Levels of naturally occurring radioisotopes in local and imported bottled drinking water available in Québec City, Canada

Consumption of local and imported bottled water in Canada has greatly increased during the past three decades. While the presence of natural radioactivity is often overlooked when dealing with the water quality of these bottled products, it could contribute substantially to the uptake of radionuclides especially when sourced from regions with higher radioactivity levels compared to where it is consumed. In this study, the activity of several naturally occurring radionuclides (i.e., 210Po, 226,228Ra, 230,232Th, 234,235,238U) were measured in bottled water available in Québec, Canada after sample pretreatment and analysis by either radiometric or mass spectrometry approaches. 230,232Th and 228Ra concentrations were below minimum detectable activity levels in all samples tested. Analytical results for 234U, 235U, 238U, and 226Ra showed concentrations that ranged from 0.38 to 115 mBq/L, (2.2-313) x 10-2 mBq/L, 0.48-58.4 mBq/L, and 1.1-550 mBq/L, respectively. 210Po was detected in only 5 samples and its activity ranged from 2 to 26 mBq/L. To determine variability in activity within brands, the same brands of bottled water were purchased during two consecutive years and analyzed. The possible radiological impact of the consumption of these types of water was assessed based on different drinking habit scenarios. Some of the imported water brands showed higher activity concentrations than local sources or tap water, suggesting that individuals drinking predominantly imported bottled water would receive a higher radiation dose than those who drink mainly local water.

Of logos and men: semantic memory impairment for unique entities in a case of semantic variant of primary progressive aphasia

In this study, an individual (NG) with the semantic varient of primary progressive aphasis (svPPA) was assessed with tasks designed to investigate the recognition and activation of semantic knowledge about unique entities. NG had significant difficulties in the recognition of brand names and famous names but was largely unimpaired in the recognition of logos and famous faces. However, she was impaired in tasks requiring the activation of semantic representations of logos, brand names, famous faces, and famous names. These results suggest that the recognition of unique entities results from the interaction of perceptual and conceptual processes and, that the ability to activate semantic information about these entities can be affected in svPPA.

A1 COLONOSCOPY FINDINGS FOLLOWING A FECAL IMMUNOCHEMICAL TEST: A RETROSPECTIVE STUDY ASSESSING THE SCREENING TEST PERFORMANCE

Background

Fecal Immunochemical Testing (FIT) is the preferred test for colorectal cancer screening in the average risk population in Canada.

Aims

This study aims to assess colonoscopy findings in patients who have undergone a FIT within the previous 2 years.

Methods

This retrospective study included all adult patients that have undergone a single diagnostic colonoscopy from March 2013 to March 2016 following a single FIT test at the CIUSSS de l’Estrie, a tertiary hospital. The primary outcome was to evaluate rates of clinically significant lesion when comparing FIT positive (FIT+) to FIT negative (FIT-) colonoscopy, using Quebec’s current threshold of 175 ng/ml of hemoglobin. Secondary outcomes included all other type of lesions, delays between FIT testing and colonoscopy, procedural time, caecal intubation rates and withdrawal time.

Results

Overall, 2230 patients were included, aged 62.0±10.5 years, 55.0% were female and 26.1% had a positive FIT. Patients with a positive FIT had a significantly higher polypectomy rate (62.4% vs 41.3%, p<0.01) and higher number of polyps per patient (2.9±2.5 vs 2.1±1.5, p<0.01). FIT+ had significantly higher rates of adenocarcinoma (3.4% vs 0.7%, p<0.01) with 11 out of 31 patients bearing a negative FIT with the current threshold. No difference was found for sessile serrated polyps (7.8% vs 6.0%, p=0.13). Patients with a FIT+ had significantly higher advanced adenomas (24.0% vs 5.6%, p<0.01), proximal polyps (33.6% vs 22.4%, p<0.01), distal polyps (52.8% vs 28.2%, p<0.01), non-advanced adenomas (38.5% vs 23.9%, p<0.01) and benign polyps (25.1% vs 17.2%, p<0.01). Patients with FIT+ received their colonoscopy 7.5 months earlier than FIT- patients (3.3±2.2 vs 10.8±8.3 months, p<0.01). FIT+ also yielded a significant longer procedural time (28.5±14.1 vs 25.5±12.1, p<0.01) but no difference was noted for caecal intubation rates and withdrawal time (93.3% vs 94.0%, p=0.55 and 14.0±8.4 vs 12.0±7.7, p=0.20 respectively). Results were similar when lowering the threshold to 150, 100, 75 and even 50 ng/ml. 8 patients with an adenocarcinoma had a FIT level lower than 50 ng/ml.

