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Biomedical subjects

S X Xu

Publications and source records attributed to S X Xu.

At least 55 records · Page 3Linked to original sources
PubMed1993

[Follow-up study on physical and mental development in small-for-gestational age infants].

A follow-up study on physical and mental development was carried out in 35 small-for-gestational-age (SGA) and 35 appropriated-for-gestational age (AGA) infants. Excluded for congenital abnormality, intrauterine infection, and neonatal asphyxia SGA and AGA infants were similar in maternal education level, infant sex, illness, and feeding history. The results revealed that the body weight (8.09 +/- 0.73kg), height (69.55 +/- 2.49 cm), head circumference (43.27 +/- 1.67cm), Kaup index (16.17 +/- 1.05), and development quotient (96.37 +/- 5.76, Gesell diagnostic method) level at 40 weeks of age in SGA infants was lower than that in AGA infants (P < 0.001), and the development quotient (DQ) in SGA infants was especially low in language and receptive regions. Cord serum insulin level was significantly correlated with follow-up body weight, height, and DQ level (P < 0.01). This article proposed that infants with intrauterine growth retardation have a physical development delay at 40 weeks of age, and which could be predicted by measuring cord insulin level.

Body Height↗
PubMed1992

Speciation of tissue and cellular iron with on-line detection by inductively coupled plasma-mass spectrometry.

Iron accumulating to excess in tissues of humans and animal models occurs mainly as complexes with transferrin, ferritin, other hemoproteins, and insoluble hemosiderin particles. To determine the distribution of Fe amongst these molecular species, we have used inductively coupled plasma-mass spectrometry as a means of on-line, isotope-specific detection for their liquid chromatographic separation. The stable isotope 57Fe is a suitable isotope for monitoring the Fe content of each fraction, and its availability at high isotopic enrichment makes it an attractive choice for tracer studies when the use of a radioisotope is undesirable, e.g., in human subjects. The detection system offers the advantages of high sensitivity (detection limits in the parts per billion range), a wide dynamic range (linearity of the calibration curve over several orders of magnitude), and on-line analysis facilitating real-time evaluation of the chromatographic separation, in addition to isotope-specific information. The Fe distributions in healthy rat livers, liver and heart tissue from Fe-loaded human subjects, and human hepatocyte cultures are reported. The ferritin:hemosiderin ratio in these samples is shown to be an indicator of the degree of Fe loading and correlates well with that determined by Zeeman-corrected electrothermal atomic absorption as an alternative means of detection.

Animals↗
PubMed1992

Regulation of D1A and D2 dopamine receptor mRNA during ontogenesis, lesion and chronic antagonist treatment.

The developmental characteristics of D1A and D2 dopamine receptor mRNA levels were determined by Northern blot analyses. Striatal D1A and D2 dopamine receptor mRNAs of male Fischer 344 rats were about 60% of adult (day 120) levels at postnatal day 1 and reached their highest levels at day 30 (126 and 139% adult levels) and then decreased by day 120 (100%). D1 and D2 dopamine receptors showed much greater quantitative changes with densities at day 30 about 6- and 14-fold higher than at day 1, respectively, while mRNA levels showed only a 2-fold increase. The highest level of D2 dopamine receptor mRNA in the midbrain was reached at day 14 (195% of adult levels) while the level at day 1 was 31% higher than that at day 120. Striatal beta-actin mRNA levels decreased gradually as the rats developed with the level at postnatal day 1 almost twice that at day 120 postpartum. Treatment of adult rats with the selective D2 dopamine receptor antagonist, haloperidol (0.5 mg/kg/day, s.c., for 2 h, 7, 14, 21 days or 21 days + 3 days withdrawal) had no effect on striatal D2 dopamine receptor mRNA levels in spite of significant increases in dopamine receptor density at the later time points. However, 21 days following a 6-hydroxydopamine lesion of the nigrostriatal pathway, striatal D2 dopamine receptor mRNA levels were increased by 53%.

Age Factors↗
PubMed1992

Expression of rat striatal D1 and D2 dopamine receptor mRNAs: ontogenetic and pharmacological studies.

The developmental characteristics of D1 and D2 dopamine receptor mRNA levels were determined by Northern blot analyses. Striatal D1 and D2 receptor mRNAs of male Fischer 344 rats were about 60% of adults levels at postnatal day 1 and reached their highest measured levels at day 30 (126-139% adults levels) and then decreased by day 120 (100%). D1 and D2 receptor densities at day 30 were about 8-fold higher than at day 1, while mRNA levels showed only a 2-fold increase. The highest level of D2 receptor mRNA in midbrain as reached at day 14 (195% adult level) while levels at day 1 were 31% higher than dose at day 120. Treatment with selective D2 receptor antagonist, haloperidol (0.5 mg/kg/day, s.c., for 2 h, 7, 14, 21 days or 21 days + 3 days withdrawal) had no effect on Sprague-Dawley rat striatal D2 receptor mRNA levels in spite of significant increases in receptor density at the later time points. However, the selective D1 receptor antagonist, SCH 23390 (0.5 mg/kg/day, s.c.) produced increases in striatal D1 receptors and mRNA levels after treatments of 7, 14 and 21 days + 3 days withdrawal.

