Radioimmunoassay of Vasopressin in Unextracted Plasma

A radioimmunoassay (RIA) for arg₈-vasopressin (AVP) in unextracted human plasma was based on a sensitive anti-AVP rabbit antiserum, inhibition of enzymatic damage to [¹²⁵I]AVP and AVP, and the use of an individual plasma blank, to correct for interference of plasma factors with the RIA. Sensitivity was 0.4 pg of synthetic AVP detected, corresponding to 1.2 pg/ml of AVP in human plasma. Recovery of AVP added to pooled plasma was 94 ± 9.3% (mean± S.D.) in the low range (AVP, 2.8 pg/ml added) and 106 ± 11.7% in the high range (45.0 pg/ml added). In 26 healthy, ambulatory subjects on ad lib. water intake, plasma AVP concentration was 2.0 ± 1.22 pg/ml in the supine position and in 28 healthy subjects, 6.2 ± 4.3 pg/ml in the upright position. Water loading suppressed the plasma AVP concentration. Smoking caused increased plasma AVP in 3 subjects despite water loading.     

Comparison of [18F]-Tracers in Various Experimental Tumor Models by PET Imaging and Identification of an Early Response Biomarker for the Novel Microtubule Stabilizer Patupilone

Purpose  The suitability of [¹⁸F]FDG, [¹⁸F]FLT, [¹⁸F]FET, and [¹⁸F]FCH as non-invasive positron emission tomography (PET) biomarkers for monitoring response to chemotherapy was analyzed in various experimental tumor models. Procedures  Tracer uptake into three syngeneic rodent tumor models and ten human xenograft models was evaluated using semiquantitative analysis of small-animal PET data. Murine RIF-1 fibrosarcomas and [¹⁸F]FLT were selected to monitor the effects of the novel cytotoxic patupilone. Results  Except [¹⁸F]FCH, all tracers provided good tumor visualization. Highest [¹⁸F]FDG uptake was identified in syngeneic tumors. Xenograft models, however, showed low [¹⁸F]FDG SUVs and were better visualized by [¹⁸F]FLT. Monitoring the effects of patupilone on [¹⁸F]FLT uptake in RIF-1 tumors revealed a significant decrease of tracer uptake after 24 h, which strongly negatively correlated with apoptosis. Conclusion  [¹⁸F]FLT PET of experimental tumors is a viable complement to [¹⁸F]FDG for preclinical drug development. [¹⁸F]FLT may be an excellent biomarker for patupilone-induced apoptosis. T. Ebenhan and M. Honer contributed equally to this work. An erratum to this article can be found at     

Simultaneous [99mTc]TRODAT-1 and [123I]ADAM Brain SPECT in Nonhuman Primates

Purpose  This study examined the feasibility of simultaneous dopamine and serotonin transporter imaging using [¹²³I]ADAM and [^99mTc]TRODAT-1 single photon emission computed tomography (SPECT). Procedures  Simultaneous [¹²³I]ADAM (185 MBq) and [^99mTc]TRODAT-1 (740 MBq) SPECT was performed in three age-matched female Formosan rock monkeys. An asymmetric energy window was used for dual, and symmetric energy windows were used for single-isotope imaging. Oral fluoxetine (20 mg) and intravenous methylphenidate HCl (1 mg/kg) were given 24 h and 10 min, respectively, before dual-isotope SPECT to test imaging specificities of [¹²³I]ADAM and [^99mTc]TRODAT-1. Results  Comparable image quality and uptake ratios between dual- and single-isotope SPECT scans were found. Dual-isotope SPECT in fluoxetine-pretreated monkeys showed decreased uptake of [¹²³I]-ADAM, but not of [^99mTc]TRODAT-1. Dual-isotope SPECT in methylphenidate-pretreated monkeys showed decreased [^99mTc]TRODAT-1 uptake without affecting [¹²³I]-ADAM uptake. Conclusion  Simultaneous [¹²³I]-ADAM and [^99mTc]TRODAT-1 SPECT appears promising in nonhuman primates and may provide a suitable preclinical model with further clinical implications.     

