Effect of exogenous somatotropin in Holstein calves on mammary gland composition and proliferation

Pubertal mammary gland growth and development are hormonally regulated, but the details are poorly understood in calves. Our purpose was to evaluate the effects of exogenous growth hormone (GH) on the biochemical composition of the prepubertal mammary gland, mRNA expression of selected genes, and histological characteristics of the developing parenchyma (PAR). In this experiment, 19 calves (7 ± 4 d of age) were randomly assigned to 1 of 2 treatments: bovine somatotropin (bST, 500 mg; n = 10) or placebo (Sal; 0.9% saline; n = 9). Animals were treated every 3 wk beginning on d 23. Calves were assigned to an early (65 d; tissue harvested after 2 treatment injections) or late collection time (107 d; tissue harvested after 4 treatment injections). Calves were fed milk replacer and calf starter for 8 wk and starter and hay thereafter. Parenchyma and mammary fat pad (MFP) from one udder half were harvested for analysis of protein, lipid, and DNA. Additional tissues were preserved for histological analysis or snap-frozen for quantitative real-time PCR. Somatotropin treatment did not significantly alter the mass of PAR or MFP or the general pattern of development of epithelial structures. Significant increases were observed in protein/100 kg of body weight (BW), total protein, DNA concentration, DNA/100 kg of BW, and total DNA in 107-d calves, and a significant treatment by day interaction was observed for DNA and lipid concentrations in PAR. In MFP, a significant decrease was observed in protein/100 kg of BW in bST-treated calves and in total MFP protein in 65-d calves. A treatment by day interaction was found for total protein, DNA, and protein/100 kg of BW. In PAR, relative expression of ATPase-binding cassette 3 and growth hormone receptor were reduced by bST and both were lower in 107-d-harvest calves. Epithelial cell retention of bromodeoxyuridine (BrdU; possible indicator of stem-like cells) was greatest in 65-d bST-treated calves, and a significant time of sampling response and treatment × time interaction were observed. Expression of the proliferation marker protein Ki67 was numerically higher in bST-treated calves but the difference was nonsignificant. Retention of the BrdU label was reduced in 107-d calves. Exogenous growth hormone given to calves may affect mammary tissue composition and epithelial cell gene expression in subtle ways but exogenous supplementation with bST alone is not likely to alter overall development patterns or affect the mass of mammary parenchymal tissue. Whether such subtle changes have an effect on subsequent development or function is unknown.     

Rugged, portable tungsten coil atomic emission spectrometer

Tungsten coil atomic emission spectrometry is an ideal technique for field applications because of its simplicity, low cost, low power requirement, and independence from cooling systems. A new, portable, compact design is reported here. The tungsten coil is extracted from an inexpensive 24 V, 250 W commercial light bulb. The coil is housed in a small, aluminum cell. The emission signal exits from a small aperture in the cell, while the bulk of the blackbody emission from the tungsten coil is blocked. The resulting spectra exhibit extremely low background signals. The atomization cell, a single lens, and a hand-held charge coupled device (CCD) spectrometer are fixed on a 1 × 6 × 30 cm ceramic base. The resulting system is robust and easily transported. A programmable, miniature 400 W solid-state constant current power supply controls the temperature of the coil. Fifteen elements are determined with the system (Ba, Cs, Li, Rb, Cr, Sr, Eu, Yb, Mn, Fe, Cu, Mg, V, Al, and Ga). The precision ranges from 4.3% to 8.4% relative standard deviation for repetitive measurements of the same solution. Detection limits are in the 0.04 to 1500 μg/L range. Accuracy is tested using standard reference materials for polluted water, peach leaves, and tomato leaves. For those elements present above the detection limit, recoveries range from 72% to 147%.     

Application of photonic crystal enhanced fluorescence to cancer biomarker microarrays

We report on the use of photonic crystal surfaces as a high-sensitivity platform for detection of a panel of cancer biomarkers in a protein microarray format. The photonic crystal surface is designed to provide an optical resonance at the excitation wavelength of cyanine-5 (Cy5), thus providing an increase in fluorescent intensity for Cy5-labeled analytes measured with a confocal microarray scanner, compared to a glass surface. The sandwich enzyme-linked immunosorbent assay (ELISA) is undertaken on a microarray platform to undertake a simultaneous, multiplex analysis of 24 antigens on a single chip. Our results show that the resonant excitation effect increases the signal-to-noise ratio by 3.8- to 6.6-fold, resulting in a decrease in detection limits of 6-89%, with the exact enhancement dependent upon the antibody-antigen interaction. Dose-response characterization of the photonic crystal antibody microarrays shows the capability to detect common cancer biomarkers in the <2 pg/mL concentration range within a mixed sample.     

