Gram Of Organ Research Articles

A novel dipeptide coupled with pyrazine-oxadiazole derivative as a potential antitubercular agent: Synthesis, radioiodination and bioevaluation

Tuberculosis (TB) is a disease caused by Mycobacterium and usually attack the lung. Synthesis of new dipeptide derivatives attached to antitubercular active heterocyclic rings like pyrazine and 1,3,4-oxadiazole called ethyl 2-(2-(5-((pyrazin-2-ylamino) methyl)-1,3,4-oxadiazol-2-ylthio) acetamido) acetamido)-3-(4-hydroxyphenyl) propanoate (EPOGTP) and iodinated EPOGTP are reported. The compounds have been characterized by mass, FT-IR and 1H NMR spectroscopy. Their in vitro investigation against Mycobacterium tuberculosis cell line indicated good IC50value of 210 μg/ml for EPOGTP and 86 μg/ml for iodo-EPOGTP. For study the biodisriution, the direct radioiodination of EPOGTP with iodine-131 using mild oxidizing agent, N-Bromosuccinimide (NBS), was performed and optimized for obtaining the maximum radiochemical purity (97.3 ± 0.47%). Then, the in vivo biodistribution in healthy mice showed good accumulation of radioiodinated EPOGTP in lung of about 41.83 ± 0.23% (the percentage of injected dose per gram of organ) at 15 min post-injection. As a conclusion, the synthetized dipeptide and its iodinated derivative could be further evaluated as a potential antitubercular agents.

Shape mediated splenotropic delivery of buparvaquone loaded solid lipid nanoparticles.

Buparvaquone (BPQ)-loaded asymmetric solid lipid nanoparticles (SLN) prepared by a modified nanoprecipitation method were evaluated for splenotropic drug delivery. BPQ SLN exhibited an average particle size of 650.28 ± 6.75nm with polydispersity index ≤ 0.3, entrapment efficiency of 96.57 ± 0.190%, and drug loading of 24.63 ± 0.042%. Scanning electron microscopy (SEM) revealed elongated particles with flattened and rounded edges. Aspect ratio, an important determinant of asymmetricity of the BPQ SLN, measured as the ratio of average length (1143 ± 0.083nm) to width (419 ± 0.031nm) was found to be 2.727 ± 0.19. The hemolytic potential of 10.86 ± 0.04% and good serum stability suggested feasibility for intravenous administration. 99mTc-labeled BPQ SLN revealed high radiolabeling efficiency (> 95%) and good stability. Intravenous administration in mice revealed > 75% accumulation in the reticuloendothelial system organs. The percent radioactivity per gram of organ was in the order spleen > kidney > lungs > liver > lymph nodes, with high splenic accumulation and significantly lower concentration in the liver. An astoundingly high spleen/liver ratio with a maximum of 11.94 ± 1.37 at 3h, which confirmed high splenic uptake is attributed to Kupffer cell bypass. Other factors contributing to splenotropy are the rigidity and the low molecular weight of the lipid in the BPQ SLN which enabled translocation of the particles into the splenic pulp. Our study proposes asymmetric BPQ SLN as a promising splenotropic delivery system for improved efficacy in theileriosis, a spleen resident infection.

Assessment of 47Ca Distribution and Biological Half-Life in Japanese Quail Chicks

ABSTRACT A study was conducted to assess 47Calcium (47Ca) distribution and biological half-life in different body organs of Japanese quail chicks. A total of 85, 4 week old chicks, were dosed with 1ml/chick volume of 1% (w/v) CaCl2 solution containing 7.51x10-08 Ci 47Ca which is equivalent to 1.27x10-13 g. 47Ca activity, in terms of decay per minute (DPM), was measured in different body organs at 12 hours time intervals, after 24 hours from ingestion for five days. The total activity of 47Ca for each organ and activity per gram of organ (D.min-1.g-1) was calculated. Data were Statistically analyzed using completely randomized design (CRD), one way analysis of variance (ANOVA) as per the procedure given by SPSS (2002), 9.0 version for Windows. The results obtained indicated that following 47Ca administration most of the total 47Ca concentration was found in the bones with count rates of 110267±550 DPM. While in the fifth day following administration, most of the 47Ca was found in the feathers with a total activity of 13322±760 DPM. The biological half-life time was found to be highest in the heart and kidneys, respectively compared to the other body organs. In conclusion, the current results suggest that the main excretory pathway for Ca is through the skin. Regarding organ dependency on Ca for the normal functioning, the results obtained in our study suggest that the heart is the most dependent organ on Ca.

