Climate Change and the Outbreak Ranges of Two North American Bark Beetles

1- One expected effect of global climate change on insect populations is a shift in geographical distributions toward higher latitudes and higher elevations. Southern pine beetle Dendroctonus frontalis and mountain pine beetle Dendroctonus ponderosae undergo regional outbreaks that result in large-scale disturbances to pine forests in the south-eastern and western United States, respectively. 2- Our objective was to investigate potential range shifts under climate change of outbreak areas for both bark beetle species and the areas of occurrence of the forest types susceptible to them. 3- To project range changes, we used discriminant function models that incorporated climatic variables. Models to project bark beetle ranges employed changed forest distributions as well as changes in climatic variables. 4- Projected outbreak areas for southern pine beetle increased with higher temperatures and generally shifted northward, as did the distributions of the southern pine forests. 5- Projected outbreak areas for mountain pine beetle decreased with increasing temperature and shifted toward higher elevation. That trend was mirrored in the projected distributions of pine forests in the region of the western U.S. encompassed by the study. 6- Projected outbreak areas for the two bark beetle species and the area of occurrence of western pine forests increased with more precipitation and decreased with less precipitation, whereas the area of occurrence of southern pine forests decreased slightly with increasing precipitation. 7- Predicted shifts of outbreak ranges for both bark beetle species followed general expectations for the effects of global climate change and reflected the underlying long-term distributional shifts of their host forests

Fluoride therapy of type I osteoporosis.

Sodium Fluoride (NaF) is the only medication so far clinically available with a bone formation stimulating property, through its peculiar mitogenic dose-dependent action on the osteoblast cell line. Bone strength is commensurate to bone mass, and in a condition with fragility fractures, like osteoporosis, it seems logical to restore bone mass without weakening bone strength. However, as with any active drug. NaF therapy requires adhesion to elementary rules if drawbacks are to be prevented. A first mandatory rule is not to prescribe NaF without calcium supplementation, if bone loss at the appendicular skeleton is to be avoided; to prevent this, the availability of monofluorophosphate (MFP), containing the fluoride and calcium salts in the same preparation has enhanced the compliance to calcium supplementation. A second rule is not to give supraphysiological doses of vitamin D, for the same reason. Third, if one wants to avoid a calcium shift from cortical to trabecular bone and osteomalacia, one should use small doses of NaF, of the order of 50 mg/day. With this in mind, the bioavailability of the drug has to be taken into account, particularly its gastrointestinal absorption which is dramatically enhanced if a plain non entericoated (EC) capsule is used, as compared to that of an EC tablet with the same face value. Too much NaF is deleterious to bone, a fact known for years. Already in 1972, it was noted that in all patients receiving 60 mg or more of NEC NaF, daily, morphologically abnormal bone developed and which appeared irregular and contained areas of incompletely mineralized bone. The bone was histologically and microradiographically normal in patients receiving 45 mg or less of NEC NaF/day. Fourth, NaF therapy is contraindicated in renal insufficiency owing to an enhanced retention in the skeleton. NaF is, however, by no means the ideal medication, because its therapeutic window is narrow. It has many bothersome drawbacks, and notably it is irritating for the gastric mucosa, a hazard which may be partly circumvented by the use of an Ec or slow release tablet. Furthermore, peripheral stress fractures may occur, and, in our experience, they were seen in 17% of patients, almost exclusively in females with a low lumbar BMD. Their occurrence should be curtailed by not allowing an increase in alkaline phosphatase activity of more than 50%. This is a relatively benign complication, because no stress fracture degenerated into a complete fracture. In all cases, the stress fractures healed after a transitory drug discontinuation. If there is some concern about cortical bone, NaF therapy may be associated with an antiresorber like estrogens which will prevent any further bone loss, and does not impair the response to NaF. NaF therapy should be reserved for patients suffering chiefly from trabecular osteoporosis and should be avoided in senile osteoporosis, because of a frequently impaired renal function. Currently, we would recommend in clinical practice a daily dose of 50 mg EC-NaF or 150 mg Ca-MFP as the therapy of involutional osteoporosis in women, reserving the dose of 75 mg EC-NAF or 200 mg MFP for males or female patients resistant to lower dose. The therapy should be maintained for 2 to 3 years, or more, according to the bone response, taking into account that patients with the vertebral crush fracture syndrome have lost on average 30%, as compard to the young adult mean