A lead isotopic study of the human bioaccessibility of lead in urban soils from Glasgow, Scotland

The human bioaccessibility of lead (Pb) in Pb-contaminated soils from the Glasgow area was determined by the Unified Bioaccessibility Research Group of Europe (BARGE) Method (UBM), an in vitro physiologically based extraction scheme that mimics the chemical environment of the human gastrointestinal system and contains both stomach and intestine compartments. For 27 soils ranging in total Pb concentration from 126 to 2160 mg kg^− 1 (median 539 mg kg^− 1), bioaccessibility as determined by the ‘stomach’ simulation (pH ~ 1.5) was 46-1580 mg kg^− 1, equivalent to 23-77% (mean 52%) of soil total Pb concentration. The corresponding bioaccessibility data for the ‘stomach + intestine’ simulation (pH ~ 6.3) were 6-623 mg kg^− 1 and 2-42% (mean 22%) of soil Pb concentration. The soil ²⁰⁶Pb/²⁰⁷Pb ratios ranged from 1.057 to 1.175. Three-isotope plots of ²⁰⁸Pb/²⁰⁶Pb against ²⁰⁶Pb/²⁰⁷Pb demonstrated that ²⁰⁶Pb/²⁰⁷Pb ratios were intermediate between values for source end-member extremes of imported Australian Pb ore (1.04) - used in the manufacture of alkyl Pb compounds (1.06-1.10) formerly added to petrol - and indigenous Pb ores/coal (1.17-1.19). The ²⁰⁶Pb/²⁰⁷Pb ratios of the UBM ‘stomach’ extracts were similar (< 0.01 difference) to those of the soil for 26 of the 27 samples (r = 0.993, p < 0.001) and lower in 24 of them. A slight preference for lower ²⁰⁶Pb/²⁰⁷Pb ratio was discernible in the UBM. However, the source of Pb appeared to be less important in determining the extent of UBM-bioaccessible Pb than the overall soil total Pb concentration and the soil phases with which the Pb was associated. The significant phases identified in a subset of samples were carbonates, manganese oxides, iron-aluminium oxyhydroxides and clays.     

网上电视也要从BT开始

虽说我们早已进入宽带时代,但是网络视频不能流畅播放的现象却始终存在,看着卡住的画面和无休止的缓冲,再好的心情也会瞬时蒸发。笔者不禁突发奇想:要是网络视频能像BT下载一样,看的人越多速度越快,岂不是软件史上一大奇事?没想到正应了那句老话:“只有想不到,没有做不到”,现在还真有这么一款BT的网络电视——Coolstreaming。     

解读显卡供电

自从Intel和AMD同时将设计重点放在性能功耗比上以来，我们并没有如愿看到整机功耗的真正下降，反倒是超过800瓦的电源数量与日俱增，其根本原因就在于显卡功耗的飞升!     

庖丁解牛(上) 显卡结构看个明白

显卡是大家对显示适配器的通俗叫法。从过去的仅仅用来成像,绘制2D图形,到如今已经初步迈向展示“电影级”的3D效果,从功能单一的“小卡”到家庭媒体中心的最关键部分,可见显卡已经成为传统“三大件”外又一重要部件。下图便是最先进的ATiX1800XT显卡。介绍一下显卡的组成,正中间印有ATi字样的芯片便是显示核心,由于是高端显卡,功能非常丰富,性能异常强劲,所以集成度也很高,我们可以从核心大小看出来,即使使用了0.09微米工艺,3.2亿晶体管把核心撑得很大。围绕着核心半圈的8个长方形的芯片便是显存芯片,X1800XT采用了速度最快的1.26纳秒显存,采用FBGA封装。在显存右边那一大堆贴片元件以及6pin的外接电源接口构成了供电电路,电容全部采用无极性电容,比很多玩家推崇的钽电容更加昂贵。     

庖丁解牛——显卡结构看个明白（上）

显卡是大家对显示适配器的通俗叫法。从过去的仅仅用来成像，绘制2D图形，到如今已经初步迈向展示“电影级”的2D效果，从功能单一的“小卡”到家庭媒体中心的最关键部分，可见显卡已经成为传统“三大件”外又一重要部件。 下图便是最先进的ATi X1800XT显卡。介绍一下显卡的组成，正中间印有ATi字样的芯片便是显示核心，由于是高端显卡，功能非常丰富，性能异常强劲，所以集成度也很高，我们可以从核心大小看出来，即使使用了0.09微米工艺，3.2亿晶采用了速度最快的1.26纳秒显存，采用FBGA封装。在显存右边那一大堆贴片元件以及6pin的外接电源接口构成了供电电路，电容全部采用无极性电容，比很多玩家推崇的钽电容更加昂贵。[编者按]     

热重法确定MMH微晶中各种水分的相对含量

借助热分析仪对MMH微晶进行了TG和DTG分析,研究了MMH微晶中各种水分的相对含量。提出MMH微晶中存在4种水分,即自由水、松散吸附水和紧密吸附水、结晶水和羟基水,给出了MMH微晶的完整表达式,即 MgAl_(0.965)(OH)_(4.75)Cl_(0.145·1.70)H_2O。