18F-FBHGal for asialoglycoprotein receptor imaging in a hepatic fibrosis mouse model

Quantification of the expression of asialoglycoprotein receptor (ASGPR), which is located on the hepatocyte membrane with high-affinity for galactose residues, can help assess ASGPR-related liver diseases. A hepatic fibrosis mouse model with lower asialoglycoprotein receptor expression was established by dimethylnitrosamine (DMN) administration. This study developed and demonstrated that 4-¹⁸F-fluoro-N-(6-((3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)hexyl)benzamide (¹⁸F-FBHGal), a new ¹⁸F-labeled monovalent galactose derivative, is an asialoglycoprotein receptor (ASGPR)-specific PET probe in a normal and a hepatic fibrosis mouse models. Immunoassay exhibited a linear correlation between the accumulation of GalH-FITC, a fluorescent surrogate of FBHGal, and the amount of ASGPR. A significant reduction in HepG2 cellular uptake (P <0.0001) was observed using confocal microscopy when co-incubated with 0.5 μM of asialofetuin, a well known ASGPR blocking agent. Animal studies showed the accumulation of ¹⁸F-FBHGal in fibrosis liver (14.84 ± 1.10 %ID/g) was appreciably decreased compared with that in normal liver (20.50 ± 1.51 %ID/g, P <0.01) at 30 min post-injection. The receptor indexes (liver/liver-plus-heart ratio at 30 min post-injection) of hepatic fibrosis mice derived from both microPET imaging and biodistribution study were significantly lower (P <0.01) than those of normal mice. The pharmacokinetic parameters (T_1/2α, T_1/2β, AUC and Cl) derived from microPET images revealed prolonged systemic circulation of ¹⁸F-FBHGal in hepatic fibrosis mice compared to that in normal mice. The findings in biological characterizations suggest that ¹⁸F-FBHGal is a feasible agent for PET imaging of hepatic fibrosis in mice and may provide new insights into ASGPR-related liver dysfunction.     

Synthesis and biodistribution of a new class of 99mTc-labeled fatty acid analogs for myocardial imaging

A series of ^99mTc-bis(aminoethanethiol)-fatty acid (^99mTc-BAT-fatty acid) analogs were synthesized and evaluated as potential tracers of myocardial metabolism. The BAT-fatty acid precursors were prepared using a new synthetic route that avoids the use of strong reducing agents such as lithium aluminum hydride. Biodistribution studies of the no-carrier-added ^99mTc-complexes were conducted in rats using [¹²⁵I]IPPA as an internal standard. The myocardial uptake of the ^99mTc-BAT-fatty acid analogs was significantly less than that of [¹²⁵I]IPPA and indicates the ^99mTc analogs are not suitable candidates for SPECT-based myocardial imaging studies.     

Tetrazolium Reduction-Malachite Green Method for Assessing the Viability of Filamentous Bacteria in Activated Sludge

A method was developed to assess the activity of filamentous bacteria in activated sludge. It involves the incubation of activated sludge with 2(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride followed by staining with malachite green. Both cells and 2(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride-formazan crystals can be observed in prepared specimens by using bright-field microscopy. This procedure allowed us to distinguish between inactive and actively metabolizing filaments after chlorine application to control the bulking of activated sludge.     

Preparation,radiolabeling and biodistribution of a new class of bisaminothiol (BAT) ligands as possible imaging agents

