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At least 505 records · Page 28Linked to original sources
PubMed1989

Image quality and radiopharmaceutical parameters of indium-111 granulocytes in scintigraphy of inflammatory bowel disease.

This study was undertaken to investigate the influence of various parameters of injected autologous 111In labelled granulocytes on scintigraphic image quality. Forty-two scintigrams of 37 patients with inflammatory bowel disease were evaluated. The images were divided into three groups according to quality: good, intermediate and poor. The relationships between image quality and such radiopharmaceutical parameters as injected dose of 111In, number of injected cells and specific activity were investigated. It appeared that in order to obtain interpretable images, a specific activity of at least 85 kBq 111In/million cells was necessary. The activity of the injected dose must exceed 7 MBq if poor quality images and very long acquisition times are to be avoided.

Cycloheptanes↗
PubMed1984

Brain and serum concentrations of dopamine analogues after peripheral administration to rats.

Concentrations of dopamine (DA) analogues were determined in rat brain regions and serum after peripheral administration of the drugs. The time course of the concentrations of four N,N-dialkylated DA derivatives is reported in relation to the simultaneously measured effects on DA metabolism. Maximum brain concentrations were reached at about 10 min after injection, followed by a rapid elimination of the parent compounds. O-Methylation was found to be of major importance in this early disappearance. The 3-O-methyl metabolite of N,N-dipropyl-DA (DiPr-DA) was very rapidly formed and was eliminated much more slowly than the parent compound. Inhibition of O-methylation as well as subcutaneous, instead of intraperitoneal (ip), administration resulted in higher brain and serum levels of DiPr-DA. Brain concentrations of 11 DA analogues were determined 10 min after ip injection and were compared with their octanol/water (pH 7.4) partition coefficients. Within one group of compounds with a similar metabolic profile the brain concentrations and partition coefficients showed a good correlation.

Animals↗
PubMed1983

Liposome/white-cell interactions in vivo.

The purpose of this study was to establish whether liposomes administered via the intravenous route promote granulocyte aggregation and pulmonary leukostasis. White cells (labelled with [111In]tropolanate) and positively and negatively charged liposomes (containing entrapped [99mTc]DTPA) were administered i.v. to rats. The blood clearance and tissue distribution of 111In label was not altered by the administration of liposomes (and vice versa) and it is inferred that on intravenous liposome administration liposome/white-cell interactions are unlikely to compromise lung function.

Animals↗
PubMed1986

Granulocyte migration in uncomplicated intestinal anastomosis in man.

We have investigated the presence, duration, and clinical significance of granulocyte accumulation, using indium-111 granulocyte scanning, in patients following uncomplicated intestinal anastomosis. Eight patients underwent intestinal resection and anastomosis (right hemicolectomy, 5; sigmoid colectomy, 2; ileal resection, 1) for carcinoma, angiodysplasia, or perforation. All patients had an uneventful postoperative course, with no evidence of any leakage or infection. Indium-111 granulocyte scan and abdominal ultrasound were performed 7-20 days (12 +/- 4.7 means +/- SD) following surgery. Indium-111 granulocyte scan showed the presence of labeled granulocytes at the site of anastomosis in all patients. In three of eight, cells subsequently passed into the lumen of the bowel. In contrast, granulocytes were not visualized along the abdominal incision. Thus, in contrast to skin wounds, granulocytes continue migrating into the intestinal wall in areas of anastomosis for at least up to 20 days following surgical trauma. They may play a significant role both in healing the anastomosis and in preventing systemic bacterial infection. Moreover, indium-111 granulocyte scans following intestinal surgery should be interpreted with care, and the presence of labeled granulocytes around anastomoses does not necessarily indicate abscess formation.

Aged↗
PubMed2004

(-)-Epigallocatechin-3-gallate and hinokitiol reduce melanin synthesis via decreased MITF production.

In this study, the effects of (-)-epigallocatechin-3-gallate (EGCG) and/or hinokitiol (beta-thujaplicin) on melanogenesis were investigated. Our results showed that both EGCG and hinokitiol significantly inhibited melanin synthesis in a concentration-dependent manner, and that their hypopigmenting effects were stronger than that of kojic acid, which is known to inhibit melanin formation in melanocytes and melanoma cells. Interestingly, EGCG did not show any additive hypopigmenting effect in combination with kojic acid, though EGCG did show a synergistic effect in combination with hinokitiol. Several reports indicate that the activation of extracellular signal-regulated kinase (ERK) induces microphthalmia-associated transcription factor (MITF) degradation. Accordingly, the effects of EGCG and hinokitiol on the ERK signaling pathway were examined. EGCG and hinokitiol induced neither ERK activation nor MITF degradation. On the other hand, both EGCG and hinokitiol reduced the protein levels of MITF and of tyrosinase, the rate limiting melanogenic enzyme, whereas kojic acid had no effect. In addition, hinokitiol strongly downregulated the activity of tyrosinase, whereas EGCG or kojic acid had only a little effect. These results show that both EGCG and hinokitiol reduce MITF production, and suggest that reduced tyrosinase activity by hinokitiol explains their synergistic effect on melanogenesis.