Conclusions

Patients with a colonoscopy and a positive FIT have higher rates of significant findings. Although commonly used for colorectal cancer screening, FIT still failed to detect almost 30% of adenomas and adenocarcinomas found during colonoscopy. It also does not perform very well for serrated polyps. Our data also fails to show an improved yield of the FIT when lowering the its threshold from 175 to 50. There is still a great need for a more sensitive non-invasive colon cancer screening test.

Funding Agencies

None

c-Src tyrosine kinase co-associates with and phosphorylates signal transducer and activator of transcription 5b which mediates the proliferation of normal human B lymphocytes

c-Src is the normal human cellular protein homologue of the viral oncogene v-src. c-Src activity was reported recently to increase in CD40-activated human B lymphocytes, suggesting its involvement in proliferation. To elucidate the exact role of c-Src in this process, we investigated the effects of c-Src over-expression on normal B lymphocyte growth. B lymphocytes purified from human peripheral blood were infected with Ad5/F35 vector encoding either a constitutively active c-Src (c-Src/dominant-positive) or a dominant-negative c-Src (c-Src/DN). Little variation of B lymphocytes expansion could be observed between control enhanced yellow fluorescent protein and c-Src/dominant-positive-infected cells. In contrast, over-expression of c-Src/DN results in a 40% inhibition of B lymphocyte expansion. These results suggest that DN c-Src may compete with endogenous c-Src, resulting in partial inhibition of a transcriptional pathway involved in B lymphocyte proliferation. We demonstrate further that c-Src can phosphorylate signal transducer and activator of transcription 5b (STAT5b) on tyrosine 699 and that c-Src and STAT5b co-associate during B lymphocyte proliferation. These results confirm an important role for c-Src in the expansion of normal human B lymphocytes in vitro, in which c-Src may regulate STAT5b in the intracellular signalling pathway important for the proliferation of normal human B lymphocytes.

Does predation risk influence habitat use by northern redbelly dace Phoxinus eos at different spatial scales?

This study investigated the relationship between spatial variations in predation risk and abundance of northern redbelly dace Phoxinus eos at both macroscale (littoral v. pelagic zones) and microscale (structured v. open water habitats in the littoral zone) of Canadian Shield lakes. Minnow traps were placed in both structured and open water habitats in the littoral zone of 13 Canadian Shield lakes, and estimates of the relative predation risk of P. eos in both the pelagic and the littoral zones were obtained from tethering experiments. Results showed that (1) the mean abundance of P. eos in the littoral zone was positively correlated with the relative predation risk in the pelagic zone, (2) P. eos preferentially used structured over open water habitats in the littoral zone and (3) this preference was not related to the relative predation risk in the littoral zone but decreased as the relative predation risk increased in the pelagic zone. At the lake level, these results support the hypothesis that P. eos enter the littoral zone to avoid pelagic piscivores. At the littoral zone level, the results do not necessarily contradict the widely accepted view that P. eos preferentially use structured over open habitats to reduce their predation risk, but suggest that flexibility in antipredator tactics (e.g. shelter use v. shoaling) could explain the spatial distribution of P. eos between structured and open water habitats.

Dead space ventilation parallels changes in scintigraphic vascular obstruction at recurrence of pulmonary embolism and after thrombolytic therapy: a case report

Physiological and alveolar dead space ventilation both increase in pulmonary embolism (PE) in proportion to the severity of vascular obstruction. The case of a patient with recurrent PE while on heparin therapy is presented. The recurrence was characterized clinically by severe pulmonary vascular obstruction and right heart dysfunction. The patient was treated with thrombolytic therapy, with excellent clinical and scintigraphic resolution. Dead space ventilation measurements at baseline, at the time of recurrence and after thrombolytic therapy are presented. The potential utility of dead space ventilation measurements for PE diagnosis and management are discussed.