In developing new ligands as potential brain and heart perfusion imaging agents two ligands based upon N₂S₂ donor atoms with the biphenyl backbone were synthesized. Biphenyl-2,2′-bis(N-1-amino-2-methyl-propane-2-thiol) (BP-BAT-TM) and biphenyl-2,2′-bis(N-1-amino-2-ethyl-butane-2-thiol) (BP-BAT-TE) form stable, neutral and lipid soluble complexes with [^99mTc]pertechnetate in the presence of tin(II) tartarate as a reducing agent. The [^99mTc]BP-BAT-TM complex penetrates the blood-brain barrier following i.v. injection into rats. Washout from the brain is fast, indicating no retention. The biodistribution of [^99mTc]BP-BAT-TE in rats showed an intitial heart uptake (0.8% /organ, at 2 min) and a slow washout (0.74% at 15 min). No brain uptake was found (0.05%). Significant uptake and retention in liver was observed. An imaging study of [^99mTc]BP-BAT-TE in a monkey showed no brain uptake and a clear indication of liver uptake and gall bladder clearance. These results indicate that this ligand system may be suitable as the basic core structure for the development of new imaging agents. Further studies with structural variations in the biphenyl backbone are warranted to develop new ^99mTc imaging agents for clinical applications.     

Amidino-substituted aromatic heterocycles as probes of the specificity pocket of trypsin-like proteases.

The effect of pargyline on the uptake of acetaldehyde (in the presence of pyrazole) by isolated rat liver cells was studied after incubating the liver cells for 0, 10, 30, 45, and 60 min with 0.40, 1.30, and 2.6 mm pargyline. Without any incubation period, pargyline had no effect on acetaldehyde uptake. With increasing time of incubation, there was a progressive increase in the extent of inhibition of acetaldehyde uptake by pargyline. This suggests the possibility that pargyline is metabolized to the effective inhibitor or the incubation period allows pargyline to reach its site(s) of action. Pargyline was also a more effective inhibitor of the uptake of lower concentrations of acetaldehyde, e.g., 0.167 mm, than of higher concentrations (1.0 mm) of acetaldehyde, especially after short incubation periods or when pyrazole was omitted from the reaction medium. After a 20- to 30-min incubation period, pargyline inhibited the control rate of ethanol oxidation by the liver cells, as well as the accelerated rate of ethanol oxidation found in the presence of pyruvate or an uncoupling agent. Pargyline had no effect on hepatic oxygen consumption. During ethanol oxidation, a time-dependent release of acetaldehyde into the medium was observed. Pyruvate, by increasing the rate of ethanol oxidation, increased the output of acetaldehyde five- to tenfold. Pargyline increased the output of acetaldehyde two- to threefold, despite decreasing the rate of ethanol metabolism by the liver cells. These data indicate that pargyline inhibits the low K_m aldehyde dehydrogenase in intact rat liver cells and that this enzyme plays the major role in oxidizing the acetaldehyde which arises during the metabolism of ethanol. Although most of the acetaldehyde generated during the oxidation of ethanol is removed by the liver cells in an effective manner, changes in the activity of aldehyde dehydrogenase or the rate of acetaldehyde generation significantly alter the hepatic output of acetaldehyde.     

Synthesis and bioevaluation of radioiodinated nitroimidazole hypoxia imaging agents by one-pot click reaction

Eight radioiodinated 2-nitroimidazole derivatives for use as hypoxia imaging agents were synthesized by one-pot click reaction using four azides, two alkynes, and [¹³¹I]iodide ions and evaluated by hypoxic cellular uptake and biodistribution experiments. The results suggested that radiotracers with suitable partition coefficients (log P: −0.2–1.2) were more likely to have higher hypoxic cellular uptake. Among these eight molecules, [¹³¹I]15 ([¹³¹I]-(5-iodo-1-(2-(2-(2-nitro-1H-imidazol-1-yl)ethoxy)ethyl)-4-((2-nitro-1H-imidazol-1-yl)methyl)-1H-1,2,3-triazole)) had a suitable log P (0.05 ± 0.03) and contained two 2-nitroimidazole groups. The hypoxic/aerobic cellular uptake ratio of [¹³¹I]15 was 4.4 ± 0.5, and the tumor/blood (T/B) and tumor/muscle (T/M) ratios were 2.03 ± 0.45 and 6.82 ± 1.70, respectively. These results suggested that [¹³¹I]15 was a potential hypoxia imaging agent.     

