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Biomedical subjects

R Colombo

Publications and source records attributed to R Colombo.

At least 163 records · Page 9Linked to original sources
PubMed1984

Preparation and evaluation of [99mTc]DEPE as a cardiac perfusion agent.

Technetium-99m labeled bis(1,2-diethylphosphino)ethane was evaluated as a cardiac perfusion agent in mice, dogs and normal human volunteers. The agent produced as a single cationic compound was prepared by a simple kit type method and had a rapid myocardial uptake in animals. The cardiac uptake of the agent in dogs averaged 4.6% of administered dose and delineated left and right ventricles by in vivo imaging. In dogs with experimental myocardial infarction, the agent was distributed according to the regional myocardial blood flow, had excellent correlation with myocardial distribution of 85Sr microspheres (r = 0.96, 0.93)] and 201Tl (r = 0.91 and 0.83), and enabled us to detect perfusion defects by in vivo scintigraphy. The agent, however, failed to have a useful degree of cardiac uptake in humans.

Animals↗
PubMed1984

Experimental convulsions in rats induced by intraventricular administration of kynurenine and structurally related compounds.

Administration of L-kynurenine and some analogous molecules into the right lateral ventricle caused convulsive attacks in rats. These convulsions are tonic-clonic. Various modifications of the structure of L-kynurenine affected the production of convulsions. In particular, methylation of the carboxyl group increased the potency. Methylation of the carboxyl function and hydroxylation of the benzene ring greatly increased the latency and the duration of the convulsions. Removal of the carboxyl function or its reduction resulted in the loss of the epileptogenic effect. Masking of the amino function with formyl or acetyl residues also produced inactive compounds. The results of structural modification of the kynurenine carbon skeleton clearly show that the structure essential for stimulation of convulsive activity includes a free amino group and a free or masked carboxyl function. The molecular structure able to induce convulsive effects appears to be the laevo -isomer of kynurenine, since the dextro-form has been proved to be inactive. The convulsant activity, evaluated as the ED50, for L-kynurenine, is between that of bicuculline and pentamethylenetetrazole . The convulsant mechanism of kynurenine is unknown, but might very possibly involve interference with the activity of certain inhibitory neurotransmitters.

Animals↗
PubMed1984

Doxorubicin affects actin assembly in vitro.

In vitro experiments on actin polymerization in the presence of doxorubicin show that the rate of salt-induced actin assembly is negatively affected by the drug. The decreased amount of actin monomers keeping their ability to self-interact to give F actin (microfilaments) probably explains the reduction of assembly value. Drug action is dose-dependent and various discrepancies are explained by the limitations of the techniques used.

Actins↗
PubMed1984

Tomographic assessment of regional cerebral perfusion using intravenous I-123 HIPDM and a rotating gamma camera.

The feasibility of assessing regional cerebral perfusion using the new brain imaging agent N,N,N'-trimethyl-N'-(2)-hydroxy-3-methyl-5-(123I) iodobenzyl)-1,3-propanediamine 2 HCl (I-123 HIPDM) and single photon emission computed tomography (SPECT) was evaluated in normal subjects and patients with cerebrovascular disorders. Following intravenous injection, I-123 HIPDM was rapidly extracted from the circulating blood by the brain (6.7%) and other organs. Its intracerebral distribution, as tomographically assessed by SPECT with a rotating gamma camera, reflected the distribution of blood flow within brain structures (gray and white matter, basal ganglia, etc.). Asymptomatic patients with history of transient ischemic attacks or minor stroke and angiographic evidence of internal carotid artery occlusion showed large cortical areas of reduced I-123 HIPDM distribution with normal or slightly positive CT. After extracranial-intracranial bypass surgery, reperfusion could be shown in previously ischemic areas. This study indicates the clinical usefulness of using I-123 HIPDM and gamma camera SPECT for the functional evaluation of brain disorders.

Adult↗
PubMed1984

Inhibitory effects of 2-guanidinebenzimidazole and 1-phenylbiguanide on gastric acid secretion in rats.

In this study 2-guanidinebenzimidazole (GBI) and 1-phenylbiguanide (PBG) appear to be capable of decreasing gastric acid secretion, while the compounds dimethylbiguanide and cyanoguanidine do not. Thus, the antisecretory effect is present when the biguanide groups are associated with lipophilic molecules. GBI and PBG depress gastric acid secretion, even when it has been stimulated by carbamoylcholine (carbachol) or betazole. The antihistamine effects of GBI and PBG on betazole-stimulated gastric acid secretion were confirmed by the inhibitory activity of these compounds on the isolated guinea pig auricle stimulated by histamine. The antimuscarine activity of GBI and PBG on carbachol-stimulated gastric acid secretion in rats is also supported by the way in which these same drugs depress the motility of the duodenum and colon of the anaesthetized cat stimulated by prostigmine. The above mentioned effects of these compounds are also associated with myolytic activity, since they decrease the spontaneous and histamine-stimulated motility of the duodenum and colon. GBI and PBG probably depress gastric acid secretion by interfering with both histamine and acetylcholine receptors and with other sites involved in the secretory process.

