Fast,epithermal and thermal photoneutron dosimetry in air and in tissue equivalent phantom for a high-energy X-ray medical accelerator

Photoneutron (PN) dosimetry in fast, epithermal and thermal energy ranges originated from the beam and albedo neutrons in high-energy X-ray medical accelerators is highly important from scientific, technical, radiation protection and medical physics points of view. Detailed dose equivalents in the fast, epithermal and thermal PN energy ranges in air up to 2 m as well as at 35 positions from the central axis of 12 cross sections of the phantom at different depths were determined in 18 MV X-ray beams of a Siemens ONCOR accelerator. A novel dosimetry method based on polycarbonate track dosimeters (PCTD)/¹⁰B (with/without cadmium cover) was used to determine and separate different PN dose equivalents in air and in a multilayer polyethylene phantom. Dose equivalent distributions of PNs, as originated from the main beam and/or albedo PNs, on cross-plane, in-plane and diagonal axes in 10 cm × 10 cm fields are reported. PN dose equivalent distributions on the 3 axes have their maxima at the isocenter. Epithermal and thermal PN depth dose equivalent distributions in the phantom for different positions studied peak at ～3 cm depth. The neutron dosimeters used for the first time in such studies are highly effective for separating dose equivalents of PNs in the studied energy ranges (beam and/or albedo). The PN dose equivalent data matrix made available in this paper is highly essential for detailed patient dosimetry in general and for estimating secondary cancer risks in particular.     

The Molecular Energetics of the Failing Heart from Animal Models—Large Animal Models

Large animal models of left ventricular hypertrophy (LVH) and cardiac failure are associated with alterations of myocardial high energy phosphate (HEP) content and abnormalities of oxidative phosphorylation regulation. Concentric LVH secondary to pressure overload can result in loss of myocardial ATP, a decrease of the phosphocreatine (PCr)/ATP ratio, and an increase of calculated free ADP; these changes are, at least in part, the result of alterations in the regulation of oxidative phosphorylation, but can be aggravated by impaired blood flow to the subendocardium during increased cardiac workloads. Eccentric LVH resulting from volume overload produces only modest reductions of the myocardial PCr/ATP ratio which are not worsened during increases of cardiac work. Post-infarction left ventricular remodeling is associated with a decrease of the myocardial PCr/ATP ratio that is most marked in animals that develop overt congestive heart failure. The depressed PCr/ATP ratio and ATP content in hypertrophied hearts are not the result of persistent myocardial hypoperfusion, since they are not corrected by pharmacologic coronary vasodilation. Furthermore, the additional decrease of myocardial PCr/ATP which occurs during high workloads in hypertrophied as well as in normal hearts occur without evidence of myoglobin desaturation, indicating that these changes cannot be ascribed to oxygen insufficiency. There is some evidence that impairment of long chain fatty acid uptake contributes to HEP abnormalities in hypertrophied or failing hearts. Furthermore, alterations in creatine kinase isoform expression in hypertrophied or failing hearts may result in higher levels of free ADP that could contribute to the observed HEP abnormalities.     

Stimulation of mu- and delta-opioid receptors enhances phosphoinositide metabolism in mouse spinal cord: evidence for subtypes of delta-receptors.

