Correlation of Tumor Perfusion Between Carbon-13 Imaging with Hyperpolarized Pyruvate and Dynamic Susceptibility Contrast MRI in Pre-Clinical Model of Glioblastoma

Molecular Imaging and Biology - The purpose of this study was to compare C-13 imaging parameters with hyperpolarized [1-13C]pyruvate with conventional gadolinium (Gd)-based perfusion weighted...     

Quantitative Ultrasound Imaging: In Vivo Results in Normal Liver

A method for quantitative imaging of ultrasonic backscatter levels has been implemented on a clinical imager. The method is based on comparing echo signal data from a sample or patient to echo data processed in the same way but acquired from a reference phantom. The attenuation coefficient and the backscatter coefficient of the reference phantom are known, permitting these quantities to be estimated for the sample. In the present paper, the spatial location of echo data acquisition is retained in the backscatter data analysis; quantitative "backscatter estimator" images are constructed, from which the backscatter coefficient over a region of interest may be obtained. When applied to human liver images, backscatter coefficients determined in 10 normal subjects were in approximate agreement with in vitro liver backscatter coefficients reported by previous workers.     

Studies of the In Vivo Metabolism of Mevalonic Acid in the Normal Rat

Studies were performed to examine synthesis, tissue localization, and metabolism of mevalonic acid in normal rats. Circulating mevalonate was found to have a rapid turnover phase of 5 min and a slower phase of 40-50 min. Under in vitro conditions the synthesis of mevalonate is carried out most actively by the liver and only to a minor extent by the other tissues studied. The most unexpected finding of this study was that both in vivo and in vitro the kidneys rather than the liver are the primary site of the metabolism of circulating mevalonate. Whereas mevalonate in the liver is rapidly transformed to cholesterol, the major products of mevalonate metabolism in the renal tissues during the same time period are squalene and lanosterol. Exogenous in contrast to circulating mevalonate is metabolized primarily in the intestine.     

Metabolic Changes in Different Stages of Liver Fibrosis: In vivo Hyperpolarized 13C MR Spectroscopy and Metabolic Imaging

Molecular Imaging and Biology - The objective was to assess metabolic changes in different stages of liver fibrosis using hyperpolarized C-13 magnetic resonance spectroscopy (MRS) and metabolic...     

Cellular Accumulation of L-Cystine in Rat Kidney Cortex In Vivo

Cellular accumulation of L-cystine in rat kidney cortex in vivo has been studied using L-[(35)S]cystine. The L-[(35)S]cystine radioactivity in plasma decreases to less than 10% of the initially calculated value by 15 min. Four (35)S-containing intracellular products of L-cystine metabolism were identified including cystine, cysteine, reduced glutathione, and an as yet unidentified compound. The latter is probably taurine, cysteinesulphinate, or cysteic acid. Cellular accumulation of these products was found to be more rapid in vivo than in vitro. Cellular accumulation of the products of L-cystine metabolism was found to be essentially unchanged in the presence of ureter ligation. Unlabeled L-lysine administered simultaneously with L-[(35)S]cystine, in both the presence and absence or ureter ligation, enhanced the cellular accumulation of intracellular metabolic products of L-[(35)S]cystine. Simultaneous (35)S cellular accumulation and L-cystine clearance studies were performed both in the presence and absence of L-lysine. L-Lysine enhanced cellular accumulation of (35)S-products despite an accompanying increase in L-cystine clearance. The results are interpreted as evidence for a dissociation between cellular accumulation and transepithelial transport. This evidence for independent luminal transport and peritubular cellular accumulation could explain the apparent paradox in the disease cystinuria where there appears to be a luminal transport defect for L-cystine, but no defect for cellular accumulation of L-cystine metabolic products in vitro.     

