Recent research suggests that LKB1 is the major AMP-activated protein kinase kinase (AMPKK). Peroxisome-proliferator-activated receptor-␥ coactivator-1␣ (PGC-1␣) is a master coordinator of mitochondrial biogenesis. Previously we reported that skeletal muscle LKB1 protein increases with endurance training. The purpose of this study was to determine whether training-induced increases in skeletal muscle LKB1 and PGC-1␣ protein exhibit a time course and intensity-dependent response similar to that of citrate synthase. Male Sprague-Dawley rats completed endurance-and interval-training protocols. For endurance training, rats trained for 4, 11, 25, or 53 days. Interval-training rats trained identically to endurance-trained rats, except that after 25 days interval training was combined with endurance training. Time course data were collected from endurance-trained red quadriceps (RQ) after each time point. Interval training data were collected from soleus, RQ, and white quadriceps (WQ) muscle after 53 days only. Mouse protein 25 (MO25) and PGC-1␣ protein increased significantly after 4 days. Increased citrate synthase activity, increased LKB1 protein, and decreased AMPKK activity were found after 11 days. Maximal increases occurred after 4 days for hexokinase II, 25 days for MO25, and 53 days for citrate synthase, LKB1, and PGC-1␣. In WQ, but not RQ or soleus, interval training had an additive effect to endurance training and induced significant increases in all proteins measured. These results demonstrate that LKB1 and PGC-1␣ protein abundances increase with endurance and interval training similarly to citrate synthase. The increase in LKB1 and PGC-1␣ with endurance and interval training may function to maintain the traininginduced increases in mitochondrial mass. adenosine 5Ј-monophosphate-activated protein kinase, AMP-activated protein kinase kinase; diabetes; MO25, Ste-20-related adaptor protein THE INCIDENCE OF TYPE 2 DIABETES and obesity is increasing at an alarming rate. As of 2002, 8.7% of Americans over age 20 yr and 18.3% of Americans over age 60 yr were diabetic (1). Type 2 diabetes is strongly associated with obesity and is characterized primarily by a reduction in insulin-stimulated glucose uptake. Type 2 diabetes is often accompanied by a decreased skeletal muscle mitochondrial content and a higher-than-normal proportion of type IIx (IIb) muscle fibers (9,24,31,37,48). Regular exercise prevents type 2 diabetes directly by increasing insulin sensitivity and indirectly by decreasing adiposity. Physical activity also increases skeletal muscle mitochondrial mass and induces an increased expression of type IIa myosin heavy chain (MHC) and a decreased expression of type IIx (IIb) MHC (40). Training intensity regulates fiber typespecific training adaptations (2, 57). Higher-intensity training is required for the maximal recruitment and training of type IIx (IIb) fibers (16,46). Hence, interval training might be particularly important for type 2 diabetics.Research during the past decade has characterized some of t...

Objectives-To investigate psychological correlates of exercise dependence in experienced and inexperienced bodybuilders and weightlifters. Secondary objectives included measuring social physique anxiety, bodybuilding identity, and social support among bodybuilders and weightlifters. Methods-Thirty five experienced bodybuilders, 31 inexperienced bodybuilders, and 23 weightlifters completed the bodybuilding dependence scale, a bodybuilding version of the athletic identity measurement scale, the social physique anxiety scale, and an adapted version of the social support survey-clinical form. Results-A between subjects multivariate analysis of variance was calculated on the scores of the three groups of lifters for the four questionnaires. Univariate F tests and follow up tests indicated that experienced bodybuilders scored significantly higher than inexperienced bodybuilders and weightlifters on bodybuilding dependence (p<0.001), social identity and exclusivity subscales of bodybuilding identity (p<0.001), and social support scales (p<.001), and significantly lower on social physique anxiety (p<0.001). Conclusion-Experienced bodybuilders exhibit more exercise dependence, show greater social support behaviour, and experience less social physique anxiety than inexperienced bodybuilders and weightlifters. (Br J Sports Med 2000;34:431-435)

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A model, which employs the use of high precision stable lead isotopic analyses, has been developed to estimate the age of hydrocarbon releases. The ALAS Model (Anthropogenic Lead ArchaeoStratigraphy) is based on calibrated, systematic increases in lead isotope ratios of gasolines caused by shifts in sources of lead ores used by the U.S. lead industry, including manufacturers of alkylleads, to more radiogenic Mississippi Valley Type (MVT) deposits. Acquisition of high quality samples ( free product, gasoline-impacted soil and groundwater) of known age and subsequent analyses of the hydrocarbon component by high precision lead isotopic analyses by thermal ionization mass spectrometry (TIMS) have produced the ALAS Model calibration curve. Age uncertainties range from + 1 to 2 years for gasoline releases which occurred between 1965 and 1990, the major era of leaded gasoline usage. Analytical methods required to measure lead isotope ratios on $5 nanograms of lead with precisions and accuracy of 5 + 0.1% (2 SEM ) are discussed in detail. Published lead isotopic measurements of gasoline-derived anthropogenic lead of samples throughout the United States are used to demonstrate the wide geographic range over which the ALAS Model may be applied. Two representative case studies involving an early 1970s free product release in California and the discrimination of a 1970s from modern unleaded gasoline release in Florida demonstrate the use of the model on single and multiple hydrocarbon releases, respectively, in dierent geographic regions of the United States. A third investigation focuses on the use of lead isotopes to correlate dissolved phase hydrocarbons with their source, in this case, unleaded (aka low lead) gasoline releases in New Jersey. Dissolved phase hydrocarbons (BTEX/MTBE) are shown to carry the lead isotopic signature of the unleaded gasoline into groundwater, allowing the speci®c source of the release to be identi®ed. Investigations of lead isotopes as tracers of MTBE in groundwater are ongoing. However, both laboratory and ®eld data indicate MTBE carries the lead isotopic signature of its unleaded gasoline source into groundwater, demonstrating the potential of the lead isotopic system as a discriminant of MTBE sources. Although developed to estimate the age of leaded gasoline releases, the ALAS Model has been successfully applied in studies requiring age dating of jet-A, diesel, kerosene, motor oil, and heating oil. These petroleum distillates are suspected of accidentally acquiring small, yet signi®cant quantities of alkylleads during re®ning, allowing accurate ALAS Model ages to be determined. When lead levels in these petroleum distillates are within their normal range, typically tens to hundreds of ppb lead, it is possible to use lead isotopic ratios to correlate environmental releases of these products to their source or other releases.# 2000 AEHS

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