Improved work-up procedure for the production of [F]flumazenil and first results of its use with a high-resolution research tomograph in human stroke

IntroductionThe central benzodiazepine receptor (cBZR)–gamma-aminobutyric acid (GABA_A) receptor complex in the human brain plays an important role in many neurological and psychiatric disorders. ¹⁸F-Labeled flumazenil ([¹⁸F]FZ) provides a potentially useful tracer to investigate those disorders by means of positron emission tomography (PET).Methods[¹⁸F]Flumazenil was synthesized from its nitro-precursor Ro 15-2344 in DMF at high temperatures between 150°C and 160°C. Other solvents like acetonitrile and dimethylsulfoxide were also investigated as reaction media. A new HPLC method for the final purification of [¹⁸F]FZ was developed to circumvent some difficulties associated with a previously published procedure sometimes led to a contamination of [¹⁸F]FZ with Ro 15-2344. The final purification of the radiotracer was achieved using a Waters Symmetry Prep C18 HPLC column with elution with 0.05 M sodium acetate (NaOAc) buffer (pH 5)/THF/MeOH (80:10:10).Results[¹⁸F]FZ could be synthesized in reproducible radiochemical yields (RCYs) of 15–20% (decay corrected to EOB) after 80 min overall synthesis time. The synthesized [¹⁸F]FZ was applied for the first time in a human PET study in a patient with ischemic right middle cerebral artery stroke using the HRRT high-resolution research scanner (Siemens Medical Solution, Knoxville, TN, USA).Conclusions[¹⁸F]FZ is a potentially useful GABA receptor-binding PET ligand. A modified procedure for its preparation in reproducibly high radiochemical yields has been described and the [¹⁸F]FZ thus produced has been used successfully in a pilot clinical study.     

A method of measuring quantitative hepatic function and hemodynamics in cirrhosis: The changes following distal splenorenal shunt

Quantiative measurement is required to define the severity of chronic liver disease and the effects of therapy on its complications. This paper presents a method of such assessment based on measurement of hepatocyte function, liver volume, functional liver blood flow, portal perfusion and cardiac output. Data are presented on 54 patients evaluated prior to, and one year after DSRS for variceal bleeding. Preoperative testing showed that alcoholics (n=24) had significantly (p<0.05) larger liver and smaller spleen volumes than nonalcoholic cirrhotics (n=22) and patients with portal vein thrombosis (n=8), but that the other parameters were not significantly different by etiologies. At one year after DSRS: all groups showed a significant (p<0.01) reduction of 41 per cent in spleen size: liver volume was significantly (p<0.05) reduced in cirrhotics: there was a significantly (p<0.01) greater loss of portal perfusion in alcoholic cirrhosis: liver blood flow showd a significant (p<0.05) rise in alcoholics when compared to nonalcoholics and portal vein thrombosis patients: cardiac output ros in alcoholic cirrhosis: hepatocyte function was not significantly different in any group. This study shows that in patients all doing well clinically one year after DSRS, there are markedly different hemodynamic responses. Further studies on cirrhosis aimed at improving therapy for its complications should include some objective, quentitative assessment, first to define the study population, and second to measure the effect of the therapy.     

Cloning of the mouse sodium iodide symporter.

The iodide-concentrating ability of the thyroid gland is essential to the production of thyroid hormone. We report the nucleotide and amino acid sequence of the mouse sodium iodide symporter (mNIS), which mediates this activity within the thyroid gland. An open reading frame of 1,857 nucleotides codes for a protein of 618 amino acids with 95% identity to rat NIS and 84% identity to human NIS. Transient expression of the mNIS cDNA in Chinese hamster ovary (CHO) cells, a nonthyroid cell line, resulted in sodium-dependent, perchlorate-sensitive iodide uptake. Western blot analysis of membrane preparations of CHO cells transiently transfected with mNIS cDNA showed a band of 90 kd when probed with an antibody directed against rat NIS. mNIS will serve as an important reagent in determining the role of NIS in experimental thyroid diseases and for monitoring the immune response to in animal models of NIS-mediated gene therapy.     

Cellular pharmacology of mu-[1,2-bis(diphenylphosphino)ethane]bis[(1-thio-beta-D-gluco pyranosato-S)gold(I)]: a novel antitumor agent

SK&F 102912 (mu-[1,2-bis(diphenylphosphino)ethane]bis[(1-thio-beta-D- glucopyranosato-S)gold(I)], [(Autg)2(dppe)]) has shown reproducible and significant activity in transplantable murine tumor models and represents a structurally unique class of antineoplastic agents. A number of in vitro studies were performed to elucidate the cellular pharmacology of this gold-containing complex. [(Autg)2(dppe)] is a potent cytotoxic agent in vitro as demonstrated by its ability to inhibit the clonogenic capacity of a variety of tumor cell lines following a brief exposure to the drug. Cell-cycle analysis using HL-60 cells showed that low concentrations (2 microM) of [(Autg)2(dppe)] induced an S-phase block and higher concentrations induced a secondary block at the G1/S boundary. [(Autg)2(dppe)] had several effects on DNA metabolism and structure including preferential inhibition in cells of DNA synthesis (relative to RNA and protein synthesis) and the production of DNA single- and double-strand breaks as measured by alkaline elution. The cytoxic mechanism of this gold complex appears to be distinct from that of the monophosphine-gold complex auranofin.     