Increase in antilipoperoxidant activity of plasma as a consequence of an inflammatory reaction induced by subcutaneous turpentine in the rabbit

In the rabbit, an acute inflammatory reaction triggered by the subcutaneous administration of turpentine induces in hepatic tissues an oxidative stress, as well as a decrease in activity of enzymatic scavengers of reactive oxygen species (ROS). The objective of this study was to investigate, the repercussions of a local inflammatory reaction on the antioxidant capacity and markers of systemic oxidative stress in plasma. To this purpose, rabbits received a.s.c. injection of turpentine (5 mL/kg) or NaCl 0.9% (w/v). Blood samples were collected at different times during the 48 hours of the experiment to evaluate: firstly, the antilipoperoxidant activity of plasma by measuring the inhibition of autoxidation of brain homogenate, and the concentrations of tocopherol and ascorbic acid; secondly, the severity of oxidative stress in plasma by assaying the concentration of thiobarbituric acid reactive substances (TBARS), and the concentration of ascorbyl radical. The results show that the antilipoperoxidant capacity of plasma gradually increased to be 167% higher than baseline values (p < 0.05) after 48 hours of experiment. alpha-Tocopherol and ascorbic acid levels increased by 49% and 80%, respectively (p < 0.05) during the first 24 hours. Lipid peroxidation continuously increased to be 98% higher than baseline values (p < 0.05) at 48 hours, while ascorbyl radical levels were not modified (p < 0.05). In summary, an acute local inflammatory reaction causes a steady progression of oxidative stress, while it stimulates the antilipoperoxidant activity of plasma, to which alpha-tocopherol and ascorbic acid appear to contribute, essentially early in the inflammation.

Acute moderate hypoxia in conscious rabbits: effect on hepatic cytochrome P450 and on reactive oxygen species

This study aimed to document whether acute moderate hypoxia modifies the amount and activity of hepatic cytochrome P450 and in addition, induces changes in the production or the ability to neutralize oxygen reactive species (ORS). Rabbits were exposed to a low partial pressure of oxygen (12%) for 8 or 24 h, killed, and the amount and activity of cytochrome P450, lipid peroxidation, microsomal chemiluminescence and enzymatic scavenger activity were assessed in the liver. After 8 h of hypoxia, total amount but not the activity of cytochrome P450 was decreased, although after 24 h of hypoxia, both the amount and the activity of cytochrome P450 were decreased. Hypoxia for 8 h increased the activity of glutathione peroxidase. However, after 24 h of hypoxia, lipid peroxidation, microsomal chemiluminescence and superoxide dismutase activity were increased, while hepatic glutathione and glutathione peroxidase activity were reduced, modifications that suggest an enhanced presence of ORS. In in-vitro studies, an ORS generating system reduced the activity of cytochrome P450 and enhanced lipid peroxidation of hepatic microsomal membranes, supporting the view that ORS can impair cytochrome P450. The results of the present study show that hypoxia induces changes in the amount and activity of cytochrome P450, as well as in the production or the ability to neutralize ORS, and that these changes are time-dependent.

Inflammation-induced decrease in hepatic cytochrome P450 in conscious rabbits is accompanied by an increase in hepatic oxidative stress

It has been documented that cytokines can induce the formation of reactive oxygen species (ROS) in the liver, and that an inflammatory reaction can locally increase the production of ROS, but it remains unknown whether in vivo a subcutaneous (s.c.) inflammatory reaction can induce the formation of ROS in the liver. To determine in vivo whether an inflammatory reaction, able to decrease the amount of hepatic cytochrome P450, enhances the presence of ROS in the liver, turpentine was injected s.c. to rabbits, which were sacrificed 48 hours later. Control rabbits received saline s.c. The amount and activity of cytochrome P450, as well as several parameters reflecting the presence of ROS were assessed in the liver. Total amount of cytochrome P450 was reduced, as was its activity, assessed by the rates of hydroxylation of aniline and of demethylation of aminopyrine. Moreover, lipid peroxidation increased, while the activity of the enzymatic scavengers, i.e. catalase, glutathione peroxidase and superoxide dismutase decreased. In addition, hepatic concentrations of reduced glutathione were diminished. On the other hand, the activity of the xanthine oxidase system was enhanced by almost 200%. These results strongly suggest an increased presence of ROS. The changes in the amount of cytochrome P450 were inversely correlated with lipid peroxidation. In conclusion, these results show that in vivo an inflammatory reaction, that reduces total cytochrome P450 and its activity, produces simultaneously an oxidative stress in the liver.

