Validation of the use of exogenous gonadotropins (PG600) to increase the efficiency of gilt development programs without affecting lifetime productivity in the breeding herd.

The objective of this study was to validate the use of exogenous gonadotropin (PG600) treatment for stimulating estrus in noncyclic gilts and to compare lifetime productivity of gilts recorded as having natural (NAT) versus PG600-induced (PG600) first estrus in a commercial setting. Prepubertal Camborough gilts ( = 4,489) were delivered to a gilt development unit (GDU) with the goal of delivering known cyclic breeding-eligible females to the sow farm (SF). A boar exposure area (BEAR) was designed to facilitate stimulation and detection of puberty by providing fence line and direct contact (15 min daily) with mature boars over an intensive 28-d period, starting at approximately d 160 (d 0). At d 14, nonpubertal gilts were mixed in new pen groups. At d 23, noncyclic "opportunity" gilts with no record of vulval development and required to meet breeding targets, were eligible for treatment with PG600 to induce puberty. Overall, 77.6% ( = 3,475) of gilts exhibited standing estrus (NAT = 2,654; PG600 = 821) and were eligible for shipping to the SF at approximately 35 d, and 76.6% of gilts that were administered PG600 exhibited the standing reflex within 13 d of treatment. Ultimately, 72.0% of gilts entering the GDU were delivered to the SF as breeding-eligible females. Considering the gilts delivered, a greater proportion of NAT than PG600 gilts were successfully bred ( < 0.001) and had better farrowing rates to first service, and overall farrowing rates (including gilts that returned to estrus and were rebred) were greater for NAT compared to PG600 gilts ( < 0.001) . Farrowing rates at second and third parity were similar between NAT and PG600 gilts; however, at fourth parity, a greater proportion of NAT gilts farrowed. In comparison, considering only gilts served, there was no difference ( > 0.05) in the proportion of NAT and PG600 gilts farrowing a third litter, but a greater proportion of NAT than PG600 gilts farrowed their fourth litter ( < 0.001). There was no difference between NAT and PG600 gilts for litter size at parity 1 through 4 or total pigs born over 4 parities ( > 0.05). A negative correlation ( < 0.0001) was detected between age at puberty and lifetime growth rate at puberty, and growth rate classification affected age and weight at puberty. However, retention rates and total sow productivity to parity 4 were not affected by growth rate classification at puberty.

SU-E-T-89: Characterization of Dental Restoration Material for Cs-137 Radiation Dosimetry.

PURPOSE: The purpose of this work is to characterize the radiation-induced thermoluminescence properties of a dental restoration material and to see if the material might be feasible for use in retrospective radiation dosimetry. METHODS: Retrospective, or accidental, dosimetry is the study of using nearby materials to measure radiation received by individuals. In this project we obtained samples of Ivoclar Vivadent e.max CAD material, a glass-ceramic used for making dental restorations such as full or partial crowns. The samples were machined into square chips .32 cm × .32 cm × .089 cm and annealed in the same furnace used by the dentist. The samples were exposed to a Cs-137 source using a PMMA source holder and then read in a Harshaw 3500 TLD reader. The samples were read without nitrogen gas flux using heating rates of 5 degrees C/s or 10 degrees C/s up to a maximum temperature of 400 degrees Celsius. The glow curves were analyzed using Systat PeakFIT peak-fitting software and Microsoft Excel spreadsheets. The authors gratefully thank Dr. Aaron Imdieke and the staff of River City Dental, St. Cloud, MN for the dental restoration materials and the use of their dental furnace. RESULTS: A sample subjected to a radiation exposure of .04 C/kg exhibits a glow curve with a prominent peak at approximately 140 degrees Celsius, which is well-modeled by the first order glow curve deconvolution formula developed by Kitis, Gomez-Ros, and Tuyn. The activation energy corresponding to this peak is approximately 1 eV. The thermoluminescent signal fades with time after exposure. CONCLUSIONS: Ivoclar Vivadent e.max CAD dental restoration material has the potential to be used as a material for retrospective Cs-137 radiation dosimetry. Future work could look at its thermoluminescent dosimetry properties in more detail and also at other dental restoration materials. The authors would like to thank Dr. Aaron Imdieke and the staff of River City Dental, St. Cloud, MN, for the donation of scrap dental restoration materials and the use of their dental furnace.

Thiazolidinediones increase the wingless-type MMTV integration site family (WNT) inhibitor Dickkopf-1 in adipocytes: a link with osteogenesis.

AIMS/HYPOTHESIS: Dickkopf-1 (DKK1) is a secreted inhibitor of canonical wingless-type MMTV integration site family (WNT) signalling; the key pathway for cell fate and development. Inhibition of WNT signalling by DKK1 in precursor cells promotes adipogenesis and inhibits osteogenesis. Previous studies have shown that treatment of type 2 diabetic patients with thiazolidinediones (TZDs) reduces bone density and increases risk of bone fractures, while body fat is increased. METHODS: We examined the effect of TZDs on secretion and DKK1 levels in pre-adipocytes and mature adipose cells and also measured circulating DKK1 levels in 11 patients with type 2 diabetes before and after treatment with the TZD rosiglitazone for 90 days. RESULTS: TZDs added in vitro rapidly increased DKK1 protein levels and secretion in both fully differentiated adipose cells and pre-adipocytes undergoing differentiation. In parallel, beta-catenin levels, a marker of canonical WNT signalling, were reduced. Serum levels of DKK1 were also increased in several of the patients with type 2 diabetes after treatment with rosiglitazone for 90 days. CONCLUSIONS/INTERPRETATION: These results provide a novel mechanism whereby peroxisome proliferator-activated receptor-gamma activation can terminate WNT signalling and promote adipogenesis. Furthermore, they provide an explanation for why TZD treatment can lead to reduced bone formation and increased risk of fractures, since inhibited WNT signalling in progenitor cells promotes adipogenesis while osteogenesis is reduced.

