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Biomedical subjects

E Chiotellis

Publications and source records attributed to E Chiotellis.

35 records · Page 2Linked to original sources
PubMed1993

Indium-111-labelled cationic complexes of aminothiols: structure-activity correlation.

In the present work a series of NxS2 ligands were synthesized, investigated for the formation of cationic, indium chelates and evaluated comparatively in experimental animals. The compounds under study formed indium complexes which were stable in vitro and presented myocardial uptake. Animal studies showed that the chemical structure of the ligand plays an important role in biodistribution. A system of one six-membered and two five-membered rings, formed by the metal and the donor atoms of the ligand, may constitute a basic structure for the development of new indium tracers with myocardial affinity.

Animals↗
PubMed1993

Correlation of lipophilicity to biodistribution of 99mTc-labelled aminothiols.

A series of 99mTc-DADT complexes substituted with heterocyclic amines were synthesized and tested for their ability to cross the BBB. Each 99mTc-DADT complex analysed by HPLC was found to consist of two epimers. The more lipophilic epimers were biodistributed in mice. The data demonstrated a significant brain uptake (3-12% dose/g whole brain) and a high lung accumulation (11-85% dose/g) at 2 min p.i. Between the partition coefficients of the technetium complexes, a linear correlation for lung accumulation was observed, while a parabolic curve for brain uptake was found.

Animals↗
PubMed1993

99mTc-DADT complexes substituted with heterocyclic amines: effect of substitution on in vivo reactivity.

Alkylpiperidinyl and alkylpyrrolidinyl 99mTc-DADT complexes were synthesized and tested for their ability to cross the BBB. Each complex was a mixture of two epimers separated by HPLC. More lipophilic epimers were biologically evaluated in mice, at various time intervals. Similar biodistribution patterns were obtained for both piperidinyl and pyrrolidinyl DADT-complexes. Brain uptake or retention was influenced by the heterocyclic amine introduced into the DADT backbone. Subcellular concentration of selected 99mTc-DADT complexes was more profound in crude nuclear and post-microsomal fractions. Moreover, interaction of 99mTc-2,2,6,6,9,9-hexamethyl-4,7-diaza-4-(3-methylpyrroli dinyl)-ethyl-1,10- decanedithiol with either lipids or microsomes of whole brain was almost unaffected by time. This may suggest that a possible selective site of interaction and metabolism for DADT complexes occurs in brain.

Amines↗
PubMed1993

Renal elimination of some 99mTc-labelled cysteamine derivatives.

It is generally believed that -CO-NH-(CH2)n-COOH moiety promotes tubular excretion of organic anions. Recently it was reported that newly developed renal agents, containing the oxotechnetium(V) glycine group, may mimic the carbonyl amide sequence of [131]I-o-iodohippuric acid. In this study the renal excretion of certain carboxy-cysteamine derivatives is investigated in mice, in the presence of renal tubular transport inhibitor. A similar pattern of renal depression was observed for complexes containing the oxotechnetium glycine sequence, suggesting that this group may satisfy structural parameters for tubular secretion of anionic technetium complexes.

Animals↗
PubMed1992

Synthesis, radiochemistry and biological evaluation of technetium-99m complexes with 1,8-diamine-3,6-dithiaoctane (DDO) ligands.

The synthesis, radiochemical analysis and biological characteristics of some 1,8-diamine-3,6-dithiaoctane derivatives labelled with Tc-99m are reported. Analysis by HPLC shows that most of the 99mTc-chelates are multicomponent. Furthermore, almost all 99mTc-complexes isolated by HPLC are lipophilic and stable in vitro. The biodistributions of the most lipophilic of these complexes were evaluated in mice. The N-morpholinylethyl and N,N'-bisalicylyl derivatives of 1,8-diamine-3,6-dithiaoctane yielded 99mTc-complexes which exhibit considerable uptake and retention in organs of interest, such as the heart and the brain.

