Differential effects of total and partial sleep deprivation on salivary factors in Wistar rats

Piezoelectric hydrogel for treatment of periodontitis through bioenergetic activation

The impaired differentiation ability of resident cells and disordered immune microenvironment in periodontitis pose a huge challenge for bone regeneration. Herein, we construct a piezoelectric hydrogel to rescue the impaired osteogenic capability and rebuild the regenerative immune microenvironment through bioenergetic activation. Under local mechanical stress, the piezoelectric hydrogel generated piezopotential that initiates osteogenic differentiation of inflammatory periodontal ligament stem cells (PDLSCs) via modulating energy metabolism and promoting adenosine triphosphate (ATP) synthesis. Moreover, it also reshapes an anti-inflammatory and pro-regenerative niche through switching M1 macrophages to the M2 phenotype. The synergy of tilapia gelatin and piezoelectric stimulation enhances in situ regeneration in periodontal inflammatory defects of rats. These findings pave a new pathway for treating periodontitis and other immune-related bone defects through piezoelectric stimulation-enabled energy metabolism modulation and immunomodulation.

Salivary α-amylase as a marker of sleep disorders: A theoretical review

Sleep disorders are commonplace in our modern societies. Specialized hospital departments are generally overloaded, and sleep assessment is an expensive process in terms of equipment, human resources, and time. Biomarkers would usefully complement current measures in the screening and follow-up of sleep disorders and their daytime repercussions. Among salivary markers, a growing body of literature suggests that salivary α-amylase (sAA) may be a cross-species marker of sleep debt. However, there is no consensus as to the direction of variation in sAA with sleep disorders. Herein, after describing the mechanisms of sAA secretion and its relationship with stress, studies assessing the relationship between sAA and sleep parameters are reviewed. Finally, the influence of confounding factors is discussed, along with methodological considerations, to better understand the fluctuations in sAA and facilitate future studies in the field.

Degenerative changes induced by paradoxical sleep deprivation in rat sublingual glands

PURPOSE

The aim of this study was to evaluate whether sleep deprivation can induce degenerative changes in rat sublingual glands.

METHODS

For this purpose, a total of 24 males were distributed into three groups: control (n = 8), in which the animals were not subjected to any procedure; sleep deprivation (n = 8) in which the animals were submitted to sleep deprivation for 96 h; recovery (n = 8), in which the animals were subjected to paradoxical sleep deprivation for 96 consecutive hours followed by 96 h without intervention. Morphological changes in sublingual glands as well as the immunoexpressions of some proteins, such as Ki-67, p16, cleaved caspase-3 and BCL-2 were investigated in this setting.

RESULTS

The results showed that paradoxical sleep deprivation induced tissue degeneration as a result of the presence of pyknosis, vacuoles and areas of salivary retention, in the experimental groups. Expression of cleaved caspase 3 and BCL-2 were increased in both sleep deprivation and recovery groups. The analysis of Ki-67 showed an increase in expression only in the recovery group, associated with a decrease in p16 levels.

CONCLUSION

Sleep deprivation can induce a degenerative process in the parenchyma of sublingual gland by means of dysregulation of apoptosis associated with proliferative activity.

Association between sleep duration and dental caries in a nationally representative U.S. population

BACKGROUND

Dental caries is considered one of the most prevalent chronic diseases worldwide despite all dental public health efforts. Short sleep duration has been established as a risk factor for several medical conditions. In this study, we aimed to examine the relationship between sleep duration and dental caries.

METHODS

Data were collected from the 2017-2018 cycle of the National Health and Nutrition Examination Survey, a nationally representative health survey conducted in the United States. Participants who completed sleep questionnaires were examined by dentists using standardized clinical criteria. Analysis was limited to Individuals aged ≥ 16 years with complete clinical oral examination data and who completed the sleep questionnaire (N = 5,205). The data were weighted to provide a national estimate, and multiple potential covariates were included in the analysis to account for the complex sample design. The main outcomes of the study were untreated dental caries and dental caries experience. The main predictor variables were average sleep hours/night and a binary variable with 7 h/night as a cut off. Multiple weighted Poisson and logistic regression analyses were conducted to test the hypothesis that people with short sleep duration are more likely to exhibit dental caries.