Binding of Bacteriocin Clo DF13 to Clo DF13 Plasmid Deoxyribonucleic Acid In Vivo and In Vitro

The bacteriocinogenic plasmid Clo DF13 is present in Escherichia coli to the extent of 10 copies per cell. A complex of Clo DF13 plasmid deoxyribonucleic acid (DNA) and protein can be isolated from cells. Treatment of the complex with ionic detergents or proteases dissociates the complex but does not convert any supercoiled Clo DF13 DNA to the open circular form, indicating that this complex is not a relaxation complex. The complex is stable in 0.5 M NaCl and contains one polypeptide species. The protein, present in the complex, appeared to be bacteriocin Clo DF13 for the following reasons: (i) the protein is de novo synthesized in Clo DF13-harboring minicells, indicating that this protein is Clo DF13 specific; (ii) this protein shows bacteriocinogenic activity on a bacteriocin Clo DF13-susceptible indicator strain; (iii) this protein has the same molecular weight (60,000) as bacteriocin Clo DF13. DNA-protein binding experiments, involving QAE-Sephadex column chromatography and nitrocellulose membrane filters, demonstrate that bacteriocin Clo DF13 has also affinity in vitro for Clo DF13 DNA. Membrane filter binding experiments revealed that bacteriocin Clo DF13 does not interact with other DNA species, such as ColE1 DNA, yeast DNA, calf thymus DNA, X174 DNA, and also not with denatured Clo DF13 DNA. In addition no binding to Clo DF13 DNA of a related bacteriocin, colicin E3, could be detected. These results indicate that the binding of bacteriocin Clo DF 13 to double-stranded Clo DF13 DNA is very specific.     

Androgen Receptor Signaling in Castration-Resistant Prostate Cancer Alters Hyperpolarized Pyruvate to Lactate Conversion and Lactate Levels In Vivo

Molecular Imaging and Biology - Androgen receptor (AR) signaling affects prostate cancer (PCa) growth, metabolism, and progression. Often, PCa progresses from androgen-sensitive to...     

Influx of Thyroid Hormones into Rat Liver In Vivo: DIFFERENTIAL AVAILABILITY OF THYROXINE AND TRIIODOTHYRONINE BOUND BY PLASMA PROTEINS

The transport of [¹²⁵I]thyroxine (T₄) and [¹²⁵I]triiodothyronine (T₃) into liver was investigated with a tissue sampling-portal vein injection technique in the anesthetized rat. The method allows the investigation of the effects of plasma proteins in human serum on the unidirectional influx of T₄ or T₃ into liver cells. The percent extraction of unidirectional clearance of T₃ and T₄ was 77±2% and 43±2%, respectively, after portal injection of a bolus of Ringer's solution. Cell membrane transport of T₄ or T₃ was nonsaturable because 50-μM concentrations of unlabeled hormone had no effect on transport. The addition of bovine albumin in concentrations of 1, 5, or 10 g/100 ml bound >98% of T₄ or T₃ in vitro, but had no significant effect on T₃ or T₄ transport in vivo. Conversely, 10% rabbit antisera specific for T₃ or T₄, completely abolished the intracellular distribution of thyroid hormone into liver. In the presence of rat serum, which contains albumin and thyroid hormone binding pre-albumin (TBPA), 18 and 81% of total plasma T₄ and T₃, respectively, were available for transport in vivo. The fraction of hormone available for transport in the presence of normal human serum, which contains albumin, TBPA, and thyroid hormone binding globulin (TBG) was 11% for T₄ and 72% for T₃. The fraction of hormone transported into liver after injection of serum obtained from pregnant or birth control pilltreated volunteers was 4% for T₄ (but this was not significantly different from zero) and 54% for T₃.     

Sodium-coupled Taurocholate Transport in the Proximal Convolution of the Rat Kidney In Vivo and In Vitro

Using the standing droplet technique in the renal proximal convolution and simultaneous microperfusion of the peritubular capillaries, the zero net flux transtubular concentration difference of taurocholate (ΔC_TC⁻) at 45 s was determined as a measure of active bile acid reabsorption in vivo. Starting with 0.1 mmol/liter taurocholate in both perfusates the control ΔC_TC⁻ of 0.042 mmol/liter fell to 0.006 mmol/liter (P < 0.001) when the Na⁺ concentration in the perfusates was reduced to zero. Removal of bicarbonate from the perfusates to alter pH had no influence on ΔC_TC⁻. When glycocholate was added to the perfusates ΔC_TC⁻ was decreased, while probenecid increased ΔC_TC⁻.     

In Vivo Evaluation of the Genotoxic Effects of Gonadotropins on Rat Reticulocytes

Background

Gonadotropins, as ovulation-inducing drugs, have been used widely to treat infertility. An epidemiologic correlation between infertility therapy and ovarian cancer development has been reported. However, the effect of gonadotropins in the formation of reproductive tract cancers is controversial.

