Patterns of multiple health risk-behaviours in university students and their association with mental health: application of latent class analysis

INTRODUCTION

University and college campuses may be the last setting where it is possible to comprehensively address the health of a large proportion of the young adult population. It is important that health promoters understand the collective challenges students are facing, and to better understand the broader lifestyle behavioural patterning evident during this life stage. The purpose of this study was to examine the clustering of modifiable health-risk behaviours and to explore the relationship between these identified clusters and mental health outcomes among a large Canadian university sample.

METHODS

Undergraduate students (n = 837; mean age = 21 years) from the University of Toronto completed the National College Health Assessment survey. The survey consists of approximately 300 items, including assessments of student health status, mental health and health-risk behaviours. Latent class analysis was used to identify patterning based on eight salient health-risk behaviours (marijuana use, other illicit drug use, risky sex, smoking, binge drinking, poor diet, physical inactivity, and insufficient sleep).

RESULTS

A three-class model based on student behavioural patterns emerged: "typical," "high-risk" and "moderately healthy." Results also found high-risk students reporting significantly higher levels of stress than typical students (χ2(1671) = 7.26, p < .01).

CONCLUSION

Students with the highest likelihood of engaging in multiple health-risk behaviours reported poorer mental health, particularly as it relates to stress. Although these findings should be interpreted with caution due to the 28% response rate, they do suggest that interventions targeting specific student groups with similar patterning of multiple health-risk behaviours may be needed.

Immunostaining for thyroid transcription factor 1 and cytokeratin 20 aids the distinction of small cell carcinoma from Merkel cell carcinoma, but not pulmonary from extrapulmonary small cell carcinomas

OBJECTIVE

To study the expression of thyroid transcription factor 1 (TTF-1) and cytokeratin 20 (CK20) in pulmonary small cell carcinomas, extrapulmonary small cell carcinomas, and Merkel cell carcinomas, and thereby determine whether these markers are helpful in distinguishing these 3 groups of small cell neuroendocrine carcinomas.

MATERIALS AND METHODS

Immunostaining for TTF-1 and CK20 was performed in 102 cases of small cell carcinoma (pulmonary, 52; extrapulmonary, 50) and 23 cases of Merkel cell carcinoma. The results for the 3 groups were compared.

RESULTS

Thyroid transcription factor 1 was expressed in 82.7% of pulmonary small cell carcinomas, 42.0% of extrapulmonary small cell carcinomas (range, 33.3--53.3% for the various sites), and 0% of Merkel cell carcinomas. Cytokeratin 20 staining was consistently negative in pulmonary small cell carcinomas, and positive in 4.0% of extrapulmonary small cell carcinomas and 100% of Merkel cell carcinomas.

CONCLUSIONS

Immunostaining for TTF-1, especially when combined with immunostaining for CK20, can aid in the distinction between Merkel cell carcinoma and small cell carcinoma (both pulmonary and extrapulmonary). However, in individual cases, these markers cannot be used to distinguish between pulmonary and extrapulmonary small cell carcinomas due to the extensive overlap in immunophenotypes.

Reflections on the use of controls in immunohistochemistry and proposal for application of a multitissue spring-roll control block

The conventional positive control in immunohistochemistry consists of a separately immunostained slide containing tissue known to show positive reaction with the antibody. Although it can indicate that the reagents are sound, it cannot guarantee that the appropriate reagents have indeed been dispensed in the correct order on the test cases. Furthermore, positive controls are costly because they often account for 20% to 40% of all immunostained slides in a diagnostic surgical pathology laboratory. We describe a simple method to produce a multitissue spring-roll control block, comprising mostly normal tissues. The multitissue controls are mounted on the same slides of the test cases, and thus undergo the identical immunostaining procedures as the test tissues. Therefore they can provide the best assurance that the immunostains are working properly on the individual slides, the expected sensitivity is achieved, and the specificity is as expected. The wisdom of the conventional negative control is also questioned. When two or more immunostains are performed on a case, they should be sufficient to indicate the presence or absence of nonspecific staining.