Characterization of Intestinal and Hepatic CYP3A-Mediated Metabolism of Midazolam in Children Using a Physiological Population Pharmacokinetic Modelling Approach

PurposeChanges in drug absorption and first-pass metabolism have been reported throughout the pediatric age range. Our aim is to characterize both intestinal and hepatic CYP3A-mediated metabolism of midazolam in children in order to predict first-pass and systemic metabolism of CYP3A substrates.MethodsPharmacokinetic (PK) data of midazolam and 1-OH-midazolam from 264 post-operative children 1–18 years of age after oral administration were analyzed using a physiological population PK modelling approach. In the model, consisting of physiological compartments representing the gastro-intestinal tract and liver,intrinsic intestinal and hepatic clearances were estimated to derive values for bioavailability and plasma clearance.ResultsThe whole-organ intrinsic clearance in the gut wall and liver were found to increase with body weight, with a 105 (95% confidence interval (CI): 5–405) times lower intrinsic gut wall clearance than the intrinsic hepatic clearance (i.e. 5.08 L/h (relative standard error (RSE) 10%) versus 527 L/h (RSE 7%) for a 16 kg individual, respectively). When expressed per gram of organ, intrinsic clearance increases with increasing body weight in the gut wall, but decreases in the liver, indicating that CYP3A-mediated intrinsic clearance and local bioavailability in the gut wall and liver do not change with age in parallel. The resulting total bioavailability was found to be age-independent with a median of 20.8% in children (95%CI: 3.8–50.0%).ConclusionIn conclusion, the intrinsic CYP3A-mediated gut wall clearance is substantially lower than the intrinsic hepatic CYP3A-mediated clearance in children from 1 to 18 years of age, and contributes less to the overall first-pass metabolism compared to adults.

EVALUATION OF THE EFFECT OF ANTI-TOXOPLASMIC DRUGS ON THE BIODISTRIBUTION OF THE RADIOPHARMACEUTICAL SODIUM PERTECHNETATE

The human toxoplasmosis is a disease caused by the parasite Toxoplasma gondii that can affect the growing baby in pregnancy and it is the most common CNS infection in patients with AIDS. Its treatment is made by the synergistic association of the drugs pyrimethamine (PM) and sulfadiazine (SDZ). Objective: the aim of this study was to evaluate if the use of the combination of PM and SDZ changes the sodium pertechnetate (Na99mTcO4-) biodistribution in non-infected animals by the T. gondii. It was used 24 male Swiss mice equally divided into 4 groups: 1 control group and 3 treated groups. Methods: the control group received 0.5 mL of distilled water; the treated group 1 received 0.5 mL of a PM solution; the treated group 2 received 0.5 mL of a SDZ solution and the treated group 3 received 0.5 mL of the PM+SDZ, all by the gavage method for 10 days. On the 10th day and 1 h after the last dose, all groups received 0.1mL of Na99mTcO4- (0.66MBq) via the femoral vein. After 40 min, the animals were euthanized, and blood and brain samples were isolated. The percentage of total activity injected per gram of organ (%ATI/g) was calculated on the gamma counter. Statistical analysis were performed using the T-test, considering a level of significance of p

Preparation and preclinical evaluation of radioiodinated secnidazole as a possible tumor imaging agent

To develop a radiopharmaceutical localizing in tumor hypoxic tissues, secnidazole (SECN) was labeled with 125I. The labeled product was prepared with the radiochemical yield higher than 96% when performing the reaction at 45°C for 30 min. The electrophilic radioiodination of SECN was done using different oxidizing agents. Iodogen appeared to be more effective than chloramine-T (CAT) and N-bromosuccinimide (NBS). 125I-SECN was tested in vivo with a tumor model prepared by the intramuscular injection of Ehrlich cell line into the thigh muscle of mice. 125I-SECN showed high accumulation in tumor hypoxic tissue (3.6% of injected dose per gram of organ at 2 h post injection). The target/nontarget (T/NT) ratio was high (T/NT = 6 at 24 h post injection). Thus, radioiodinated SECN shows promise as a selective imaging agent for diagnosis of tumor hypoxia.

