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Biomedical subjects

T Tan

Publications and source records attributed to T Tan.

At least 73 records · Page 4Linked to original sources
PubMed1994

[125I-alpha-sec-butyl-p-hydroxybenzyl alcohol receptor competitive binding assays in animal body].

Based on the receptor competitive binding assays in the mice and rat body, it has been proved that both diazepam and alpha-sec-butyl-p-hydroxybenzyl alcohol (G-018) can inhibit 125I-G-018 binding with brain benzodiazepine receptor. Inhibiting effects were obvious in the cortex, cerebellum, hippocampus and midbrain. But in the medullao blongata and hypothalamus no inhibiting effect was observed. Experimental results have demonstrated that the inhibiting effect is consistent with distribution of benzodiazepine receptor in the brain. Also, experimental results have shown no difference between in vitro and in vivo. The G-018 binding with benzodiazepine receptor has been clarified under physiologic conditions.

Animals↗
PubMed1994

[Biodistribution and metabolism of 3H-gastrodigenin and 3H-gastrodin in mice].

The biodistribution and metabolism of 3H-gastrodigenin and 3H-gastrodin after intravenous injection were studied by the detection of their radioactivity in mice tissue; the radioactive elements of mice tissue extracts after intravenous injection of 3H-gastrodin were analyzed with thin-layer chromatography (TLC). The results demonstrated that gastrodin could penetrate through the blood-brain barrier into the brain, and it was rapidly decomposed into the gastrodigenin in brain, liver and blood. Then gastrodigenin preserved in brain and mediated its pharmacological inhibitive effects on the central nervous system. Most of the gastrodigenin and gastrodin were excreted by the kidney. The findings also suggested that gastrodin might exist in the enterohepatic circulation.

Animals↗
PubMed1994

[Characterization of receptor-mediated binding of 99mTc-NGA in vitro].

This paper reports results of an assay of the binding of 99mTc-galactosylneoglycoalbumin (NGA) and plasma membranes of the rat liver in vitro. The data showed that 99mTc-NGA could be bound to the membrane receptor with high affinity. Specificity and saturability, and that the amount of membrane-bound 99mTc-NGA varied linearly with the amount of membrane within each reaction tube. The biphasic curve of scatchard plot revealed that 99mTc-NGA was bound to two sites of the receptor with different affinity and concentration (K1 8.4089 x 10(9) L/mol, R1 1.7350 x 10(-12) mol/mg); K2 2.0827 x 10(8) L/mol, R2 6.9530 x 10(-12) mol/mg). Therefore, the authors consider that 99mTc-NGA is a promising hepatic receptor agent for imaging.

Albumins↗
PubMed1993

Efficacy and safety of multidrug therapy in paucibacillary leprosy in Singapore.

A total of 49 patients with paucibacillary leprosy (PB) who completed multidrug therapy (MDT) between 1985 and 1990 were analysed retrospectively for efficacy and complications; 20 (40.8%) patients had borderline-tuberculoid (BT), 13 (26.5%) had tuberculoid (TT), 1 (2.1%) had indeterminate (I) and 15 (30.0%) had pure neural (N) leprosy; 26 patients (76.5% of 34 non-neural leprosy) were skin biopsied for histological cure before MDT was stopped. Of these 26 patients, 19 had histological clearance at 6 months while the remaining 7 cleared beyond 1 year (18-36 months). The remaining 8 non-neural patients who refused rebiopsy had MDT for 6-8 months and the MDT was stopped when there was clinical clearance. Of the 15 neural (N) leprosy patients, 11 were given MDT for 6 months while the rest had 12-18 months of treatment; 1 patient with neural leprosy, who was treated for 6 months, relapsed with BT leprosy 18 months post-treatment. There were few complications among the 49 patients-4 (8.2%) patients developed reaction to dapsone, 1 (2.0%) had the dapsone syndrome, 2 (4.1%) had haemolytic anaemia and 1 (2.0%) had dapsone hepatitis; 7 (14.3%) patients had type I reaction.

Adult↗
PubMed1993

[The preparation of 99mTc-NGA instant lyophilized kit for hepatic imaging].

The preparation of one-step kit for the 99mTc labelled galactosyl-neo-glycoalbumin (NGA) using SnCl2 reduced method was reported in this paper. We developed a method of quality control and established the optimum scheme of technetium labelling on the basis of exploring the effects of varied labelled conditions on radiochemical purity. Our data indicates : (a) the kit is sterile, pyrogen-free and no toxic effects; (b) the operation is simple and fast; (c) its period of validity lasts no less than 3 months; (d) the radiochemical purity > 95%; (e) the stability of 99mTc-NGA in vitro > 4 hours; (f) the results of animal imaging and clinical probation are satisfactory.