Nocturnal positive-pressure nasal ventilation for respiratory failure during pregnancy

Images

Molecular structure of opiate alkaloids. Part I. Crystal structure of two 16-alkyl analogues of thebaine and oripavine

The crystal structures of two 16-alkyl thebaine and oripavine analogues are described, in an attempt to put forward the particular requirements of these compounds to interact with the opiate receptor. Conformational congruencies accounting for the very high potency of these compounds are also emphasized.In light of the crystal structures, the influence of the 16-alkyl substitution is discussed, as well as the differentiation in the agonist activity observed between diastereomers at C(19) characterizing these classes of opioids.Significant distortions in the condensed ring system and the existence of an intramolecular hydrogen bonding are the main geometrical observations. They are invoked to account for particular modulations in the analgesic activity.

Use of egg washwater pH to prevent survival of Salmonella at moderate temperatures

The survival and thermal resistance of Salmonella typhimurium N+L141083 was examined in egg washwater at moderate temperatures over a range of pH values. Salmonella were able to grow at 38 and 42 C when washwater pH was less than or equal to 9.5, but substantial lethality was noted at greater than or equal to pH 10. At pH 10.5 and 11, Salmonella were eliminated within 5 hr. At 6 C, Salmonella levels were maintained for 18 hr without lethality up to pH 11. At pH 11, some lethality was noted after 5 hr. A D42 value at pH 7.0 could not be calculated, but at pH 10, a value of 40.8 sec was determined. Narrow range pH paper (pH 8 to 10) responded to egg washwater contact at or above pH 10 with a clear color reaction. Below pH 10, the paper signalled the need for addition of alkaline detergent to prevent the growth of Salmonella.

A single glutamyl-tRNA synthetase aminoacylates tRNAGlu and tRNAGln in Bacillus subtilis and efficiently misacylates Escherichia coli tRNAGln1 in vitro

In the presence or absence of its regulatory factor, the monomeric glutamyl-tRNA synthetase from Bacillus subtilis can aminoacylate in vitro with glutamate both tRNAGlu and tRNAGln from B. subtilis and tRNAGln1 but not tRNAGln2 or tRNAGlu from Escherichia coli. The Km and Vmax values of the enzyme for its substrates in these homologous or heterologous aminoacylation reactions are very similar. This enzyme is the only aminoacyl-tRNA synthetase reported to aminoacylate with normal kinetic parameters two tRNA species coding for different amino acids and to misacylate at a high rate a heterologous tRNA under normal aminoacylation conditions. The exceptional lack of specificity of this enzyme for its tRNAGlu and tRNAGln substrates, together with structural and catalytic peculiarities shared with the E. coli glutamyl- and glutaminyl-tRNA synthetases, suggests the existence of a close evolutionary linkage between the aminoacyl-tRNA synthetases specific for glutamate and those specific for glutamine. A comparison of the primary structures of the three tRNAs efficiently charged by the B. subtilis glutamyl-tRNA synthetase with those of E. coli tRNAGlu and tRNAGln2 suggests that this enzyme interacts with the G64-C50 or G64-U50 in the T psi stem of its tRNA substrates.

Lactose transport in Streptococcus mutans: isolation and characterization of factor IIIlac, a specific protein component of the phosphoenolpyruvate-lactose phosphotransferase system

The transport of lactose in Streptococcus mutans is mediated via an inducible phosphoenolpyruvate-lactose phosphotransferase system. This system requires for catalytic activity a membrane fraction (enzyme II), two general proteins called enzyme I and HPr, and a soluble specific protein termed factor IIIlac. This protein factor was purified from S. mutans ATCC 27352 by chromatographies on DEAE-cellulose, hydroxylapatite, Ultrogel AcA 34, and phosphocellulose. The purified protein migrated as a single band with a molecular weight of 10,000 on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and urea. The molecular weight calculated from the amino acid composition was 10,541. Gel filtration of the native protein gave a molecular weight of 41,500. Its isoelectric point was ca. 4.70. A specific antiserum was prepared against purified factor IIIlac. Immunodiffusion experiments revealed that only cellular extracts from lactose-grown cells contained factor IIIlac. A cross-reaction was observed with all of the S. mutans strains tested as well as with Streptococcus sanguis 10556, Streptococcus lactis 11454, and Staphylococcus aureus 6538. No precipitin band was observed with extracts of Streptococcus salivarius, Streptococcus faecalis, Lactobacillus casei, and Bacillus subtilis.