RESULTS

This study showed a statistically significant negative relationship between sleep duration and dental caries amongst all weighted adjusted analyses conducted. For a one hour increase in average sleep hours, the Adjusted Odds Ratio (AOR) of having a dental caries experience might decrease by 0.86 (AOR = 0.86, 95% CI = 0.75-0.98, P < 0.05). Individuals who reported an average sleep of ≥ 7 h were less likely to have a dental caries experience compared to individuals who reported an average sleep of < 7 h (AOR = 0.52, 95% CI = 0.33-0.82, P < 0.05). For a one hour increase in average sleep hours, the Adjusted Mean Ratio (AMR) of having a dental caries experience might decrease by 0.97 (AMR = 0.97, 95% CI = 0.96-0.99, P < 0.05), and was lower for those who reported sleeping ≥ 7 h/night than individuals who reported sleeping < 7 h/night (AMR = 0.92, 95% CI = 0.87-0.99, P < 0.05).

CONCLUSION

Findings of this cross-sectional representative study of the U.S. population revealed a statistically significant negative association between sleep duration and dental caries. In this study, individuals who slept < 7 h/night were more likely to exhibit dental caries.

Paradoxical sleep deprivation induces tissue changes in the parotid gland of rats

PURPOSE

This study aimed to evaluate if paradoxical sleep deprivation induces some tissue changes in the parotid gland of rats.

METHODS

A total of 24 male Wistar rats were distributed into the following groups, as follows: Group 1-Control (CTRL; n = 8); Group 2-Sleep deprivation (PS; n = 8): the animals were submitted to Paradoxical Sleep deprivation for 96 h and Group 3-Recovery (R; n = 8): the animals were submitted to sleep loss for 96 h, followed by a period of 96 h without any intervention. The following parameters were evaluated: microscopic analysis, immunohistochemistry for Caspase-3, Ki-67, and COX-2 and gene expression of cytochrome C, TNF-α, and Interleukins 6, 10.

RESULTS

The results pointed out acinar atrophy, and the presence of cytoplasmic vacuoles in the parenchyma of the experimental groups. In the same groups, there was differential expression of interleukins 6, 10 and TNF-α. Apoptosis was also increased by means of cleaved caspase 3 expression. The cellular proliferation (ki-67 expression) was increased the R group.

CONCLUSION

Taken together, sleep deprivation induces tissue degeneration, inflammatory process, as well as activate apoptosis in the parotid gland of rats.

Inflammatory activity and apoptosis are associated with tissue degeneration in the submandibular gland of rats submitted to paradoxical sleep deprivation

The aim of this study was to evaluate if paradoxical sleep deprivation is able to induce tissue degeneration, inflammatory activity and apoptosis in the submandibular gland of rats. A total of 24 male Wistar rats were distributed into the following groups: group 1-control (CTRL; n = 8): the animals were not submitted to any procedures; group 2-sleep deprivation (PS; n = 8): the animals were submitted to paradoxical sleep deprivation for 96 h and group 3-recovery (R; n = 8): the animals were submitted to sleep deprivation for 96 h, followed by a period of 96 h without any intervention. The following parameters were evaluated: histopathological analysis, immunohistochemistry for Ki-67, COX-2 and cleaved caspase-3 and gene expression of TNF-α, Interleukin 6 (IL-6), Interleukin 10 (IL-10) and cytochrome C by real-time PCR. The results pointed out cytoplasmic vacuoles and congested vessels in the parenchyma of submandibular gland the in PS and R groups. The expression of interleukins 6, 10 and TNF-ɑ was differentially expressed in the PS and R groups. Apoptosis was also triggered by means of increasing cleaved caspase-3 and cytochrome c expression. The cellular proliferation (Ki-67 index) was also positive in the R group. Taken together, our results demonstrate that sleep deprivation is capable of promoting tissue degeneration in the submandibular gland, as a result of inflammatory response and cellular death in rats.

Paradoxical sleep deprivation induces oxidative stress in the submandibular glands of Wistar rats

OBJECTIVES

Paradoxical sleep deprivation has been associated with impaired salivary secretion in rats. However, the mechanism that underlies this is not known. Therefore, this study assessed salivary and serum oxidative stress levels following paradoxical sleep deprivation in rats.

METHODS

Twenty-one male Wistar rats randomly divided into three groups of seven rats each as; Control (C); partial sleep-deprived (PSD); and total sleep-deprived (TSD) were used. Malondialdehyde (MDA) concentration, Superoxide dismutase (SOD), and catalase activities were evaluated in saliva, serum, and submandibular glands after seven days of sleep deprivation. Data were expressed as mean ± standard error of the mean and analyzed using one-way ANOVA, Tukey HSD post hoc, and Pearson's correlation tests.