Albumins↗
PubMed1993

[Pharmacokinetic studies on 99mTc-NGA in human].

Two normal subjects and three patients with hepatic disease were intravenously injected each with a single dose of 99mTc-NGA (galactosyl-neoglycoalbumin), a liver receptor imaging agent. The results showed that pharmacokinetics of 99mTc-NGA accorded with the two compartment open model. In the normal subjects, T1/2 alpha and T1/2 beta averaged 1.65 and 19.39 min respectively, indicating a rapid distribution process and a slow elimination process. There were significant differences in pharmacokinetics of 99mTc-NGA between the normal subjects and the patients with hepatic disease, and therefore the relevant parameters are of importance for the evaluation of hepatic function.

Adolescent↗
PubMed1992

[Hepatic carcinoma treated by hepatic arterial embolization using 131I and chemotherapeutic agent gelatin microspheres: report of 9 cases].

Nine patients with inoperable hepatoma were treated by using hepatic arterial embolization 131I and chemotherapeutic agent gelatin microsphere (131I-CA-GM). The emission CT after operation detected that the microspheres were concentrated on tumor area. The ratio between the radioactivity in tumor and that in liver was 4.1:1. A case died of ictopic embolization; the others survived 3, 4, 5, 19, 24, 7, 8, and 12 months respectively. Three of them were still alive. 131I-CA-GM has triple anticarcinogenic actions, including the arterial occlusion, targeting chemotherapy and internal radiation. The microspheres can selectively accumulate in the tumor artery and can be easily traced by gamma-camera or emission CT. 131I-CA-GM is a hopeful embolic agent for the treatment of liver cancer, but some problems about ectopic arterial embolization should be further studied.

Carcinoma, Hepatocellular↗
PubMed1991

Characterization of the performance of shoe insert materials.

It has been widely reported that shoe inserts are an effective interventional modality either for the relief of discomfort to the feet associated with a variety of orthopedic disorders or conditions or simply for comfort. Results from many types of experimental tests have been used to obtain the shock absorption capacity of shoe insert materials. The authors contend in this study that, while shock absorption is a highly desirable property, it is by no means the only that should be used to characterize these materials. Thus, a new index of performance of these materials is proposed. This index is computed from data, obtained in a simple experimental test, on both the shock absorption and energy return performances of the insert material.

Data Collection↗
PubMed1991

[Study of the mechanism of gastrodin and derivatives of gastrodigenin].

The tritiated alpha-isobutylhydroxybenzyl alcohol (3H-G018) was found to be able to bind benzodiazepine (BZ) receptor on the rat brain membrane. The 125I labeled G-018 also had the similar binding activity with this receptor. In the present investigation, we observed that gastrodigenin and its derivatives inhibited the 125I-G018 binding of BZ receptor competitively, but no inhibition was observed with gastrodin. The results suggested that Gastrodigenin was bound to BZ receptor, and otherwise, gastrodin would have no direct interaction with BZ receptor. Probably, it might metabolize into gastrodigenin in vivo, and then got through the blood brain barrier and bound to BZ receptor, which mediated its pharmacological effects on the central nervous system.

Animals↗
PubMed1991

[An experimental study on hepatic arterial embolization with 131I-MMC-GM].

We designed a new gelatin microsphere (GM, 65 micron in diameter), which could combine with mitomycin C and 131I. The test in vitro showed that the GM had excellent drug release effect. Hepatic arterial embolization was carried out in 6 dogs with 131I-MMC-GM. The dogs survived from 4 to 28 days before being killed. Scintigraphy indicated that high radioactivity was concentrated in the liver, but was very low in the blood and thyroid. Pathologic study found that the GM was trapped in hepatic arterioles. The GM was eliminated by foreign body giant cells and the lumen of arterioles was occupied by granulations 14-28 days after operation. 131I-MMC-GM is a multiple anticancer agent which can exert triple action of targeting chemotherapy, internal radiotherapy and arterial embolization.

Animals↗
PubMed1991

[Synthesis of hexamethyl propylamine oxime and comparative study of its diastereoisomers].