Dissection of differentially regulated (G+C)-rich promoters of the human parathyroid hormone (PTH)/PTH-related peptide receptor gene

The PTH/PTH-related peptide (PTHrP) receptor (PTHR) is required for normal skeletal development, and a wide array of physiological responses mediated by PTH and PTHrP. We have previously identified three promoters, P1-P3, which control human PTHR gene transcription. P2 and P3 are (G+C)-rich, function in a number of tissues, lie within the same CpG island, and display many hallmarks of housekeeping promoters. However, they are differentially regulated during development as P2, but not P3, functions in fetal tissues. Here, we have used both stably and transiently transfected human osteoblast-like cells to delineate regions of P2 and P3 required for promoter activity. Deletion analyses performed in stably transfected cells indicated that sequences extending from -91 to -12 relative to the transcription start site were required for function of the P2 promoter. No negative regulatory elements were detected in P2. In contrast, deletion of an A-rich region of P3 extending from -147 to -115 was required for optimal basal activity, suggesting that this sequence acts as a repressor of P3. Strikingly, however, whereas the A-rich region also functioned as a negative element when inserted upstream of the (G+C)-rich P2 promoter, it enhanced expression from the thymidine kinase promoter, suggesting that its function depends on other transcription factors bound to promoter sequences. Fine deletion of P3 sequences proximal to -115 implicated Spl motifs and downstream initiation sites in P3 function. These studies indicate that function of P2 and P3 is controlled by ubiquitously expressed transcription factors and raise the possibility that P3 activity is repressed during fetal development.

Methylation patterns of human parathyroid hormone (PTH)/PTH-related peptide receptor gene promoters are established several weeks prior to onset of their function

Expression of the human parathyroid hormone (PTH)/PTH-related peptide receptor (PTHR) gene is controlled by three promoters, P1-P3. P1 functions specifically in kidney, whereas P2 is ubiquitously active. P3 is also widely active, although more so in kidney than other tissues. However, only P2 functions at midgestation. We examined the role of methylation in controlling PTHR promoter activity. Function of all promoters was inhibited by CpG methylation in vitro. Significantly, P1 is selectively hypomethylated in adult kidney in vivo, strongly suggesting that demethylation is required for renal P1 function. Moreover, this pattern is established by 11. 75 weeks of fetal age, several weeks prior to the onset P1 activity. P3 is unmethylated at midgestation, although it is inactive at this stage of development, and thus exhibits characteristics of both tissue-specific and ubiquitously active promoters. These results show that adult methylation patterns of P1 and P3 are established several weeks prior to their induction, indicating that their function requires factors expressed late in development.

Vitamin D3 differentially regulates parathyroid hormone/parathyroid hormone-related peptide receptor expression in bone and cartilage

Transcription of the mouse parathyroid hormone (PTH)/PTH-related peptide (PTHrP) receptor (PTHR) gene is controlled by promoters P1 and P2. We performed transcript-specific in situ hybridization and found that P2 is the predominant promoter controlling PTHR gene expression in bone and cartilage. Treatment with 1alpha, 25-dihydroxyvitamin D3 (D3) in vivo specifically downregulated P2-specific transcripts in osteoblasts, but not in chondrocytes, under conditions where it enhanced bone resorption. Treatment of the osteoblastic cell line MC3T3-E1 with D3 in vitro reduced expression of both P2-specific transcripts and PTHR protein. This effect was not blocked by cycloheximide, indicating that D3 inhibits PTHR expression by downregulating transcription of the P2 promoter. A similar inhibitory effect of D3 was not observed in the chondrocytic cell line CFK2. Gene-transfer experiments showed that P2, but not P1, is active in both MC3T3-E1 and CFK2 cells, and that D3 specifically inhibited P2 promoter activity in MC3T3-E1, but not in CFK2 cells. Inhibition of P2 activity by D3 required promoter sequences lying more that 1.6 kb upstream of the P2 transcription start site. Thus, the P2 promoter controls PTHR gene expression in both osteoblasts and chondrocytes. D3 downregulates PTHR gene transcription in a cell-specific manner by inhibiting P2 promoter activity in osteoblasts, but not in chondrocytes.

Cloning and characterization of the promoter regions of the human parathyroid hormone (PTH)/PTH-related peptide receptor gene: analysis of deoxyribonucleic acid from normal subjects and patients with pseudohypoparathyroidism type 1b

Expression of the PTH/PTH-related peptide (PTHrP) receptor (PTHR) in the mouse is controlled by at least two promoters. The downstream promoter (P2) is ubiquitously expressed, whereas expression of the upstream promoter (P1) is largely restricted to kidney. These observations may provide a genetic basis for a human PTH resistance syndrome, pseudohypoparathyroidism type 1b (PHP1b), in which renal, but not osseous, signaling by PTH is defective. We, therefore, cloned and characterized the 5'-end of the human PTHR gene and found that its organization is very similar to that of the mouse. Transcription initiation sites of human P1 and P2 promoters are in similar, but not identical, positions to those of the mouse gene. The identification of a human P2 promoter is significant because no P2-specific human PTHR complementary DNAs have been isolated to date. Southern analysis of genomic DNA from seven PHP1b patients did not reveal any rearrangements in proximal promoter regions or exons encoding 5'-untranslated region sequences. No significant sequence differences were found in clones of normal and patient DNAs encompassing proximal promoter sequences, and untranslated region and signal sequence exons. Thus, in the seven PHP1b patients analyzed, no defects were identified that would influence initiation site selection, stability, or splicing of renal PTHR transcripts. These data indicate that the genetic defect(s) in PHP1b in these patients lies in distal enhancer elements of the gene, in an essential transcriptional regulator, or in some as yet unidentified cofactor required for renal PTH signaling.

