From freshwaters to bivalves: Microplastic distribution along the Saint-Lawrence river-to-sea continuum

Despite the close connection of freshwaters to human health, the occurrence and fate of microplastics in marine estuaries remain poorly documented. To study these particles in the Saint-Lawrence River (Quebec, Canada), surface water and marine bivalve samples were collected along the river-to-sea continuum. The water samples were subdivided to characterize the large microplastics (LMPs; 300-3200 µm) and the small microplastics (SMPs; 20-300 µm). Particles were identified by microscopy and infrared spectroscopy techniques. The concentration of LMPs was higher in the surface water in the downstream stations (0.0319 ± 0.0147 items.L^-1) compared to the upstream stations (0.0007 ± 0.0006 items.L^-1). No clear trend was observed for the SMPs. After digestion of the biological tissues, the microplastics ingested by the bivalves were recovered and characterized by microscopy coupled with infrared spectroscopy. Up to 3 items were found per bivalve suggesting that these particles are also present in the water column of the marine estuary and the gulf. The physico-chemical gradients along the continuum were monitored since they could be directly involved in the vertical and horizontal transport of microplastics. This study provides scarce field data collected along the world's largest estuary and gives new insights concerning the fate of microplastics along a river-to-sea continuum.

Réactions Plaquettaires et Processus Immunitaires

Nous avons étudié de quelle façon les substrats et inhiteurs de la chymotrypsine inhibent l’agrégation plaquettaire induite par le collagène. Nous avons trouvé que ces substances inhibent la libération d’ADP plaquettaire provoquée par le collagène.

Cette observation, ajoutée à plusieurs autres, indique que les processus plaquettaires et mastocytaires de libération de substances intracellulaires ont plusieurs caractéristiques biologiques communes.

Le rôle possible d’une estérase plaquettaire chymotrypsinoide dans les réactions de la thrombogénèse est discuté.

Where's the Tube? Evaluation of Hand-held Ultrasound in Confirming Endotracheal Tube Placement

Introduction:

The diagnosis of endotracheal tube (ETT) mal-position may be delayed in extreme environments. Several methods are utilized to confirm proper ETT placement, but these methods can be unreliable or unavailable in certain settings. Thoracic sonography, previously utilized to detect pneumothoraces, has not been tested to assess ETT placement.

Hypothesis:

Thoracic sonography could correlate with pulmonary ventilation, and thereby, help to confirm proper ETT placement.

Methods:

Thirteen patients requiring elective intubation under general anesthesia, and data from two trauma patients were evaluated. Using a portable, hand-held, ultrasound (PHHU) machine, sonographic recordings of the chest wall visceral-parietal pleural interface (VPPI) were recorded bilaterally in each patient during all phases of airway management: (1) preoxygenation; (2) induction; (3) paralysis; (4) intubation; and (5) ventilation. Results: The VPPI could be well-imaged for all of the patients. In the two trauma patients, right mainstem intubations were noted in which specific pleural signals were not seen in the left chest wall VPPI after tube placement. These signs returned after correct repositioning of the ETT tube. In all of the elective surgery patients, signs correlating with bilateral ventilation in each patient were imaged and correlated with confirmation of ETT placement by anesthesiology.

Conclusions:

This report raises the possibility that thoracic sonography may be another tool that could be used to confirm proper ETT placement. This technique may have merit in extreme environments, such as in remote, prehospital settings or during aerospace medical transports, in which auscultation is impossible due to noise, or capnography is not available, and thus, requires further scientific evaluation.

Hand-held thoracic sonography for detecting post-traumatic pneumothoraces: the Extended Focused Assessment with Sonography for Trauma (EFAST)

BACKGROUND

Thoracic ultrasound (EFAST) has shown promise in inferring the presence of post-traumatic pneumothoraces (PTXs) and may have a particular value in identifying occult pneumothoraces (OPTXs) missed by the AP supine chest radiograph (CXR). However, the diagnostic utility of hand-held US has not been previously evaluated in this role.