Global Cerebral Blood Flow in Relation to Cognitive Performance and Reserve in Subjects with Mild Memory Deficits

Purpose This study was undertaken to explore the mechanisms underlying cognitive reserve in subjects with mild memory deficits by using positron emission tomography (PET).Methods Global cerebral blood flow (gCBF) and cerebrovascular reserve (CVR) measurements were performed in 15 elders (5 men, 10 women, 62–84, 71.8 ± 6.2 years) meeting criteria for mild cognitive impairment (MCI). PET consisted of quantitative [¹⁵O]water determinations of CBF, two at baseline and one postadministration of acetazolamide (ACZ).Results Mean gCBF were 44.9 ± 5.5 during counting, 44.5 ± 6.7 for the memory task, and 60.2 ± 4.8 ml/min/100 g for post-ACZ (CVR of 33.9 ± 13.2%). Task-related gCBF change was significantly related to memory score, performance on the Trail Making Test B (Trails-B), premorbid IQ, and education, and differed significantly between the learning-based groups.Conclusions Cognitive reserve appears analogous to cardiac reserve. The ability to alter gCBF paralleled performance on general cognitive measures, was enhanced in higher levels of cognitive reserve, and was impaired in individuals who no longer appear to benefit from repeated exposure to testing.     

In vivo cytotoxic T lymphocyte elicitation by mycobacterial heat shock protein 70 fusion proteins maps to a discrete domain and is CD4(+) T cell independent

To gain insights into the mechanisms by which soluble heat shock protein (hsp) fusions can elicit CD8(+) cytotoxic T lymphocytes (CTLs) against the fusion partner, mycobacterial (Mycobacterium tuberculosis) hsp70 was dissected to ascertain whether a particular hsp domain is necessary, and knockout mice were used to determine whether the fusion protein's immunogenicity is dependent on CD4(+) T lymphocytes. We found that the ability to elicit CD8(+) CTLs depends on a discrete 200-amino acid protein domain, indicating that the fusion protein's immunogenicity for CD8(+) T cells does not require coupled chaperone function or peptide binding. Further, we found that ovalbumin (OVA).hsp70 fusion protein elicited anti-OVA CD8(+) CTLs about equally well in CD4 knockout and wild-type C57BL/6 mice, and also when the hsp70 was of murine (self) origin. The ability of hsp70 fusion proteins to elicit CD4-independent CTL responses suggests that hsp70 fusion proteins may be useful for immunological prophylaxis and therapy against disease in CD4(+) T cell-deficient individuals.     

Comparison of [<Superscript>14</Superscript>C]FMAU, [<Superscript>3</Superscript>H]FEAU, [<Superscript>14</Superscript>C]FIAU,and [<Superscript>3</Superscript>H]PCV for Monitoring Reporter Gene Expression of Wild Type and Mutant Herpes Simplex Virus Type 1 Thymidine Kinase in Cell Culture

Purpose To assess the optimal reporter probe/reporter gene combination for monitoring herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene expression, we compared the cellular uptake of 1-(2′-fluoro-2′-deoxy-d-arabinofuranosyl)-5-methyluracil (FMAU), 2′-fluoro-2′-deoxyarabinofuranosyl-5-ethyluracil (FEAU), 2′-fluoro-2′-deoxy-β-d-arabinofuranosyl-5-iodouracil (FIAU) and penciclovir (PCV) in both HSV1-tk and HSV1-sr39tk expressing cells. Procedures For stably transfected cell studies, C6 rat glioma cells, C6 HSV1-tk transfectant, C6 mutant HSV1-sr39tk transfectant, rat Morris hepatoma cells (MH3924A), and MH3924A HSV1-tk transfectant cells were used. For adenoviral infection studies, C6 rat glioma cells were exposed to serial titers of AdCMV–HSV1-tk, AdCMV–HSV1-sr39tk, or AdCMV–fluc for 24 hours. These cells were incubated with [¹⁴C]FMAU, [³H]FEAU, [¹⁴C]FIAU, and [³H]PCV, and cellular uptake of radioactivity was measured. Results [³H]FEAU exhibited the highest or second highest accumulation and the most selectivity regardless of the mode of gene transfer for both HSV1-tk and mutant HSV1-sr39tk reporter genes. Conclusion This combination of high accumulation and high selectivity for both HSV1-tk and HSV1-sr39tk makes suitably radiolabeled FEAU a promising candidate as a radiotracer for imaging HSV1-tk/HSV1-sr39tk gene expression in living subjects.     