Cell-specific expression of the parathyroid hormone (PTH)/PTH-related peptide receptor gene in kidney from kidney-specific and ubiquitous promoters

The kidney is the major site of expression of the PTH/PTH-related peptide receptor (PTHR) gene. Previously we have shown that the PTHR gene is expressed from two promoters in kidney, an upstream kidney-specific promoter (P1) and a downstream promoter (P2) that is active in a wide variety of tissues. Here, we have used immunohistochemical and transcript-specific in situ hybridization techniques to map the expression of the PTHR gene and protein and to determine the distribution of P1- and P2-driven messenger RNAs in renal tissue. Immunohistochemical and immunoelectron microscopic analysis showed that PTHR protein is expressed on both basolateral and luminal membranes of proximal tubular epithelial cells, strongly suggesting a bipolar mode of action of PTH. Receptor protein also was detected on the surface of glomerular podocytes. Strikingly, immunoelectron microscopic analysis showed that endothelial cells of the peritubular vasculature, but not the glomerular vasculature, contain high levels of PTHR protein. We found that both P1 and P2 are expressed at moderate levels in both cortical and medullary epithelial cells of nephrons, correlating well with the immunohistochemical localization of PTHR protein. However, although abundant transcripts were detected in peritubular endothelial cells with P1-specific and coding sequence probes, P2-specific expression was not observed in these cells. These results provide evidence that the physiological effects of PTH- and/or PTH-related peptide on renal tubular function may be mediated not only through direct effects on epithelial cells but also indirectly through endothelial cell-based signaling. In addition to expression in vascular endothelial cells, high levels of P1-specific, but not P2-specific, PTHR messenger RNA were detected in vascular smooth muscle. Taken together, these experiments provide evidence for strong PTHR gene expression in renal vascular tissues. Moreover, given that previous studies have shown that P2, but not P1, is active in other tissues with an abundant vasculature, our results suggest that regulation of PTHR gene expression in renal vascular tissue is distinct from that of other organs.

Overexpression of human prostaglandin G/H synthase-1 and -2 by recombinant vaccinia virus: inhibition by nonsteroidal anti-inflammatory drugs and biosynthesis of 15-hydroxyeicosatetraenoic acid

Human prostaglandin G/H synthase (hPGHS)-1 and hPGHS-2, key enzymes in the formation of prostanoids from arachidonic acid, were expressed at high levels in COS-7 cells using a T7 RNA polymerase/vaccinia virus expression system. The open reading frame of hPGHS-2 cloned into vaccinia virus without its natural 5' and 3' untranslated regions directed only low levels of hPGHS-2 enzyme activity in COS-7 cells. High-level hPGHS-2 expression was achieved by appending the 3' untranslated region of hPGHS-1 to the hPGHS-2 open reading frame, with subsequent expression of the hybrid mRNA using vaccinia virus. Enzymatically active recombinant hPGHS-1 and hPGHS-2 were present as glycosylated proteins in the microsomal fraction prepared from infected cells, whereas recombinant hPGHS-1 and hPGHS-2 prepared from the microsomal fraction of cells treated with tunicamycin, an inhibitor of N-linked glycosylation, were enzymatically inactive. The major prostanoid products formed by microsomes from COS-7 cells containing either recombinant hPGHS-1 or hPGHS-2 after incubation with arachidonic acid were prostaglandin D2 and E2, with lower levels of prostaglandin F2 alpha and 6-keto-prostaglandin F1 alpha. A range of potencies were observed for various nonsteroidal anti-inflammatory drugs as inhibitors of prostaglandin E2 synthesis by hPGHS-1 and hPGHS-2. Recombinant hPGHS-1 and hPGHS-2 both produced 15- and 11-hydroxyeicosatetraenoic acid (HETE) from arachidonic acid, with 15-HETE production by hPGHS-2 being stimulated 5-fold by preincubation with aspirin. Chiral phase high performance liquid chromatography analysis showed that aspirin-treated hPGHS-2 produced 15(R)-HETE, with no detectable 15(S)-HETE.