The effects of ascorbic acid deficiency and repletion on pulmonary, renal, and hepatic drug metabolism in the guinea pig.

The effects of ascorbic acid (AA) deficiency on microsomal and soluble (postmicrosomal supernatant) enzymes which catalyze drug metabolism were studied in the guinea pig liver, lung, and kidney, (i) Twenty-one days of AA depletion produced a 50–60% decrease in hepatic cytochrome P-450 levels, 20–30% decreases in renal levels, but no significant changes in pulmonary cytochrome P-450 content. Upon repletion of ascorbic acid, recovery to control levels occurred within 7 days. (ii) The decreases in hepatic cytochrome P-450 in scurvy were not accompanied by a corresponding increase in cytochrome P-420. (iii) Aminopyrine N-demethylation decreased by 40% in livers of deficient animals, and recovered within 3 days, but there were no corresponding changes in lungs and kidneys. (iv) There were no significant alterations of NADPH-cytochrome c reductase activity in scorbutic animals in any of the three organs. (v) Activity of “native” UDP-glucuronyl transferase was increased in liver microsomes after 21 days of deficiency, but this apparent increase was not observed when the enzyme was fully activated in vitro with UDP N-acetylglucosamine. “Native” UDP-glucuronyl transferase was increased in kidneys of deficient animals and unchanged in lungs. (vi) In the postmicrosomal supernatant, glutathione S-aryl transferase activity in deficient livers decreased tc 50% of control and did not fully recover after 14 days of ascorbic acid repletion. These changes were not seen in kidney and lung. (vii) Also in the postmicrosomal supernatant, p-aminobenzoic acid (PABA) N-acetyl transferase activity increased in the kidneys of deficient animals, but was unchanged in liver and lungs. (viii) Addition of ascorbic acid in vitro to hepatic microsomes prepared from scorbutic animals had no effect on activities of aminopyrine N-demethylase, NADPH-cytochrome c reductase, PABA N-acetyl transferase, and glutathione S-aryl transferase.     

Radiosynthesis and biological evaluation of an fluorine-18 labeled galactose derivative [18F]FPGal for imaging the hepatic asialoglycoprotein receptor

The asialoglycoprotein receptor (ASGPR) is abundantly expressed on the surface of hepatocytes where it recognizes and endocytoses glycoproteins with galactosyl and N-acetylgalactosamine groups. Given its hepatic distribution, the asialoglycoprotein receptor can be targeted by positron imaging agents to study liver function using PET imaging. In this study, the positron imaging agent [¹⁸F]FPGal was designed to specifically target hepatic asialoglycoprotein receptor and its effectiveness was assessed in in vitro and in vivo models. The radiosynthesis of [¹⁸F]FPGal required 50 min with total radiochemical yields of [¹⁸F]FPGal from [¹⁸F]fluoride as 10% (corrected radiochemical yield). The K_d of [¹⁸F]FPGal to ASGPR in HepG2 cells was 1.99 ± 0.05 mM. Uptake values of 0.55% were observed within 30 min of incubation with HepG2 cells, which could be blocked by 200 mM d(+)-galactose (<0.1%). In vivo biodistribution analysis showed that the liver accumulation of [¹⁸F]FPGal at 30 min was 4.47 ± 0.96% ID/g in normal mice compared to 1.33 ± 0.07% ID/g in hepatic fibrotic mice (P < 0.01). Reduced uptake in the hepatic fibrosis mouse models was confirmed through PET/CT images at 30 min. Compared to normal mice, the standard uptake value (SUV) in the hepatic fibrosis mice was significantly lower when assessed through dynamic data collection for 1 h. Therefore, [¹⁸F]FPGal is a feasible PET probe that provide insight into ASGPR related liver disease.     

