Habitual sleep, sleep duration differential, and weight change among adults: Findings from the Wisconsin Sleep Cohort Study

OBJECTIVES

Assess longitudinal associations between diary-measured sleep duration and clinically assessed body mass index (BMI).

DESIGN

Multilevel growth curve analyses examined how within-person changes and between-person differences in habitual sleep duration were associated with BMI trajectories.

SETTING

Sleep diaries across 2-6 consecutive weekday and weekend nights at each data collection point, repeatedly collected at approximate 4-year intervals, for an average of 9.2 (standard deviation [SD] = 3.6) years between 1989 and 2011.

PARTICIPANTS

About 784 participants (47% women) enrolled in the Wisconsin Sleep Cohort Study (mean [SD] age = 51.1 [8.0] years at baseline).

MEASUREMENTS

The outcome variable was BMI (kg/m²). Key predictors were habitual sleep duration (defined as average weekday nighttime sleep duration) and sleep duration differential (defined as the difference between average weekday and average weekend nighttime sleep duration) at each data collection wave.

RESULTS

Men with shorter habitual sleep duration on weekdays had higher BMI than men with longer habitual sleep duration on weekdays (β = -0.90 kg/m²/hour, se = 0.34, p = .008). Participants with larger differentials between weekday and weekend sleep duration experienced more rapid BMI gain over time for both men (β = 0.033 kg/m²/year per hour differential, se = 0.017, p = .044) and women (β = 0.057 kg/m²/year per hour differential, se = 0.027, p = .036).

CONCLUSION

This study suggests that habitual short sleep is associated with higher BMI levels in men and that a larger weekday-weekend sleep differential is associated with increasing BMI trajectories among both men and women in mid-to-late life.

Contributors to Wisconsin's persistent black-white gap in life expectancy

Background

Although the black-white gap in life expectancy has narrowed in the U.S., there is considerable variability across states. In Wisconsin, the black-white gap exceeds 6 years, well above the national average. Reducing this disparity is an urgent public health priority, but there is limited understanding of what contributes to Wisconsin’s racial gap in longevity. Our investigation identifies causes of death that contribute most to Wisconsin’s black-white gap in life expectancy among males and females, and highlights specific ages where each cause of death contributes most to the gap.

Methods

Our study employs 1999–2016 restricted-use mortality data provided by the National Center for Health Statistics. After generating race- and sex-specific life tables for each 3-year period of observation (e.g., 1999–2001), we trace recent trends in the black-white life expectancy gap in Wisconsin. We subsequently conduct a series of analyses to decompose the black-white gap in three time periods into 13 separate causes and 19 different age groups.

Results

In 2014–16, Wisconsin’s black-white gap in life expectancy was 7.34 years for males (67% larger than the national gap), and 5.61 years for females (115% larger than the national gap). Among males, homicide was the single largest contributor, accounting for 1.56 years of the total gap. Heart disease and cancer followed, contributing 1.43 and 1.42 years, respectively. Among females, heart disease and cancer were the two leading contributors to the gap, accounting for 1.12 and 1.00 years, respectively. Whereas homicide contributed most to the racial gap in male longevity during late adolescence and early adulthood, heart disease and cancer exerted most of their influence between ages 50–70 for both males and females. Other notable contributors were unintentional injuries (males), diabetes and cerebrovascular disease (females), and perinatal conditions (males and females).

Conclusions

Our study identifies targets for future policy interventions that could substantially reduce Wisconsin’s racial gap in life expectancy. Concerted efforts to eliminate racial disparities in perinatal mortality and homicide early in the life course, and chronic conditions such as cancer and heart disease in later life, promise to help Wisconsin achieve the public health objective of racial parity in longevity.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7145-y) contains supplementary material, which is available to authorized users.