Animals↗
PubMed2004

Rapid accumulation and metabolism of polyphosphoinositol and its possible role in phytoalexin biosynthesis in yeast elicitor-treated Cupressus lusitanica cell cultures.

Inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)] rapidly accumulates in elicited Cupressus lusitanica Mill. cultured cells by 4- to 5-fold over the control, and then it is metabolized. Correspondingly, phospholipase C (PLC) activity toward phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] is stimulated to high levels by the elicitor and then decreases whereas Ins(1,4,5)P(3) phosphatase activity declines at the beginning of elicitation and increases later. These observations indicate that elicitor-induced biosynthesis and dephosphorylation of Ins(1,4,5)P(3) occur simultaneously and that the Ins(1,4,5)P(3) level may be regulated by both PtdIns(4,5)P(2)-PLC and Ins(1,4,5)P(3) phosphatases. Studies on the properties of PLC and Ins(1,4,5)P(3) phosphatases indicate that PLC activity toward PtdIns(4,5)P(2) was optimal at a lower Ca(2+) concentration than activity toward phosphatidylinositol whereas Ins(1,4,5)P(3) phosphatase activity is inhibited by high Ca(2+) concentration. This suggests that Ins(1,4,5)P(3) biosynthesis and degradation may be regulated by free cytosolic Ca(2+). In addition, a relationship between Ins(1,4,5)P(3) signaling and accumulation of a phytoalexin (beta-thujaplicin) is suggested because inhibition or promotion of Ins(1,4,5)P(3) accumulation by neomycin or LiCl affects elicitor-induced production of beta-thujaplicin. Moreover, ruthenium red inhibits elicitor-induced accumulation of beta-thujaplicin while thapsigargin alone induces beta-thujaplicin accumulation. These results suggest that Ca(2+) released from intracellular calcium stores may mediate elicitor-induced accumulation of beta-thujaplicin via an Ins(1,4,5)P(3) signaling pathway, since it is widely accepted that Ins(1,4,5)P(3) can mobilize Ca(2+) from intracellular stores. This work demonstrates an elicitor-triggered Ins(1,4,5)P(3) turnover, defines its enzymatic basis and regulation, and suggests a role for Ins(1,4,5)P(3) in elicitor-induced phytoalexin accumulation via a Ca(2+) signaling pathway.

Calcium↗
PubMed2005

Fungal diversity from western redcedar fences and their resistance to beta-thujaplicin.

The work reported here investigated the fungal community inhabiting western redcedar fence material with a focus on species colonizing wood below the surface, of which little is known. From seven pieces of fence material, twenty-three different fungal species were isolated and characterized using both traditional morphology and molecular identification methods. The species identified included thirteen ascomycetous and ten basidiomycetous fungi. Isolates were tested for their resistance to beta-thujaplicin - one of the principle fungicidal agents of western redcedar heartwood extractives. Generally, ascomycetous fungi exhibited greater resistance to beta-thujaplicin than basidiomycetous fungi. Interestingly, three ascomycetous and two basidiomycetous species frequently isolated had high tolerance to this compound. These species could be candidate 'pioneer' species that invade and detoxify western redcedar extractives, paving the way for colonization by decay fungi.

Antifungal Agents↗
PubMed1984

The structure of 2-methoxy-5-(2',3',4'-trimethoxyphenyl)tropone, an effective analog of colchicine.

-Methoxy-5-(2',3',4'-trimethoxyphenyl) tropone is an active analog of colchicine, a mitotic spindle inhibitor, which is missing the middle "B" ring. This compound crystallizes in the triclinic system, space group P1, with Z = 2; a = 10.135(2), b = 10.166 (4), and c = 7.863(2) A; alpha = 82.15(3), beta = 103.49(3), and gamma = 107.16(2); degrees and V = 750.7(4) A. The structure was solved by direct methods and refined by full-matrix least-squares to a final R = 0.063, using 2503 observed reflections and 271 parameters. Despite the absence of the middle ring, the conformation of the molecule is similar to that of colchicine, isocolchicine , and their derivatives. The troponoid ring is dissimilar to the phenyl ring in that it is not aromatic and does have alternating short and long bond lengths. The dihedral angle between the least-squares planes of the two rings is -57.4 degrees. Van der Waals surface representations of the analog and colchicine are presented to demonstrate the similarity and differences of these two molecules . The structural information of the analog is consistent with the interpretation of thermodynamic parameters which govern the interactions between brain tubulin and the analog.