METHODS

Thoracic US examinations were performed during the initial resuscitation of injured patients at a provincial trauma referral center. A high frequency linear transducer and a 2.4 kg US attached to a video-recorder were used. Real-time EFAST examinations for PTXs were blindly compared with the subsequent results of CXRs, a composite standard (CXR, chest and abdominal CT scans, clinical course, and invasive interventions), and a CT gold standard (CT only). Charts were reviewed for in-hospital outcomes and follow-up.

RESULTS

There were 225 eligible patients (207 blunt, 18 penetrating); 17 were excluded from the US examination because of battery failure or a lost probe. Sixty-five (65) PTXs were detected in 52 patients (22% of patients), 41 (63%) being occult to CXR in 33 patients (14.2% whole population, 24.6% of those with a CT). The US and CXR agreed in 186 (89.4%) of patients, EFAST was better in 16 (7.7%), and CXR better in 6 (2.9%). Compared with the composite standard, the sensitivity of EFAST was 58.9% with a likelihood ratio of a positive test (LR+) of 69.7 and a specificity of 99.1%. Comparing EFAST directly to CXR, by looking at each of 266 lung fields with the benefit of the CT gold standard, the EFAST showed higher sensitivity over CXR (48.8% versus 20.9%). Both exams had a very high specificity (99.6% and 98.7%), and very predictive LR+ (46.7 and 36.3).

CONCLUSION

EFAST has comparable specificity to CXR but is more sensitive for the detection of OPTXs after trauma. Positive EFAST findings should be addressed either clinically or with CT depending on hemodynamic stability. CT should be used if detection of all PTXs is desired.

Myocardial contractile responsiveness to endothelin-1 in the post-infarction rat model of heart failure: effects of chronic quinapril

Cardiac endothelin-1 (ET-1) levels and ET receptor expression are increased in congestive heart failure (CHF). In order to determine whether this results in increased responsiveness of ET-A or ET-B receptors to ET-1, we evaluated the contractile effects of ET-1 in isolated papillary muscles isolated from hearts of control rats and from rats 4 weeks post myocardial infarction (MI) having received no therapy or chronic quinapril therapy. The ET-1 dose-response was biphasic in normal muscles. The use of the selective ET-A receptor antagonist BQ123 and the selective ET-B receptor antagonist BQ788 revealed that the initial decrease in tension was the result of ET-B receptor stimulation. Blockade of nitric oxide (NO) production with L-NAME abolished the initial decrease in tension. MI resulted in CHF that was partially reversed by quinapril. In MI, the positive inotropic effects of ET-1 were enhanced due to the loss of the initial ET-B receptor mediated decrease in tension, as well as an increase in the positive inotropic effects of ET-A receptors. This was associated with an increase in ET-A and ET-B receptor mRNA and a decrease in cardiac ecNOS protein. Four weeks of therapy with quinapril attenuated the positive inotropic effects of ET-1 and prevented the increase in ET-A receptor mRNA. Although quinapril did not restore the effects of ET-B receptor stimulation or prevent the increase in ET-B mRNA, it did restore cardiac ecNOS protein expression. Thus, the inotropic response to ET-1 is biphasic due to an overall positive inotropic effect of ET-A receptor stimulation and an ET-B receptor mediated decrease in contractility at low ET-1 concentrations which appears to be mediated by cardiac ecNOS (NO). In post-MI CHF, responsiveness to ET-A receptors increases and the ET-B mediated negative inotropic response is lost despite an increase in both receptor subtypes. Quinapril therapy attenuates these effects and normalises cardiac ecNOS protein.