Purification of proteins similar to HPr and enzyme I from the oral bacterium Streptococcus salivarius. Biochemical and immunochemical properties

The phosphoenolpyruvate:sugar phosphotransferase system (PTS) is made of several proteins. Two of them are designated general proteins because they are required for the transport and phosphorylation of all sugars of the PTS. These two proteins are found in the soluble fraction of cellular extracts and are termed HPr and enzyme I (EI). We reported in this work the purification and the characterization of these two proteins from Streptococcus salivarius ATCC 25975. HPr was purified by DEAE-cellulose chromatography, molecular sieving on Ultrogel AcA44, and carboxymethylcellulose chromatography. Sodium dodecyl sulfate electrophoresis in the presence of urea revealed a single band with a molecular weight of 6700. The protein contained no tryptophan and had a pI of 4.8. The purification scheme of EI was as follows: DEAE-cellulose chromatography, hydroxylapatite chromatography, DEAE-Sephadex A-50 chromatography, preparative electrophoresis, and molecular sieving on Ultrogel AcA34. The five-step purification for EI produced a 199-fold purified preparation with a specific activity of 530 mumol of HPr phosphorylated per minute per milligram of protein at 37 degrees C. The fraction obtained after filtration on Ultrogel AcA34 gave one band (68 000) on sodium dodecyl sulfate - polyacrylamide gel electrophoresis. The molecular weight of the native enzyme determined by gel filtration at 4 degrees C was 135 000, suggesting that it was a dimer. Enzyme I had a pI of 4.2, a pH optimum of 6.7, a Km for HPr of about 27 microM, a Km for phosphoenolpyruvate of 0.48 mM, and kinetics that were consistent with a Ping-Pong mechanism. Evidence had been obtained which indicated that S. salivarius enzyme I was antigenically very similar to enzyme I from various strains of Streptococcus mutans, but not to the enzyme from Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, and Escherichia coli.

The monomeric glutamyl-tRNA synthetase from Bacillus subtilis 168 and its regulatory factor. Their purification, characterization, and the study of their interaction

The glutamyl-tRNA synthetase from Bacillus subtilis has been purified to homogeneity. It is a monomer of Mr = 65,500 whose NH2-terminal sequence is Met-Asn-Glu-Val-Arg-Val-Arg-Tyr-Ser-Pro-Ser-Pro-Thr-Gly-His-Leu. The number of tryptic peptides indicates the absence of a significant amount of sequence duplication. Under certain conditions, this monomeric enzyme is co-purified with a polypeptide beta of Mr = 46,000, which increases the affinity of the enzyme about 10-fold for glutamate and for ATP, and stabilizes it against heat inactivation. gamma-Globulins prepared against the monomeric enzyme can inhibit completely the glutamyl-tRNA synthetase activity of a B. subtilis extract and precipitate from this extract both the monomeric enzyme and the regulatory factor beta. These anti-alpha immunoglobulins do nt precipitate pure beta. These results show that the glutamyl-tRNA synthetase of B. subtilis has a structure similar to that of the Escherichia coli enzyme (Lapointe, J., and Söll, D. (1972) J. Biol. Chem. 247, 4966-4974) and indicate that the beta factor has a function in the regulation of glutamyl-tRNA biosynthesis in vivo.

Effect of gramicidin D on the acidogenic properties of oral streptococci and human dental plaque

The effect of gramicidin D, Gramicidin S, and carbonylcyanide p-trifluoromethoxyphenyl hydrazone on the glycolysis of various oral streptococci was investigated. Gramicidin D was the most effective and inhibited the glycolysis of all the streptococci studied in the presence of the most common sugars found in man's diet (sucrose, lactose, glucose, and fructose). A concentration of 2.5 X 10(-6) M gramicidin D was sufficient to decrease significantly the rate of glycolysis of human dental plaque in the presence of sucrose. The use of this ionophore as a caries preventive agent is discussed.