RESULTS

Serum MDA levels were significantly higher in both the TSD and PSD groups compared to the control group whereas only the TSD group showed higher submandibular MDA levels compared to the PSD group and the control group. Submandibular SOD activity was significantly lower in both the TSD and PSD groups compared to the control group. Serum catalase activity was significantly lower in the TSD group only compared to the control group.

CONCLUSIONS

These results have demonstrated for the first time that paradoxical sleep deprivation was associated with changes in the oxidant/antioxidant defense system in the submandibular salivary glands of male Wistar rats which may contribute to impairment in salivary secretion.

Relationship between Insufficient Sleep and Bad Breath in Korean Adolescent Population

This cross-sectional study sought to evaluate the association between insufficient sleep and bad breath among Korean adolescent population. It was based on the 13th Korea Youth Risk Behavior Web-Based Survey (2017). From 64,991 participants (aged 13-18 years), the final participation rate in the survey was 95.8% (62,276 participants; 31,624 boys and 30,652 girls). A complex sample logistic regression was performed to identify the relationship between insufficient sleep and halitosis, after adjusting for all covariates. In Model II for estimating the adjusted odds ratio (AOR) for general characteristics, students who answered "not at all sufficient", indicating insufficient sleep, were at higher risk of bad breath than those who answered "completely sufficient" (AOR = 2.09, 95% confidence interval, CI = 1.91-2.30). In Model III, for estimating the AOR adjusted for all covariates, students who answered "not at all sufficient", indicating insufficient sleep, were at higher risk of bad breath than those who answered "completely sufficient" (AOR = 1.47, 95% CI = 1.33-1.83). It is necessary for families and schools to have health education lessons that recognize insufficient sleep among adolescents may be a cause of bad breath and therefore optimal sleeping habits and oral health behaviors should be promoted.

Insufficient Sleep and Incidence of Dental Caries in Deciduous Teeth among Children in Japan: A Population-Based Cohort Study

OBJECTIVES

To examine whether late bedtime and short nighttime sleep duration at age 18 months are associated with risk of caries in deciduous teeth.

STUDY DESIGN

Population-based cohort study using health check-up data of 71 069 children born in Kobe City, Japan, who were free of caries at age 18 months and had information on sleep variables at age 18 months and records of dental examinations at age 3 years. Sleep variables were assessed by standardized parent-reported questionnaires, and the incidence of caries in deciduous teeth was defined as the occurrence of at least 1 decayed, missing, or filled tooth assessed by qualified dentists without radiographs. Logistic regression was used to estimate the effects of late bedtime and short sleep duration on dental caries with adjustment for clinical and lifestyle characteristics.

RESULTS

Overall, 11 343 (16.0%) cases of caries were observed at age 3 years. aORs for children with late or irregular bedtimes compared with those with bedtimes before 21:00 were 1.26 (95% CI 1.19-1.33), 1.48 (1.38-1.58), 1.74 (1.58-1.92), 1.90 (1.58-2.29), and 1.66 (1.53-1.81) for bedtimes at 21:00, 22:00, 23:00, 0:00, and irregular bedtime, respectively. aORs for children with short or irregular sleep duration compared with those with sleep duration of ≥11 hours were 1.30 (95% CI 1.15-1.47), 1.16 (1.09-1.24), 1.11 (1.05-1.18), and 1.35 (1.25-1.46) for sleep duration of ≤ 8, 9, 10 hours, and irregular sleep duration, respectively.

CONCLUSIONS

In this exploratory study, late bedtime and short sleep duration were both consistently associated with increased risk of caries in deciduous teeth.

Linking stress and immunity: Immunoglobulin A as a non-invasive physiological biomarker in animal welfare studies

As the animal welfare community strives to empirically assess how care and management practices can help maintain or even enhance welfare, the development of tools for non-invasively measuring physiological biomarkers is essential. Of the suite of physiological biomarkers, Immunoglobulin A (IgA), particularly the secretory form (Secretory IgA or SIgA), is at the forefront because of its crucial role in mucosal immunity and links to physical health, stress, and overall psychological well-being. While interpretation of changes in SIgA concentrations on short time scales is complex, long-term SIgA patterns are consistent: conditions that create chronic stress lead to suppression of SIgA. In contrast, when welfare is enhanced, SIgA is predicted to stabilize at higher concentrations. In this review, we examine how SIgA concentrations are reflective of both physiological stress and immune function. We then review the literature associating SIgA concentrations with various metrics of animal welfare and provide detailed methodological considerations for SIgA monitoring. Overall, our aim is to provide an in-depth discussion regarding the value of SIgA as physiological biomarker to studies aiming to understand the links between stress and immunity.