Cloning and characterization of the groE locus from Actinobacillus pleuropneumoniae

A 4.4-kb DNA fragment was cloned from Actinobacillus pleuropneumoniae (strain 4074, serotype 1) by genetic complementation with Escherichia coli groES-groEL mutant strains. Sequence analysis of this fragment revealed a purine nucleoside phosphorylase (DeoD)-encoding gene homolog (deoD), heat-shock response-encoding genes for the small (groES) and large subunits (groEL) and a partial open reading frame encoding an alcohol dehydrogenase homolog (adhE). The predicted amino-acid sequence of groES and groEL genes showed extensive sequence identity (80-95%) with other Pasteurellaceae. The gene organization surrounding the groE locus was different from that of Haemophilus infuenzae. When expressed in E. coli, groES-groEL genes were capable of complementing the growth of a lambda lytic phage, indicating a structural as well as functional conservation.

Sequencing of Comamonas testosteroni strain B-356-biphenyl/chlorobiphenyl dioxygenase genes: evolutionary relationships among Gram-negative bacterial biphenyl dioxygenases

In a previous work, all three components of Comamonas testosteroni B-356 biphenyl (BPH)/chlorobiphenyls (PCBs) dioxygenase (dox) have been purified and characterized. They include an iron-sulphur protein (ISPBPH) which is the terminal oxygenase composed of two subunits (encoded by bphA and bphE), a ferredoxin (FERBPH) encoded by bphF and a reductase (REDBPH) encoded by bphG. bphG Is not located in the neighbourhood of bphAEF in B-356. We are reporting the cloning of B-356-bphG and the sequencing of B-356-BPH dox genes. Comparative analysis of the genes provided genetic evidence showing that two BPH dox lineages have emerged in Gram-negative bacteria. The main features of the lineage that includes B-356 are the location of bphG outside the bph gene cluster and the structure of REDBPH which is very distinct from all other aryl dioxygenase-reductases.

Sleep apnea following a pharyngeal flap: a feared complication

Pharyngeal flaps are often used to correct velopharyngeal insufficiency. They produce a permanent partial obstruction of the velopharyngeal space. Respiratory obstruction and obstructive sleep apnea have been reported following this surgery. We undertook a study to find out the incidence of sleep apnea associated with pharyngeal flap surgery. Forty-one children (aged 2 to 22 years) admitted for a pharyngeal flap underwent a polysomnographic recording prior to their surgery. One child with Steinert's disease showed some episodes of obstructive apnea, and the surgery was canceled. Forty children underwent pharyngeal flap surgery, and polysomnography with continuous arterial saturation was repeated following surgery. Postoperative polysomnograms were normal in 26 patients (65 percent) and abnormal in 14 patients (35 percent). Among the 14 abnormal patients, we found 6 with obstructive apneas, 6 with central apneas, and 2 with both central and obstructive apneas. Ten of the 14 abnormal patients were restudied in the following months. Eight children had normal recordings, while 2 had central apneas. The 4 patients who declined a follow-up recording had no clinical symptoms of respiratory difficulty when sleeping. Of the 2 children with abnormal recordings on long-term follow-up, 1 is asymptomatic, while the second has persistent snoring, nocturnal awakening, sweating, and daytime lethargy. A section of his flap has been recommended. Independent analysis of arterial oxygen saturation revealed that the percentage of time with a saturation of less than 90 percent identifies patients with clinically significant apneas. Our data show that significant sleep apneas following pharyngeal flaps may not be as frequent or permanent as previously reported.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular distribution of ROB-1 beta-lactamase in Actinobacillus pleuropneumoniae

The plasmid content and molecular distribution of the ROB-1 beta-lactamase was investigated in 31 swine isolates of Actinobacillus pleuropneumoniae. Three types of plasmid patterns were observed in ampicillin-resistant isolates: a predominant one consisting of 2.6-, 2.9-, and 5.0-kb plasmids and two other patterns consisting of 4.2- and 5.5-kb plasmids and of a 6.8-kb plasmid. Plasmid DNA preparations were hybridized with a blaROB-1 intragenic fragment from the Haemophilus influenzae Rrob plasmid. Positive hybridizations were observed with all ampicillin-resistant isolates. The blaROB-1 gene was found on 3 plasmids of 2.6, 5.5, and 6.8 kb. One swine isolate of Pasteurella multocida also had a 2.6-kb plasmid bearing blaROB-1. ROB-1 was confirmed in typical isolates by isoelectric focusing and blaROB-1 sequences were confirmed by polymerase chain reaction amplification with an intragenic set of primers. Plasmids bearing blaROB-1 were successfully electro-transformed in a susceptible A. pleuropneumoniae isolate. These results emphasize the importance of ROB-1 in A. pleuropneumoniae and identify a possible reservoir of beta-lactam resistance.