The accumulation of inositol phosphates (IPs) induced by agonist-activated opioid receptors was analysed in mouse spinal cord slices pre-labelled with myo-[3H]inositol. Agonists showing selectivity to mu-opioid receptors, morphine and [D-Ala2,MePhe4, Gly(ol)5]enkephalin (DAMGO), promoted concentration-dependent increases in the formation of IPs. The activation of delta-opioid receptors by the selective agonists [D-Pen2,5]enkephalin (DPDPE) and [D-Ala2]deltorphin II produced similar increases in phosphoinositide (PI) metabolism. Pre-treatment of the slices with pertussis toxin (PTX) blocked the effect of opioid agonists on IP production. The involvement of Gi/Go-protein (guanine nucleotide-binding protein) classes in this opioid effect is therefore suggested. The activity of the opioid agonists was reduced by the opioid antagonists naltrexone and naloxone. The antagonist at delta1-receptors, 7-benzylidenenaltrexone (BNTX), exhibited greater potency than the antagonists at delta2-receptors, naltriben methanesulphonate (NTB) or naltrindrole 5'-isothiocyanate (NT II), in reducing the activating effect of DPDPE on phosphoinositide metabolism. Conversely, NTB and NT II were more potent antagonists of the activity of [D-Ala2]deltorphin II than BNTX. This work demonstrates the coupling of spinal mu- and delta-opioid receptors to phospholipase C and the generation of IPs. It also provides biochemical evidence for pharmacological subtypes of delta-opioid receptors in the activation of this signalling pathway.     

高能震波治疗骨不连接的实验研究

目的 观察高能震波（ｈｉｇｈ ｅｎｅｒｇｙ ｓｈｏｃｋ ｗａｖｅｓ,ＨＥＳＷ）对骨愈合的影响,探讨促进骨折愈合的新方法。方法 手术造成５０只家兔双侧胫骨中段６ｍｍ骨缺损后用外固定器固定。１２周后选择经Ｘ线片检查证实的６８侧胫骨骨不连接,随机分成两组进行研究。治疗组３４侧,对其胫骨骨折部施以ＨＥＳＷ治疗（１４．５ｋＶ,２０００次）;对照组３４侧,不加任何治疗。术后２,６,１２周进行摄片、组织学及透射     

基于磷酸丙糖异构酶基因序列的蓝氏贾第鞭毛虫分子系统发育的研究

[目的 ]探讨蓝氏贾第鞭毛虫种内系统发育及遗传多样性。 [方法 ]对不同来源虫株的磷酸丙糖异构酶(tim)基因进行 PCR扩增、序列测定后 ,用简约法和 NJ法构建分子系统树进行系统学分析。 [结果 ]在所测序列中共有 12 4个位点存在变异 (2 3% ) ,且大多数为发生在第三密码子的同义突变 ,两种构树方法所得两树的分枝结构相似 ,均将受试的 16株蓝氏贾第鞭毛虫分为明显的两组。 [结论 ]tim基因可作为研究蓝氏贾第鞭毛虫群体遗传结构一个有效的遗传标记     

Differences between platelet phosphoinositide metabolism stimulated by thrombin or SFLLRN are not accounted for by interaction of thrombin with glycoprotein Ib

The formation of inositol phosphates was compared in aspirin-treated, washed human platelets suspended in Tyrode's-albumin solution containing 2 mM calcium and stimulated with SFLLRN (thrombin receptor-activating peptide) or thrombin. SFLLRN (20 μM) and thrombin (1 U/ml) resulted in maximal irreversible aggregation and 80–90% secretion of dense granule contents. SFLLRN (50–100 μM) caused larger increases at 10 sec than 20 μM SFLLRN in the formation of inositol trisphosphate (IP₃, measured as [³H]inositol label). These increases were not significantly less than those caused by thrombin (1 unit/ml). However, whereas the labeling of IP₃ increased from 10–60 sec with thrombin, with SFLLRN it was much less at 60 sec than that at 10 sec. The decrease was not due to degradation of SFLLRN by ectopeptidases, since it was not prevented by amastatin, an inhibitor of ectopeptidases. Degradation of glycoprotein Ib (GPIb) with an O-sialoglycoprotein endopeptidase did not affect the thrombin-stimulated labeling of inositol phosphates, indicating that binding to GPIb is not involved in the sustained thrombin-induced formation of inositol phosphates. The finding that the thrombin-stimulated formation of IP₃ was not dependent on Ca²⁺ in the medium (EGTA added) indicates that the transient SFLLRN-induced formation of IP₃ is not due to failure to cause Ca²⁺ influx. The finding that formation of IP₃ was transient in SFLLRN-stimulated platelets, whereas platelet aggregation and secretion were maximal, indicates that the sustained activation of phospholipase C caused by thrombin may have roles related to later processes in which platelets participate. Am. J. Hematol. 54:288–295, 1997. © 1997 Wiley-Liss, Inc.     