125I粒子植入对兔正常肝组织的损伤效应

目的 探索125I粒子植入对兔正常肝组织的损伤效应.方法 新西兰大白兔36只,随机分为3个实验组和1个对照组,每组9只.实验组兔行经皮肝穿刺后植入放射活度分别为0.6、0.9、1.4 mCi的125I粒子,其中1.4 mCi为两枚0.7 mCi的粒子紧密并排植入形成,对照组植入1枚空粒子.粒子植入后2、4、8、16周时抽取耳缘静脉血,行血常规和肝、肾功能检测;4、8、16周时分批处死动物,取出粒原旁肝组织行光镜、电镜及凋亡检测.结果 ①1.4 mCi粒子植入2周时谷丙转氨酶(ALT)显著升高(P＜0.05),4、8、16周时降至术前水平,该组其他血液化验指标未见明显改变;其他组别的各项血液化验指标植入前后均未见明显改变;②光镜下观察显示粒子植入前后除汇管区可见炎症细胞浸润外,未见明显肝细胞形态学改变;透射电镜观察显示1.4 mCi组4、8、16周时可见相似的肝细胞凋亡超微结构变化,其他组别未见明显的超微结构改变;凋亡检测显示与其他组别相比,1.4 mCi组4周可见明显的细胞凋亡(P＜0.05),而该组8周、16周时凋亡细胞指数显著升高(P＜0.05),16周时凋亡与8周时凋亡差异无统计学意义(P＜0.05),其他各组均未见明显凋亡现象.结论 肝脏植入125I粒子是一种安全的微创技术,但应避免高活度的粒子(活度大于0.7 mCi)植入时出现重叠现象,以预防局部肝组织受到损伤.     

First Evaluation of [11C]R116301 as an In Vivo Tracer of NK1 Receptors in Man

Purpose  NK1 receptors have been implicated in various neuropsychiatric and other disorders. R116301 is a selective NK1 receptor antagonist. In this pilot study, [¹¹C]R116301 was evaluated as a potential positron emission tomography (PET) ligand for the NK1 receptor. Procedures  Two dynamic PET studies were performed in three normal volunteers before and after a blocking dose of aprepitant. Data were analyzed using striatum to cerebellum standardized uptake value (SUV) ratios. Results  Baseline SUV ratios at 60–90 min after injection ranged from 1.22 to 1.70. Following aprepitant administration, this specific signal was completely blocked. Aprepitant administration did not significantly affect uptake in cerebellum, confirming the absence of NK1 receptors in cerebellum. Conclusion  These preliminary results indicate that [¹¹C]R116301 has potential as a radioligand for in vivo assessment of NK1 receptors in the human brain.     

Cytotoxic T lymphocyte-based control of simian immunodeficiency virus replication in a preclinical AIDS vaccine trial

Recently, encouraging AIDS vaccine trials in macaques have implicated cytotoxic T lymphocytes (CTLs) in the control of the simian human immunodeficiency virus SHIV89.6P that induces acute CD4(+) T cell depletion. However, none of these vaccine regimens have been successful in the containment of replication of the pathogenic simian immunodeficiency viruses (SIVs) that induce chronic disease progression. Indeed, it has remained unclear if vaccine-induced CTL can control SIV replication. Here, we show evidence suggesting that vaccine-induced CTLs control SIVmac239 replication in rhesus macaques. Eight macaques vaccinated with DNA-prime/Gag-expressing Sendai virus vector boost were challenged intravenously with SIVmac239. Five of the vaccinees controlled viral replication and had undetectable plasma viremia after 5 wk of infection. CTLs from all of these five macaques rapidly selected for escape mutations in Gag, indicating that vaccine-induced CTLs successfully contained replication of the challenge virus. Interestingly, analysis of the escape variant selected in three vaccinees that share a major histocompatibility complex class I haplotype revealed that the escape variant virus was at a replicative disadvantage compared with SIVmac239. These findings suggested that the vaccine-induced CTLs had "crippled" the challenge virus. Our results indicate that vaccine induction of highly effective CTLs can result in the containment of replication of a highly pathogenic immunodeficiency virus.     

Radioimmunoassay of plasma carcinoembryonic antigen (CEA): Consideration of the results of two methods

Summary The two methods used to analyze 384 plasma samples were the carcinoembryonic antigen test (CRT) performed at the Roche laboratories and the direct radioimmunoassay plasma carcinoembryonic antigen (DRPC) technique. The first test, which is quantitative, gave many false positives below the 5 ng/ml level (also when used in a larger series of 4,628 subjects), thus invalidating its use for detection of gastrointestinal neoplasms. The DRPC technique was positive in 62.3 % of 101 cases of gastrointestinal adenocarcinoma and gave very few false positives.     

