Characterization of membrane potential-dependent uptake of the novel PET tracer <Superscript>18</Superscript>F-fluorobenzyl triphenylphosphonium cation

Purpose Mitochondrial dysfunction has been attributed a critical role in the etiology and pathogenesis of numerous diseases, and is manifested by alterations of the organelle’s membrane potential (Δψ_m). This suggests that Δψ_m measurement can be highly useful for diagnostic purposes. In the current study, we characterized the capability of the novel PET agent ¹⁸F-fluorobenzyl triphenylphosphonium (¹⁸F-FBnTP) to assess Δψ_m, compared with the well-established voltage sensor ³H-tetraphenylphosphonium (³H-TPP). Methods ¹⁸F-FBnTP and ³H-TPP uptake under conditions known to alter Δψ_m and plasma membrane potential (Δψ_p) was assayed in the H345 lung carcinoma cell line. ¹⁸F-FBnTP biodistribution was assessed in CD1 mice using dynamic PET and ex vivo gamma well counting. Results ¹⁸F-FBnTP and ³H-TPP demonstrated similar uptake kinetics and plateau concentrations in H345 cells. Stepwise membrane depolarization resulted in a linear decrease in ¹⁸F-FBnTP cellular uptake, with a slope (−0.58±0.06) and correlation coefficient (0.94±0.07) similar (p>0.17) to those measured for ³H-TPP (−0.63±0.06 and 0.96±0.05, respectively). Selective collapse of Δψ_m caused a substantial decrease in cellular uptake for ¹⁸F-FBnTP (81.6±8.1%) and ³H-TPP (85.4±6.7%), compared with control. Exposure to the proapoptotic staurosporine, known to collapse Δψ_m, resulted in a decrease of 68.7±10.1% and 71.5±8.4% in ¹⁸F-FBnTP and ³H-TPP cellular uptake, respectively. ¹⁸F-FBnTP accumulated mainly in kidney, heart and liver. Conclusion ¹⁸F-FBnTP is a mitochondria-targeting PET radiopharmaceutical responsive to alterations in membrane potential with voltage-dependent performance similar to that of ³H-TPP. ¹⁸F-FBnTP is a promising new voltage sensor for detection of physiological and pathological processes associated with mitochondrial dysfunction, such as apoptosis, using PET.     

Mechanism of asynchronous Ca2+ waves underlying agonist-induced contraction in the rat basilar artery

Background and purpose:

Uridine 5''-triphosphate (UTP) is a potent vasoconstrictor of cerebral arteries and induces Ca²⁺ waves in vascular smooth muscle cells (VSMCs). This study aimed to determine the mechanisms underlying UTP-induced Ca²⁺ waves in VSMCs of the rat basilar artery.

Experimental approach:

Isometric force and intracellular Ca²⁺ ([Ca²⁺]_i) were measured in endothelium-denuded rat basilar artery using wire myography and confocal microscopy respectively.

Key results:

Uridine 5''-triphosphate (0.1–1000 µmol·L⁻¹) concentration-dependently induced tonic contraction (pEC₅₀ = 4.34 ± 0.13), associated with sustained repetitive oscillations in [Ca²⁺]_i propagating along the length of the VSMCs as asynchronized Ca²⁺ waves. Inhibition of Ca²⁺ reuptake in sarcoplasmic reticulum (SR) by cyclopiazonic acid abolished the Ca²⁺ waves and resulted in a dramatic drop in tonic contraction. Nifedipine reduced the frequency of Ca²⁺ waves by 40% and tonic contraction by 52%, and the nifedipine-insensitive component was abolished by SKF-96365, an inhibitor of receptor- and store-operated channels, and KB-R7943, an inhibitor of reverse-mode Na⁺/Ca²⁺ exchange. Ongoing Ca²⁺ waves and tonic contraction were also abolished after blockade of inositol-1,4,5-triphosphate-sensitive receptors by 2-aminoethoxydiphenylborate, but not by high concentrations of ryanodine or tetracaine. However, depletion of ryanodine-sensitive SR Ca²⁺ stores prior to UTP stimulation prevented Ca²⁺ waves.

Conclusions and implications:

Uridine 5''-triphosphate-induced Ca²⁺ waves may underlie tonic contraction and appear to be produced by repetitive cycles of regenerative Ca²⁺ release from the SR through inositol-1,4,5-triphosphate-sensitive receptors. Maintenance of Ca²⁺ waves requires SR Ca²⁺ reuptake from Ca²⁺ entry across the plasma membrane via L-type Ca²⁺ channels, receptor- and store-operated channels, and reverse-mode Na⁺/Ca²⁺ exchange.     

Column-switching HPLC for the analysis of plasma in PET imaging studies

A column-switch high performance liquid chromatography method for the analysis of 4 mL of plasma is described with six examples of chromatography of [(11)C]-labeled positron-emission tomography imaging agents. Complete extraction of all but the most polar metabolites by the reverse phase capture column is achieved by disruption of plasma protein binding by 8 M urea.     

激光生物效应及医学应用研究

激光作用于生物体会产生物理、化学或生物学的效应,激光正是通过这些效应达到医学基础研究、诊断和治疗疾病的目的.本文简介了激光与生物组织相互作用所产生的生物效应,概述了激光生物效应在生物学和医学研究中的应用.     