Left ventricular volume measurement using cardiac axis nuclear magnetic resonance imaging. Validation by calibrated ventricular angiography

Proton nuclear magnetic resonance (NMR) imaging has the potential to serially assess left ventricular (LV) volumes with optimal accuracy because it is a high-resolution, three-dimensional, noninvasive modality. Previous NMR studies to assess LV volumes have been suboptimal, as they have used either planes aligned with the axes of the body, which are compromised by partial volume effects, or spin-echo techniques that have been time-consuming to acquire and analyze. Accordingly, for LV volume measurement, we developed a gradient-echo (cine) NMR strategy that uses two orthogonal planes intersecting along the intrinsic long axis of the heart (two-chamber and four-chamber). This approach was validated against calibrated contrast biplane LV cineangiography (CATH) and also compared with a previously reported short-axis spin-echo NMR method. Twenty-one patients underwent CATH and NMR (long-axis, n = 21; short-axis, n = 14) within a 3-day interval. Although both long- and short-axis NMR LV volumes and ejection fractions correlated well with CATH (r greater than 0.90, p less than 0.001 in all), end-diastolic volumes by both long-axis (161 +/- 85 ml) and short-axis (151 +/- 81 ml) NMR were systematically less than those by CATH (182 +/- 85 ml) (p less than 0.05). Consequently, ejection fractions by long-axis (48 +/- 17%) and short-axis (49 +/- 17%) NMR consistently underestimated those by CATH (54 +/- 16%, p less than 0.05). End-systolic volumes by long-axis (94 +/- 71 ml) and short-axis (87 +/- 72 ml) NMR were not significantly different from those by CATH (92 +/- 69 ml). Both NMR techniques had low intraobserver and interobserver variation (less than 11%); however, short-axis spin-echo NMR involved longer acquisition/reconstruction (35 versus 18 minutes) and analysis (25 versus 10 minutes) times. We conclude that both short-axis spin-echo and long-axis gradient-echo NMR approaches reliably estimate LV volumes. Currently, the long-axis strategy appears more practical for clinical use because the scan and analysis times are relatively short.     

Immunosuppression following 7,12-dimethylbenz[a]anthracene exposure in B6C3F1 mice--II. Altered cell-mediated immunity and tumor resistance

We have previously demonstrated that the polycyclic aromatic hydrocarbons benzo[a]pyrene (B[a]P) and 7,12-dimethylbenz[a]anthracene (DMBA) produce a marked decrease in spleen weight, spleen and bone marrow cellularity and the number of IgM plaque forming cells generated in response to a T-dependent antigen. Exposure to DMBA, but not B[a]P, increased susceptibility to challenge with PYB6 tumor cells and Listeria monocytogenes suggesting that DMBA produces immune impairment involving cell-mediated immunity (CMI) and tumor resistance mechanisms. In this study, female B6C3F1 mice received total doses of 5, 50 and 100 micrograms DMBA/g of body weight in ten subcutaneous injections of 0.5, 5, or 10 micrograms/g over a 2 week period and CMI and tumoricidal functions were examined 3-5 days following the final injection of DMBA. DMBA exposed mice exhibited suppressed splenic cellularity (decreased 62%) and decreased numbers of resident peritoneal cells (down to 47% of control), although the proportion of T cell and T cell subsets, B cells and macrophages in spleens from exposed mice was not altered. Lymphocyte blastogenesis in response to mitogens was suppressed up to 49% with PHA, 48% with Con A and 76% with LPS. The response to alloantigens in unidirectional mixed lymphocyte culture was depressed as much as 73% following exposure to DMBA. Tumor cytolysis mediated by cytotoxic T cells (CTL) was impaired at doses of 50 and 100 micrograms DMBA/g body weight (88-95% suppressed respectively) as was natural killer cell (NK)-mediated tumor cytolysis (24% and 55% suppressed). Antibody-dependent cytotoxicity was significantly depressed in the highest exposure group. Peritoneal macrophage accumulation was decreased in DMBA-treated mice, but the macrophages present were pushed towards activation. The ability of DMBA-exposed mice to eliminate intravenously injected B16F10 tumor cells from the lungs was not impaired. Since NK- and M phi-mediated tumor cytotoxicity are thought to be primarily responsible for pulmonary elimination of B16F10 melanoma cells, the extent of NK suppression observed following DMBA exposure appeared to be insufficient to alter in vivo B16F10 pulmonary elimination. In contrast, the loss of the CTL tumoricidal response correlated with an increased frequency of tumors following challenge with PYB6 tumor cells.     

Factors influencing the temporal phase of response to bar and grating stimuli for simple cells in the cat striate cortex

Summary We have characterized the speed of response of simple cells in cat striate cortex by the temporal phase of the response to bar and grating stimuli. Stimulation of the most responsive sub-region (either ON or OFF) in the receptive field with a 1 Hz temporally modulated bar elicited responses whose phase led the excitatory phase of the stimulus by about 25°. The response to stationary gratings whose contrast was sinusoidally modulated at 2 Hz also showed a phase lead. The differences in the phase of response of ON and OFF sub-regions exhibited a marked scatter about the expected value of 180°. The phase of response to both temporally modulated bars and laterally moving gratings advanced by 20–35° as the stimulus contrast was raised by a factor of 5.