Loss of HIV-1-specific CD8+ T cell proliferation after acute HIV-1 infection and restoration by vaccine-induced HIV-1-specific CD4+ T cells

Virus-specific CD8(+) T cells are associated with declining viremia in acute human immunodeficiency virus (HIV)1 infection, but do not correlate with control of viremia in chronic infection, suggesting a progressive functional defect not measured by interferon gamma assays presently used. Here, we demonstrate that HIV-1-specific CD8(+) T cells proliferate rapidly upon encounter with cognate antigen in acute infection, but lose this capacity with ongoing viral replication. This functional defect can be induced in vitro by depletion of CD4(+) T cells or addition of interleukin 2-neutralizing antibodies, and can be corrected in chronic infection in vitro by addition of autologous CD4(+) T cells isolated during acute infection and in vivo by vaccine-mediated induction of HIV-1-specific CD4(+) T helper cell responses. These data demonstrate a loss of HIV-1-specific CD8(+) T cell function that not only correlates with progressive infection, but also can be restored in chronic infection by augmentation of HIV-1-specific T helper cell function. This identification of a reversible defect in cell-mediated immunity in chronic HIV-1 infection has important implications for immunotherapeutic interventions.     

Effects of in vivo CD8(+) T cell depletion on virus replication in rhesus macaques immunized with a live, attenuated simian immunodeficiency virus vaccine

The role of CD8(+) T lymphocytes in controlling replication of live, attenuated simian immunodeficiency virus (SIV) was investigated as part of a vaccine study to examine the correlates of protection in the SIV/rhesus macaque model. Rhesus macaques immunized for >2 yr with nef-deleted SIV (SIVmac239Deltanef) and protected from challenge with pathogenic SIVmac251 were treated with anti-CD8 antibody (OKT8F) to deplete CD8(+) T cells in vivo. The effects of CD8 depletion on viral load were measured using a novel quantitative assay based on real-time polymerase chain reaction using molecular beacons. This assay allows simultaneous detection of both the vaccine strain and the challenge virus in the same sample, enabling direct quantification of changes in each viral population. Our results show that CD8(+) T cells were depleted within 1 h after administration of OKT8F, and were reduced by as much as 99% in the peripheral blood. CD8(+) T cell depletion was associated with a 1-2 log increase in SIVmac239Deltanef plasma viremia. Control of SIVmac239Deltanef replication was temporally associated with the recovery of CD8(+) T cells between days 8 and 10. The challenge virus, SIVmac251, was not detectable in either the plasma or lymph nodes after depletion of CD8(+) T cells. Overall, our results indicate that CD8(+) T cells play an important role in controlling replication of live, attenuated SIV in vivo.     

The in vitro Uptake of Vitamin B12 by Diphyllobothrium Latum and its Blockage by Intrinsic Factor

^99mTc-labelling procedures are described. They are standardized and simple enough for technicians without special chemical training to perform, so that smaller hospitals with facilities for isotope scintigraphy can produce their own ^99mTc-labelled compounds. The experimental background for the procedures is described.     

Evaluation of a proposed index of myocardial blood flow in dogs

An index of myocardial blood flow developed from studies with a computer and a mechanical circulatory model has been investigated in 18 dogs. An intravenous injection of¹³¹I is used with external scintillation detection over the left ventricle and the lung. The index is given by the ratio of the half time of the downslope of the curve recorded from the left ventricle to that of the curve recorded from the lung. This index has been compared with that suggested by Mena et al in which the left ventricular half time is compared with the half time of the brain curve. The effect on these indices and on the clearance of¹³³Xe of clamping the anterior descending branch of the left coronary artery has been observed. Statistically significant differences in both indices and in Xenon clearance were seen to be induced by coronary artery clamping but there was overlap between the clamped and unclamped values. The method used for coronary clamping also affected the results.     

Low dose Leishmania major promotes a transient T helper cell type 2 response that is down-regulated by interferon gamma-producing CD8+ T cells

An unresolved issue in the field of T helper (Th) cell development relates to the findings that low doses of antigen promote Th2 cell development in vitro, whereas several classic in vivo studies suggest the opposite. Here we resolve this paradox by studying the early immune response in mice after infection with different doses of Leishmania major. We found that low parasite doses induced a Th2 response in C57BL/6 (B6) mice, whereas high doses induced a Th1 response. However, the Th2 response in low dose-infected mice was transient and the animals healed. The appearance of a Th1 response after low dose infection was dependent upon the concomitant activation of interferon gamma-producing CD8+ T cells. In the absence of CD8+ T cells, the Th2 response was maintained. However, either neutralization of interleukin (IL)-4 or administration of IL-12 promoted a Th1 response after low dose infection of CD8-deficient mice, indicating that the required role for CD8+ T cells was limited to modulation of CD4+ T cell responses. Thus, the discrepant results seen between in vivo and in vitro studies on the effects of antigen dose on Th cell differentiation may depend upon whether CD8+ T cells participate in the immune response.     

