteen of these patients required prolonged (>24 hours) postoperative mechanical ventilation because of associated injuries. Two patients later required a tracheotomy because of prolonged respiratory failure. One patient died of multiple organ failure. One complication of the submental intubation was observed: a superficial infection of the submental wound. CONCLUSION Submental intubation is a simple technique associated with a low morbidity. It is an attractive alternative to tracheotomy in the surgical management of selected cases of maxillofacial trauma.

The major androgen‐dependent protease in dog prostate belongs to the kallikrein family: confirmation by partial amino acid sequencing

Canine prostate fluids and seminal plasma contain a major androgen‐dependent protein which was identified as a proteolytic enzyme exhibiting an Arg‐esterase activity. This protease, as characterized, is shown to be present as a two‐chain structure held together by at least one disulfide bridge and composed of approximately 220 amino acids. Amino acid sequence determination of both chains has revealed a clear homology to other known amino acid sequences of serine proteases. Furthermore, the comparison of the presented 58 amino acids of the Arg‐esterase with the other sequences revealed a very strong homology (larger than 50%) to members of the kallikrein family. The two chain structure could thus result from autolysis of a single chain enzyme in the ‘kallikrein autolysis loop’. Amino acid composition of the canine prostatic enzyme suggests that it is related, but not identical, to pancreatic canine kallikrein.

The expression pattern of the ITIM-bearing lectin CLECSF6 in neutrophils suggests a key role in the control of inflammation

In our study of the modulation of the expression of inflammation‐related genes in neutrophils, we have found a gene called CLECSF6 (C‐type lectin superfamily 6). CLECSF6 expresses two mRNA species at low levels in resting neutrophils. Here, we describe for the first time the sequence of the short mRNA version. It lacks amino acids that are likely to affect the functionality of its protein product. GM‐CSF, IL‐3, IL‐4, and IL‐13 caused an accumulation of the short CLECSF6 mRNA in neutrophils. The surface expression of the CLECSF6 protein was reduced by TNF‐α, IL‐1α, LPS, and Matrigel®. CLECSF6 bears the immunoreceptor tyrosine‐based inhibition motif (ITIM) involved in signal transduction resulting in the inhibition of leukocyte activation. We propose that some neutrophil activators modulate the expression of CLECSF6 at the mRNA (GM‐CSF, IL‐3, IL‐4, and IL‐13) or protein (TNF‐α, IL‐1α, LPS, and Matrigel®) levels in ways that block ITIM‐based transduction of anti‐inflammatory signals and therefore promote inflammation.

Effects of interleukin-13 on human neutrophil functions.

It was recently shown that interleukin‐13 (IL‐13) induces the expression and release of the IL‐1 decoy receptor (type II) in human neutrophils along with the production of the IL‐1 receptor antagonist. In the present study we focused on further studying the modulatory effects of IL‐13 on these cells. We found that recombinant human IL‐13 (rhIL‐13) induces cellular morphological changes in neutrophils that are typical of activated cells. Furthermore, rhIL‐13 was shown to increase tyrosine phosphorylation of several neutrophil proteins. We also demonstrate that this cytokine stimulates de novo RNA synthesis in a concentration‐dependent fashion as measured by [5‐3H]uridine incorporation and that rhIL‐13 induces the synthesis of several neutrophil proteins according to high‐resolution two‐dimensional gel electrophoresis of metabolically [35S]‐labeled cells. We observed that the IL‐8 levels in the external milieu of IL‐13‐stimulated cells was almost fivefold increased when compared with control cells. Finally, we observed that rhIL‐13 has no significant effect on phagocytosis and apoptosis. Taken together, our results demonstrate that IL‐13 is a modulator of several human neutrophil functions. This leads us to conclude that the modulatory role of IL‐13 on human neutrophils, a potentially important anti‐inflammatory cytokine, is more complex than previously believed. Furthermore, because we show that the synthesis of several as yet unidentified proteins was up‐regulated by IL‐13, our findings open new avenues of research on the effects of this cytokine on human neutrophils.

Selective synthesis and secretion of a 23 kD protein by neutrophils following stimulation with granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-alpha.

We tested a wide range of pro-inflammatory cytokines for their capacity to activate protein synthesis in neutrophils as analyzed b y [35S] methionine metabolic labelling experiments. Of all the cytokines tested, only GM-CSF and TNF alpha stimulated significant synthesis and secretion of a 23 kD protein which resolved into two bands on two dimensional gels. Under non-reducing conditions on one dimensional gels, its migration pattern remained the same indicating that the two bands most likely represent isoforms of the same protein. Immunoisolation studies using antibodies directed against size-relevant molecules did not lead to the identification of this molecule. The fact that this 23 kD molecule is induced in a highly specific and selective manner by GM-CSF and TNF alpha indicates that it may play a key role in some of the responses of neutrophils to these two cytokines. Therefore, full characterization of this 23 kD protein could provide important new knowledge on the mechanisms by which these two cytokines exert their biological effects on neutrophils.

Granulocyte-macrophage colony-stimulating factor modulates tapasin expression in human neutrophils.

Differential display‐polymerase chain reaction (DD‐PCR) was used to evaluate changes in mRNA expression of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) treated human neutrophils to better understand how this cytokine affects the functions of neutrophils at the molecular level. Although a variety of cDNA fragments were identified as modulated by GM‐CSF with the use of DD‐PCR, one fragment in particular, NGS‐17 (neutrophil GM‐CSF‐stimulated fragment #17), was characterized. The NGS‐17 fragment hybridized to a 3.8‐kb mRNA that encodes for a protein of a predicted molecular mass of 47.6 kDa. After cloning and sequencing, this gene was found to code for the recently sequenced tapasin or TAP‐A protein. Immunoprecipitation and immunoblotting studies using anti‐tapasin antibodies showed that tapasin is expressed in neutrophils and is associated with the MHC class I‐TAP complex. Moreover, tapasin expression was found to be induced by dimethyl sulfoxide and by retinoic acid in HL‐60 cells. This is the first report on the expression of tapasin in human neutrophils. It provides novel information, at the molecular level, on how GM‐CSF enhances the functions of these cells. J. Leukoc. Biol. 65: 205–210; 1999.

Crown Ether Catalysis in the Synthesis of Xanthates

Abstract Xanthates (0,S-dialkyl dithiocarbonates) received much attention in connection with technological1 and synthetic applications2. Pyrolytic elimination of xanthates, called the Chugaev reaction, has been widely used as a method of dehydrating alcohols without rearrangement of carbon skeleton3.

Purification of ram seminal plasma acid alpha-glucosidase

1. Ram seminal plasma alpha-glucosidase has been purified in order to increase our knowledge of this enzyme and of its role in epididymal physiology. 2. Since the enzyme behaved differently from other known acid alpha-glucosidases and was not affinity-adsorbed on dextran gels, another approach had to be used. 3. The final procedure included an ethanol precipitation step, sequential chromatography on hydroxylapatite and DEAE Sepharose CL-6B, isoelectric focusing in polyacrylamide gels and ultrafiltration. 4. The resulting purification factor of alpha-glucosidase was 9822 with an overall yield of 5%. 5. The purified material consisted of several isoforms with a mol. wt of 105,000 and isoelectric points varying between 4 and 5.