In the present study, we show a biphasic activation of hypoxia inducible factor 1␣ (HIF-1) after stroke that lasts for up to 10 d, suggesting the involvement of the HIF pathway in several aspects of the pathophysiology of cerebral ischemia. We provide evidence that HIF-1-mediated responses have an overall beneficial role in the ischemic brain as indicated by increased tissue damage and reduced survival rate of mice with neuron-specific knockdown of HIF-1␣ that were subjected to transient focal cerebral ischemia. In addition, we demonstrated that drugs known to activate HIF-1 in cultured cells as well as in vivo had neuroprotective properties in this model of cerebral ischemia. This protective effect was significantly attenuated but not completely abolished in neuron-specific HIF-1␣-deficient mice, suggesting that alternative mechanisms of neuroprotection are also implicated. Last, our study showed that hypoxia-induced tolerance to ischemia was preserved in neuron-specific HIF-1␣-deficient mice, indicating that the neuroprotective effects of hypoxic preconditioning do not depend on neuronal HIF-1 activation.

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The clinical response to donepezil in patients with mild and moderate dementia was investigated in relation to the drug plasma concentration and APOE and CYP2D6 polymorphisms. In a prospective naturalistic observational study, 42 patients with Alzheimer's disease (AD) and AD with cerebrovascular disease who took donepezil (10 mg) for 12 months were evaluated. Their DNA was genotyped, and the donepezil plasma concentrations were measured after 3, 6, and 12 months. Good responders scored ≥-1 on the Mini-Mental State Examination at 12 months in comparison to the baseline score. The study results indicated the good response pattern was influenced by the concentration of donepezil, but not by APOE and CYP2D6 polymorphisms.

Alzheimer's disease (AD) is characterized by impairment in memory and autonomy, causing excessive pressure on family and an overburdened health care system. Early diagnosis, with the appropriate treatment, is important to reduce the pattern of disease progression.ObjectiveThe study sought to identify the most probable causes of delay in diagnosis.MethodsA cross-sectional study involving AD patients followed at an Outpatient Geriatric Clinic from a tertiary public university hospital was conducted between June 2009 and February 2011.ResultsNinety-four patients were evaluated (66% women), aged 77.76±6.8 years and with median educational level of 3 years (95% CI 2.7-3.80). Regarding severity of dementia, 51.8% of patients were classified as having mild dementia (CDR 1), 40% moderate dementia (CDR 2) and 8.2% severe dementia (CDR 3). Mean educational level of caregivers was 8.3±3.9 years. Among those who believed there was a delay, 36% stated that the "family thought that the changes were normal for the age of the patient" reporting average delay of 1.8 years (95% CI: 1.3-2.5) while 45.3% stated that the "doctor did not reach a diagnosis" reporting a median delay of 1.5 years (95% CI: 1.4-2.3).ConclusionBased on these results, it can be concluded the time between onset of symptoms and diagnosis was excessive. This study may be useful to help increase awareness of issues not sufficiently discussed in the literature, such as diagnostic delay and influence of caregivers' educational level on treatment.

The influence of mitochondrial activity on gene expression programs, particularly those involved in neuroprotection and repair, is likely to play an important role in the pathophysiology of neurodegenerative diseases. One such gene expression program is activated by the cellular pathway that senses a decrease in optimal oxygen levels and leads to activation of a family of transcriptional activators called hypoxia-inducible factors (HIFs). HIFs are members of the bHLH-PAS family of transcription factors and are heterodimers composed of HIF-alpha and HIF-beta (also known as aryl hydrocarbon receptor nuclear translocator) subunits that bind to canonical DNA sequences (hypoxia-regulated elements) in the promoters or enhancers of target genes. HIFs activate the expression of more than a hundred genes encoding proteins that regulate cell metabolism, survival, angiogenesis, vascular tone, hematopoiesis, and other functions. There is considerable evidence showing a bidirectional crosstalk between mitochondrial signals and HIF activity. For instance, mitochondrial reactive oxygen species and metabolic substrates from the tricarboxylic acid cycle are implicated in the regulation of the HIF pathway. Conversely, HIF activity leads to the expression of target genes that influence mitochondrial function. In this chapter we will review the complex interactions between mitochondria and the HIF pathway and we will discuss the relevance of this interaction for metabolic adaptation to hypoxia.