Optical frequency conversion by a rotating molecular wave plate.

We demonstrate efficient four-wave mixing in low-pressure molecular deuterium without the need for phase matching. We use two laser fields with opposite circular polarizations to produce a strong excitation of a rovibrational transition at a frequency of 3167 cm(-1) . The coherent molecular motion, in turn, modulates a third laser field (also circularly polarized) and results in highly efficient single-sideband conversion.

Men who consume vegetable oils rich in monounsaturated fat: their dietary patterns and risk of prostate cancer (New Zealand).

OBJECTIVES: To investigate (i) dietary patterns associated with consumption of vegetable oils rich in monounsaturated fatty acids (MUFA), and (ii) the risk of prostate cancer associated with consumption of these oils. METHODS: A population-based case-control study was conducted in Auckland, New Zealand, involving 317 prostate cancer cases and 480 controls. A food-frequency questionnaire was used to collect data concerning consumption of MUFA-rich vegetable oils (including olive oil, canola or peanut oil) and other dietary variables. Biomarkers for fatty acids were measured in erythrocytes. RESULTS: The group of participants who reported regular consumption of greater than 5.5 ml of MUFA-rich vegetable oils per day had a diet relatively high in monounsaturated fat, vegetables, lycopene, vitamin E, selenium, and n-3 fish oils. Increasing levels of MUFA-rich vegetable oil intake were associated with a progressive reduction in prostate cancer risk (multivariate relative risk = 0.5; 95% confidence interval 0.3-0.9; > 5.5 ml per day vs. nonconsumption, p trend = 0.005), and similar trends were observed across all strata of socioeconomic status. Prostate cancer risk was not associated with intake of total MUFA or the major animal food sources of MUFA. CONCLUSION: This finding may be explained by the protective effect of an associated dietary pattern high in antioxidants and fish oils, an independent protective effect of MUFA-rich vegetable oils unrelated to the MUFA component, or a combination of these factors.

Prostate cancer and dietary carotenoids.

This population-based case-control study investigated associations between prostate cancer risk and dietary intake of the carotenoids beta-carotene and lycopene and their major plant food sources, including carrots, green leafy vegetables, and tomato-based foods. The study was carried out in Auckland, New Zealand, during 1996-1997 and recruited 317 prostate cancer cases and 480 controls. The authors found that dietary intake of beta-carotene and its main vegetable sources was largely unassociated with prostate cancer risk, whereas intake of lycopene and tomato-based foods was weakly associated with a reduced risk. These results suggest that in contrast to the findings regarding many types of cancers, vegetables rich in beta-carotene are not protective against prostate cancer. However, lycopene from tomato-based foods was found to be associated with a small reduction in risk.

Heterocyclic amine content of cooked meat and risk of prostate cancer.

BACKGROUND: Some epidemiologic studies have described positive associations between prostate cancer risk and meat consumption, but underlying mechanisms have not been identified. Heterocyclic amines are mutagens formed during the cooking of meat. Well-done meat has been associated with increased risks of colorectal and breast cancers in humans. This study examined associations between prostate cancer risk and 1) estimated daily intake of heterocyclic amines from cooked meat and 2) level of cooked-meat doneness. METHODS: A population-based, case-control study involving 317 case patients with prostate cancer and 480 age-matched control subjects was carried out in Auckland, New Zealand. Levels of meat doneness and daily intake of heterocyclic amines were determined from self-reported dietary data and experimentally measured heterocyclic amine levels in locally sourced meat samples cooked under controlled conditions to varying degrees of doneness. RESULTS: The heterocyclic amines found in the highest concentrations in meat samples were 2-amino-1,6-dimethylfuro[3,2-e]imidazo[4,5-b]pyridine (IFP) and 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) from well-done chicken and pork and very well-done beefsteak. Meat doneness was weakly and inconsistently associated with prostate cancer risk for individual types of meat, but increased risk was observed for well-done beefsteak (relative risk = 1.68; 95% confidence interval = 1.02-2.77; two-sided P for trend =.03). A weak positive gradient of increased risk was associated with estimated daily exposure to IFP but not with the other major heterocyclic amines. CONCLUSIONS: Meat doneness and estimated intake of heterocyclic amines from cooked meat were not clearly associated with prostate cancer risk.