Effects of Metformin on Burn-Induced Hepatic Endoplasmic Reticulum Stress in Male Rats

Severe burn injury causes hepatic dysfunction that results in major metabolic derangements including insulin resistance and hyperglycemia and is associated with hepatic endoplasmic reticulum (ER) stress. We have recently shown that insulin reduces ER stress and improves liver function and morphology; however, it is not clear whether these changes are directly insulin mediated or are due to glucose alterations. Metformin is an antidiabetic agent that decreases hyperglycemia by different pathways than insulin; therefore, we asked whether metformin affects postburn ER stress and hepatic metabolism. The aim of the present study is to determine the effects of metformin on postburn hepatic ER stress and metabolic markers. Male rats were randomized to sham, burn injury and burn injury plus metformin and were sacrificed at various time points. Outcomes measured were hepatic damage, function, metabolism and ER stress. Burn-induced decrease in albumin mRNA and increase in alanine transaminase (p < 0.01 versus sham) were not normalized by metformin treatment. In addition, ER stress markers were similarly increased in burn injury with or without metformin compared with sham (p < 0.05). We also found that gluconeogenesis and fatty acid metabolism gene expressions were upregulated with or without metformin compared with sham (p < 0.05). Our results indicate that, whereas thermal injury results in hepatic ER stress, metformin does not ameliorate postburn stress responses by correcting hepatic ER stress.     

Fatty Acid Toxicity and Methyl Ketone Production in Aspergillus niger

Vegetative hyphae of Aspergillus niger rapidly converted caproic acid into 2-pentanone. More caproic acid was required for maximal ketone production at alkaline as compared to acidic pH values. Further increases in caproate concentrations at each pH value tested (4.5, 5.5, 6.5, 7.5, and 8.5) resulted in inhibition of ketone production and O₂ uptake. At alkaline pH values (8.5 and 7.5), oxygen uptake above the endogenous level and the production of 2-pentanone were parallel. This relationship did not hold at acidic pH values. At these pH values, ketone production continued (pH 6.5) or attained a maximum (pH 5.5 and 4.5) at caproate concentrations at which oxygen uptake was inhibited below endogenous levels. These data indicate that endogenous oxygen uptake was not inhibited by caproate at alkaline pH values at concentrations which did inhibit caproate oxidation and 2-pentanone production. Conversely, at acidic pH values, endogenous oxygen uptake was vigorously inhibited by caproate at concentrations at which exogenous fatty acid oxidation and 2-pentanone production were less affected. Simon-Beevers plots of these data showed that the undissociated acid was the permeant form of caproic acid. The fatty anion appeared to be the active or inhibitory form of caproate within the cell. Vegetative hyphae of A. niger were poorly buffered. Once the hyphae were washed and resuspended in phosphate buffer, they were well buffered towards inhibitory concentrations of caproic acid. These findings suggest that the primary mechanism(s) by which caproate inhibits oxygen uptake and ketone formation does not involve a change in the intracellular pH.     

Pulmonary Surfactant Model Systems Catch the Specific Interaction of an Amphiphilic Peptide with Anionic Phospholipid