SYNTHESIS OF TETRAKIS-N,N,N-TRIMETHYLAMMONIUMMETHYL-C-3,4-DIMETHOXYPHENYLCALIX[4]RESORCINARENE IODIDE BASED VANILLIN AND ITS ANTIDOTE ACTIVITY FOR CHROMIUM(VI) INTOXICATION

A research has been conducted to synthesize tetrakis-N,N,N-trimethylammoniummethyl-C-3,4-dimethoxyphenylcalix[4]resorcinarene iodide from vanillin and investigate its antidote capability for Cr(VI) intoxication. The synthesis was carried out in four steps i.e. (1) O-alkylation of 4-hydroxy-3-methoxybenzaldehyde, (2) HCl-catalyzed condensation of 3,4-dimethoxybenzaldehyde with resorcinol, (3) Mannich reaction of C-3,4-dimethoxyphenylcalix[4]resorcinarene with formaldehyde and dimethylamine in the presence of HCl to yield tetrakis-N,N-dimethylaminomethyl-C-3,4-dimethoxyphenylcalix[4]resorcinarene, and (4) treatment the Mannich base with methyl iodide to produce the quaternary ammonium salt of tetrakis-N,N,N-trimethylammoniummethyl-C-3,4-dimethoxyphenylcalix[4]resorcinarene iodide. According to the analysis of 1H-NMR spectrometer, the targeted compounds tend to exist in the chair (C2h) conformation. The capability of resorcinarene for Cr(VI) antidote was examined by orally injection method on mice groups. Based on LD50 determination, the resorcinarene was classified as non toxic compound according to Loomis criteria. Therapeutic using quaternary ammonium-modified resorcinarene was able to reduce metal concentrations of Cr(VI) in liver, kidney, and serum in the magnitude of 78.30; 85.72, and 88.79%, respectively. The higher dose of drug administered the greater decrease in the level of heavy metal. Judging from the amount of milligrams of reduced chromium per gram of organ, kidney is the organ having highest decreasing metal concentrations.

Experimental pharmacokinetics of niferidil upon intravenous administration

The kinetics of niferidil concentration change in blood serum, organs, and urine of rats was studied after i.v. administration at a dose of 5 mg/kg. The blood concentration profile was shown to be described by a bi-exponential equation corresponding to a two-compartment model. Niferidil disappeared quickly from the blood pool with a distribution half-life of 5.13 min. The elimination half-life from blood was 23.3 min. Niferidil penetrated rapidly into organs such as the liver, kidneys, and heart. The concentration calculated per gram of organ 30 min after i.v. administration was six times greater than that in blood (in 1 mL). Accumulation in these organs was not observed. The elimination half-life from the organs was about 1 h. Niferidil was not detected in brain tissue. Niferidil was excreted after i.v. administration unchanged in urine in small amounts. About 10% of the injected dose was eliminated after 24 h. Niferidil was not found in feces.

Metabolism and Gastric Remnant Changes after Roux-en-Y Gastric Bypass in Rats

ABSTRACTBackground: The Roux-en-Y gastric bypass (RYGB) may affect metabolism, microbiology, and histology of gastric remnant. Therefore, this study aimed to investigate these issues in rats. Methods: Twelve rats were randomly allocated to a RYGB group (n = 6) and nonoperated normal rats group (n = 6). After 30 postoperative days, all rats were injected with 0.1ml of Na99mTc− i.v. (radioactivity 0.66 MBq). After 30 min, liver, stomach, thyroid, heart, lung, kidney, and femur samples were harvested and weighed. Percentage radioactivity per gram of organ (%ATI/g) was determined using a Perkin-Elmer gamma counter. Serum albumin, calcium, aminotransferases (ALT, AST), T3, T4, and PTH were determined. Samples of the excluded stomach mucosa were harvested for bacterial and fungal count such as colony-forming units/g and histology. Results: A significant reduction (t test) in %ATI/g was observed in the liver, stomach, and femur in the RYGB rats, compared with normal rats (p < .05). A significant reduction in serum albumin and calcium in RYGB rats was detected, compared with normal rats (p < .05). ALT and AST were significantly different between the two groups. T3 and T4 levels were significantly lower in RYGB rats than in normal rats (p < .05); PTH levels were higher in RYGB rats than in controls (p = .009). The gastric remnant mucosa of RYGB rats showed higher bacterial and fungal count, atrophy, intestinal metaplasia, and neutrophilic polymorphonuclear inflammation than in normal rats. Conclusions: This investigation demonstrated that a model of murine RYGB significantly modified metabolic parameters and the microbiology/histology of the remnant stomach.

