Search PubMed⌕ Search

Biomedical subjects

H Neu

Publications and source records attributed to H Neu.

At least 19 recordsLinked to original sources
PubMed1997

Synthesis of [11C-methyl]-(-)-OSU6162, its regional brain distribution and some pharmacological effects of (-)-OSU6162 on the dopaminergic system studied in the rhesus monkey by positron emission tomography.

The labelling of the presynaptic dopamine receptor antagonist (-)-OSU6162, ((S)-(-)-3-(3-(methylsulfonyl)phenyl)-1-propylpiperidine) was performed by an alkylation with [11C]methyl iodide of the thio anion (-)-OSU1281, followed by a selective oxidation to the corresponding methyl sulfone, [11C-methyl]-(-)-OSU6162. The total radiochemical yield calculated from the produced [11C]carbon dioxide to final product was about 25% and the time of synthesis was in the range of 40 min from end of bombardment. The synthesis of the precursor, (-)-OSU1281, was performed from (-)-3PPP in a three-step synthesis. The regional brain distribution of (-)-OSU6162 radiolabelled with 11C was studied in rhesus monkeys by means of positron emission tomography, PET. [11C-Methyl]-(-)-OSU6162 was rapidly and uniformly distributed to gray matters of the brain, and no decrease of radioactivity uptake in the brain was seen after pretreatment with 1 to 3 mg/kg/h of (-)-OSU6162. The effect of doses of 1 to 3 mg/kg/h of (-)-OSU6162 on the dopamine binding was studied by PET using [11C-methyl]raclopride. Radioactivity in the striatum was significantly and dose-dependently decreased by (-)-OSU6162 (r = 0.88), supporting competition with dopamine for selective binding to dopamine receptors.

Animals↗
PubMed1996

Receptor imaging technique with 11C-labeled receptor ligands in living brain slices: its application to time-resolved imaging and saturation analysis of benzodiazepine receptor using [11C]Ro15-1788.

Recently we developed a novel imaging technique using positron emitter-labeled compounds as probes and a storage phosphor screen as a detector. This approach makes it possible to follow a variety of biochemical processes with spatial information in living brain slices. Further technical development is reported here in terms of time-resolved imaging and receptor characterization in a real equilibrium state. The method was validated by use of [11C]Ro15-1788, a benzodiazepine receptor antagonist. Fresh brain slices were incubated with [11C]Ro15-1788 in oxygenated Krebs-Ringer solution at 37 degrees C, in a specially designed chamber. By placing the chamber on a storage phosphor screen, we could obtain two-dimensional images of radioactivity in the slices. Time-resolved imaging was made at 5 min intervals, revealing that it took 60 min to reach equilibrium binding. The dissociation process was observed by adding an excess amount of unlabeled Ro15-1788 to the chamber, 25 min was required for the full dissociation. In the equilibrium state, i.e. in the presence of free radio-ligand, Scatchard plot analysis was performed on the cerebral cortex (Kd = 7.4 nM, Bmax = 146 fmol/mg tissue) and striatum (Kd = 7.5 nM, Bmax = 107 fmol/mg tissue), suggesting the presence of a single component of binding site in these two regions. The present method, for the first time, made it possible to study a ligand-receptor interaction in living brain slices with temporal and spatial resolutions. This technique should prove useful for studies of receptor function under physiological conditions.

Animals↗
PubMed1996

[Doppler echocardiography of heart valve defects in the dog].

In the diagnosis of heart diseases the Doppler echocardiography makes it possible to distinguish physiological and pathological blood flow and thus to prove and judge valve defects in a noninvasive way. The color Doppler gives a survey about place and direction of the streams. The exact analysis and quantification of the stream speed results from the spectral Doppler. Valve stenosis is characterized by a flow acceleration on the level of the stenosis. The increased speed is used for estimation of the severity of the stenosis. Valve insufficiency is recognized by a reflux of blood to the ventricle or atrium, respectively. The extent of the insufficiency can be evaluated semiquantitatively.

Animals↗
PubMed1996

[Echocardiographic reference ranges of sedated cats].

