Changes in the concentration and relative abundance of alkanes and PAHs from the Deepwater Horizon oiling of coastal marshes.

We determined changes of 28 alkanes and 43 different PAHs in 418 wetland soil samples collected on ten sampling trips to three Louisiana estuaries before and after they were oiled from the 2010 Deepwater Horizon disaster. There was a significant decline in 22 of the 28 alkane analytes (0.42% day(-1)), no change in 6, over 2.5 years. The concentration of five aromatic petroleum hydrocarbons (PAHs) increased (range 0.25-0.70% day(-1)), whereas the total PAH pool did not change. Of these five, naphthalene and C-1-naphthalenes are suggested to be of higher toxicity than the other three because of their relatively higher volatility or solubility. The relative proportions of alkane analytes, but not PAHs, does not yet resemble that in the pre-oiled marshes after 3 years, The trajectories of nine indicators for degradation/weathering were either inconclusive or misleading (alkanes) or confirmed the relatively meager degradation of PAHs.

Changes in the structural properties of peripheral nerves after transection.

Changes in peripheral nerve structural properties after transection were measured weekly for 5 weeks in the distal stump of the sciatic nerve in 50 Sprague-Dawley rats. Each week after transection, the distal stump of the transected nerve showed increased stiffness when compared to intact nerves. Linear elastic stiffness reached a maximum at weeks 1 and 2 after transection, when the transected nerves were 15% stiffer than the contralateral control sides. Toughness was also increased and reached a maximum at week 4 with a 50% difference between values for experimental and control sides. Overall failure load was between 21% and 27% greater, peaking at week 3. An increase in stiffness of the distal stump would result in increased tension at the suture line, as the nerve gap is overcome when performing a delayed neurorraphy. These data suggest, with respect to structural properties, that an end-to-end repair should be carried out at the time of injury; after only 1 week, significant stiffness in the distal segment of the nerve developed, which should result in an increase in tension at the repair site.

Role of cholecystokinin in regulation of gastrointestinal motor functions.

By means of loxiglumide, a potent and highly specific antagonist for cholecystokinin (CCK), the effects of blocking CCK receptors on gastrointestinal motility were investigated in a placebo-controlled study in healthy young men (aged 21-39, mean 24 years). Gallbladder contraction stimulated by ingestion of a liquid test meal was completely abolished by oral administration of loxiglumide 30 min before the test meal. Gastric emptying of radio-opaque markers ingested with the test meal was significantly accelerated by loxiglumide (area under the curve [markers x h] 33.3 [SEM 3.8] vs 17.9 [2.7] after placebo). No effect of loxiglumide was found on small-bowel transit time, but 7 days' treatment with oral loxiglumide (800 mg three times daily) significantly shortened colonic transit time (29.4 [4.1] h after placebo, 15.0 [3.4] h after loxiglumide). It is concluded that CCK is an important mediator of meal-induced gallbladder contraction and is involved in the regulation of gastrointestinal motility in man.

Bentiromide test is not affected in patients with small bowel disease or liver disease.

The bentiromide test reliably detects exocrine pancreatic insufficiency. The synthetic peptide attached to p-aminobenzoic acid (PABA) is cleaved by chymotrypsin, PABA is absorbed in the small intestine, partially conjugated in the liver, and excreted in the urine. It has been claimed that the bentiromide test is abnormal not only in patients with pancreatic insufficiency but also in patients with small bowel or liver disease because of impaired PABA absorption or conjugation, respectively. This study prospectively evaluates the bentiromide test in 12 patients with small bowel disease and 18 patients with biopsy-proven liver disease. One of 30 patients had an abnormal bentiromide test. Cumulative 6-h urinary arylamine excretion and plasma PABA concentration, 2 h after administration, were in the same range as healthy controls. We conclude that the bentiromide test is not affected by small bowel or liver disease. An abnormal test is virtually diagnostic for exocrine pancreatic insufficiency.

Role of exercise in prevention of involutional bone loss.

Physical inactivity has been cited as a possible cause of osteoporosis. Because involutional bone loss in the female can begin as early as age 40, the purpose of this investigation was to compare the skeletal status of two groups of premenopausal middle-aged (30-49 yr) women of diverse physical activity levels. Bone mineralization was determined by x-ray densitometry (middle phalanx of fifth finger and os calcis) and photon absorptiometry (distal and midshaft radius) in 42 marathon runners and 38 sedentary females. Mean values for bone mineral content (BMC) and bone density were greater in the marathon runners at the midshaft radius (P less than 0.05) and at the middle phalanx of the fifth digit (P less than 0.001). Mean density of the os calcis was higher in the physically inactive women (P less than 0.001). Following normalization of the data for differences in age and body size, regression analysis suggests that the runners maintain their bone mass longer at the distal radius, a site frequently fractured in women after midlife.

The acute cardiac risk of strenuous exercise.

During a 65-month period, 2,935 adults (mean age, 37 years) kept computer logs of amount and intensity of exercise performed. A total of 374,798 person-hours of exercise, including 2,726,272 km or running and walking, was recorded. Two cardiac events and no deaths occurred during this period. Considered in age-specific categories, the maximum risk estimates (MREs) consistent with these data (upper 95% confidence limits) range from 0.3 to 2.7 events per 10,000 person-hours of exercise for men and 0.6 to 6.0 events per 10,000 person-hours for women. The MREs for women were higher because there were fewer women in the study. If exercise were performed three time per week for 30 minutes per session for a year, these results would lead to MREs from .002 to .027 events per person-year for men and .005 to .05 events per person-year for women. Actual risks are likely to be lower.