Blood Clearance and Tissue Distribution of PEGylated and Non-PEGylated Gold Nanorods After Intravenous Administration in Rats

To develop and determine the safety of gold nanorods, whose aspect ratios can be tuned to obtain plasmon peaks between 650 and 850 nm, as contrast enhancing agents for diagnostic and therapeutic applications. In this study we compared the blood clearance and tissue distribution of cetyl trimethyl ammonium bromide (CTAB)-capped and polyethylene glycol (PEG)-coated gold nanorods after intravenous injection in the tail vein of rats. The gold content in blood and various organs was measured quantitatively with inductively coupled plasma mass spectrometry. The CTAB-capped gold nanorods were almost immediately (< 15 min) cleared from the blood circulation whereas the PEGylation of gold nanorods resulted in a prolonged blood circulation with a half-life time of 19 h and more wide spread tissue distribution. While for the CTAB-capped gold nanorods the tissue distribution was limited to liver, spleen and lung, the PEGylated gold nanorods also distributed to kidney, heart, thymus, brain and testes. PEGylation of the gold nanorods resulted in the spleen being the organ with the highest exposure, whereas for the non-PEGylated CTAB-capped gold nanorods the liver was the organ with the highest exposure, per gram of organ. The PEGylation of gold nanorods resulted in a prolongation of the blood clearance and the highest organ exposure in the spleen. In view of the time frame (up to 48 h) of the observed presence in blood circulation, PEGylated gold nanorods can be considered to be promising candidates for therapeutic and diagnostic imaging purposes.

Donor Engraftment Following α-Emitter Astatine-211 (211At) Labeled Anti-CD45 Monoclonal Antibody (mAb) Nonmyeloablative Conditioning for Dog Leukocyte Antigen (DLA)-Identical Marrow Transplantation

AbstractAbstract 76Previously we have demonstrated that an anti-CD45 mAb labeled with the α-emitter bismuth-213 (213Bi), could replace 2 Gy total body irradiation (TBI) in nonmyeloablative conditioning for dogs transplanted with marrow from DLA identical littermates (Blood, 2002; 100: 318). However, due to several obstacles, including availability and cost of 213Bi, the translation of the 213Bi-labeled mAb into clinical studies was not possible. In the current study, we used astatine-211 (211At) as an alternative α-particle-emitting isotope. 211At is readily available in quantities that can be scaled up for clinical trials. We also hypothesized that the longer half-life of 211At (7.2 h) compared to 213Bi (46 min) would make it more effective in killing targeted hematopoietic cells (including immune cells responsible for host versus graft reactions). This was confirmed in our murine studies comparing the two isotopes (Cancer Res. 2009; 69: 2408). In this study, 211At was linked to the anti-CD45 mAb through a conjugated closo-decaborate(2-) derivative (denoted as B10). The biodistribution in the dog showed that the spleen received the highest dose of radioactivity, 0.3% injected dose per gram of organ (%ID/g) while kidney and liver received 0.03 and 0.10% ID/g, respectively. Dose finding and toxicity studies were performed in 11 dogs receiving 211At-labeled anti-CD45 mAb doses ranging between 0.07 and 0.62 mCi/kg. All dogs experienced myelosuppression but recovered from the neutrophil nadirs (range, 0–1484.8/μ L) and lymphocyte nadirs (range, 32.0–411.0/μ L) without hematopoietic cell rescue. In 6 dogs receiving 211At–labeled anti-CD45 mAb conjugated with B10 through lysine amines, effective myelosuppression without pronounced non-hematopoietic toxicities, except for transient elevation of liver transaminases, was observed within the dose range of 0.20–0.41mCi/kg 211At. Subsequently, four dogs have been transplanted with marrow from DLA-identical littermates. In those studies 0.20–0.41mCi/kg 211At-labeled anti-CD45 mAb was given on day -3 as conditioning, and immunosuppression with mycophenolate and cyclosporine administered for 28 and 35 days, respectively, following transplantation. With 17 to 26 weeks follow-up, all dogs are alive, without graft-versus-host-disease, and with maximum and final donor chimerism in mononuclear cells ranging from 36%-68% and 26%-37% respectively. There was no renal toxicity, with blood urea nitrogen and creatinine levels within the normal range, and only negligible liver toxicity with a transient increase in liver enzymes to no more than 2 times the upper limit of the normal range. Immune reconstitution was prompt with normal T and natural killer function by day 60. In conclusion, our study demonstrated that low dose immunotherapy with 0.20–0.41mCi/kg 211At-labeled anti-CD45 mAb could replace TBI in DLA-identical littermate transplantation. The 211At-labeled anti-CD45 mAb provided sufficient immunosuppression to enable stable mixed chimerism with only minimal toxicity, making it a candidate for future clinical trials of nonmyeloablative transplantation. Disclosures:No relevant conflicts of interest to declare.