This is a report on the synthesis of hexamethyl-propylene-amine oxime (HM-PAO), a new agent for regional cerebral blood flow (gamma CBF) imaging, the separation of its diastereoisomers (dl- and meso-HM-PAO), and a comparative study of three forms of Tc- 99m labelled HM-PAO (dl-, meso- and mixture-) in chromatography, mice biodistribution and rabbit imaging. The results showed that the Rf value of Tc-99m-dl-HM-PAO (0.8-1.0) on silica G thin layer chromatography with MEK as solvent was different from that of Tc-99m-meso-HM-PAO (0.6-0.8), and that the retention of dl- isomer in the brain was higher and more static than those of meso-and mixture HM-PAO but identical with Ceretec, a dl-HM-PAO kit manufactured by Amersham Inc., England. The primary clinical applications for gamma CBF SPECT imaging demonstrated a satisfactory result.

Animals↗
PubMed1991

[Galactosyl neoglycoalbumin:preparation and studies of its binding with hepatic special receptor].

Galactosyl-neoglycoalbumin (NGA) can bind with the asialoglycoproteins receptor specifically on the surface of mammal's liver. We prepared NGA in different carbohydrate density and made some animal and clinical tests with technetium-99m labeled NGA. The maximum absorption of 99mTc-NGA-21 was 82.6% in liver. We also got the satisfactory radiographs of liver. NGA was synthesized by the covalent coupling of a carbohydrate bifunctional reagent, 2-imino-2-methoxyethyl-1-thio-galactose (4), to human serum albumin. The cyanomethyl-1-thio-glycoside of beta-D-galactose (3) was prepared from the pseudothiourea derivative (2) which was synthesized by acetylation, bromination and substitution of galactose (3) could be converted to (4) by treatment with sodium methoxide.

Albumins↗
PubMed1990

Enhanced penetration of zona-free hamster ova by sperm prepared by Nycodenz and Percoll gradient centrifugation.

The effect of sperm penetration capacity after selection procedures using Percoll (Pharmacia AB, Uppsala, Sweden) and Nycodenz (Nycomed Diagnostics, Oslo, Norway) gradient centrifugation was compared with double-washed and swim-up in 47 subfertile men. The results of sperm motility, velocity, and amplitude lateral head displacement showed no significant improvement with the centrifugation procedures. The sperm penetration assay results obtained with double-washed and swim-up technique were poor (2.7% +/- 1.7%), however, a significant enhancement was obtained by Percoll (16.3% +/- 3.7%) and Nycodenz (15.8% +/- 3.3%) processing. Nycodenz centrifugation allowed sperm penetration of zona-free hamster ova at comparable rates to Percoll separation.

Adult↗
PubMed1990

[Analgesic activity of morphine suppository in rats].

Analgesic activity of morphine administered rectally as a suppository was investigated in rats in order to ascertain analgesic activity of morphine suppository. Morphine hydrochloride given rectally as a suppository produced analgesic activity in a dose-related manner in the tail pressure and acetic acid-induced writhing tests, and its potency (ED50 = about 17 and 0.689 mg/kg, respectively) was approximately twice that of morphine hydrochloride administered orally as an aqueous solution. The analgesic action was as durable as that of oral morphine, but its onset was faster. The plasma and brain levels of morphine reached peak until 30 min after rectal administration of morphine suppository, and these time-courses approximately corresponded with that of the analgesic action. These results suggest that morphine given rectally to rats as a suppository produces analgesic action equivalent or superior to orally administered morphine after absorption from the rectum.

Analgesics↗
PubMed1990

[Morphine hydrochloride suppositories. I. Bioavailability of morphine hydrochloride suppositories in rats].

Bioavailabilities of morphine after rectal administration of three different morphine-HCl suppositories (5 mg/kg) were evaluated in rats. The suppositories were prepared with three fatty bases (Witepsol H-15, Witepsol W-35, Suppocire AT) by the fusion method. The plasma and brain concentrations of morphine and its metabolites, morphine-3-glucuronide and morphine-6-glucuronide, were determined by high-performance liquid chromatography. The bioavailabilities of morphine after rectal administration were compared with those after intravenous and oral administration of morphine.HCl solution (5 mg/kg). The plasma levels of morphine after rectal administration of morphine.HCl solution were higher than those after oral administration, whereas the plasma levels of metabolite, morphine-3-glucuronide was lower than those after oral administration. Morphine after rectal administration of Witepsol H-15 suppository released more easily than other suppositories. The inter-animal variation in the plasma levels of morphine after rectal administration of Witepsol H-15 suppository was smaller than those of other suppositories. Results obtained in this study indicate that morphine.HCl suppository prepared with Witepsol H-15 is a promising material as preparation of suppositories.

Animals↗