We previously described a method for isolating murine hematopoietic stem cells capable of reconstituting lethally irradiated recipients, which depends solely on dual-wavelength flow cytometric analysis of murine bone marrow cells stained with the fluorescent DNA-binding dye Hoechst 33342. This method, which appears to rely on the differential ability of stem cells to efflux the Hoechst dye, defines an extremely small and homogeneous population of cells (termed SP cells). We show here that dual-wavelength analysis of Hoechst dye-stained human, rhesus and miniature swine bone marrow cells reveals a small, distinct population of cells that efflux the dye in a manner identical to murine SP cells. Like the murine SP cells, both human and rhesus SP cells are primarily CD34-negative and lineage marker-negative. In vitro culture studies demonstrated that rhesus SP cells are highly enriched for long-term culture-initiating cells (LTC-ICs), an indicator of primitive hematopoietic cells, and have the capacity for differentiation into T cells. Although rhesus SP cells do not initially possess any hematopoietic colony-forming capability, they acquire the ability to form colonies after long-term culture on bone marrow stroma, coincident with their conversion to a CD34-positive phenotype. These studies suggest the existence of a hitherto unrecognized population of hematopoietic stem cells that lack the CD34 surface marker classically associated with primitive hematopoietic cells.

To reduce the spread of COVID-19, the World Health Organization and the majority of governments have recommended that the entire human population should 'stay-at-home'. A significant proportion of the population live alone or are vulnerable to mental health problems yet, in the vast majority of cases, individuals in social isolation have no access to mental healthcare. The only resource is people themselves using self-help, self-medication and self-care. During prolonged COVID-19 isolation, an in-built system of homeostasis can help rebalance activity, thought and feeling. Increased physical activity enables a reset of physical and mental well-being. During periods of lockdown, it is recommended that exercise should be as vigorously promoted as social distancing itself.

No abstract

Health is regulated by homeostasis, a property of all living things. Homeostasis maintains equilibrium at set-points using feedback loops for optimum functioning of the organism. Imbalances in homeostasis causing overweight and obesity are evident in more than 1 billion people. In a new theory, homeostatic obesity imbalance is attributed to a hypothesized ‘Circle of Discontent’, a system of feedback loops linking weight gain, body dissatisfaction, negative affect and over-consumption. The Circle of Discontent theory is consistent with an extensive evidence base. A four-armed strategy to halt the obesity epidemic consists of (1) putting a stop to victim-blaming, stigma and discrimination; (2) devalorizing the thin-ideal; (3) reducing consumption of energy-dense, low-nutrient foods and drinks; and (4) improving access to plant-based diets. If fully implemented, interventions designed to restore homeostasis have the potential to halt the obesity epidemic.

This research has two purposes: (1) to study developmental changes and differences in visual and movement imagery in male and female children and adults; (2) to investigate whether systematic differences in imagery vividness can be measured in specialist groups. In Study 1, the Vividness of Visual Imagery Questionnaire and the Vividness of Movement Imagery Questionnaire were administered to 547 individuals in age groups from 7-8 to 50+ years of age. Significant increases in imagery vividness were found in females at 8-9 and in males at 10-11 years. In general females report more vivid imagery than males but at about 50 females' movement imagery reduced in vividness. In Studies 2-5 imagery differences in specialist groups were examined using the same two questionnaires with a total of 655 participants. In Study 2, children aged 7-15 years with poor movement control were found to be extremely poor imagers with 42 per cent reporting no imagery at all. In Study 3, physical education students reported more vivid imagery than students specializing in physics, English, and surveying. In Study 4, significant differences were found between elite athletes' imagery and that of matched controls. In Study 5, air traffic controllers and pilots were found to have significantly more vivid imagery than matched control groups. Introspective reports of imagery experience show a systematic pattern of relationships with age, gender, and specialization requiring high-level performance of perceptual motor skills. These findings support the theory that mental imagery plays a key role in the planning and implementation of action.