Outcomes for aging adults following total hip arthroplasty in an acute rehabilitation facility versus a subacute rehabilitation facility: a pilot study.

PURPOSE: The purpose of our study was to determine if aging adults who received rehabilitation following total hip arthroplasty (THA) due to osteoarthritis had better short-term outcomes in an Inpatient Rehabilitation Facility (IRF) compared with those currently receiving rehabilitation in subacute rehabilitation units. METHODS: Thirty-six adults, aged 65 to 88 years, who received inpatient rehabilitation following THA secondary to osteoarthritis participated in this study. A prospective descriptive study of 4 aging adults receiving rehabilitation in 2 subacute rehabilitation facilities and a retrospective descriptive study of 32 aging adults who received rehabilitation in an IRF were conducted. Socioeconomic, medical, rehabilitative care, and demographic data were obtained by review of participants' medical charts. FIM scores of the aging adults in the IRF were obtained by chart review, while FIM scores of the aging adults in the subacute facilities were collected by one of the investigators. RESULTS: In this sample, the aging adults in the IRF appeared to have greater changes in total FIM score, motor subscale FIM score, and self-care subscale FIM score than the aging adults in the subacute facilities. In this sample, discharge setting appeared similar for the aging adults in the two rehabilitation settings. CONCLUSIONS: It is imperative that further research determine if rehabilitation provided in different settings that offer different intensities and durations of rehabilitation affects functional outcomes for aging adults following THA procedures.

Astrocyte HIF-2α supports learning in a passive avoidance paradigm under hypoxic stress.

BACKGROUND: The brain is extensively vascularized, uses20% of the body's oxygen, and is highly sensitive to changes in oxygen. While synaptic plasticity and memory are impaired in healthy individuals by exposure to mild hypoxia, aged individuals appear to be even more sensitive. Aging is associated with progressive failure in pulmonary and cardiovascular systems, exposing the aged to both chronic and superimposed acute hypoxia. The HIF proteins, the "master regulators" of the cellular response to hypoxia, are robustly expressed in neurons and astrocytes. Astrocytes support neurons and synaptic plasticity via complex metabolic and trophic mechanisms. The activity of HIF proteins in the brain is diminished with aging, and the increased exposure to chronic and acute hypoxia with aging combined with diminished HIF activity may impair synaptic plasticity. PURPOSE: Herein, we test the hypothesis that astrocyte HIF supports synaptic plasticity and learning upon hypoxia. MATERIALS AND METHODS: An Astrocyte-specific HIF loss-of-function model was employed, where knock-out of HIF-1α or HIF-2α in GFAP expressing cells was accomplished by cre-mediated recombination. Animals were tested for behavioral (open field and rotarod), learning (passive avoidance paradigm), and electrophysiological (long term potentiation) responses to mild hypoxic challenge. RESULTS: In an astrocyte-specific HIF loss-of-function model followed by mild hypoxia, we identified that the depletion of HIF-2α resulted in an impaired passive avoidance learning performance. This was accompanied by an attenuated response to induction in long-term potentiation (LTP), suggesting that the hippocampal circuitry was perturbed upon hypoxic exposure following HIF-2α loss in astrocytes, and not due to hippocampal cell death. We investigated HIF-regulated trophic and metabolic target genes and found that they were not regulated by HIF-2α, suggesting that these specific targets may not be involved in mediating the phenotypes observed. CONCLUSION: Together, these results point to a role for HIF-2α in the astrocyte's regulatory role in synaptic plasticity and learning under hypoxia and suggest that even mild, acute hypoxic challenges can impair cognitive performance in the aged population who harbor impaired HIF function.