Determinants of Plasma Renin Activity: Role of a Human Renin Gene Variant as a Genetic Factor

The plasma renin activity (PRA) is affected by a number of environmental factors. However, significant heritability has been shown for the activity. A hypothesis that a candidate regulatory single-nucleotide polymorphism, C-5312T, of human renin gene should have a significant effect on PRA was elucidated and updating of independent determinants of PRA was attempted.Cross sectional study.Outpatient study.We enrolled consecutive 810 subjects who had consulted our hospitals for lifestyle-related diseases.Genotypes were assayed with genomic DNA for C-5312T. Among the genetic variants, the difference of PRA was evaluated. Monovariate linear regression analysis was performed to test the correlation between PRA and clinical variables. Finally, stepwise multiple regression analysis was performed to evaluate the independent determinants.On comparing 2 genotype groups, CC/CT and T allele homozygote, the geometric means of PRA were 0.778 and 0.941 ng/ml/h, respectively (F = 5.992, P = 0.015). Monovariate linear regression analysis revealed that a number of variables have a significant correlation with the activity, including urinary salt excretion. A stepwise multivariate regression analysis revealed that renin C-5312T variant (TT) is one of the independent determinants of PRA.Thus, for the first time, a human renin gene variant was associated with a significant increase in PRA as a genetic factor and the independent determinants for the activity were updated including genetic factor.     

Improved Stability and Practicality for Synthesis of 4-Borono-2-[18F]fluoro-l-phenylalanine by Combination of [18O]O2 Single-Use and [18F]CH3COOF Labeling Agents

Purpose4-Borono-2-[¹⁸F]fluoro-l-phenylalanine ([¹⁸F]FBPA) synthesized with [¹⁸F]F₂, produced using the ¹⁸O(p, n)¹⁸F reaction, has been reported for increasing radioactivity. However, a dedicated system and complex procedure is required to reuse the costly [¹⁸O]O₂ gas; also, the use of [¹⁸F]F₂ as a labeling agent reduces the labeling rate and radiochemical purity. We developed a stable and practical method for [¹⁸F]FBPA synthesis by combining [¹⁸F]F₂, produced using a [¹⁸O]O₂ single-use system, and a [¹⁸F]CH₃COOF labeling agent.MethodsThe produced [¹⁸F]F₂ was optimized, and then [¹⁸F]FBPA was synthesized. For passivation of the target box, 0.5% F₂ was pre-irradiated in argon. Gaseous products were discarded; the target box was filled with [¹⁸O]O₂ gas, and then irradiated (first irradiation). Then, the [¹⁸O]O₂ gas was discarded, 0.05–0.08% F₂ in argon was fed into the target box, and it was again irradiated (second irradiation). The [¹⁸F]F₂ obtained after this was passed through a CH₃COONa column, converting it into the [¹⁸F]CH₃COOF labeling agent, which was then used for [¹⁸F]FBPA synthesis.ResultsThe mean amount of as-obtained [¹⁸F]F₂ was 55.0 ± 3.3 GBq and that of as-obtained [¹⁸F]CH₃COOF was 21.6 ± 1.4 GBq after the bombardment. The radioactivity and the radiochemical yield based on [¹⁸F]F₂ of [¹⁸F]FBPA were 4.72 ± 0.34 GBq and 12.2 ± 0.1%, respectively. The radiochemical purity and molar activity were 99.3 ± 0.1% and 231 ± 22 GBq/mmol, respectively.ConclusionWe developed a method for [¹⁸F]FBPA production, which is more stable and practical compared with the method using [¹⁸O]O₂ gas-recycling and [¹⁸F]F₂ labeling agent.     

Interleukin-12 activates human γδ T cells: synergistic effect of tumor necrosis factor-α

γδ T cell populations are known to expand in response to intracellular bacterial infectious agents regardless of previous priming. We have shown previously that soluble factor(s) produced by Mycobacterium-stimulated monocytes activate cord blood γδ T cells to proliferate. In this study, we investigated whether cytokines produced by monocytes are responsible for γδ T cell activation in vitro: interleukin (IL)-1β, IL-6, IL-8, IL-12, tumor necrosis factor (TNF)-α and granulocyte/macrophage colony-stimulating factor were examined. Recombinant human IL-12 stimulated γδ T cells, but not αβ T cells in peripheral blood mononuclear cells, to express CD25 on their surfaces, and to expand in number in vitro. IL-12-primed γδ T cell numbers increased to a greater extent in the culture to which exogenous IL-2 (5 U/ml) was added. Anti-TNF-α monoclonal antibody inhibited IL-12-induced up-regulation of CD25 on γδ T cells, suggesting that endogenous TNF-α may play a role in IL-12-induced activation of γδ T cells. Recombinant TNF-α synergistically augmented IL-12-induced activation of γδ T cells. Furthermore, IL-12 up-regulated TNF receptors on γδ T cells in vitro: TNF-α binding to its receptor induced CD25 expression on the γδ T cells in an autocrine or paracrine fashion, or perhaps both. It also became evident that both IL-12 and TNF-α were produced by mycobacterial lysate-stimulated monocytes. Taken together, these results suggest that upon confrontation with mycobacterial organisms, γδ T cells can be quickly and antigen-nonspecifically activated by soluble factors including IL-12 and TNF-α, both of which are produced by mononuclear phagocytes in response to mycobacterial organisms.     