Animals↗
PubMed1983

[Diagnostic and prognostic value of the carcinoembryonic antigen in colonic cancer].

A group of 50 patients operated for carcinoma of the colon in June 1980-December 1981 with a follow-up period of min. 2 months-max. 15 months is presented. C.E.A. measurements were taken in all patients pre and post-operatively and then every 2 months in an attempt to establish its diagnostic and prognostic value. In immediate diagnostic and prognostic terms, pre-operative C.E.A. appears to be insignificant. However both pre-operative C.E.A. and C.E.A. at a distance of 6 months were found to be reliable for long term (max. 15 months) prognosis.

Adenocarcinoma↗
PubMed1983

Immunocytochemical localization of acrosin in boar spermatozoa.

Acrosin was localized on the acrosomal membranes of boar sperm by immunofluorescence and immunoelectron microscopy. Indirect labeling of sperm head sections was performed with an Imposil (iron-dextran) antibody conjugate. The results of electron microscopy indicated a preferential deposition of the antiacrosin antibodies on the outer acrosomal membrane, although a lesser deposition was also found on the inner acrosomal membrane. No labeling was detected in the acrosomal content when such material was still present.

Acrosin↗
PubMed1983

Actin behaviour in doxorubicin treatment.

The inhibition of neural tube closure in early chick embryos explanted in vitro by New's technique was used as a model to study the possible involvement of actin polymerization during doxorubicin treatment. The investigation was performed with indirect immunofluorescence staining, fluorescence staining with NBD-Ph, and DNase I inhibition activity. 8 x 10(-6) M doxorubicin induces alteration in the distribution of actin fluorescence on neural tube and in CEF cell cytoskeleton, and an appreciable increase in the critical concentration of monomeric actin as measured in cell extracts.

Actins↗
PubMed1983

4-Chloromethylphenoxyacetyl polystyrene and polyamide supports for solid-phase peptide synthesis.

Two functionalised supports for the solid-phase synthesis of peptides under mild reaction conditions were prepared: 4-chloromethylphenoxyacetamidomethyl-copoly (styrene-1%-divinylbenzene) and 4-chloromethylphenoxyacetyl-norleucyl-poly (dimethylacrylamide). They were devised in order to avoid the danger of racemization which exists during base-catalyzed esterification of the first protected amino acid to the 4-alkoxybenzyl alcohol resins formerly employed in combination with N alpha-9-fluorenylmethoxycarbonyl and tert.-butyl side-chain protecting groups. Esterification of N alpha-protected amino acids to the new resins can be achieved easily and without significant levels of racemization by means of their caesium salts, while cleavage from the supports is possible by treatment with trifluoroacetic acid. The 4-chloromethylphenoxyacetyl polystyrene resin was tested by the synthesis of Leu-enkephalin which was cleaved, at the end of the synthesis, from the solid support in 91% yield by 60% trifluoroacetic acid in methylene chloride, and was shown to be more than 99% pure by ion-exchange chromatography and reverse phase high pressure liquid chromatography.

Glycolates↗
PubMed1983

Neurilemmoma of the ciliary body: report of a case.

A case of ciliary body neurilemmoma is described. This neoplasm is extremely rare in the uveal tract and has been reported only once in the ciliary body. After extensive clinical studies of the rapidly growing tumour enucleation was performed. Subsequent histological examination showed typical features of highly vascular benign neurilemmoma. The main clinical and pathological features are reported and diagnostic problems are discussed.

Adult↗
PubMed1983

Determination of isoxsuprine in human plasma by gas chromatography with electron capture detection.

A rapid and sensitive gas chromatographic method for the determination of the beta-adrenergic agent isoxsuprine in human plasma has been developed. The procedure involves the extraction of the drug with ether and an internal standard (propranolol) from plasma at alkaline pH, solvent evaporation, and the formation of a tri-trifluoroacetyl derivative by reaction with trifluoroacetic anhydride in ethyl acetate. Analyses were carried out by gas-liquid chromatography on a 3% OV-17 column using an electron capture detector. The minimum detectable amount of isoxsuprine was 0.5 ng/ml of plasma and the electron capture detector response was tested to be linear (r2 greater than 0.999) between 0.5 and 20 ng/ml. No interferences from endogenous substances were found. Precision of the method was found to be 9.9, and 6.1% coefficient of variation at 1 ng/ml and 10 ng/ml of plasma, respectively. Determination of isoxsuprine at the nanogram level in cord plasma samples from newborns at the time of the delivery was possible using the described procedure.

Chromatography, Gas↗
PubMed1983

Actin in Xenopus yolk platelets: a peculiar and debated presence.

Our previous work showed that Xenopus yolk platelets exhibited, when reacted with actin antibodies or fluorescent DNase 1, a shiny halo of fluorescence, which revealed an external actin cover around the platelets themselves. This structure was named the 'actin-shell'. Now we have demonstrated the actin-containing coat of Xenopus yolk platelets by agglutination tests, using anti-Xenopus-muscle-actin rabbit serum, and by indirect immunofluorescence microscopy, when the platelets reacted with antibodies directed against DNase 1. We chose these procedures to minimize the difficulties of the techniques used previously and to confirm the data obtained.

Actins↗