Prostate cancer risk and consumption of fish oils: a dietary biomarker-based case-control study.

Experimental studies suggest that the risk of prostate cancer is reduced with the intake of long-chain n-3 polyunsaturated fatty acids derived from marine foods, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, few human studies have been conducted due to difficulties in assessing the dietary intake of these fatty acids. The authors examined the relationship between prostate cancer risk and EPA and DHA in erythrocyte biomarkers in a population-based case-control study in Auckland, New Zealand during 1996-1997 involving 317 prostate cancer cases and 480 age-matched community controls. Reduced prostate cancer risk was associated with high erythrocyte phosphatidylcholine levels of EPA (multivariate relative risk = 0.59; 95% confidence interval 0.37-0.95, upper vs lowest quartile) and DHA (multivariate relative risk = 0.62; 95% confidence interval 0.39-0.98, upper vs lowest quartile). These analyses support evidence from in vitro experiments for a reduced risk of prostate cancer associated with dietary fish oils, possibly acting via inhibition of arachidonic acid-derived eicosanoid biosynthesis.

The impact of modernisation on the diets of adults aged 20-40 years from Samoan church communities in Auckland.

The objective of this study was to describe the food and nutrient intakes of adults in three Samoan church communities located in Auckland, New Zealand. The study had a cross-sectional design and measured usual dietary intake in 437 participants, aged 20 years and over, using a self-completed, 89-item quantitative food frequency questionnaire. Median daily energy and nutrient intakes were calculated and compared by gender and age groups. Men obtained a significantly (p < 0.05) lower proportion of their energy from breads and cereals, fruits and vegetables and fats and oils than women. Compared to those aged 40+ years, those aged < 40 obtained a significantly (p < 0.01) lower proportion of their energy from meat, pulses and eggs, fruit and vegetables, and starchy staples. A significantly (p < 0.01) higher proportion of their energy intake came from takeaways, soft drinks, snacks and dairy products. Nutrient analysis revealed that those aged < 40 years obtained significantly (p < 0.001) more energy from fat and sugar, and less energy from protein (p < 0.001) than the older group. They also had significantly lower intakes, per 1000 kilocalories, of a wide selection of vitamins and minerals. A dietary transition has occurred for New Zealand Samoans, reflecting a shift from traditional to modern dietary patterns and a decline in the nutritional quality of the diet.

Efficient gas-phase generation of coherent vacuum ultraviolet radiation.

We report the demonstration of a pulsed atomic lead (Pb) vapor-based vacuum ultraviolet frequency converter from 233 to 186 nm with unity photon-conversion efficiency. This conversion is attained without phase matching.

Measuring the dietary intake of Samoans living in New Zealand: Comparison of a food frequency questionnaire and a 7 day diet record.

The purpose of this study was to determine the accuracy of a quantitative food frequency questionnaire for measuring the usual dietary intake of Samoans living in New Zealand. We compared a self-administered 89 item quantitative food frequency questionnaire (FFQ) with a 7 day diet record (DR) in a sample of 55 Samoan adults aged 20 years and over. The FFQ asked people to report their dietary intake in frequency and amount and included photos of standard serving sizes. The DR was collected over non-consecutive three and four day periods, including two weekend days. Food weighing scales and measuring cups and spoons were provided to measure food portions. Correlations between the two methods were poor for both crude (range -0.03-0.48) and energy-adjusted (range -0.12-0.54) nutrient intakes. Approximately 29-53% of people fell into the same tertile when classified by the two methods and 9-22% of subjects were grossly misclassified into opposite tertiles. Agreement was also poor when the differences in energy, fat, protein and carbohydrate intake between the methods were plotted against mean intake. Relative to an estimate of energy expenditure, both methods underestimated usual energy intake; however, underestimation occurred to a greater extent with the DR. We conclude that agreement between the two dietary assessment methods was poor and we were unable to use the DR to calibrate the FFQ. In terms of total energy, the FFQ gave a better assessment of usual dietary intake than did the DR.

Regional topography of rod and immunocytochemically characterized "blue" and "green" cone photoreceptors in rabbit retina.