Objective

The aim of the study was to determine the in vivo genotoxic effects of gonadotropins on rat reticulocytes.

Methods

In this prospective, randomized, controlled study, rats were randomly assigned to 1 of 5 groups. The calculated rat doses of 0.65 human menopausal gonadotropin (hMG), 0.95 hMG, 0.65 follitropin beta (FB), 0.95 FB, or normal saline (control group) were injected, respectively. These calculated rat doses (U/g) are based on average human gonadotropin doses of 150 and 225 IU/d for a 70-kg woman given in 2-mL saline (the control group received 2 mL of saline). Injections were administered once per day for 5 days, followed by 5 days of rest. Each treatment was repeated for 6 estrus cycles in the rats for a total of 12 estrus cycles. Six months after the last day of the 12^th cycle, the rats were euthanized. Bone marrow tissues were removed, and pluripotent reticulocyte cells with micronuclei, nuclear buds, and binuclear abnormalities were analyzed using an in situ micronuclei assay under light microscopy. The proportion of micronucleated cells, cells with anaphase bridge, nuclear buds, and other nuclear abnormalities were measured.

Results

The number of cells with nuclear buds and binuclear abnormalities in the hMG 225 and FB 225 groups was significantly higher (P < 0.05) than that from the hMG 150, FB 150, and control groups in the cytogenetic analysis of bone marrow stem cells. An increased rate of genotoxicity in all gonadotropin groups versus that of placebo was found.

Conclusion

In rats, the micronucleus genotoxicity assay suggests a dose-dependent gonadotropin effect on genomic instability in bone marrow stem cells in vivo.     

A Novel Method for Efficient Collection of Normal Mesothelial Cells In Vivo

Asbestos-induced mesothelioma is a challenging social problem in many countries, and oxidative stress via iron is closely associated with its carcinogenesis. Mesothelioma is thought to originate from the mesothelial cells that cover the somatic cavity such as pleural, pericardial and peritoneal cavities. They are single layered and so flat that it is extremely difficult to obtain pure mesothelial cells as control samples from experimental animals. Here we describe a novel method to collect mesothelial cells from animals by the use of simple equipments. Surface of the most organs including lung, spleen and liver are covered with a single layer of mesothelial cells. Scraping the surface of those organs with razor blades after snap-freeze in liquid nitrogen satisfactorily confers almost pure population of mesothelial cells. This simple method would be helpful for obtaining mesothelial control samples from animals to elucidate the molecular mechanisms of a variety of mesothelial pathology.     

中国正常成年男性前列腺的MRS定量分析

目的用磁共振波谱分析方法定量测量中国正常成年男性前列腺的代谢水平. 方法 10例20～40岁的成年男性,临床无前列腺疾病的征象.在前列腺的中央带和外周带、右侧和左侧的底部、中间和尖部各取一兴趣区,共12个兴趣区,测量其(胆碱+肌酸)/枸椽酸盐[(Choline+Creatine)/Citrate,(Cho+Cre)/Cit]的比值. 结果 10例正常前列腺中央带各区(Cho+Cre)/Cit比值之间无显著性差异(P>0.05),平均为0.75±0.33;外周带各区(Cho+Cre)/Cit比值之间无显著性差异(P>0.05),平均为0.51±0.20.前列腺中央带与外周带之间的(Cho+Cre)/Cit比值有显著性差异(P<0.01). 结论正常成年男性前列腺的代谢情况可用MRS来定量评价,前列腺中央带和外周带的代谢水平不同.     

Multimodality Hyperpolarized C-13 MRS/PET/Multiparametric MR Imaging for Detection and Image-Guided Biopsy of Prostate Cancer: First Experience in a Canine Prostate Cancer Model

Molecular Imaging and Biology - To assess whether simultaneous hyperpolarized C-13 magnetic resonance spectroscopy (MRS)/positron emission tomography (PET)/multiparametric magnetic resonance (mpMR)...     