Interfacial behavior was studied in pulmonary surfactant model systems containing an amphiphilic α-helical peptide (Hel 13-5), which consists of 13 hydrophobic and five hydrophilic amino acid residues. Fully saturated phospholipids of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) were utilized to understand specific interactions between anionic DPPG and cationic Hel 13-5 for pulmonary functions. Surface pressure (π)-molecular area (A) and surface potential (ΔV)-A isotherms of DPPG/Hel 13-5 and DPPC/DPPG (4:1, mol/mol)/Hel 13-5 preparations were measured to obtain basic information on the phase behavior under compression and expansion processes. The interaction leads to a variation in squeeze-out surface pressures against a mole fraction of Hel 13-5, where Hel 13-5 is eliminated from the surface on compression. The phase behavior was visualized by means of Brewster angle microscopy, fluorescence microscopy, and atomic force microscopy. At low surface pressures, the formation of differently ordered domains in size and shape is induced by electrostatic interactions. The domains independently grow upon compression to high surface pressures, especially in the DPPG/Hel 13-5 system. Under the further compression process, protrusion masses are formed in AFM images in the vicinity of squeeze-out pressures. The protrusion masses, which are attributed to the squeezed-out Hel 13-5, grow larger in lateral size with increasing DPPG content in phospholipid compositions. During subsequent expansion up to 35 mN m⁻¹, the protrusions retain their height and lateral diameter for the DPPG/Hel 13-5 system, whereas the protrusions become smaller for the DPPC/Hel 13-5 and DPPC/DPPG/Hel 13-5 systems due to a reentrance of the ejected Hel 13-5 into the surface. In this work we detected for the first time, to our knowledge, a remarkably large hysteresis loop for cyclic ΔV-A isotherms of the binary DPPG/Hel 13-5 preparation. This exciting phenomenon suggests that the specific interaction triggers two completely independent processes for Hel 13-5 during repeated compression and expansion: 1), squeezing-out into the subsolution; and 2), and close packing as a monolayer with DPPG at the interface. These characteristic processes are also strongly supported by atomic force microscopy observations. The data presented here provide complementary information on the mechanism and importance of the specific interaction between the phosphatidylglycerol headgroup and the polarized moiety of native surfactant protein B for biophysical functions of pulmonary surfactants.     

Linear sucrose transport in protoplasts from developing soybean cotyledons

Previous studies with isolated soybean cotyledon protoplasts revealed the presence of a saturable, simple diffusion, and nonsaturating carrier-mediated uptake of sucrose into soybean cotyledon cells. A proton/sucrose cotransport may be involved in the saturable sucrose uptake (Lin et al. 1984 Plant Physiol 75: 936-940 and Schmitt et al. 1984 Plant Physiol 75: 941-946). In this study, we investigated the linear sucrose uptake mechanism by treating isolated protoplasts with 15 micromolar p-trifluoromethoxy-carbonylcyanide phenylhydrazone (FCCP) or 100 micromolar p-chloromecuribenzenesulfonic acid to eliminate the saturable uptake. We found: (a) increasing external pH decreases the linear sucrose uptake; (b) fusicoccin at 20 micromolar stimulates and FCCP at 15 micromolar inhibits this linear sucrose uptake; and (c) the ratio of the initial influx of proton to sucrose is close to one in both saturable and nondiffusive linear (difference between the total linear and diffusive components) uptakes. The results suggest that a proton/sucrose cotransport is also involved in the nondiffusive linear sucrose uptake into soybean cotyledon cells.     

Synthesis and bio-evaluation of a new fatty acid derivative for myocardial imaging

Development of a (99m)Tc-fatty acid analogue is of interest, as (99m)Tc is logistically advantageous over the cyclotron-produced (11)C and (123)I. Synthesis of a 16 carbon fatty acid derivative and its radiolabeling with the novel [(99m)TcN(PNP)](2+) core is described here. Hexadecanedioic acid was conjugated to cysteine in an overall yield of 55%. This ligand could be labeled with (99m)Tc via the [(99m)TcN(PNP)](2+) core, in 80% yield, as a mixture of two isomers (syn and anti). The major isomer isolated by HPLC was used for bioevaluation studies in swiss mice and compared with radioiodinated iodophenyl pentadecanoic acid (IPPA), an established agent for myocardial metabolic imaging. (99m)Tc-labeled complex cleared faster from the non-target organs, namely, liver, lungs, and blood compared to that of [(125)I]-IPPA. However, the complex exhibited lower uptake and faster washout from the myocardium as compared to [(125)I]-IPPA.     