Urinary antimony in infancy

OBJECTIVE: To determine whether antimony may be detected in the urine during infancy and early childhood and its association with passive exposure to tobacco smoke, as assessed by urinary cotinine. DESIGN: Analysis of spare aliquots of urine collected from infants participating in studies of respiratory function and passive smoking. Urinary antimony was assayed using inductively coupled plasma mass spectroscopy in 201 urine specimens collected at different ages throughout the first two years of life from 122 term and 26 preterm infants. Urinary cotinine was measured using gas liquid chromatography. MAIN OUTCOME MEASURE: Urinary antimony concentrations. RESULTS: Absolute antimony concentrations varied widely between infants, being below the laboratory detection limit of 0.02 microgram/l in 7% of samples, below 0.5 microgram/l in 90.5%, and above the reference value of 1 microgram/l reported for non-occupationally exposed UK populations in 4%. Creatinine standardised antimony values were unrelated to postnatal age or urinary cotinine concentrations and were highest in urine collected from preterm infants within 24 hours of birth (geometric mean (95% confidence interval): 2.3 ng/mg (1.5 to 3.4)). CONCLUSIONS: Although antimony is present at very low concentrations in urine during infancy and early childhood, the relevance to health is uncertain. The higher levels found in preterm infants may reflect prematurity or fetal assimilation of antimony. Tobacco is unlikely to be an important source of environmental exposure to antimony during infancy and early childhood.     

Parental attitudes about sexually transmitted infection vaccination for their adolescent children

OBJECTIVES: To evaluate parental attitudes about adolescent vaccination as a function of vaccine characteristics, including whether the vaccine prevented a sexually transmitted infection (STI), and to explore possible sociodemographic predictors of acceptability of STI vaccines. DESIGN: Participants were 278 parents who accompanied their children (69.1% female, aged 12-17 years) to appointments at medical clinics. By using computer-based questionnaires, parents rated 9 hypothetical vaccine scenarios, each of which was defined along 4 dimensions: mode of transmission (STI or non-STI), severity of infection (curable, chronic, or fatal), vaccine efficacy (50%, 70%, or 90%), and availability of behavioral methods for prevention (available or not available). Willingness by parents to vaccinate their adolescents under each vaccine scenario was assessed on a scale that ranged from 0 to 100. Conjoint analysis was used to determine the relative contribution of each dimension to the ratings. RESULTS: The mean vaccine scenario rating was 81.3. Sexually transmitted infection vaccines (mean, 81.3) were not rated differently than non-STI vaccines (mean, 80.0). Conjoint analysis indicated that severity of infection and vaccine efficacy had the strongest influence on ratings, followed by availability of behavioral prevention. Mode of transmission had a negligible effect on ratings. Child age (P = .08) and sex (P = .77), parent age (P = .32) and education (P = .34), insurance status (P = .08), and data collection site (P = .48) were not significantly associated with STI vaccine acceptability. CONCLUSIONS: Parents were accepting of the idea of vaccinating their adolescent children against STIs. The most salient issues were severity of infection and vaccine efficacy, not sexual transmissibility. Parents also favored vaccines for infections that had no method of behavioral prevention available.     

Radiolabeled small-molecule ligands for prostate-specific membrane antigen: in vivo imaging in experimental models of prostate cancer.

PURPOSE: Prostate-specific membrane antigen (PSMA) is a cell surface protein that is overexpressed in prostate cancer, including hormone-refractory and metastatic disease. Our goal in this study was to develop a series of PSMA-based imaging agents for clinical use. EXPERIMENTAL DESIGN: We have synthesized and evaluated the in vivo biodistribution of two radiolabeled urea derivatives that have high affinity for PSMA in severe combined immunodeficient mice harboring MCF-7 (breast, PSMA-negative), PC-3 (prostate, PSMA-negative), and LNCaP (prostate, PSMA-positive) xenografts. Radiopharmaceutical binding selectivity and tumor uptake were also evaluated in vivo using dedicated small animal positron emission tomography, single photon emission computed tomography, and gamma scintigraphic imaging devices. N-[N-[(S)-1,3-dicarboxypropyl]carbamoyl]-S-[(11)C]methyl-L-cysteine ([(11)C]DCMC K(i), 3.1 nmol/L) and N-[N-[(S)-1,3-dicarboxypropyl]carbamoyl]-S-3-[(125)I]iodo-L-tyrosine ([(125)C]DCIT K(i), 1.5 nmol/L) were synthesized using [(11)C]CH(3)I and with [(125)I]NaI/Iodogen, respectively.RESULTS: At 30 minutes postinjection, [(11)C]DCMC and [(125)I]DCIT showed tumor/muscle ratios of 10.8 and 4.7, respectively, with clear delineation of LNCaP-derived tumors on imaging. MCF-7- and PC-3-derived tumors showed significantly less uptake of [(11)C]DCMC or [(125)I]DCIT. CONCLUSION: These results show the feasibility of imaging PSMA-positive prostate cancer using low molecular weight agents.     

Diagnosis and management of cystic duct leakage after laparoscopic cholecystectomy, report of 3 cases

BACKGROUND： Operative complications after laparoscopic cholecystectomy （LC） vary. Abdominal pain and other symptoms caused by fluid accumulation in the operative area are not uncommon. Cystic duct （CD） leakage is one of the main sources of the fluid. This study was to evaluate the procedures used in the diagnosis and management of CD leakage after LC. METHOD： The clinical materials of 3 patients with CD leakage after LC were studied retrospectively.