Animals↗
PubMed1988

Comparative evaluation of 99mTc-labeled aminothiols as possible brain perfusion imaging agents.

Several new 99mTc aminodithiols were prepared and evaluated comparatively in experimental animals. The ligands were diamine, triamine or tetramine dithiols. Substituents were either attached on one of the nitrogens or introduced in between the two nitrogens of diamino dithiol (DADT) backbone. 99mTc-derivatives prepared by coupling DADT to secondary amines via ethylene group showed in mice high initial brain uptake and significant retention in brain tissue. These preparations were mixtures of more than one 99mTc-complex differing in brain uptake and clearance from the brain. The highest brain retention (brain to blood ratio 2.53, 15 min p.i.) was achieved with the 99mTc-complex prepared by coupling DADT with ethylene pyrrolidine. Lengthening the chain between the nitrogens of DADT moiety by introducing methyl or amino alkyl groups resulted in 99mTc-complexes with poor brain accumulation.

Animals↗
PubMed1984

Red blood cell labelling by intravenous injection of 99mTc-PAEP.

In vivo red blood cell (RBC) labelling after the intravenous administration of PAEP (N- phosphorylamino -ethyl -phosphate) and the subsequent injection of sodium pertechnetate 24 hrs later was studied. The results in rats were found to be similar to those obtained after i.v. administration of 99mTc -PYP, a radiopharmaceutical routinely used for in vivo RBC labelling.

Animals↗
PubMed1982

Structure-activity relationships of some technetium-99m labeled [(thioethyl)amino] carboxylates.

The synthesis, NMR studies, radiochemical labeling with technetium-99m, and tissue-distribution characteristics of some [(thioethyl)amino] carboxylates are described. The 99mTc agents prepared were eliminated either by the urinary of the hepatobiliary system of mice. The excretion route of the 99mTc complexes was influenced by the structure and total charge of the ligands.

Amino Acids, Sulfur↗
PubMed1981

Comparative in vivo kinetics of some new 99mTc-labelled acetanilido iminodiacetates.

The in vivo kinetics of five new 99mTc-labelled acetanilido iminodiacetates, analogous to 99mTc-p-butyl IDA, were studied in experimental animals by means of their distribution in mice and scintigrams of rabbits. The new compounds were specifically eliminated via the hepatobiliary system with various rates of hepatic extraction. Urinary excretion of the complexes was minimal.

Animals↗
PubMed1979

Absorbed dose estimation of some 99mTc-hepatobiliary agents.

The absorbed dose estimates of several organs after administration in humans of six new hepatobiliary agents (five 99mTc-Pyridoxal amino acid complexes and the 99mTc-HIDA) are presented in comparison with 131I-Rose-Bengal. The results indicated that the radiation doses absorbed by the total body and gonads as well as by the critical organ (upper part of the large intestine) are significantly lower than those of Rose Bengal. Therefore, the new 99mTc-agents can be safely applied to humans.

Adult↗
PubMed1978

99MTc-HIDA, a gallbladder imaging agent: experimental aspects.

The molecule N-(2,6-dimethyl-phenyl-carbamoyl-methyl)-iminodiacetic acid (HIDA), capable of chelating reduced 99mTc, was synthesized, characterized, labeled with 99mTc, and studied in experimental animals. The results indicated that the new 99mTc-radiopharmaceutical is rapidly cleared from the blood to the liver, then rapidly removed to the gallbladder and excreted into the duodenum through the common bile duct. A comparative kinetic study of 99mTc-HIDA and 131I-Rose Bengal performed in rabbits demonstrated that both radiopharmaceuticals had a similar blood clearance rate, but cleared at a different rate from liver to gallbladder. 99mTc-HIDA showed a faster accumulation in the gallbladder than 131I-Rose Bengal. These findings, combined with the advantage of the low acute toxicity of HIDA, were promising enough to encourage a further evaluation and clinical investigation of this new Tc-99m hepatobiliary agent.

Animals↗