Angiogenin protects motoneurons against hypoxic injury

Cells can adapt to hypoxia through the activation of hypoxia-inducible factor-1 (HIF-1), which in turn regulates the expression of hypoxia-responsive genes. Defects in hypoxic signaling have been suggested to underlie the degeneration of motoneurons in amyotrophic lateral sclerosis (ALS). We have recently identified mutations in the hypoxia-responsive gene, angiogenin (ANG), in ALS patients, and have shown that ANG is constitutively expressed in motoneurons. Here, we show that HIF-1alpha is sufficient and required to activate ANG in cultured motoneurons exposed to hypoxia, although ANG expression does not change in a transgenic ALS mouse model or in sporadic ALS patients. Administration of recombinant ANG or expression of wild-type ANG protected motoneurons against hypoxic injury, whereas gene silencing of ang1 significantly increased hypoxia-induced cell death. The previously reported ALS-associated ANG mutations (Q12L, K17I, R31K, C39W, K40I, I46V) all showed a reduced neuroprotective activity against hypoxic injury. Our data show that ANG plays an important role in endogenous protective pathways of motoneurons exposed to hypoxia, and suggest that loss of function rather than loss of expression of ANG is associated with ALS.

Smoking and patterns of bone loss in early-onset periodontitis

BACKGROUND

The aims of this study were to investigate the extent and distribution of bone loss in subjects with early-onset periodontitis (EOP) referred for periodontal care and to study the relationship between smoking and EOP.

METHODS

A total of 71 consecutive referrals (21 male, 50 female) under 35 years old, who were otherwise healthy, with a clinical diagnosis of severe periodontitis were recruited for the study. Bone loss was measured from available radiographs using a Schei ruler to identify 2 patterns of destruction: localized (LEOP) in 41 (58%) and generalized early-onset periodontitis (GEOP) in 30 (42%) subjects.

RESULTS

The study population had a mean of 25.0 (SD 2.4) teeth, excluding third molars, and mean bone loss of 28.7% (SD 13.0). Bone loss was more severe in the maxilla, 30.9% (SD 13.8) compared with 26.6% (SD 14.0) in the lower arch. More than one-third (36%) of the teeth examined had at least 30% bone loss. Mean smoking experience was 9.2 pack years (SD 5.6), and 39 (55%) of the EOP subjects smoked. Smokers had significantly more maxillary bone loss than non-smokers. A much higher proportion of GEOP (70%) currently smoked compared with 44% of LEOP, P = 0.029.

CONCLUSIONS

It is concluded that young adults with early-onset forms of periodontitis often have advanced periodontal destruction before they are referred for specialist care. In addition, there was a relationship between smoking and severe bone destruction in subjects with EOP, particularly those with generalized disease.