Outbreak of tuberculosis among substance users and homeless people in Greater Montréal, Canada, 2003-2016.

BACKGROUND: In Canada, active tuberculosis (TB) is found mainly among migrants from endemic countries and Indigenous populations. However, cases of active tuberculosis in substance users and homeless persons have been reported in Greater Montréal since 2003. OBJECTIVE: To describe the Montréal TB outbreak in terms of the sociodemographic characteristics, risk factors and clinical characteristics of cases, as well as the intensity of public health interventions, the follow-up and identification of locations of potential transmission. METHODS: All cases of active tuberculosis with the same genotype of interest residing in Quebec and epidemiologically linked cases were included in the analysis. Data were retrospectively extracted from routine public health investigations. Characteristics of cases were summarized using Excel. Spatial analysis of locations frequented during cases' infectiousness periods was performed. RESULTS: Between January 2003 and February 2016 a total of 35 cases were identified. Most (86%) were non-Indigenous people born in Canada. Of these, 28 had several risk factors, including substance use (93%), alcohol abuse (64%), homelessness (46%), comorbidities such as HIV coinfection (36%) and advanced stage of the disease. Seven cases without risk factors were all close contacts of cases. Intensity of case management by public health authorities was high. Locations frequented by cases with risk factors included crack houses, shelters and rehabilitation centers in Montréal's downtown core and a residential setting in a suburban area. CONCLUSION: TB outbreaks can occur in marginalized Canadian-born urban populations, especially those with substance use. Tailored interventions in this population may be needed for screening, and earlier identification of both latent and active TB and better linkage to care.

The occurrence of intra-operative hypotension varies between hospitals: observational analysis of more than 147,000 anaesthesia.

BACKGROUND: Hypotension, a common intra-operative incident, bears an important potential for morbidity. It is most often manageable and sometimes preventable, which renders its study important. Therefore, we aimed at examining hospital variations in the occurrence of intra-operative hypotension and its predictors. As secondary endpoints, we determined to what extent hypotension relates to the risk of post-operative incidents and death. METHODS: We used the Anaesthesia Databank Switzerland, built on routinely and prospectively collected data on all anaesthesias in 21 hospitals. The three outcomes were assessed using multi-level logistic regression models. RESULTS: Among 147,573 anaesthesias, hypotension ranged from 0.6% to 5.2% in participating hospitals, and from 0.3% up to 12% in different surgical specialties. Most (73.4%) were minor single events. Age, ASA status, combined general and regional anaesthesia techniques, duration of surgery and hospitalization were significantly associated with hypotension. Although significantly associated, the emergency status of the surgery had a weaker effect. Hospitals' odds ratios for hypotension varied between 0.12 and 2.50 (P < or = 0.001), even after adjusting for patient and anaesthesia factors, and for type of surgery. At least one post-operative incident occurred in 9.7% of the procedures, including 0.03% deaths. Intra-operative hypotension was associated with a higher risk of post-operative incidents and death. CONCLUSION: Wide variations remain in the occurrence of hypotension among hospitals after adjustment for risk factors. Although differential reporting from hospitals may exist, variations in anaesthesia techniques and blood pressure maintenance may also have contributed. Intra-operative hypotension is associated with morbidities and sometimes death, and constant vigilance must thus be advocated.

Non-patient factors related to rates of ruptured appendicitis.

BACKGROUND: Adult rates of ruptured appendicitis vary from 13.2 to 41.9 per cent in urban hospitals, despite controlling for individual factors. This suggests an effect of hospital organization. Surgeons report that appendicectomies may be delayed because of lack of access to operating rooms. METHODS: Combining interviews with hospital personnel and information from medical records for 1998-1999, a cross-sectional study using logistic regression, taking hospital clustering of patients into account, was conducted on 861 patients from 12 hospitals. Hospitals were grouped into organizational models. The diagnostic information was recoded to ensure interhospital validity. RESULTS: Hospitals with high activity and volumes of patients, but without an operating room designated for urgent surgery, were associated with a significantly higher risk of peritonitis (P<0.050). Time to surgery was very long in all hospitals, particularly time after departure from the emergency department and for elderly patients. CONCLUSION: Organizational characteristics, in unfavourable combinations, influence the course of time-dependent diseases such as appendicitis. Difficulties in gaining access to operating rooms, even for urgent operations, have emerged. Delays in treatment must be addressed when planning healthcare reforms.

An Escherichia coli strain deficient for both exonuclease V and deoxycytidine triphosphate deaminase shows enhanced sensitivity to ionizing radiation.

An Escherichia coli mutant lacking deoxycytidine triphosphate deaminase (Dcd) activity and an unknown function encoded by a gene designated ior exhibits sensitivity to ionizing radiation whereas dcd mutants themselves are not sensitive. A DNA fragment from an E. coli genomic library that restores the wild type level of UV and gamma ray resistance to this mutant has been cloned in the multicopy vector pBR322. Comparison of its restriction map with the physical map of the E. coli chromosome revealed complete identity to the recBD genes. ior affects ATP-dependent exonuclease activity, suggesting that it is an allele of recB. This mutation alone does not confer sensitivity to UV and gamma radiation, indicating that lack of Dcd activity is also required for expression of radiation sensitivity.