Chemical Phenomena↗
PubMed1986

Tropylium tetrafluoroborate, a novel substrate for aldehyde oxidase.

The stabilized carbonium ion salt, tropylium tetrafluoroborate, was oxidized to tropone (cycloheptatrienone) by rabbit liver aldehyde oxidase but not by the closely related molybdenum hydroxylase, xanthine oxidase. The tropylium cation is an aromatic hydrocarbon which lacks the aldehyde, imine, or iminium functional groups present in other substrates of aldehyde oxidase. The unique structural features of the tropylium ion should make it a useful tool for mechanistic studies of aldehyde oxidase.

Aldehyde Oxidase↗
PubMed1978

Aspects of influx and efflux of homovanillic acid of rat cerebrospinal fluid.

In rats, different methods of perfusion (lumbar-cisternal or ventricular-cisternal) with artificial cerebrospinal fluid were performed at velocities of about 30 and 180 microliter/min. Levels of homovanillic acid (HVA) in the outflow were assayed with a semiautomated fluorimetric technique. Intravenous administration of 20 microgram HVA did not substantially enhance the outflow of this acid, indicating that in our preparations HVA found in the perfusate is of central origin. In the lumbar-cisternal preparation probenecid (200 mg/kg, i.p.) was found to inhibit the efflux of a significant fraction of HVA added to the medium, at both perfusion rates. The proportions of HVA eliminated by a probenecid sensitive transport was much higher at the lower rate of perfusion. Following probenecid the increase of endogenous HVA in the ventricular-cisternal perfusate was higher at a lower rate of perfusion. We determined the turnover rate of HVA in the whole brain and compared this value with the HVA outflow in the various preparations. The highest efflux of HVA was found in the ventricular-cisternal preparation during probenecid treatment and did not appear to be dependent upon the rate of perfusion. A maximal value of 3.5% of HVA formed in the central nervous system was found to be released into the cerebrospinal fluid.

Animals↗
PubMed1991

Reserpine-insensitive dopamine release in the substantia nigra?

Dopamine (DA) is synthesized and released not only from the terminals of the nigrostriatal dopaminergic pathway, but also from the dendrites in the substantia nigra (SN). Whether the DA release in the SN is sensitive to reserpine treatment, as it is in the stratum, has, however, not been clarified. We have determined the effects of reserpine on the concentrations of DA, serotonin and their metabolites in the SN and in the striatum and as an index of DA release in vivo we have assessed the accumulation of the DA metabolite 3-methoxytyramine (3-MT) following inhibition of monoamine oxidase by pargyline. The effects of reserpine on the concentrations of DA and its metabolites were different in the SN as compared to in the striatum. In the striatum there was a maximal depletion of DA to 2% of controls, but in the SN the DA concentration decreased only to 17% of controls. In the SN, the increases of the DA metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were less pronounced than in the striatum. In the striatum reserpine treatment (given 15 h, 3.75 h, or 1.75 h before pargyline) decreased the pargyline-induced 3-MT accumulation to 30% of pargyline-treated controls. However, in the SN no effects of reserpine were observed. The results indicate that DA in the SN partly is situated in a reserpine insensitive pool and that the release of DA might be insensitive to reserpine. These differences between the SN and the striatum could be due to different storage mechanisms. In the striatum DA is stored in classical storage granulas but in SN DA is partly stored in storage granulas and partly in smooth endoplasmatic reticulum.

Animals↗
PubMed1979

3,4-Dihydroxyphenylacetic acid and homovanillic acid in rat plasma: possible indicators of central dopaminergic activity.

The concentrations of dopamine (DA) metabolites (free and conjugated) was measured in plasma and brain regions of rats by the mass spectrometric method of selected ion monitoring. Experimental treatments which altered the function of central dopamine neurons also induced concomitant changes in plasma 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). Stimulation of the nigrostriatal pathway increased plasma DOPAC and HVA whereas lesion of the pathway decreased plasma metabolites. Several drug treatments induced parallel changes in brain and plasma concentrations of DA metabolites. It is suggested that changes in the concentration of DOPAC and HVA in rat brain are reflected by parallel changes in plasma. No conjugated forms of DOPAC and HVA were found in plasma and brain tissue of vervet monkeys (Cercopithecus aethiops).

3,4-Dihydroxyphenylacetic Acid↗