HIFU联合HL-1损伤正常兔肝脏组织的体内实验研究

目的　探讨一种脂质体 (HIFU L iposomes- 1,HL - 1)增强兔肝高强度聚焦超声 (high intensity focused ultrasound,HIFU )能量沉积和灰阶超声实时监控的效果。方法　将兔随机分为 A,B两组 ,A组右肝为实验侧 (HL - 1侧 ) ,左肝为生理盐水侧 ,B组相反。输入生理盐水后以一定参数行 A组左肝或 B组右肝 HIFU损伤 ;然后输入 HL - 1以相同参数行对侧组织 HIFU损伤 ;记录 HIFU靶区 B超灰度值。实验后 2 4h解剖 ,测量凝固性坏死组织大小、计算能效因子 (energy efficiency factor,EEF)并行组织病理检查。结果　灰度增强出现率在 A、 B两组的 HL - 1侧均有所增加 ,但差异无显著性 (P>0 .0 5 ) ;A,B两组 HL - 1侧的 EEF均明显低于对照侧 (P<0 .0 1) ;损伤组织大体观及病理检查两组两侧均为典型的凝固性坏死。结论　 HL - 1联合 HIFU能导致靶区组织发生凝固性坏死 ,并有增强正常兔肝脏组织 HIFU能量沉积的作用 ,灰阶超声对靶区组织凝固性坏死的实时监控作用有待进一步研究。     

Threshold Methotrexate Concentration for In Vivo Inhibition of DNA Synthesis in Normal and Tumorous Target Tissues

The suppression of DNA synthesis in host and tumor tissues by methotrexate has been monitored in mice by determining the in vivo incorporation of tritium-labeled deoxyuridine ([(3)H]UdR) into DNA. The duration of inhibition of [(3)H]UdR incorporation in normal tissues was related to the dose of methotrexate and was a direct function of plasma drug concentration. [(3)H]UdR incorporation recovered to 50% of pretreatment levels in bone marrow when plasma methotrexate concentration was 10(-8) M or less, irrespective of the dose administered, while 50% recovery of DNA synthesis in intestinal epithelium was not observed until plasma methotrexate levels were 5 x 10(-9) M or less. Ascitic L1210 leukemia cells did not fully return to pretreatment levels of [(3)H]UdR incorporation at any time, although a partial recovery of incorporation was noted at methotrexate ascitic fluid concentrations of approximately 10(-8) M.Methotrexate did not suppress the incorporation of tritium-labeled thymidine ([(3)H]TdR) into bone marrow and duodenal mucosa, confirming the specificity of its action in inhibiting thymidylate synthesis in host tissues. In the ascites tumor a gradual decline in [(3)H]TdR incorporation was seen after methotrexate, indicating that the tumor tissue depression of [(3)H]UdR incorporation is not solely due to inhibition of thymidylate synthesis.These studies indicate that host tissues are inhibited by extremely low concentrations of methotrexate, and indicate the importance of the slow final phase (t((1/2))=12 h) of drug elimination from plasma in producing a prolonged exposure of sensitive host tissues to inhibitory drug concentrations.     

Monodisperse versus Polydisperse Ultrasound Contrast Agents: In Vivo Sensitivity and safety in Rat and Pig

Recent advances in the field of monodisperse microbubble synthesis by flow focusing allow for the production of foam-free, highly concentrated and monodisperse lipid-coated microbubble suspensions. It has been found that in vitro, such monodisperse ultrasound contrast agents (UCAs) improve the sensitivity of contrast-enhanced ultrasound imaging. Here, we present the first in vivo study in the left ventricle of rat and pig with this new monodisperse bubble agent. We systematically characterize the acoustic sensitivity and safety of the agent at an imaging frequency of 2.5 MHz as compared with three commercial polydisperse UCAs (SonoVue/Lumason, Definity/Luminity and Optison) and one research-grade polydisperse agent with the same shell composition as the monodisperse bubbles. The monodisperse microbubbles, which had a diameter of 4.2 μm, crossed the pulmonary vasculature, and their echo signal could be measured at least as long as that of the polydisperse UCAs, indicating that microfluidically formed monodisperse microbubbles are stable in vivo. Furthermore, it was found that the sensitivity of the monodisperse agent, expressed as the mean echo power per injected bubble, was at least 10 times higher than that of the polydisperse UCAs. Finally, the safety profile of the monodisperse microbubble suspension was evaluated by injecting 400 and 2000 times the imaging dose, and neither physiologic nor pathologic changes were found, which is a first indication that monodisperse lipid-coated microbubbles formed by flow focusing are safe for in vivo use. The more uniform acoustic response and corresponding increased imaging sensitivity of the monodisperse agent may boost emerging applications of microbubbles and ultrasound such as molecular imaging and therapy.