Evidence from several sources indicates that the photoreceptors of rabbit retina include rods, green cones and blue cones, and that blue-green color opponency occurs in select retinal ganglion cells. One of us (Famiglietti) has identified wide-field cone bipolar cells as probable blue-cone-selective bipolars, and type C horizontal cells as possibly connected to blue cones. We wished to extend the analysis of blue cone pathways in rabbit retina and to characterize the topographic distribution of blue and green cones. Two monoclonal antibodies raised against chicken visual pigments are reported to label medium- and long-wavelength cones (COS-1) and short-wavelength cones (OS-2) in all mammalian retinas studied thus far (Szél and colleagues). Using selective labeling with these two antibodies and a nonselective method in nasal and temporal halves of the same retinas, we have found that densities of photoreceptors vary systematically, depending upon the size of the eye and age of the animal. In 'standard' New Zealand rabbits of 2-3 kg (2-3 months old), rods reached a peak density of about 300,000/mm2 just dorsal to the visual streak, while cones exhibit peak density at mid-visual streak of about 18,000/mm2. Published measurements of visual acuity in rabbit are less than predicted by this calculation. The ratio of cones to rods is significantly higher in ventral retina, where the density of cones declines to a plateau of 10,000-12,000/mm2, when compared to dorsal retina, where cones are uniformly distributed at a density of about 7000/mm2. The density of OS-2 labeled (presumably "blue") cones is uniformly low, 1000-1500/mm2, in a wide expanse that includes dorsal retina, the visual streak, and much of ventral retina, except for a region of higher density along the vertical midline. We confirm that there is a far ventral horizontal region near the perimeter that is populated exclusively by a high density (about 13,000/mm2) of OS-2-positive cones (Juliusson and colleagues). This region does not extend to the ventral retinal margin, however, where cone density drops precipitously. Transitional zones between COS-1 and OS-2 labeling, in a region of relatively high and uniform cone density, where sums of COS-1 and OS-2 labeling are higher than expected and in which weakly and strongly labeled cones are intermixed, raise questions about the identities of the visual pigment epitopes, the possibility of double labeling, and therefore the possibility of dual expression of pigments in single cones. The "inverted-T-shaped" topography of higher density OS-2 labeling raises doubts about the significance of a ventral concentration of blue cones for visual function in rabbit retina.

Long-term effects of calcium supplementation on bone loss and fractures in postmenopausal women: a randomized controlled trial.

PURPOSE: To determine the long-term effects of calcium supplements or placebo on bone density in healthy women at least 3 years postmenopause. PATIENTS AND METHODS: Eighty-six women from our previously reported 2-year study agreed to continue on their double-blind treatment allocation (1 g elemental calcium or placebo) for a further 2 years, with 78 women (40 on placebo) reaching the 4-year end point. Median (interquartile range) dietary calcium intakes for the whole group were 700 mg (range 540 to 910) per day at baseline, 670 mg (range 480 to 890) per day at 2 years, and 640 mg (range 460 to 880) per day at 4 years. The bone mineral density (BMD) of the total body, lumbar spine, and proximal femur was measured every 6 months by dual-energy, x-ray absorptiometry. RESULTS: There was a sustained reduction in the rate of loss of total body BMD in the calcium group throughout the 4-year study period (P = 0.002), and bone loss was significantly less in the calcium-treated subjects in years 2 through 4 also (difference between groups 0.25% +/- 0.11% per year, P = 0.02). In the lumbar spine, bone loss was reduced in the calcium group in year 1 (P = 0.004), but not subsequently. There was, however, a significant treatment effect at this site over the whole 4-year period (P = 0.03). In the proximal femur, the benefit from calcium treatment also tended to be greater in the first year and was significant over the 4-year study period in the femoral neck (P = 0.03) and the trochanter (P = 0.01). Nine symptomatic fractures occurred in 7 subjects in the placebo group and 2 fractures in 2 subjects receiving calcium (P = 0.037). CONCLUSIONS: Calcium supplementation produces a sustained reduction in the rate of loss of total body BMD in healthy postmenopausal women.

Determinants of the rate of bone loss in normal postmenopausal women.