酸碱滴定法测定磷酸钠盐灌肠液的含量

目的:建立酸碱滴定法测定磷酸钠盐灌肠液的含量.方法:加入0.5 mol·L-1氢氧化钠溶液,使溶液成分为PO43-与HPO42-,用0.5mol·L-1盐酸滴定液滴定至两个等当点,测定磷酸钠盐灌肠液中磷酸二氢钠与磷酸氢二钠的含量.结果:第一个等当点pH为9.2,第二个等当点pH为4.4,磷酸二氢钠的平均回收率(n=6)为100.2%,RSD为0.80%;磷酸氢二钠的平均回收率(n=6)为101.5%,RSD为0.94%.结论:本法简便、快速、准确.     

Resorbable Mg2+-Containing Phosphates for Bone Tissue Repair

Materials based on Mg²⁺-containing phosphates are gaining great relevance in the field of bone tissue repair via regenerative medicine methods. Magnesium ions, together with condensed phosphate ions, play substantial roles in the process of bone remodeling, affecting the early stage of bone regeneration through active participation in the process of osteosynthesis. In this paper we provide a comprehensive overview of the usage of biomaterials based on magnesium phosphate and magnesium calcium phosphate in bone reconstruction. We consider the role of magnesium ions in angiogenesis, which is an important process associated with osteogenesis. Finally, we summarize the biological properties of calcium magnesium phosphates for regeneration of bone.     

高效液相色谱测定大鼠心肌组织腺苷酸含量

目的:优化高效液相色谱(HPLC)法检测大鼠心肌组织腺苷酸的含量.方法:ODS HYPERSIL C18分析柱,检测波长254 nm,流动相为50 mmol/L磷酸钾缓冲液(pH 6.5).结果:心肌三磷酸腺苷(ATP)、二磷酸腺苷(ADP)和一磷酸腺苷(AMP)平均回收率分别为99%～107%,96%～104%和95%～119%;日内和日间相对标准偏差(RSD)分别在1.5%和5.1%以下.结论:优化高效液相色谱法快速准确、简便易行.     

A case report of motor neuron disease in a patient showing significant level of DDTs, HCHs and organophosphate metabolites in hair as well as levels of hexane and toluene in blood

Motor neuron disease is a devastating neurodegenerative condition, with the majority of sporadic, non-familial cases being of unknown etiology. Several epidemiological studies have suggested that occupational exposure to chemicals may be associated with disease pathogenesis. We report the case of a patient developing progressive motor neuron disease, who was chronically exposed to pesticides and organic solvents. The patient presented with leg spasticity and developed gradually clinical signs suggestive of amyotrophic lateral sclerosis, which was supported by the neurophysiologic and radiological findings. Our report is an evidence based case of combined exposure to organochlorine (DDTs), organophosphate pesticides (OPs) and organic solvents as confirmed by laboratory analysis in samples of blood and hair confirming systematic exposure. The concentration of non-specific dialkylphosphates metabolites (DAPs) of OPs in hair (dimethyphopshate (DMP) 1289.4 pg/mg and diethylphosphate (DEP) 709.4 pg/mg) and of DDTs (opDDE 484.0 pg/mg, ppDDE 526.6 pg/mg, opDDD 448.4 pg/mg, ppDDD + opDDT 259.9 pg/mg and ppDDT 573.7 pg/mg) were considerably significant. Toluene and n-hexane were also detected in blood on admission at hospital and quantified (1.23 and 0.87 μg/l, respectively), while 3 months after hospitalization blood testing was found negative for toluene and n-hexane and hair analysis was provided decrease levels of HCHs, DDTs and DAPs.