Internal dosimetry of 210Pb in the human cranium: preliminary results from instrumentation needs for in vivo counting in a low-background underground counting facility.

Internal dosimetry of (210)Pb in the cranium deals with the determination of the amount of energy deposited in tissue by (210)Pb radiations within the cranium. (210)Pb in the human cranium was monitored by in vivo counting in a low background facility 640 m (2100 ft) underground with a germanium (Ge) gamma-ray detector having a beryllium window. The minimum detectable activity (MDA) was established with this system to be 0.2 Bq (5 pCi) in 25-h counting time with a 15-mm diameter and 7-mm thick Ge detector, having a beryllium window of thickness of 0.08 mm, in contact with the cranium just above the ear adjacent to the temple region. To establish an MDA of 0.004 Bq (0.1 pCi) with this system, the limitation arising from the ambient radon level at 10 Bq m(-3) was investigated.

Seasonality of 214Bi activity in the human body and of 222Rn concentration in home ambient air.

We studied the seasonal variation of the environmental radon progeny (214)Bi activity in the whole bodies (WB) of women and men participating in community-based studies at the Grand Forks Human Nutrition Research Center (GFHNRC), the (214)Bi background activity of the GFHNRC whole body counter (WBC) steel room, and ambient air (222)Rn concentration in the homes of Grand Forks residents, over the 1988-2004 time period. In this cross-sectional epidemiological study, (214)Bi activity in women and men, in the WBC steel room, and (222)Rn concentration in resident homes fluctuated such that the highest values were observed in winter and the lowest in summer, respectively. (214)Bi activity in the WB of human subjects was higher in women who have more (214)Bi activity per unit mass than men. Apart from their common seasonal pattern, human WB (214)Bi activity (lnBq) was comparatively higher than that for the ambient air (222)Rn activity in a human-equivalent volume of 72 L.

Natural distribution of environmental radon daughters in the different brain areas of an Alzheimer disease victim.

BACKGROUND: Radon is a ubiquitous noble gas in the environment and a primary source of harmful radiation exposure for humans; it decays in a cascade of daughters (RAD) by releasing the cell damaging high energy alpha particles. RESULTS: We studied natural distribution of RAD 210Po and 210Bi in the different parts of the postmortem brain of 86-year-old woman who had suffered from Alzheimer's disease (AD). A distinct brain map emerged, since RAD distribution was different among the analyzed brain areas. The highest RAD irradiation (mSv x year(-1)) occurred in the decreasing order of magnitude: amygdala (Amy) >> hippocampus (Hip) > temporal lobe (Tem) approximately = frontal lobe (Fro) > occipital lobe (Occ) approximately = parietal lobe (Par) > substantia nigra (SN) >> locus ceruleus (LC) approximately = nucleus basalis (NB); generally more RAD accumulated in the proteins than lipids of gray and white (gray > white) brain matter. Amy and Hip are particularly vulnerable brain structure targets to significant RAD internal radiation damage in AD (5.98 and 1.82 mSv x year(-1), respectively). Next, naturally occurring RAD radiation for Tem and Fro, then Occ and Par, and SN was an order of magnitude higher than that in LC and NB; the later was within RAD we observed previously in the healthy control brains. CONCLUSION: Naturally occurring environmental RAD exposure may dramatically enhance AD deterioration by selectively targeting brain areas of emotions (Amy) and memory (Hip).

Controlled substitution of soy protein for meat protein: effects on calcium retention, bone, and cardiovascular health indices in postmenopausal women.

In a controlled feeding study, the effects of substituting 25 g soy protein for meat on calcium retention and bone biomarkers were determined. Postmenopausal women (n = 13) ate two diets that were similar, except that, in one diet, 25 g high-isoflavone soy protein (SOY) was substituted for an equivalent amount of meat protein (control diet), for 7 wk each in a randomized crossover design. After 3 wk of equilibration, calcium retention was measured by labeling the 2-d menu with (47)Ca, followed by whole-body counting for 28 d. Urinary calcium and renal acid excretion were measured at wk 3, 5, and 7. Biomarkers of bone and cardiovascular health were measured at the beginning and end of each diet. Calcium was similarly retained during the control and SOY diets (d 28, percent dose, mean +/- pooled sd: 14.1 and 14.0 +/- 1.6, respectively). Despite a 15-20% lower renal acid excretion during the SOY diet, urinary calcium loss was unaffected by diet. Diet also did not affect any of the indicators of bone or cardiovascular health. Substitution of 25 g high isoflavone soy protein for meat, in the presence of typical calcium intakes, did not improve or impair calcium retention or indicators of bone and cardiovascular health in postmenopausal women.

Controlled high meat diets do not affect calcium retention or indices of bone status in healthy postmenopausal women.

Calcium balance is decreased by an increased intake of purified proteins, although the effects of common dietary sources of protein (like meat) on calcium economy remain controversial. We compared the effects of several weeks of controlled high and low meat diets on body calcium retention, using sensitive radiotracer and whole body scintillation counting methodology. Healthy postmenopausal women (n = 15) consumed diets with similar calcium content (approximately 600 mg), but either low or high in meat (12 vs. 20% of energy as protein) for 8 wk each, in a randomized crossover design. After 4 wk of equilibration of each diet, calcium retention was measured by extrinsically labeling the 2-d menu with (47)Ca, followed by whole body scintillation counting for 28 d. Urinary and blood indicators of bone metabolism were also determined for each diet. Calcium retention was not different during the high and low meat dietary periods (d 28, mean +/- pooled SD: 17.1 and 15.6%, +/-0.6%, respectively; P = 0.09). An initially higher renal acid excretion in subjects consuming the high meat compared with the low meat diet decreased significantly with time. The diets did not affect urinary calcium loss or indicators of bone metabolism. In conclusion, under controlled conditions, a high meat compared with a low meat diet for 8 wk did not affect calcium retention or biomarkers of bone metabolism in healthy postmenopausal women. Calcium retention is not reduced when subjects consume a high protein diet from common dietary sources such as meat.

Association of dominant somatotype of men with body structure, function during exercise, and nutritional assessment.

This study examined the hypothesis that somatotype determines body structure, functional responses at peak exercise, and nutritional status of 63 men ages 18-40 years who lived under controlled conditions. Data were grouped by dominant somatotype to emphasize differences in body types. Dominant ectomorphs (n = 19) had less (P < 0.05) body weight, fat weight, and percent body fat than endomorphs (n = 14) and mesomorphs (n = 30). Fat-free weight (FFW), total body potassium (TBK), and body cell mass (BCM), normalized for stature, were lower (P < 0.05) in the ectomorphs than in the endomorphs and mesomorphs. Comparisons between measured and predicted FFW and TBK showed that only the ectomorphs had less (P < 0.05) FFW and TBK than expected. Although all groups had the same peak power output, the ectomorphs had different functional responses during peak exercise. Ectomorphs had the greatest respiratory exchange ratio (P < 0.05), ventilatory equivalent for oxygen, and end-exercise plasma lactate concentrations (P < 0.05), and lowest peak oxygen uptake (L/min; P < 0.05). Nutrient intakes and blood biochemical markers of nutritional status were within the range of normal values in all groups. Correlations between measures of body structure, function, and nutritional status and dominant somatotype components were calculated after controlling for the effects of the other two somatotype components. Partial correlations were variable, with significant correlations ranging from -0.30 to 0.87. These data indicate that ectomorphs, as compared to endomorphs and mesomorphs, have deficits in FFW and BCM which are associated with differences in functional capacity. Am. J. Hum. Biol. 12:167-180, 2000. Published 2000 Wiley-Liss, Inc.