Despite a large number of studies assessing relationships between putative risk factors and bone density, it is not known which factors influence the rate of axial bone loss in normal postmenopausal women. We have examined the relationships between the rate of bone loss (delta BMD) and variables related to calcium metabolism, lifestyle, diet (calcium, sodium, caffeine, and protein), body composition, muscle strength, sex hormones, and spinal osteophytosis in 122 normal postmenopausal women participating in a 2-yr prospective randomized placebo-controlled trial of calcium supplementation. Univariate correlation coefficients indicated that delta BMD at most sites was inversely related to baseline BMD and positively related to rate of change in body weight (0.10 < r < 0.36) and fat mass (0.11 < r < 0.42) during the study. Lean mass and its rate of change showed no consistent relationship to delta BMD. There was no correlation between delta BMD and any of the lifestyle, muscle strength, dietary, or hormonal indices or with the severity of spinal osteophytosis. Multiple regression analysis indicated that delta BMD in the total body was directly related to fat mass (P < 0.0001), the rate of change in fat mass (P < 0.0001), the renal tubular reabsorption of calcium (P < 0.01), and calcium treatment (P < 0.01) and inversely to the initial BMD (P < 0.0001; r2 = 0.42; P < 0.0001). Similar effects were seen throughout the skeleton, although the fraction of the variance accounted for was less in the subregions, consistent with the lower precision of measurement of regional bone density. It is concluded that baseline bone density, fat mass, and renal calcium handling are important factors influencing bone loss in normal postmenopausal women.

Cholesterol-lowering and blood pressure effects of immune milk.

The plasma cholesterol-lowering and blood pressure effects of a skim milk powder (immune milk) produced from dairy cows hyperimmunized with a multivalent bacterial vaccine were assessed in a double-blind crossover study of hypercholesterolemic subjects who consumed daily 90 g immune milk or a normal product. There was a significant reduction in plasma total and LDL cholesterol of 5.2% (95% CI 2.5, 7.9) and 7.4% (95% CI 4.1, 10.7), respectively, with 10 wk of immune milk consumption compared with control, but no change in HDL cholesterol or triglycerides. A significant systolic and diastolic blood pressure-lowering effect (5 and 4 mm Hg, respectively) was also demonstrated. Thus, immune milk may be a useful adjunct in the dietary management of hypercholesterolemia and the mechanisms of its cholesterol-lowering and blood pressure effects warrant further study.

Effect of calcium supplementation on bone loss in postmenopausal women.

BACKGROUND: The use of calcium supplements slows bone loss in the forearm and has a beneficial effect on the axial bone density of women in late menopause whose calcium intake is less than 400 mg per day. However, the effect of a calcium supplement of 1000 mg per day on the axial bone density of postmenopausal women with higher calcium intakes is not known. METHODS: We studied 122 normal women at least three years after they had reached menopause who had a mean dietary calcium intake of 750 mg per day. The women were randomly assigned to treatment with either calcium (1000 mg per day) or placebo for two years. The bone mineral density of the total body, lumbar spine, and proximal femur was measured every six months by dual-energy x-ray absorptiometry. Serum and urine indexes of calcium metabolism were measured at base line and after 3, 12, and 24 months. RESULTS: The mean (+/- SE) rate of loss of total-body bone mineral density was reduced by 43 percent in the calcium group (-0.0055 +/- 0.0010 g per square centimeter per year) as compared with the placebo group (-0.0097 +/- 0.0010 g per square centimeter per year, P = 0.005). The rate of loss of bone mineral density was reduced by 35 percent in the legs (P = 0.02), and loss was eliminated in the trunk (P = 0.04). Calcium use was of significant benefit in the lumbar spine (P = 0.04), and in Ward's triangle the rate of loss was reduced by 67 percent (P = 0.04). Calcium supplementation had a similar effect whether dietary calcium intake was above or below the mean value for the group. Serum parathyroid hormone concentrations tended to be lower in the calcium group, as were urinary hydroxyproline excretion and serum alkaline phosphatase concentrations. CONCLUSIONS: Calcium supplementation significantly slowed axial and appendicular bone loss in normal post-menopausal women.