Could be radiolabeled flavonoid used to evaluate infection?

The aim of this study was to determine whether [131I]apigenin is a powerful and discrimination infection from inflammation for scintigraphic imaging. The study was carried out in inflamed rats with Staphylococcus aureus (S. aureus) and sterile inflamed rats with turpentine oil. Biodistribution study of [131I]apigenin was performed in the rats. Apigenin was labeled with 131I by iodogen method. Obtained [131I]apigenin with high yield (98%) was injected i.v. to both group rats. The results were expressed as the percent uptake of injected dose per gram of organ (%ID/g), the bacterial infected and sterile inflamed muscles. Binding of [131I]apigenin to the infected thigh muscle (target muscle = T) and normal thigh muscle (non-target muscle = NT) ratio (T/NT = 4.51 at 15 min) was higher than binding to bacterial inflamed muscle (T/NT = 2.25 at 15 min) of rats. [131I]apigenin showed good localization in both inflamed tissues. This uptake in the sterile inflamed tissue is higher than bacterial infected tissue. [131I]apigenin might be useful for imaging of inflamed tissues. However, it is not discriminate sterile inflamed tissue from bacterial infected tissue.

Effect of Zusanli (ST.36) Electroacupuncture at Two Frequencies on the Bioavailability of 99mTc-Sodium Pertechnetate and on Labeling of Blood Constituents in Rats

Objectives A study was performed on the effects of stimulation at Zusanli-point (ST.36) by electroacupuncture (EA) at two frequencies on the bioavailability of 99mTc-sodium pertechnetate (Na 99mTcO 4) in rats. Methods Forty Wistar rats were divided into four groups: untreated control, treated by manual acupuncture at ST.36 bilaterally, treated by EA at 2 Hz at ST.36 bilaterally, and the same site at 100 Hz bilaterally. Na 99mTcO 4(7.4 MBq) was administrated via the ocular-plexus and, 20 minutes before sacrifice, blood was withdrawn for radiolabeling assay (BRL). In the bioavailability analysis, organs and tissues were isolated, their radioactivity determined, and the percentage of injected dose per gram of organ or tissue (%ID/g) and the %ID were calculated for each organ or tissue (%ID/ot). For BRL, the plasma and blood cells isolated, and the fractions also precipitated with 5% trichloroacetic acid to separate the soluble and insoluble fractions; these were assessed as percentage of injected dose (%ID) in blood (%ID/b). Results The results showed significant differences in the %ID/g in some organs and tissues in comparison with controls; lung ( p = 0.0013), spleen ( p = 0.0085), pancreas ( p = 0.0167), liver ( p = 0.0003), stomach ( p<0.0001), small-intestine ( p = 0.0181), large-intestine ( p = 0.04099), urinary-bladder ( p = 0.0271), thyroid ( p< 0.0001), muscle ( p = 0.0187); %ID/ot in spleen ( p = 0.0349); and %ID/b in blood sample ( p = 0.0235). In the blood labeling analyses, EA in either frequency significantly increased insoluble fraction/blood cells ( p < 0.0001). Conclusions These findings suggested that acupuncture procedures at ST.36 could modulate responses in some organs, tissues, and blood in rats. Further rigorous experimental studies to examine the effectiveness in either acupuncture therapy need to be pursued.