Defective uptake and utilization of long chain fatty acids in muscle and adipose tissues of CD36 knockout mice

The transmembrane protein CD36 has been identified in isolated cell studies as a putative transporter of long chain fatty acids. In humans, an association between CD36 deficiency and defective myocardial uptake of the fatty acid analog 15-(p-iodophenyl)-3-(R, S)-methyl pentadecanoic acid (BMIPP) has been reported. To determine whether this association represents a causal link and to assess the physiological role of CD36, we compared tissue uptake and metabolism of two iodinated fatty acid analogs BMIPP and 15-(p-iodophenyl) pentadecanoic acid (IPPA) in CD36 null and wild type mice. We also investigated the uptake and lipid incorporation of palmitate by adipocytes isolated from both groups. Compared with wild type, uptake of BMIPP and IPPA was reduced in heart (50-80%), skeletal muscle (40-75%), and adipose tissues (60-70%) of null mice. The reduction was associated with a 50-68% decrease in label incorporation into triglycerides and in 2-3-fold accumulation of label in diglycerides. Identical results were obtained from studies of [(3)H]palmitate uptake in isolated adipocytes. The block in diglyceride to triglyceride conversion could not be explained by changes in specific activities of the key enzymes long chain acyl-CoA synthetase and diacylglycerol acyltransferase, which were similar in tissues from wild type and null mice. It is concluded that CD36 facilitates a large fraction of fatty acid uptake by heart, skeletal muscle, and adipose tissues and that CD36 deficiency in humans is the cause of the reported defect in myocardial BMIPP uptake. In CD36-expressing tissues, uptake regulates fatty acid esterification at the level of diacylglycerol acyltransferase by determining fatty acyl-CoA supply. The membrane transport step may represent an important control site for fatty acid metabolism in vivo.     

Molecular mechanisms for the hepatic uptake of magnetic resonance imaging contrast agents

The mechanisms were investigated for the hepatic transport of 4 different gadolinium complexes used as contrast agents for magnetic resonance imaging (MRI). In basolateral rat hepatocyte plasma membrane vesicles, Gd-DTPA uptake was indistinguishable from non-specific binding to vesicles; Gd-BOPTA and Gd-EOB-DTPA entered plasma membrane vesicles following a linear, concentration-dependent mechanism up to 1.5 mM of substrate. By contrast, Gd-B 20790 uptake followed a saturative kinetic with an apparent Km of 92 +/- 15 microM and a Vmax of 143 +/- 42 pmol/mg prot/15 sec, and it occurred into an osmotic-sensitive space. Sulfobromophthalein ant taurocholate, but not unconjugated bilirubin inhibited the uptake rate of Gd-B 20790 but not that of the other three compounds. Injection into Xenopus laevis oocytes of 5 ng of human OATP cRNA resulted, after 3 days, in a >/=2-fold stimulation (p < 0.001) of transport of Gd-B 20790 but not of Gd-BOPTA or Gd-EOB-DTPA. Collectively, these data indicate that the hepatic uptake of the MRI contrast agent Gd-B 20790 is a carrier-mediated mechanism operated by OATP while MRI compounds with other chemical structures enter the hepatocyte by other mechanisms.     

Anterior gradient 2 increases long-chain fatty acid uptake via stabilizing FABP1 and facilitates lipid accumulation

Anterior gradient 2 (AGR2), a protein disulfide isomerase (PDI), is a well-established oncogene. Here, we found that Agr2^-/- mice had a decreased fat mass and hepatic and serum lipid levels compared with their wild-type littermates after fasting, and exhibited reduced high-fat diet (HFD)-induced fat accumulation. Transgenic mice overexpressing AGR2 (Agr2/Tg) readily gained fat weight on a HFD but not a normal diet. Proteomic analysis of hepatic samples from Agr2^-/- mice revealed that depletion of AGR2 impaired long-chain fatty acid uptake and activation but did not affect de novo hepatic lipogenesis. Further investigations led to the identification of several effector substrates, particularly fatty acid binding protein-1 (FABP1) as essential for the AGR2-mediated effects. AGR2 was coexpressed with FABP1, and knockdown of AGR2 resulted in a reduction in FABP1 stability. Physical interactions of AGR2 and FABP1 depended on the PDI motif in AGR2 and the formation of a disulfide bond between these two proteins. Overexpression of AGR2 but not a mutant AGR2 protein lacking PDI activity suppressed lipid accumulation in cells lacking FABP1. Moreover, AGR2 deficiency significantly reduced fatty acid absorption in the intestine, which might be resulted from decreased fatty acid transporter CD36 in mice. These findings demonstrated a novel role of AGR2 in fatty-acid uptake and activation in both the liver and intestine, which contributed to the AGR2-mediated lipid accumulation, suggesting that AGR2 is an important regulator of whole-body lipid metabolism and down-regulation of AGR2 may antagonize the development of obesity.     