The aim of this study was to get echocardiographic values of sedated healthy cats of the race European short hair for further reference. After the preliminary examinations checking on the state of health (anamnesis, general and special clinical examinations, ECG, X-ray of thorax and preparation of selected laboratory parameters), 74 sedated animals and additionally 33 cats without sedation were echocardiographically measured. For sedatives we used ketamine hydrochloride and xylazine in order to minimize defending movements of the animals and to reduce the heart rate, which facilitated the echocardiographical measurements. The covariance analysis of the measured values showed a statistically significant dependence on the weight. This did not hold for the two calculated values of the fractional shortening (FS) and the quotient of left atrium and aorta (LA/Ao), where the weight-dependence of each component was compensated by the calculation of the quotient. All stated weight-dependent reference values refer to an average bodyweight of 4.0 kg. A dependence on the age did not show in the covariance analysis. Due to the sedation, the diameter of the left atrium (LA) and the diameter of the left ventricular lumen in the diastole (LVDd) as well as the fractional shortening decreased significantly.

Animals↗
PubMed1995

Laboratory assessment of antibacterial activity of zwitterionic 7-methoxyimino cephalosporins.

Zwitterionic 7-methoxyimino cephalosporins (cefpirome, cefepime, cefclidin, DQ2556, FK037 and SCE2787) possess a variable substitution at C3 which contains a quarternary nitrogen. These cephalosporins display low affinities for Class I beta-lactamase and rapid penetration through the outer membrane of Gram-negative bacilli, so that an increased number of periplasmic beta-lactam molecules interact with PBP's per unit of time. As a consequence, the new zitterionic compounds remain active against some, but not all, ceftazidime-resistant Enterobacteriaceae producing high levels of Class I beta-lactamase or Bush type 2b beta-lactamases. Antipseudomonas activities are generally similar to that of ceftazidime except that cefclidin is more active. The new zwitterionic compounds, especially cefpirome and FK037, express greater antistaphylococcal potency than does ceftazidime. A variety of animal models including meningitis and endocarditis have confirmed the potential of these compounds in-vivo. On the basis of structural and antibacterial characteristics, the expression 'forth generation' is acceptable to describe the zwitterionic 7-methoxyimino cephalosporins.

Cephalosporins↗
PubMed1990

Comparative in vitro activity of the new fluoroquinolone BMY-40062.

The results are presented of comparative in vitro susceptibility testing of BMY-40062, a new fluorinated quinolone which contains a tetrabutyl moiety at N-1 and a piperazinyl group at C-7. BMY-40062 inhibited 90% of Enterobacteriaceae strains at less than 0.5 microgram/ml, being either equal in activity to ciprofloxacin or two- to four-fold less active, depending upon the species. BMY-40062 was as active as ciprofloxacin against Pseudomonas aeruginosa (MIC90 0.5 micrograms/ml) and inhibited most other strains of Pseudomonas species at less than 1 microgram/ml. It was more active than ciprofloxacin or ofloxacin against hemolytic streptococci and Streptococcus pneumoniae, 90% of strains being inhibited at less than 0.5 micrograms/ml. MICs increased in the presence of 9 mM Mg2+ and at pH 5.5. The frequency of spontaneous mutation was low for Enterobacteriaceae, Pseudomonas aeruginosa and Staphylococcus aureus (10(-10), but repeated exposure to BMY-40062 caused selection of resistant isolates. Clinical isolates of Pseudomonas aeruginosa resistant to ciprofloxacin and ofloxacin were resistant to BMY-40062.

Anti-Infective Agents↗
PubMed1990

Suppression of feline immunodeficiency virus infection in vivo by 9-(2-phosphonomethoxyethyl)adenine.

The acyclic purine nucleoside analogue 9-(2-phosphonomethoxyethyl)adenine [PMEA; formerly referred to as 9-(2-phosphonylmethoxyethyl)adenine] is a potent and selective inhibitor of human immunodeficiency virus replication in vitro and of Moloney murine sarcoma virus-induced tumor formation in mice. In the latter system PMEA has stronger antiretroviral potency and selectivity than 3'-azido-3'-thymidine (AZT). We have now investigated the effect of the drug in cats infected with the feline immunodeficiency virus (FIV). In vitro, PMEA was found to efficiently block FIV replication in feline thymocytes (50% effective dose, 0.6 microM). When administered to cats at doses of 20, 5, or 2 mg/kg per day, PMEA caused a dose-dependent suppression of FIV replication and virus-specific antibody production. Seropositive field cats with signs of opportunistic infection (gingivitis, stomatitis, and diarrhea) showed clinical improvement during PMEA therapy (5 mg/kg per day) and recurrence of the disease after treatment was discontinued. Thus, FIV infection in cats is an excellent model to test the efficacy of selective anti-human immunodeficiency virus agents in vivo.

Adenine↗