Evaluation of 99mTc(CO)5I as a potential lung perfusion agent

The use of (99m)Tc-macroggregated albumin for lung perfusion imaging is well established in nuclear medicine. However, there have been safety concerns over the use of blood-derived products because of potential contamination by infective agents, for example, Variant Creutzfeldt Jakob Disease. Preliminary work has indicated that Tc(CO)(5)I is primarily taken up in the lungs following intravenous administration. The aim of this study was to evaluate the biodistribution and pharmacokinetics of (99m)Tc(CO)(5)I and its potential as a lung perfusion agent. (99m)Tc(CO)(5)I was synthesized by carbonylation of (99m)TcO(4-) at 160 atm of CO at 170 degrees C in the presence of HI for 40 min. Radiochemical purity was determined by HPLC using (99)Tc(CO)(5)I as a reference. (99m)Tc(CO)(5)I was administered by ear-vein injection to three chinchilla rabbits, and dynamic images were acquired using a gamma camera (Siemens E-cam) over 20 min. Imaging studies were also performed with (99m)Tc-labeled macroaggregated albumin ((99m)Tc-MAA) and (99m)TcO(4-) for comparison. (99m)Tc(CO)(5)I was administered intravenously to Sprague-Dawley rats, and tissue distribution studies were obtained at 15 min and 1 h postinjection. Comparative studies were performed using (99m)Tc-MAA. Radiochemical purity, assessed by HPLC, was 98%. The retention time was similar to that of (99)Tc(CO)(5)I. The dynamic images showed that 70% of (99m)Tc(CO)(5)I appeared promptly in the lungs and remained constant for at least 20 min. In contrast, (99m)TcO(4-) rapidly washed out of the lungs after administration. As expected (99m)Tc-MAA showed 90% lung accumulation. The percentage of injected dose per gram of organ +/-S.D. at 1 h for (99m)Tc(CO)(5)I was as follows: blood, 0.22+/-0.02; lung, 12.8+/-2.87; liver, 0.8+/-0.15; heart, 0.15+/-0.01; kidney, 0.47+/-0.08. The percentage of injected dose per organ +/-S.D. at 1 h was as follows: lung, 22.47+/-2.31; liver, 10.53+/-1.8; heart, 0.18+/-0.01; kidney, 1.2+/-0.17. Tissue distribution studies with (99m)Tc-MAA showed 100% lung uptake. (99m)Tc(CO)(5)I was synthesized with a high radiochemical purity and showed a high accumulation in the lungs. Further work on the mechanism and optimization of lung uptake of (99m)Tc-pentacarbonyl complexes is warranted.

Biodistribution of intravenously administered amphiphilic β-cyclodextrin nanospheres

Amphiphilic β-cyclodextrin (βCDa) nanospheres (mean diameter 90–110 nm) prepared by the solvent displacement method were developed as a colloidal drug delivery system. In order to survey the fate of these nanoparticles, the amphiphilic β-cyclodextrin was first iodinated by a two-step procedure involving iodination of the primary face followed by an acylation of the secondary face. After radiolabeling of this derivative with 125I, nanospheres made of βCDa/βCDa 125I were formulated. After a single intravenous injection of labeled nanoparticles in mice, the organ distribution was analyzed from 10 min to 6 days. A rapid clearance of 125I-labeled βCDa nanospheres from the blood circulation to the mononuclear phagocyte system was visualized by non-invasive planar imaging study. Radioactivity measurements in organs showed that the nanospheres mainly concentrated in the liver and the spleen where 28 and 24% of the radioactivity per gram of organ was, respectively, found 10 min after injection. At the opposite, the blood activity was low at that time and become negligible thereafter. Finally, the fact that no particular sign of toxicity is observed in injected animals should be emphasized since it is the first report on intravenous administration of βCDa nanoparticles.