Aging↗
PubMed1992

Effect of chronic nicotine treatment and withdrawal on rat striatal D1 and D2 dopamine receptors.

The effects on rat striatal dopamine receptors after chronic nicotine administration (3 and 12 mg kg-1 day-1), and after withdrawal from chronic nicotine (12 mg kg-1 day-1), were studied. After 21 days of continuous minipump infusion, the control (saline) and nicotine-treated rats were killed. The nicotine-withdrawal rats were killed on day 28, 7 days after pump removal. Radioligand studies were performed to determine D1 ([3H]SCH23390) and D2 ([3H]spiperone) striatal dopamine receptor affinity (Kd) and maximum binding (Bmax). Dopamine inhibition of antagonist binding at 3 concentrations and the effect of 0.3 mM GTP on binding affinity were examined. No statistically significant differences between control and nicotine treatment or withdrawal groups were noted in either D1 or D2 receptor Kd or Bmax. Although nicotine has been shown to affect nigrostriatal dopamine release, chronic treatment does not appear to alter overall striatal dopaminergic receptor binding parameters.

Animals↗
PubMed1992

[Studies on the chemical constituents from Aralia elata].

Eight compounds have been isolated from the root bark of Aralia elata. Their structures have been identified by means of physico-chemical and spectral analysis. They are (6'-O-palmitoyl)-beta-sitosterol-3-O-beta-D-glucoside (A5), silphiosideA (A9), chikusetusaponin Ib (A11), araloside A (A12), araloside C (A15), acanthoside D (B1). Compound A10 is a new natural product, named as araloside A methyl-ester. 3-O-beta-D-glucopyranosyl (1----3)[beta-D-glucopyranosy (1----4)]-beta-D-glucopyranosyl-oleanolic acid-28-O-beta-D-glucopyranoside (A16) is a new compound, named as araloside G. Compounds A5, A9, A10, A11, A16, and B1 were isolated for the first time from the plant. 13C-NMR chemical shifts of compounds A9 and A15 were assigned for the first time.

Drugs, Chinese Herbal↗
PubMed1992

Subchronic toxicity studies of fenbendazole in rats.

The effects of prolonged exposure of rats to fenbendazole were investigated. Fenbendazole was given daily by gavage for 14 consecutive days. These dosages (3000, 500 or 50 mg/kg/d) produced reductions in body weight gains. Renal tubular hyperemia or hemorrhage and glomerular capsule dilation, increased serum creatinine and hepatocellular granular degeneration occurred at dosages of 500 and 3000 mg/kg/d. Renal tubular epithelial cell granular degeneration and tubular dilation, increased serum glutamic pyruvic transaminase, cardiac hemorrhage and granular degeneration also occurred at 3000 mg/kg/d.

Animals↗
PubMed1992

An experimental study of pituitary transplantations in rabbits.

Experimental pituitary transplantations were carried out between the New Zealand white and American chinchilla rabbits. These two kinds of experimental rabbits were of different genotypes. The grafts were transplanted underneath the median eminences of the recipients after hypophysectomy. The rabbits with the transplants were treated with cyclosporine (CsA) and prednisone for the first month. Blood samples were taken at regular intervals for the determinations of serum thyroxine, prolactin and luteinizing hormone. The results suggested that neonatal grafts could survive and function almost normally with the aid of CsA and prednisone, but not without them. The results also disclosed that the interrelationship between the pituitary graft and the host's hypothalamus could be established. Pituitary transplantation from adult rabbit donors failed even though the recipients had been treated with CsA and prednisone in our experiment.

Animals↗
PubMed1991

N-(p-isothiocyanatophenethyl)spiperone, a selective and irreversible antagonist of D2 dopamine receptors in brain.

