Meta-analysis of age and actigraphy-assessed sleep characteristics across the lifespan

Study ObjectivesSleep quantity and continuity vary across the lifespan. Actigraphy is a reliable and widely used behavioral measure of sleep in research and personal health monitoring. This meta-analysis provides a novel examination of whether age (in years) is associated with actigraphy-assessed sleep across the lifespan.MethodsA systematic search of PubMed, Embase.com, Cochrane CENTRAL, and PsycINFO using “actigraphy” and “sleep” terms provided 7079 titles/abstracts; studies of individuals with known psychiatric or medical comorbidities were excluded. Ninety-one articles (N = 23 365) provided data for six meta-analyses examining sleep duration (k = 89), sleep efficiency (k = 58), bedtime (k = 19) and waketime (k = 9) for individuals ages 6–21, and bedtime (k = 7) and waketime (k = 7) for individuals ages 22 and older.ResultsAt older ages, sleep duration was shorter (r = −0.12) and sleep efficiency was lower (r = −0.05). Older age was associated with later bedtime (r = 0.37) and wake-up time (r = 0.24) from ages 6–21, whereas older age was associated with earlier bedtime (r = −0.66) and wake-up time (r = −0.59) for ages 22 and above. The strength of these associations was modified by study continent, but not by any other moderator.ConclusionsAge was negatively associated with actigraphy-assessed sleep duration and efficiency, but the effects were small in magnitude. On the other hand, large associations were observed between age and sleep timing, despite a smaller literature and the absence of analyzable data for ages 30–60. Changes in sleep timing, rather than changes in sleep duration or continuity, may better characterize the effects of age on human sleep.     

Cognitive Processing Speed Is Related to Fall Frequency in Older Adults With Multiple Sclerosis

Objective

To examine mobility, balance, fall risk, and cognition in older adults with multiple sclerosis (MS) as a function of fall frequency.

Design

Retrospective, cross-sectional design.

Setting

University research laboratory.

Participants

Community-dwelling persons with MS (N=27) aged between 50 and 75 years were divided into 2 groups—single-time (n=11) and recurrent (n=16; >2 falls/12 mo) fallers—on the basis of fall history.

Intervention

Not applicable.

Main Outcome Measures

Mobility was assessed using a variety of measures including Multiple Sclerosis Walking Scale-12, walking speed (Timed 25-Foot Walk test), endurance (6-Minute Walk test), and functional mobility (Timed Up and Go test). Balance was assessed with the Berg Balance Scale, posturography, and self-reported balance confidence. Fall risk was assessed with the Physiological Profile Assessment. Cognitive processing speed was quantified with the Symbol Digit Modalities Test and the Paced Auditory Serial Addition Test.

Results

Recurrent fallers had slower cognitive processing speed than single-time fallers (P≤.01). There was no difference in mobility, balance, or fall risk between recurrent and single-time fallers (P>.05).

Conclusions

Results indicated that cognitive processing speed is associated with fall frequency and may have implications for fall prevention strategies targeting recurrent fallers with MS.     

Short communication: no evidence of HTLV-3 and HTLV-4 infection in New York State subjects at risk for retroviral infection

The primate T-cell lymphoma viruses (PTLV) are divided into six distinct species. The biology and epidemiology of PTLV-1 and PTLV-2 are very well understood. However, that of PTLV-3, 4, 5, and 6 are not. Recently, in Cameroon, three and one humans were shown to be infected with HTLV-3 and HTLV-4, respectively. We undertook a study to ascertain whether any of these two retroviruses were present in the peripheral blood mononuclear cell DNA of New York State subjects deemed at risk for PTLV infection. Samples were analyzed by PTLV-3 and PTLV-4 specific PCR assays from the following human and simian subject types: African-American medical clinic patients; HTLV EIA+, WB indeterminate blood donors; intravenous drug users; patients with leukemia, lymphoma, myelopathy, polymyositis, or AIDS; and African chimpanzees. None of the 1200 subjects was positive for HTLV-3 or 4. The data indicate that, at the time of sample collection, no evidence exists for the dissemination of HTLV-3 or 4 to New York State. Continued epidemiological studies are warranted to explore the worldwide prevalence rates and dissemination patterns of HTLV-3 and 4 infections, and their possible disease associations.     

Explant culture: a simple,reproducible, efficient and economic technique for isolation of mesenchymal stromal cells from human adipose tissue and lipoaspirate

Adipose tissue has emerged as a preferred source of mesenchymal stem/stromal cells (MSC), due to its easy accessibility and high MSC content. The conventional method of isolation of adipose tissue‐derived stromal cells (ASC) involves enzymatic digestion and centrifugation, which is a costly and time‐consuming process. Mechanical stress during isolation, use of bacterial‐derived products and potential contamination with endotoxins and xenoantigens are other disadvantages of this method. In this study, we propose explant culture as a simple and efficient process to isolate ASC from human adipose tissue. This technique can be used to reproducibly isolate ASC from fat tissue obtained by liposuction as well as surgical resection, and yields an enriched ASC population free from contaminating haematopoietic cells. We show that explanting adipose tissue results in a substantially higher yield of ASC at P0 per gram of initial fat tissue processed, as compared to that obtained by enzymatic digestion. We demonstrate that ASC isolated by explant culture are phenotypically and functionally equivalent to those obtained by enzymatic digestion. Further, the explant‐derived ASC share the immune privileged status and immunosuppressive properties implicit to MSC, suggesting that they are competent to be tested and applied in allogeneic clinical settings. As explant culture is a simple, inexpensive and gentle method, it may be preferred over the enzymatic technique for obtaining adipose tissue‐derived stem/stromal cells for tissue engineering and regenerative medicine, especially in cases of limited starting material. Copyright © 2012 John Wiley & Sons, Ltd.     

Racial differences in prevalence and severity of non-alcoholic fatty liver disease

The aim of this review is to assess the evidence regarding racial differences in the prevalence and severity of nonalcoholic fatty liver disease(NAFLD). We reviewed the published literature that reported prevalence, severity, and genetic associations of NAFLD in different ethnic groups. The metabolic syndrome(MetS) has been associated with NAFLD, but each component of the MetS is present in various races in different percentages and their effect on NAFLD appears to be dissimilar. An elevated triglyceride(TG) level seems to have the strongest association with NAFLD. The latter is more prevalent in Hispanic patients; Blacks have lower TG levels and a lower NAFLD prevalence, compared to Caucasians or Hispanics. The severity of liver fibrosis is lower in some, but not all biopsy-based studies of Black patients. No study has evaluated the severity of liver disease controlling for the individual components of MetS, especially TG. Important racial differences in the prevalence of selected genetic polymorphisms, particularly PNPLA-3 and MBOAT7 have been documented, together with their effects on the prevalence of liver steatosis and fibrosis. Data on overall and liver mortality have found no significant differences according to race/ethnicity, with the possible exception of one paper reporting lower cirrhosis mortality in Black patients. We conclude that NAFLD is more prevalent in Hispanics and less in Blacks. This is supported by differences in key genetic polymorphisms associated with hepatic fat storage. However, there is presently insufficient evidence to firmly conclude that race, per se, plays a role in the development of liver fibrosis and its complications. Further studies, appropriately controlled for diet, exercise, and individual MetS parameters are needed.     

Protective effect of metformin against tuberculosis infections in diabetic patients: an observational study of south Indian tertiary healthcare facility

Background

World Health Organization estimated that people with diabetes (DM) are at 2–3 times higher risk for tuberculosis (TB). Studies have shown that DM not only increases the risk of active TB, but also puts co-affected persons at increased risk of poor outcomes.