A new bisphosphonate-containing 99mTc(I) tricarbonyl complex potentially useful as bone-seeking agent: synthesis and biological evaluation

Aiming to develop new bone-seeking radiotracers based on the organometallic core fac-[(99m)Tc(CO)(3)](+) with improved radiochemical and biological properties, we have prepared new conjugates with phosphonate pendant groups. The conjugates comprise a chelating unit for metal coordination, which corresponds to a pyrazolyl-containing backbone (pz) with a N,N,N donor-atom set, and a pendant diethyl phosphonate (pz-MPOEt), phosphonic acid (pz-MPOH) or a bisphosphonic acid (pz-BPOH) group for bone targeting. Reactions of the conjugates with the precursor [(99m)Tc(H(2)O)(3)(CO)(3)](+) yielded (mote than 95%) the single and well-defined radioactive species [(99m)Tc(CO)(3)(kappa(3)-pz-MPOEt)](+) (1a), [(99m)Tc(CO)(3)(kappa(3)-pz-MPOH](+) (2a) and [(99m)Tc(CO)(3)(kappa(3)-pz-BPOH)](+) (3a), which were characterized by reversed-phase high-performance liquid chromatography . The corresponding Re surrogates (1-3), characterized by the usual analytical techniques, including X-ray diffraction analysis in the case of 1, allowed for macroscopic identification of the radioactive conjugates. These radioactive complexes revealed high stability both in vitro (phosphate-buffered saline solution and human plasma) and in vivo, without any measurable decomposition. Biodistribution studies of the complexes in mice indicated a fast rate of blood clearance and high rate of total radioactivity excretion, occurring primarily through the renal-urinary pathway in the case of complex 3a. Despite presenting moderate bone uptake (3.04 +/- 0.47% injected dose per gram of organ, 4 h after injection), the high stability presented by 3a and its adequate in vivo pharmacokinetics encourages the search for new ligands with the same chelating unit and different bisphosphonic acid pendant arms.

Metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in isolated rat lung and liver.

The tobacco specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a strong lung carcinogen in all species tested. To elicit its tumorigenic effects NNK requires metabolic activation which is supposed to take place via alpha-hydroxylation, whereas N-oxidation is suggested to be a detoxification pathway. The differences in the organ specific metabolism of NNK may be crucial for the organotropy in NNK-induced carcinogenesis. Therefore, metabolism of NNK was investigated in the target organ lung and in liver of Fischer 344 (F344) rats using the model of isolated perfused organs. High activity to metabolize 35 nM [5-3H]NNK was observed in both perfused organs. NNK was eliminated by liver substantially faster (clearance 6.9 +/- 1.6 ml/min, half-life 14.6 +/- 1.2 min) than by lung (clearance 2.1 +/- 0.5 ml/min, half-life 47.9 +/- 7.4 min). When the clearance is calculated for a gram of organ or for metabolically active cell forms, the risk with respect to carcinogenic mechanisms was higher in lung than in liver. The metabolism of NNK in liver yielded the two products of NNK alpha-hydroxylation, the 4-oxo-4-(3-pyridyl)-butyric acid (keto acid) and 4-hydroxy-4-(3-pyridyl)-butyric acid (hydroxy acid). In lung, the major metabolite of NNK was 4-(methylnitrosamino)-1-(3-pyridyl-N-oxide)-1-butanone (NNK-N-oxide). Substantial amounts of metabolites formed from methyl hydroxylation of NNK, which is one of the two possible pathways of alpha-hydroxylation, were detected in lung but not in liver perfusion. Formation of these metabolites (4-oxo-4-(3-pyridyl)-butanol (keto alcohol), and 4-hydroxy-4-(3-pyridyl)-butanol (diol) can give rise to pyridyloxobutylating of DNA. When isolated rat livers were perfused with 150 microM NNK, equal to a dosage which is sufficient to induce liver tumors in rat, glucuronidation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) was increased when compared to the concentration of 35 nM NNK. Nevertheless, the main part of NNK was also transformed via alpha-hydroxylation for this high concentration of NNK.

