Examining temporal trends in psychological distress and the co-occurrence of common substance use in a population-based sample of grade 7-12 students from 2013 to 2019

PURPOSE

Characterizing trends and correlates of adolescent psychological distress is important due to observed global increases over the last 20 years. Substance use is a commonly discussed correlate, though we lack an understanding about how co-occurrence of these concerns has been changing over time.

METHODS

Data came from repeated, representative, cross-sectional surveys of grade 7-12 students across Ontario, Canada conducted biennially from 2013 to 2019. Poisson regression with robust standard errors was used to examine changes in the joint association between psychological distress (operationalized as Kessler-6 [K6] scores ≥ 13) and substance use over time. Weighted prevalence ratios (PR) and their 99% confidence intervals were estimated, where p < 0.01 denotes statistical significance.

RESULTS

The prevalence of psychological distress doubled between 2013 and 2019, with adjusted increases of about 1.2 times each survey year. This biennial increase did not differ based on sex, perceived social standing, school level, or any substance use. Students using substances consistently reported a higher prevalence of psychological distress (between 1.2 times and 2.7 times higher). There were similarly no differential temporal trends based on substance use for very high distress (K6 ≥ 19) or K6 items explored individually.

CONCLUSION

Psychological distress steeply increased among adolescents and substance use remains important to assess and address alongside distress. However, the magnitude of temporal increases appears to be similar for adolescents reporting and not reporting substance use.

Downregulation of lysyl oxidase in cadmium-resistant fibroblasts

Lysyl oxidase, a copper-dependent metalloenzyme, plays a central role in crosslinking of collagen and elastin in the extracellular matrix. Notably, lung lysyl oxidase activity is markedly stimulated in rats exposed to cadmium vapors. To further understand the mechanism of cadmium toxicity, the mRNA expression, synthesis, post-translational processing, and catalytic activity of lysyl oxidase were examined in cadmium-resistant (CdR) cells and the cadmium-sensitive Swiss mouse 3T3 cells from which they were derived. These CdR cells synthesized and accumulated markedly elevated levels of metallothionein, a known marker for cadmium resistance, whereas the expression of lysyl oxidase was reduced considerably. In comparison to the parental, cadmium-sensitive cells, the suppression of enzyme production in the CdR cells was seen at the mRNA level, at the levels of intracellular proprotein production and mature enzyme secreted into the medium, and in terms of total enzyme activity in the culture. The presence of cupric chloride in the culture medium during the incubation of the CdR cells for 16 h significantly enhanced lysyl oxidase activity accumulating in the medium, suggesting that lysyl oxidase deficiency in CdR cells may be related to abnormal copper metabolism.

Retinoic acid prevents downregulation of ras recision gene/lysyl oxidase early in adipocyte differentiation

Adipocyte differentiation of 3T3-L1 cells is a complex process which is inhibited by retinoic acid (RA). Since RA acts by nuclear receptors which directly regulate gene expression, we postulate that the primary targets of RA action in this system are genes which are regulated early in adipose conversion. In this study, we demonstrate the use of the differential display technique to search for early events in adipose commitment which are sensitive to RA. A mRNA was identified on the basis of its RA-dependent gene expression 24 h after initiation of a standard differentiation protocol. Molecular cloning of the cDNA revealed it to be identical to the ras recision gene (rrg), for lysyl oxidase. Indeed, two mRNAs identical to those recognized by lysyl oxidase probes were expressed in preadipocytes and tandemly repressed with 24 h of exposure to differentiation conditions. Lysyl oxidase activity was similarly reduced in the media of differentiated cells. RA completely blocked the differ-entiation-related reduction in rrg/lysyl oxidase gene expression, although RA had no independent stimulatory effect on rrg/lysyl oxidase expression in cells not exposed to differentiating conditions. Thus, differential display has been successfully used to identify rrg/lysyl oxidase as an early marker for adipose conversion that is responsive to RA.

Specific detection of quinoproteins by redox-cycling staining

Quinones and related quinonoid substances catalyze redox cycling at an alkaline pH in the presence of excess glycine as reductant. With nitroblue tetrazolium and oxygen present there is concomitant reduction of the tetrazolium to formazan. This property of quinonoid compounds is used for the specific staining of quinoproteins, separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electroblotted onto nitrocellulose. The dopa-containing vitelline proteins and the 6-hydroxydopa-containing bovine serum amine oxidase are stained with the nitroblue tetrazolium/glycinate reagent. Also, the mammalian quinoproteins, diamine oxidase and lysyl oxidase, purported to contain pyrroloquinoline quinone, tested positive in this procedure. No quinonoid components were detected in three putative pyrroloquinoline quinone-containing quinoproteins, dopamine beta-hydroxylase, lipoxygenase, and peptidylglycine-amidating monoxygenase. Redox-cycling staining therefore confirms the presence of covalently bound quinones in the copper-dependent amine oxidases, but not in two putative quinoprotein oxygenases. Clarification of the biological significance of quinolation should be facilitated by identification of quinoproteins using this approach.

Induction of lung lysyl oxidase activity and lysyl oxidase protein by exposure of rats to cadmium chloride: properties of the induced enzyme

Inspiration of CdCl2 results in a focally fibrotic response in rat lungs and markedly increases the activity of lung lysyl oxidase. Western blot analyses of urea-extractable rat lung proteins revealed that the levels of an immunoreactive, 32,000-Da protein were markedly increased in the cadmium-exposed rat lung tissue, consistent with the induction of lysyl oxidase protein. Anion exchange chromatography revealed low levels of multiple peaks of catalytically functional lysyl oxidase in control rat lung extracts, while the profile of cadmium-exposed rat lung extracts displayed markedly elevated levels of multiple peaks of enzyme activity indicating that the charge heterogeneity is expressed in the activated enzyme. The cadmium-induced enzyme was purified as a species of 32 kDa, without resolving individual ionic variants. The catalytic and physical properties of the isolated enzyme were very similar to those of previously well characterized basal enzyme of bovine aorta, including the presence of a pyrroloquinoline quinone-like carbonyl cofactor. The copper and cadmium content of the cadmium-induced enzyme indicated little if any replacement of tightly-bound copper by cadmium in the exposed lung.

Antigenic variation in alkaline deoxyribonuclease induced by three different strains of Epstein-Barr virus

To determine whether biological and/or biochemical variants exist between strains of Epstein-Barr virus (EBV), we superinfected Raji cells with the nontransforming lytic strain of EBV (HR-1), and two isolates that both transform B-lymphocytes and superinfect Raji cells, B95-8, and NPC-EBV. The superinfected cells were assayed for EBV specific DNase. A new electrophoretic form of DNase was observed in cells superinfected with B95-8 EBV as compared to the enzymes induced by the HR-1 and NPC-EBV isolates. There were antigenic differences in the DNase induced by the EBV strains. Since antibody to EBV DNase is a marker for nasopharyngeal carcinoma (NPC), these data may have implications for EBV-associated disease.