N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), an irreversible and nonselective protein-modifying reagent, has been used extensively in studies involving inactivation of receptors. Here, we present N-(p-isothiocyanatophenethyl)spiperone (NIPS), a novel and highly selective irreversible inactivator of D2 but not D1 receptors. In in vitro studies, NIPS exhibited an apparent Ki of 10 nM for [3H]methylspiperone binding to D2 receptors in rat striatum. Preincubation of the striatal membranes with NIPS followed by extensive washing resulted in up to an 80% reduction of the D2 receptor maximum binding (Bmax). Coincubation with the D2 receptor antagonist domperidone could protect against this reduction. NIPS was additionally shown to irreversibly inactivate D2 receptor binding activity in cultured cells expressing the D2 receptor protein. In in vivo administration studies, using [3H]SCH 23390 and [3H]spiperone to assay D1 and D2 receptors in vitro, 24 hr after injection (s.c.) with 5 to 40 mg/kg of NIPS D2 receptor, Bmax was decreased by 58 to 76%, without a change in D2 receptor affinity. In contrast, there was no effect on D1 receptor Bmax or affinity. There was also a small (24%) reduction in frontal cortex 5-hydroxytryptamine2 receptors by 20 mg/kg of NIPS. However, there was no effect on alpha-1 or alpha-2 adrenergic receptors in the frontal cortex, or on muscarinic cholinergic or 5-hydroxytryptamine1A receptors in the hippocampus. After single doses of either 20 mg/kg of NIPS or 10 mg/kg of EEDQ, the D2 receptor recovery rate was much slower after NIPS (half-time of receptor recovery = 170 hr) than after EEDQ (half-time of receptor recovery = 76.7 hr).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1990

[Tumor markers in the monitoring of ovarian cancer].

This study was carried out to determine the serum level of Ca125, LSA (lipid associated sialic acid) and AGP (alpha acid glycoprotein) in 50 patients with ovarian tumors. Among 30 patients with ovarian cancer, 12 reacted to all three markers, 22 reacted to two markers and 27 reacted to one marker. The sensitivities of LSA and CA125 were 60% and 77%, respectively and the specificities were 85% and 90%. A sensitivity of 87% and a specificity of 95%, when the two markers were used in combination.

Adenoma↗
PubMed1989

Effects of tetrahydroprotoberberines on dopamine receptor subtypes in brain.

The effects of 12 tetrahydroprotoberberines (THPBs) on D1 and D2 receptors labelled with [3H]DA, [3H]Sch-23390 and [3H]spiperone were evaluated. Their effects on the activity of adenylate cyclase stimulated with DA 40 mumols/L were also assessed. All of the l-THPBs tested behaved as DA receptor antagonists with preferential affinity toward the D1 receptors. Among them, l-stepholidine (l-SPD), a THPB analog with 2 hydroxy groups at the C2 and C10 positions, was the most potent. Its affinity toward D1 receptors was 4-7 times higher than that toward D2 receptors. The results suggest that the hydroxy groups in l-THPBs are very important factors in determining the affinity to DA receptors. Moreover, d-tetrahydropalmatine (d-THP), a dextro-THPB analog, displayed no affinity for the D2 receptor subtype, while its optical isomer, l-THP, was a DA receptor antagonist. This indicates that the levo-optical configuration is necessary for the affinity of THPBs to DA receptors. In addition, l-SPD was 18 times more potent than haloperidol with respect to binding to D1 receptors, but 14 times weaker for D2 receptors. Thus, it is expected that the clinical effects of l-SPD can be distinguished from that of haloperidol.

Adenylyl Cyclases↗
PubMed1989

[Experimental study of anti-tumor effect with conjugates of monoclonal antibodies and hematoporphyrin derivative].

Hematoporphyrin derivative (HPD) is a photosensitizer for use in photodynamic therapy (PDT). In this paper, HPD was conjugated with monoclonal antibodies 3G9 or 3H11 for use against gastric cancer in order to enhance the photosensitive effect and reduce side effect of PDT. The biological activities of the McAb conjugates were demonstrated. The killing effect on BGC-823 cells of 3G9-HPD or 3H11-HPD conjugates plus exposure to light showed 17 fold and 8.6 fold greater cytotoxicity, respectively than free HPD at an equivalent HPD concentration in vitro. When 3G9-HPD and 3H11-HPD were used in combination at 7:3, 5:5 and 3:7 proportion, the cytotoxicity was increased 12.9, 11.8 and 9.4 fold on target cells, respectively. The results indicate that the cytotoxicity was not further enhanced by the combination scheme. When tumor-bearing nude mice were treated with the different conjugates. Significant inhibition of tumor growth was observed and the survival period of animals was markedly prolonged in comparison with PBS, free HPD and NIgG-HPD treated groups.

Animals↗
PubMed1989

[A new minor saponin from the leaves of Panax ginseng C. A. Meyer].

Two minor compounds isolated from the leaves of Panax ginseng C. A. Meyer were characterized as 20(R)-protopanaxadiol (I) and 3 beta, 6 alpha, 12 beta-trihydroxydammar-20 (22), 24-diene-6-O-alpha-L-rhamnosyl-(1----2)-beta-D-glucopyranoside (II) on the basis of spectral analysis and chemical evidences. I was isolated for the first time from the leaves; II was shown to be a new saponin and was named as ginsenoside-Rg4.

Chemical Phenomena↗