Synthesis and Biological Evaluation of [ 11C]MK-912 as an α 2-Adrenergic Receptor Radioligand for PET Studies

ABSTRACT. In vitro studies showed that MK-912 ((2S, 12bS)1’,3’-dimethylspiro(1,3,4,5’,6,6’,7,12b-octahydro-2H-benzo[b]furo[2,3-a]quinolizine)-2,4’-pyrimidin-2’-one) is a potent α 2-adrenergic receptor antagonist with high affinity (K i = 0.42, 0.26 and 0.03 nM to α 2A, α 2B and α 2C, respectively) and high selectivity (α 2A/α 1A = 240; α 2A/D-1 = 3600; α 2A/D-2 = 3500; α 2A/5-HT 1 = 700; α 2A/5-HT 2= 4100). The compound was labeled with 11C and evaluated in rodents and monkey as a specific radioligand for studying α 2-adrenergic receptors using PET. [ 11C]MK-912 ( [2]) was synthesized by methylation of its desmethyl precursor, L-668,929 ( [1]), with [ 11C]CH 3I in (Bu 3O)P=O at 85°C for 8 min followed by purification with HPLC in 18% yield in a synthesis time of 45 min from end of bombardment (EOB). The specific activity was 0.83–0.93 Ci/μmol and the radiochemical purity was 97%. The initial uptake of [ 11C]MK-912 in mouse brain, heart, lung, liver and kidney was high (5%, 4%, 5%, 17% and 8% per gram of organ, respectively, at 5 min postinjection) and the activities were then slowly cleared from these organs. The uptake of [ 11C]MK-912 in rat olfactory tubercle, a brain region with high density of α 2-adrenergic receptors, was reduced by 30%, and the ratio of radioactivity in olfactory tubercle/cerebellum was reduced from 2:1 to 1:1 by coinjection of [ 11C]MK-912 with a potent α 2-adrenergic receptor antagonist, atipamezole (3 mg/kg), indicating that compound 2 binds to α 2-adrenergic receptors. However, a PET study in a rhesus monkey revealed that the initial influx of [ 11C]MK-912 into various brain regions (cerebellum, cortex, olfactory tubercle and striatum) was high (0.02%/cc), and the radioactivity was then washed out slowly and without significantly differential retention in these brain regions. This, coupled with the fact that none of the high-density α 2-adrenergic receptor brain regions exceeds a few millimeters in diameter, suggests that [ 11C]MK-912 is probably not an ideal radioligand for studying α 2-adrenergic receptors in humans using commercially available PET.

Vaccination of juvenile turbot, Scophthalmus maximus L., against vibriosis

An intraperitoneal (IP) vaccination against vibriosis caused by Vibrio anguillarum 408 was carried out on four groups (I to IV) of juvenile turbot from the same origin at 62 (I), 76 (II), 90 (III) and 104 (IV) days post-hatching. The mean weight was 0.4 to 1.3 g. Intraperitoneal vaccination protected juvenile turbot during a challenge performed 1 month after a single immunization. The relative percentage survival (RPS) was about the same whether the vaccination occurred 62, 76 or 104 days post-hatching. Two months after this first immunization, juvenile turbot from groups III and IV were still protected and RPS values were higher than those obtained 1 month after vaccination. No booster effect was found in groups I and II. Although it was only significant in groups II and III, an increase of the spleen weight occurred in the vaccinated fish when compared to the controls. This was associated with a higher number of leucocytes per gram of organ. The immunization seemed to induce a mobilization of leucocytes in the spleen. Such results were not observed with the kidney.

The cellular composition of the blood and haematopoietic organs of turbot Scophthalmus maximus L.

The cellular composition of the blood, anterior kidney, spleen and thymus of turbot Scophrhalmus maximus L., aged 1 + was determined. Ninety‐four per cent of blood cells belonged to the erythrocyte lineage of which 82% were mature erythrocytes. The leucocytes, which represented 4.5% of the blood cells, were mainly lymphocytes (50%). The presence of crythroblasts in the anterior kidney and the spleen demonstrated an erythropoietic activity in both organs. However, this activity appeared to be prevalent in the spleen which also appeared to act as a storage zone for erythrocytes and as the centre point for thrombopoiesis. Although 96% of the anterior kidney cells were leucocytes, the number of white cells per gram of organ was higher in the spleen.