No acute effect of nateglinide on postprandial lipid and lipoprotein responses in subjects at risk for type 2 diabetes.

BACKGROUND: To study the acute effect of nateglinide, an insulinotropic agent, on the postprandial triglyceride and lipoprotein responses in subjects at risk for type 2 diabetes. METHODS: Six women and 10 men, with at least one first-degree relative with type 2 diabetes were included (Age: 48 +/- 7 years, BMI: 27.5 +/- 2.8 kg m(-2), P-triglycerides: 1.3 +/- 0.4 mmol L(-1), P-cholesterol: 5.4 +/- 0.6 mmol L(-1), B-glucose: 4.6 +/- 0.3 mmol L(-1)). They each had two 8-h meal tolerance tests with either nateglinide or placebo given 10 min prior to the meals in randomized order. Lipoprotein fractions were separated by density gradient ultracentrifugation. First-phase insulin secretion was assessed by an intravenous glucose tolerance test (300 mg kg(-1) body weight) and insulin sensitivity by a hyperinsulinaemic euglycaemic clamp (40 mU m(-2) min(-1)). RESULTS: The 1-h insulin levels during the meal tolerance test were significantly higher with nateglinide (577 +/- 81 vs 376 +/- 58 pmol L(-1), p < 0.001), as well as the response during the first two hours (IAUC: 41 243 +/- 5844 vs 29 956 +/- 4662 pmol L(-1) min, p < 0.01). Accordingly, nateglinide lowered the 8-h postprandial glucose response by around 60% compared to placebo (p < 0.001). In contrast, no significant lowering was seen in the excursion of postprandial triglycerides in total plasma or lipoprotein fractions. Consistently, the concentration of exogenous (apoB-48) and endogenous (apoB-100) lipoproteins was not reduced by nateglinide. CONCLUSIONS: Acute administration of nateglinide reduces, as expected, the postprandial glucose concentration, but no reduction in triglyceride or lipoprotein responses are seen in subjects at risk for type 2 diabetes.

Early alterations in the postprandial VLDL1 apoB-100 and apoB-48 metabolism in men with strong heredity for type 2 diabetes.

OBJECTIVES: To study the postprandial triglyceride-rich lipoprotein (TRL) metabolism, specifically the concentrations of very low-density lipoproteins (VLDL); from intestine (apoB-48) and liver (apoB-100), in men with normal fasting triglycerides but at increased risk of developing type 2 diabetes. DESIGN: Cross-sectional study. SUBJECTS AND SETTINGS: Sixteen healthy men with at least two first-degree relatives with type 2 diabetes were individually matched with 16 control subjects without known diabetes heredity for: age, body mass index, and fasting triglyceride level. They underwent an 8-h meal tolerance test (919 kcal, 51 g fat) during which lipoproteins were separated by density gradient ultracentrifugation. They were characterized by euglycaemic hyperinsulinaemic clamp, peak VO2, 7-day diet registration and computed tomography. RESULTS: The relatives were, as expected, more insulin resistant than the controls and had increased concentration of postprandial VLDL1 particles (49% higher for VLDL1 apoB-48, P = 0.04 and 21% higher for VLDL1 apoB-100, P = 0.048). The elevation was related to insulin sensitivity, but not to lifestyle and body composition. Moreover, the concentration of postprandial triglycerides in VLDL1 fraction was inversely related to low-density lipoprotein (LDL) size in both relatives (rs = -0.60, P = 0.03) and controls (rs = -0.72, P = 0.004). There were no differences in the concentration of triglycerides or apoB-48 and apoB-100 particles in the other fractions (plasma, chylomicron or VLDL2). CONCLUSION: Increased postprandial concentration of TRLs in the VLDL1 fraction seems to be present at an early stage in the development of diabetes and probably contributes to the excess risk of future coronary events in insulin-resistant men.

Growth and form of planetary seedlings: results from a microgravity aggregation experiment.

The outcome of the first stage of planetary formation, which is characterized by ballistic agglomeration of preplanetary dust grains due to Brownian motion in the free molecular flow regime of the solar nebula, is still somewhat speculative. We performed a microgravity experiment flown onboard the space shuttle in which we simulated, for the first time, the onset of free preplanetary dust accumulation and revealed the structures and growth rates of the first dust agglomerates in the young solar system. We find that a thermally aggregating swarm of dust particles evolves very rapidly and forms unexpected open-structured agglomerates.

Deflection of the local interstellar dust flow by solar radiation pressure.

Interstellar dust grains intercepted by the dust detectors on the Ulysses and Galileo spacecrafts at heliocentric distances from 2 to 4 astronomical units show a deficit of grains with masses from 1 x 10(-17) to 3 x 10(-16) kilograms relative to grains intercepted outside 4 astronomical units. To divert grains out of the 2- to 4-astronomical unit region, the solar radiation pressure must be 1.4 to 1.8 times the force of solar gravity. These figures are consistent with the optical properties of spherical or elongated grains that consist of astronomical silicates or organic refractory material. Pure graphite grains with diameters of 0.2 to 0.4 micrometer experience a solar radiation pressure force as much as twice the force of solar gravity.