Brain trauma induces expression of diacylglycerol kinase ζ in microglia

Diacylglycerol kinase (DGK) is an enzyme which phosphorylates a second messenger diacylglycerol and consists of a family of isozymes that differ in terms of structural motifs, enzymological property, and cell and tissue distribution. One of the isozymes, DGKζ was originally shown to be expressed in various kinds of neurons under physiological conditions. However, we unexpectedly found that under pathological conditions, such as cerebral infarction, DGKζ-immunoreactivity is detected in non-neuronal cells, although it remained to be elucidated in detail which cell types are responsible for the induced expression of DGKζ in this setting. To further elucidate functional implications of DGKζ in non-neuronal cells we performed detailed immunohistochemical analysis of DGKζ using rat brain cryoinjury model. As early as 1 h after cryoinjury, DGKζ-immunoreactivity was greatly decreased in the afflicted cerebral cortex and almost disappeared in the necrotic core. On day 7 after cryoinjury, however, DGKζ-immunoreactivity reappeared in this area. DGKζ-immunoreactivity was clearly detected in Iba1-immunoreactive cells of an oval or ameboid shape in the scar region, which represent activated microglia and/or macrophages. On the other hand, DGKζ-immunoreactivity was not detected in Iba1-immunoreactive, resting microglia of ramified and dendritic configuration in the intact cortex. Furthermore, DGKζ-immunoreactive cells were also positive for a microglia marker GLUT5 in the scar region, but never for an astrocyte marker GFAP. Taken together, the present study reveals that DGKζ is induced in activated microglia in brain trauma, suggesting the functional significance of DGKζ in this process.     

Modulation of the Effect of l-β-D-Arabinofuranosylcytosine by 6-Mercaptopurine in L1210 Cells

In L1210 cells incubated with l- β -D-arabinofuranosylcytosine (ara-C), 6-mercaptopurine (6-MP) significantly potentiated 1- β -D-arabinofuranosylcytosme 5'-triphosphate (ara-CTP) accumulation and ara-C incorporation into DNA (ara-C/DNA). The cytotoxicity of these two drugs was assessed to be at least additive by clonogenic assay. l- β -D-Arabinofuranosylnracil (ara-U) level in a cell suspension was suppressed by 6-MP in a concentration-dependent fashion, though intracellular cytidine deaminase (CDD) activity was not affected by 6-MP. In addition, extracted CDD activity was not directly inhibited by 6-MP or by its intracellular metabolites in vitro. After preincubation in the presence or absence of 6-MP, the cell suspension was fractionated to obtain the spent medium and cell pellet. Then, each fraction was incubated with ara-C. Ara-U formation in the spent medium was found to increase conspicuously in relation to the time of preincubation in the control and it was suppressed by 6-MP pretreatment. Ara-U formation in the cell compartment increased slightly in relation to the time of preincubation in the control and substantially no suppression of ara-U formation was observed in spite of 6-MP pretreatment. In conclusion, intracellularly synthesized CDD was thought to be rapidly shed into the medium and the released CDD could play an important role in ara-C inactivation. 6-MP interrupted some step between synthesis and shedding of CDD, resulting in a decrease of the ara-C deamination in the medium and enhancement of its antileukemic effect.     

Usefulness of dynamic digitized cerebral parenchymography for cerebral vascular disease

Aortic arch injections according to Theron's method have been performed in patients with cerebral ischemia. Digital subtraction angiograms with modified windowing (low and narrow) have been used for better visualization of cerebral parenchymal condition. This "cerebral parenchymography" allows much easier understanding of cerebral parenchymal vascularization on angiographic imaging. Although further study is necessary to estimate accurate cerebral blood flow, this technique can enable an easy and quick understanding of the overall cerebral hemodynamics.     

Simvastatin and lovastatin, but not pravastatin, interact with MDR1

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, pravastatin, was compared with simvastatin and lovastatin from the viewpoint of susceptibility to interaction with or via the multidrug transporter, MDR1 (P-glycoprotein). This was carried out using the MDR1-overexpressing cell line LLC-GA5-COL150, established by transfection of MDR1 cDNA into porcine kidney epithelial LLC-PK1 cells, and [3H]digoxin, which is a well-documented substrate for MDR1. Pravastatin, at 25-100 microM, had no effect on the transcellular transport of [3H]digoxin whereas simvastatin and lovastatin suppressed the basal-to-apical transport of [3H]digoxin and increased the apical-to-basal transport. It was suggested that recognition by MDR1 was due to the hydrophobicity. In conclusion, simvastatin and lovastatin are susceptible to interaction with or via MDR1, but pravastatin is not. This is important information when selecting the HMG-CoA reductase inhibitors for patients taking drugs that are MDR1 substrates.     

Pulmonary artery stenting for recurrent lung cancer after left pneumonectomy

We present a case of a patient with stenosis of the pulmonary artery which was successfully treated by implantation of a vascular endoprosthesis. A 50-year-old man underwent left pneumonectomy for lung cancer. Eleven months later, a computed tomographic scan revealed a soft tissue mass in the mediastinum and there was severe stenosis of the remaining right main pulmonary artery. A self-expandable vascular endoprosthesis was implanted in the stenotic portion. We used percutaneous cardiopulmonary support (PCPS) during the procedure. We recommend the technique of pulmonary artery stenting using PCPS as efficacious and safe.