Immune cell-specific delivery of beta-glucan-coated iron oxide nanoparticles for diagnosing liver metastasis by MR imaging

Glucans are reported to elicit immune responses through activation of macrophages by a specific interaction of β-glucan with an immune cell-specific (1,3)-β-d-glucan receptor or Dectin-1 receptor. In this study, superparamagnetic iron oxide nanoparticles (SPIONs) were coated with β-glucan in order to target the immune cells residing in the metastatic liver as an aid for discriminating metastasized tumor regions from normal hepatic parenchymal tissue. The morphology of prepared β-glucan-coated SPIONs (Glu-SPIONs) was characterized with dynamic light scattering (DLS) and transmission electron microscopy (TEM). The cytotoxicity of Glu-SPIONs was analyzed and compared to that of dextran- and PVA-coated SPIONs. The uptake of Glu-SPIONs by peritoneal macrophages was also confirmed with Prussian blue staining and MRI phantom tube imaging. The in vivo uptake of Glu-SPIONs in liver and lymph nodes in a metastatic mouse liver model was tracked by MR imaging after the systemic injection. The Glu-SPIONs predominantly accumulated in the macrophages surrounding the metastatic regions of the liver thereby indicating the distribution of tumor cells in the liver. MR imaging of the Glu-SPIONs clearly revealed macro- or micro-metastasized tumor regions throughout the liver, due to the preferential uptake of Glu-SPIONs into macrophages, not tumor cells. The Glu-SPION-accumulating regions were further confirmed with H&E and Prussian blue stainings after tissue sectioning. Based on our study, we propose that Glu-SPIONs can be successfully applied for diagnosing hepatic metastasis.     

The hepatoprotective effects of Hypericum perforatum L. on hepatic ischemia/reperfusion injury in rats

Little is known about the effective role of Hypericum perforatum on hepatic ischemia–reperfusion (I/R) injury in rats. Hence, albino rats were subjected to 45 min of hepatic ischemia followed by 60 min of reperfusion period. Hypericum perforatum extract (HPE) at the dose of 50 mg/kg body weight (HPE₅₀) was intraperitonally injected as a single dose, 15 min prior to ischemia. Rats were sacrificed at the end of reperfusion period and then, biochemical investigations were made in serum and liver tissue. Liver tissue homogenates were used for the measurement of malondialdehyde (MDA), catalase (CAT) and glutathione peroxidase (GPx) levels. At the same time alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were assayed in serum samples and compared statistically. While the ALT, AST, LDH activities and MDA levels were significantly increased, CAT and GPx activities significantly decreased in only I/R-induced control rats compared to normal control rats (p < 0.05). Treatment with HPE₅₀ significantly decreased the ALT, AST, LDH activities and MDA levels, and markedly increased activities of CAT and GPx in tissue homogenates compared to I/R-induced rats without treatment–control group (p < 0.05). In oxidative stress generated by hepatic ischemia–reperfusion, H. perforatum L. as an antioxidant agent contributes an alteration in the delicate balance between the scavenging capacity of antioxidant defence systems and free radicals in favour of the antioxidant defence systems in the body.