Structure of the gene complementing uvr-402 in Streptococcus pneumoniae: homology with Escherichia coli uvrB and the homologous gene in Micrococcus luteus.

The repair ability for UV-induced damage observed for Streptococcus pneumoniae proceeds through a system similar to the Uvr-dependent system in Escherichia coli. The DNA sequence of a gene complementing uvr-402, a mutation conferring UV sensitivity, was determined. Alignments of the deduced amino acid sequence revealed an extensive sequence homology of 55% with the UvrB protein of E. coli and 59% with the UvrB-homologous protein of Micrococcus luteus. Nucleotide-binding site consensus was observed. The high conservation of the uvrB-like gene among these three species suggests that the role of the UvrB protein and excision repair in general might be very important for cell survival.

Biochemical characterisation of a pancreatic elastase inhibitor from the leech Hirudinaria manillensis.

The jawed leech, Hirudinaria manillensis is closely related to Hirudo medicinalis, both belonging to the same family Arhynchobdellida. From Hirudo, two potent peptide inhibitors, hirudin (a thrombin inhibitor) and eglin (an elastase/chymotrypsin inhibitor) have been characterised in detail. During our studies to isolate thrombin inhibitor from the leech Hirudinaria a potent inhibitor, analogous to eglin, was also detected. Results indicate that this inhibitor, which we have named 'GELIN', is significantly different from eglin. Gelin was isolated and purified to homogeneity by ion exchange chromatography and reverse phase HPLC. The isoelectric point of Gelin was estimated to be 4.55, in contrast to 6.45 for eglin. The molecular weight of Gelin was similar to eglin, as estimated by SDS-PAGE. Amino-terminal sequence analysis of the first 29 residues show no sequence homology with eglin or any other serine protease inhibitors. Circular dichroism studies showed that the secondary structure of Gelin has no helix, 58% beta sheets and 42% random structures compared to 19% helix, 56% beta sheets and 25% random structures in eglin. Like eglin, Gelin inhibits elastase, cathepsin G and chymotrypsin but has little or no activity towards plasmin, thrombin, pepsin and trypsin. These data suggest that the elastase inhibitors from these two species of leech are fundamentally different in structure, indicative of independent evolutionary origin.

Excision-repair capacity in Streptococcus pneumoniae: cloning and expression of a uvr-like gene.

Although deficient in photoreactivation and some SOS-like functions, Streptococcus pneumoniae has the capacity to carry out excision repair when exposed to UV light. The repair ability and sensitivity to UV irradiation or treatment with chemical agents in the wild type and a UV-sensitive mutant strain indicate that UV-induced pyrimidine dimers might be repaired in pneumococcus by a system similar to the uvr-dependent system in Escherichia coli. A gene complementing the mutation conferring UV sensitivity of the mutant strain has been cloned. The coding region directs the synthesis of a polypeptide with a molecular weight of 78 kDa. The relationship with uvr-like protein in E. coli is discussed.

Excision-repair capacity of UV-irradiated strains of Escherichia coli and Streptococcus pneumoniae, estimated by plasmid recovery.

Although the biological role of many bacterial repair genes is known, there is still an interest in evaluating the capacity of repair pyrimidine dimers in some strains. For this purpose, we have developed a rapid assay. Cells bearing a plasmid are UV irradiated and incubated to allow recovery. The plasmid DNA is extracted, purified and treated with UV endonuclease from Micrococcus luteus that specifically produces single strand breaks at the site of pyrimidine dimers. The amount of open circular and covalently closed circular forms of the plasmid DNA after treatment and post-incubation provides an estimate of the repair capability of the host strain. The wild type strain and the uvrA mutant of Escherichia coli were used to adjust the assay. The lexA mutant of E. coli has been tested and its repair capability is equivalent to that of wild-type strain. The assay has been extended to Streptococcus pneumoniae, which is naturally deficient in photoreactivation and SOS-like functions. This strain is efficient in the repair of pyrimidine dimers, formed after UV irradiation.

The biochemical composition of venom from the pavement ant (Tetramorium caespitum L.).

The venom of the pavement ant, Tetramorium caespitum, is used for prey capture, defense and social communication. The venom is predominantly proteinaceous in nature and contains various free amino acids, predominantly aspartic and glutamic acid, as well as histamine. The activities of the enzymes phospholipase and hyaluronidase, which are believed to be present in all hymenopteran venoms could not be detected. The composition of Tetramorium caespitum venom is compared with other myrmicine venoms.

A method for the manufacture of single barrel liquid ion-selective microelectrodes: an in situ study of ant venom pH.