Macronutrient intake of dogs, self-selecting diets varying in composition offered ad libitum

The diet of the domestic dog has changed significantly from that of its wolf ancestor, with to date only two studies having examined macronutrient self-selection in dogs. Whilst the first focused solely on protein intake, determining an intake of 30% metabolisable energy (ME), the second investigated dietary protein, fat and carbohydrate (PFC), indicating an intake ratio of 30:63:7% by energy. This study's aim was to further elucidate macronutrient intake by providing greater macronutrient range, energy content, and to investigate over a longer duration than previous studies. Fifteen adult dogs were given access to three wet diets providing 500% of daily ME, twice daily over 10 days. The diets were nutritionally complete and formulated using the same four ingredients in different proportions to supply high levels of protein (58% ME), fat (86% ME) or carbohydrate (54% ME). Overall fat and carbohydrate consumption significantly declined from 6,382 to 917 kcals per day (p < 0.001) and 553 to 214 kcals day^-1 (p < .01) respectively. Protein intake, however, remained constant over the study and ranged from 4,786 to 4,156 kcals day^-1 . Such results impacted on percentage total energy intake, with fat decreasing from 68% to 52% (p < .001) and protein increasing from 29% to 44% (p < .01). Our findings suggest that dogs still possess a "feast or famine" mentality, wherein energy dense fat is prioritised over protein initially. With continued feeding over 10 days, a transition to a more balanced energy contribution from both macronutrients is evident. The study also shows that given the option, dogs do not select carbohydrate to be a significant portion of the diet. The health implications of such dietary selection are of interest.

Modulation of recombinant small-conductance Ca(2+)-activated K(+) channels by the muscle relaxant chlorzoxazone and structurally related compounds

Using the patch clamp technique we investigated the effects of the centrally acting muscle relaxant chlorzoxazone and three structurally related compounds, 1-ethyl-2-benzimidazolinone (1-EBIO), zoxazolamine, and 1,3-dihydro-1-[2-hydroxy-5-(triflu oromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one (NS 1619) on recombinant rat brain SK2 channels (rSK2 channels) expressed in HEK293 mammalian cells. SK channels are small conductance K(+) channels normally activated by a rise in intracellular Ca(2+) concentration; they modulate the electrical excitability in neurons and neuroendocrine cells. When applied externally, chlorzoxazone, 1-EBIO, and zoxazolamine activated rSK2 channel currents in cells dialyzed with a nominally Ca(2+)-free intracellular solution. The activation was reversible, reproducible, and depended on the chemical structure and concentration. The order of potency was 1-EBIO > chlorzoxazone > zoxazolamine. Activation of rSK2 channels by chlorzoxazone, 1-EBIO, and zoxazolamine declined at higher drug concentrations. Zoxazolamine, when applied in combination with chlorzoxazone or 1-EBIO, partially inhibited the rSK2 channel current responses, suggesting a partial-agonist mode of action. 1-EBIO failed to activate rSK2 channel currents when applied to excised inside-out membrane patches exposed to a Ca(2+)-free intracellular solution. In contrast, 1-EBIO activated rSK2 currents in a concentration-dependent manner when coapplied to the patches with a solution containing 20 nM free Ca(2+). NS 1619 did not activate rSK2 channel currents; it inhibited rSK2 channel currents activated by the other three test compounds or by high intracellular Ca(2+). We conclude that chlorzoxazone and its derivatives act through a common mechanism to modulate rSK2 channels, and SK channel modulation in the brain may partly underlie the clinical effects of chlorzoxazone.

Block of rat brain recombinant SK channels by tricyclic antidepressants and related compounds

SK channels are small conductance, Ca(2+)-activated K(+) channels that underlie neuronal slow afterhyperpolarization and mediate spike frequency adaptation. Using the patch clamp technique, we tested the effects of eight clinically relevant psychoactive compounds structurally related to the tricyclic antidepressants, on SK2 subtype channels cloned from rat brain and functionally expressed in the human embryonic kidney cell line, HEK293. Amitriptyline, carbamazepine, chlorpromazine, cyproheptadine, imipramine, tacrine and trifluperazine blocked SK2 channel currents with micromolar affinity. The block was reversible and concentration-dependent. The potency differed according to chemical structure. In contrast, the cognitive enhancer linopirdine was ineffective at blocking these channels. Our results point to a distinct pharmacological profile for SK channels.