全模型迭代重建算法评价125I粒子植入术后CT图像

目的 探讨全模型迭代重建（IMR）算法评价¹²⁵I粒子植入术后图像的应用价值。方法 收集接受¹²⁵I粒子植入术及术后CT随访的16例腹部肿瘤患者,对扫描原始数据分别以滤波反投影法（FBP）、IMR和高级重建迭代（iDose⁴）算法进行重建,比较3种重建方法图像的噪声、伪影指数（AI）、CNR和主观评分。结果 FBP重建图像的噪声、CNR及AI分别为（58.65±4.03） HU、1.09±0.43和51.60±9.23,iDose⁴图像分别为（48.38±5.34） HU、1.29±0.48和43.77±4.91,IMR图像分别为（41.46±3.44） HU、1.58±0.56和38.51±4.64,3种重建方法图像的噪声、CNR及AI两两比较差异均有统计学意义（P均<0.05）。IMR图像的主观图像质量评分显著高于FBP和iDose⁴算法图像（调整后P<0.001,P=0.011）。结论 IMR算法获得的图像质量较高,可有效减少¹²⁵I粒子伪影,为¹²⁵I粒子植入术后随访与疗效评估提供了更佳方法。     

CD40-independent pathways of T cell help for priming of CD8(+) cytotoxic T lymphocytes

In many cases, induction of CD8(+) CTL responses requires CD4(+) T cell help. Recently, it has been shown that a dominant pathway of CD4(+) help is via antigen-presenting cell (APC) activation through engagement of CD40 by CD40 ligand on CD4(+) T cells. To further study this three cell interaction, we established an in vitro system using dendritic cells (DCs) as APCs and influenza hemagglutinin (HA) class I and II peptide-specific T cell antigen receptor transgenic T cells as cytotoxic T lymphocyte precursors and CD4(+) T helper cells, respectively. We found that CD4(+) T cells can provide potent help for DCs to activate CD8(+) T cells when antigen is provided in the form of either cell lysate, recombinant protein, or synthetic peptides. Surprisingly, this help is completely independent of CD40. Moreover, CD40-independent CD4(+) help can be documented in vivo. Finally, we show that CD40-independent T cell help is delivered through both sensitization of DCs and direct CD4(+)-CD8(+) T cell communication via lymphokines. Therefore, we conclude that CD4(+) help comprises at least three components: CD40-dependent DC sensitization, CD40-independent DC sensitization, and direct lymphokine-dependent CD4(+)-CD8(+) T cell communication.     

Neonatal tumor necrosis factor alpha promotes diabetes in nonobese diabetic mice by CD154-independent antigen presentation to CD8(+) T cells

Neonatal islet-specific expression of tumor necrosis factor (TNF)-alpha in nonobese diabetic mice promotes diabetes by provoking islet-infiltrating antigen-presenting cells to present islet peptides to autoreactive T cells. Here we show that TNF-alpha promotes autoaggression of both effector CD4(+) and CD8(+) T cells. Whereas CD8(+) T cells are critical for diabetes progression, CD4(+) T cells play a lesser role. TNF-alpha-mediated diabetes development was not dependent on CD154-CD40 signals or activated CD4(+) T cells. Instead, it appears that TNF-alpha can promote cross-presentation of islet antigen to CD8(+) T cells using a unique CD40-CD154-independent pathway. These data provide new insights into the mechanisms by which inflammatory stimuli can bypass CD154-CD40 immune regulatory signals and cause activation of autoreactive T cells.     

An Evaluation of the Theorell Method for the Determination of Total Serum Cholesterol

Five different ⁹⁹Mo/^99mTc generators of the AI₂O₃ type have been studied. Results for recovery of ^99mTcO^?4, radionuclide purity, radiochemical purity, and aluminium content of the eluates are presented. A rapid thin-layer chromatographic method for the determination of radiochemical purity is introduced. Atomic absorption spectroscopy and neutron activation analysis was used to determine soluble and particulate aluminium, respectively. The eluates generally showed high and satisfactory radionuclidic and radiochemical purity. Aluminium was found at highly variable concentrations and was found to be present essentially in soluble form.