A method for the manufacture of single barrel ion-sensitive microelectrodes, employing liquid ion-selective sensors, is described in detail. This method had proven reliable and repeatable for the manufacture of pH-sensitive microelectrodes using a liquid proton carrier. It is believed that this method has advantages over other published methods since it allows direct visualization and control of major steps during electrode fabrication and overcomes several problems often encountered using more conventional methods. Microelectrodes fabricated using this technique have been used to measure the in situ pH of venom from two myrmicine ants, Tetramorium caespitum (L.) and Myrmica ruginodis (N.).

Characterization of a mutation conferring radiation sensitivity, ior, located close to the gene coding for deoxycytidine deaminase in Escherichia coli.

The isolation and characterization of a new mutation conferring radiation sensitivity in Escherichia coli is described. This mutation is located close to the gene coding for deoxycytidine deaminase, in the chromosomal region of the gat operon. It is very sensitive to gamma rays and exhibits a decrease in recombination ability. The expression of radiation sensitivity seems to result from the additive effect of the dcd mutation and another mutation of unknown function.

Absence of pyrimidine insertase activity in E. coli extracts, using plasmid DNA containing apyrimidinic sites.

Plasmid DNA, isolated from mutants of E. coli that are deficient in both uracil-DNA glycosylase and deoxyuridine triphosphatase, contains significant amounts of uracil. This can be removed in vitro by the action of uracil-DNA glycosylase, creating apyrimidinic sites. We have used depyrimidinated plasmid DNA isolated in this way to test the ability of E. coli extracts to preferentially incorporate labeled deoxythymidine triphosphate. No pyrimidine-insertase activity was found in extracts of bacteria that were deficient in exonuclease III. The question of the existence of such an activity in E. coli cells is discussed.

Possible correlation between transformability and deficiency in error-prone repair.

We have investigated the relationship between UV-induced mutability (as a measure of an error-prone repair process) and the genetic transformability of transformable and nontransformable bacterial strains. The data suggest a correlation between chromosomal transformability and a deficiency in an error-prone repair system in bacteria.

Lack of SOS repair in Streptococcus pneumoniae.

Wild-type strains of Streptococcus pneumoniae were non-mutable by UV radiation and thymidine starvation. Moreover, UV-irradiated pneumococcal omega 2 phages were not reactivated in an irradiated host. This suggests that, in pneumoococcus, there is no efficient inducible repair process similar to the SOS repair described in detail for E. coli. We also report that mutations cannot be induced by a process thought to be linked to competence during transformation with isogenic wild-type DNA either on wild-type strains or in strains in which the hex function of excision and repair of mismatched bases is inactive.

Thymineless death in Escherichia coli dnaB mutants and in a dnaB dnaG double mutant.

The interference of dnaB mutations of Escherichia coli with thymineless death is described. All the isogenic Thy- dnaB mutants of E. coli we have tested show a remarkable immunity towards cell death induced by thymine deprivation at the nonpermissive temperature. We have also constructed and tested an isogenic double dnaB dnaG mutant. It loses its viability in the absence of thymine at both permissive and nonpermissive temperatures. The role of the dnaB gene product is discussed.

Size and transforming activity of deoxyribonucleic acid in Diplococcus pneumoniae during thymidine starvation.

The transforming activity and the molecular structure of DNA from cells of Diplococcus pneumoniae during thymidine starvation have been analyzed and the effects of thymidine starvation have been compared with the effects of single-strand breaks produced by deoxyribonucleases in DNA of unstarved cells. The decrease in transforming activity of lysates from starved cells as a function of the size of DNA particles, measured by centrifugation in neutral and alkaline sucrose gradients, does not follow the kinetics observed after enzymatic degradation of DNA of unstarved cells. Moreover, a strain lacking exo- and endonuclease activities is not protected from thymineless death. These results suggest that the basic lethal mechanism of thymidine starvation might have an origin other than the activation of nucleases.

Interference of dna ts mutations of Escherichia coli with thymineless death.

Thermosensitive mutants of Escherichia coli in which deoxyribonucleic acid replication is inhibited at high temperature have been assayed for their response to thymine deprivation at permissive and nonpermissive temperatures. The survival rate of mutants in which initiation of replication is defective at 42 C (dnaA and dnaC-D) is much higher at nonpermissive temperatures than at 32 C. By contrast, thymineless death is not hindered at 42 C in two elongation mutants (dnaE and dnaG). Bacterial strains belonging to the dnaB class exhibit both types of behavior. These results are in accordance with the model linking thymineless death to a disruption of an active replication fork. We discuss the possibility that the dnaB protein takes part in this process of cell decay.

Transforming ability of bacterial deoxyribonucleic acid in relation to the marker efficiencies in Diplococcus pneumoniae during thymidine starvation.

Thymidine starvation induces a decrease in transforming activity of pneumococcus deoxyribonucleic acid. The integration of low- and high-efficiency markers seems to be equally affected.