Localisation of bone-forming cells during fracture healing by osteocalcin immunocytochemistry: an experimental study of the rabbit tibia

An immunocytochemical method was used to localise osteocalcin-producing cells during fracture healing in a rabbit model. In preliminary studies, tibial growth plates from young rabbits were used as a source of new bone formation, in order to determine the optimal tissue preparatory techniques. In the present study, a tibial shaft fracture was created in adult rabbits to study closed fracture healing. An indirect peroxidase method was used to stain paraffin-embedded tissue sections for osteocalcin. Osteocalcin-producing cells were positively identified at the periosteal and endosteal surfaces near the fracture site. Osteocalcin staining was not demonstrated in the surrounding soft tissues. At the interface between newly formed bone trabeculae and the cartilage layer within the callus, chondrocytic cells consistently showed localisation of osteocalcin. Within cartilaginous areas of the callus, some chondrocytes showed positive staining for osteocalcin. These cells were often seen in the proximity of blood vessels. The findings suggest that during fracture healing, under certain conditions, chondrocytes are capable of producing osteocalcin and thus could be considered capable of possible transformation into osteoblasts.

Prospective, multi-centre trial of mortality following general or spinal anaesthesia for hip fracture surgery in the elderly

In a prospective randomized multi-centre study, the mortality following internal fixation surgery for fracture of the upper femur was investigated in 538 elderly patients allocated to receive subarachnoid blockade or general (narcotic-relaxant) anaesthesia. The 28-day mortality was 6.6% with subarachnoid, and 5.9% with general, anaesthesia. The difference was not significant (95% confidence limits: -3.5 to +4.8). At 1 year following surgery, the mortality was 20.4%. Increasing age, ischaemic heart disease, cardiac failure, preoperative arrhythmias and poor ASA status were all associated with increases in early and long term mortality. A delay to surgery of more than 24 h from admission was also associated with an increased 28-day mortality. Senile dementia and admission other than from the patient's own home, were factors associated with a poorer long term outcome. From the point of view of mortality, subarachnoid anaesthesia did not appear to confer any advantages over general anaesthesia in non-prosthetic surgery for hip fracture in the elderly.

Pituitary fossa injection with alcohol for widespread cancer pain

Trans-sphenoidal injection of 95 percent dehydrated alcohol into the pituitary fossa was attempted in 10 patients to control pain associated with widely disseminated metastatic cancer. Significant pain relief was obtained in eight patients, some of whom had tumours not recognised as being hormone sensitive. Effects of pituitary destruction were easily managed, and there were few complications. There was no mortality directly attributable to the injection.

Responses of motoneurones to electrophoretically applied dopamine

1. The effect of electrophoretically applied dopamine upon motoneurone excitability has been investigated. Field potentials originating from antidromically activated motoneurones were recorded from the ventral horn of the rat lumbar spinal cord. 2. Field potentials showed an increase in amplitude following electrophoretic application of dopamine. Dopamine was shown to be less potent than noradrenaline and 5-hydroxytryptamine in producing these changes. 3. Measurement of the transport number of dopamine suggest that the relatively low potency of dopamine cannot be attributed to differences in ionic mobilities between the amines. 4. Electrophoretic application of alpha-flupenthixol was shown to discriminate between dopamine and 5-hydroxytryptamine responses. Dopamine responses were profoundly reduced. 5. Electrophoretically applied alpha-flupenthixol also discriminated between dopamine and noradrenaline. Noradrenaline responses were consistently potentiated by alpha-flupenthixol. The possibility is discussed that dopamine may not merely be a precursor for noradrenaline in the rat spinal cord.

The value of anaesthesia training in the first two postgraduate years

The value of an anaesthetic attachment during the first two postgraduate years is considered under three major headings, the value to the recent graduate, the value to the specialty, and the value to the community. The anaesthetic attachment offers all recent graduates an opportunity to perfect practical skills which should from part of the armamentarium of all doctors, and for some there is the option to acquire the ability to administer a safe anaesthetic. Exposure to the specialty at this time is important for recruitment to the specialist ranks.

Constant negative pressure: an adjunct in the treatment of gastroschisis

Three cases of gastroschisis are described, managed surgically in the neonatal period by staged reduction employing a dacron reinforced silastic sac. All three cases were treated during the postoperative period with the application of constant negative pressure around the thorax and abdomen. Reduction of the eviscerated mass appeared to be accelerated and all three cases survived. The possible benefits of constant negative pressure around the thorax and abdomen in the treatment of gastroschisis are discussed.