Construction of a DNA probe and detection of Actinobacillus pleuropneumoniae by using polymerase chain reaction

A 1.5-kb Actinobacillus pleuropneumoniae 4074 DNA fragment from a genomic library was found to hybridization. No cross-hybridization hybridization. No cross-hybridization was detected with DNAs from hemolytic members of the family Pasteurellaceae. From the nucleotide sequence of the putative genomic probe, three primers were synthesized for use in polymerase chain reactions (PCRs), with 31 strains tested by using purified and crude DNA targets. PCR amplification products of 610 and 985 bp were observed in nucleic acids extracted from the 12 known serotypes and a biotype 2 strain. Template DNAs from other gram-negative and gram-positive bacteria, some of them found in the normal flora of swine and the upper respiratory tract, were not amplified by PCR. The only exception was an amplification of a similar 610- or 985-bp sequence in Actinobacillus lignieresii, a species that is closely related to A. pleuropneumoniae but that has never been isolated from swine. Amplification of specific A. pleuropneumoniae sequences by PCR directly from clinical specimens may find applications in the identification of asymptomatic carriers as well as in efforts to eradicate porcine pleuropneumonia.

Biochemical typing of Actinobacillus pleuropneumoniae

A study was conducted to evaluate the possibility of using biochemical differences among strains of a given serotype of Actinobacillus pleuropneumoniae as epidemiological markers, to rapidly identify the source of infection in herds affected with swine pleuropneumonia. Out of 38 different biochemical and physiological tests performed on a total of 67 strains belonging to serotypes 1 and 5 of A. pleuropneumoniae, three fermentation tests, glycerol, lactose and raffinose, allowed the classification of serotype 1 strains into 6 phenotypic groups and serotype 5 strains into 4 of these groups. Groups II and III were exclusively composed of serotype 1 strains, whereas the majority of strains in groups I and IV belonged to serotypes 1 and 5 respectively, the latter comprising almost all the serotype 5 studied.

An enzyme-linked immunosorbent assay for the detection of complement components on red blood cells

A new technic using the principle of enzyme-linked immunoassay (ELISA) has been developed for the detection of complement components on red blood cells sensitized in vivo or in vitro. Using a double-antibody technic, anticomplement antisera (anti-C3c or anti-C3c/C3d) produced in rabbits was incubated with the red blood cells, followed by incubation with antirabbit alkaline phosphatase conjugated antiglobulin. The amount of the enzyme fixed was measured spectrophotometrically by the enzymatic hydrolysis of the substrate PNPP. A calibration curve was made from red blood cells on which complement was deposited by the method of Fruitstone . The technic showed a greater sensitivity than the standard antiglobulin tests and allowed simultaneous qualitative and semiquantitative estimates. The technic can be performed in any laboratory equipped with the standard equipment found in a blood bank, including a spectrophotometer. The authors made a modification of Alsever 's solution, which allowed the safe and stable preservation of complement coated red blood cells for 15 days. Significant positive results were obtained clinically using this technic, while negative or weakly positive reactions were obtained by the conventional antiglobulin tests.

C3b inactivator deficiency with immune complex manifestations

We report a complete C3b inactivator deficiency in a 28-year-old patient referred for bronchiectasis and recurrent pneumonia. In addition to these recurrent infections, previously described with this deficiency, he also had several immune complex manifestations (rheumatoid factor, circulating immune complexes and one episode of serum sickness). The consequences of C3b inactivator deficiency on complement activation, chemotaxis and opsonization, clearance of immune complexes, and on red blood cell sensitization are discussed. The study of the parents showed an autosomal dominant transmission.