Biomedical subjects

Y Deng

Publications and source records attributed to Y Deng.

At least 199 records · Page 11Linked to original sources

PubMed1995

Occlusal contact changes before and after orthodontic treatment of a group of child & adolescent patients with TMJ disturbance.

Occlusal contacts were examined before and after orthodontic treatment in 32 eight- to seventeen-years-old patients with temporomandibular joint disturbance. Add-Picture, a computer image system, was applied to a silicone occlusal record obtained in the intercuspal position (ICP) to assess the qualitative and quantitative changes of occlusal contacts. Comparing the two images before and after treatment, significant difference was noted in the number, size, location and type of contacts. After orthodontic treatment: the mean number of contacts on anterior teeth reduced, the mean area per contact decreased, the number of contacts on centric stops increased and type IV contacts (on the inclined plane) decreased. The present study indicates that orthodontic treatment has a positive effect, both qualitatively and quantitively, on the distribution of occlusal contacts in ICP and seems to contribute to the establishment of occlusal stability in ICP.

Adolescent↗

PubMed1994

Uptake of a neurotoxin-candidate, (R)-1,2-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline into human dopaminergic neuroblastoma SH-SY5Y cells by dopamine transport system.

Uptake of catechol isoquinolines to dopamine cells was studied using human dopaminergic neuroblastoma SH-SY5Y cells. Only (R)-1,2-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline [(R)-1,2-DiMeDHTIQ] was transported by dopamine uptake system, while (S)-1,2-DiMeDHTIQ, (R)- and (S)-1-methyl-6,7-dihydroxy-tetrahydroisoquinoline, and 1,2-dimethyl-6,7-dihydroxyisoquinolinum ion were not. Kinetical study showed that the uptake of (R)-1,2-DiMeDHTIQ followed the Michaelis-Menten equation, and the values of the Michaelis constant and the maximal velocity were obtained to be 102.6 +/- 36.9 microM and 66.0 +/- 2.8 pmol/min/mg protein. Dopamine was found to inhibit (R)-1,2-DiMeDHTIQ uptake competitively. These results suggest that the selective uptake by dopamine transporter may account for the specific neurotoxicity of (R)-1,2-DiMeDHTIQ to dopamine neurons.

Carrier Proteins↗

PubMed1994

Inhibition of type A monoamine oxidase by 2(N)-methyl-6,7-dihydroxyisoquinolinium ions.

In the human brain, monoamine-derived 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines and 1,2,3,4-tetrahydroisoquinolines have been identified and their enzymatic methylation into N(2)-methylisoquinolines has been also confirmed. N-methylated 6,7-dihydroxyisoquinolines were found to be oxidized into 6,7-dihydroxy-N-methylisoquinolinium ions. The effects of the isoquinolinium ions on type A and B monoamine oxidase were examined, using enzyme samples isolated from human brain synaptosomal mitochondria. 1,2-Dimethyl-6,7-dihydroxyisoquinolinium ion (N-methylsalsolinium ion) and 2-methyl-6,7-dihydroxyisoquinolinium ion (N-methylnorsalsolinium ion), were found to be potent inhibitors of type A monoamine oxidase. The inhibition was competitive to the substrate, while the isoquinolinium ions were much weaker inhibitors of type B and the inhibition was non-competitive to the substrate. Isoquinolinium ions without catechol structure, N(2)-methylisoquinolinium ion and 1,2-dimethylisoquinolinium ion also inhibited both type A and B monoamine oxidase. 1,2-Dimethylisoquinolinium was the most potent inhibitor among examined isoquinolines, followed by the N-methylsalsolinium ion. The activity-structure relationship of the isoquinolines with and without catechol structure was examined in terms of potency and selectivity of inhibition to type A and B monoamine oxidase. Catechol structure was found to increase the selectivity of inhibition to type A, as shown by comparison of N-methylsalsolinium ion with 1,2-dimethylisoquinolinium ion. N-Methylsalsolinium ion inhibited type A MAO more selectively than 1,2-dimethylisoquinolinium ion, which inhibited type A and type B with almost the sam values of the inhibitor constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗

PubMed1994

Identification and characterization of a gene cluster mediating enteroaggregative Escherichia coli aggregative adherence fimbria I biogenesis.

The aggregative pattern of adherence (AA) exhibited by enteroaggregative Escherichia coli upon HEp-2 cells is a plasmid-associated property which correlates with aggregative adherence fimbria I (AAF/I) expression and human erythrocyte hemagglutination. By using cloning and mutagenesis strategies, two noncontiguous plasmid segments (designated regions 1 and 2) required for AA expression have previously been identified in enteroaggregative E. coli 17-2. TnphoA mutagenesis was performed on clones containing region 1, and 16 TnphoA mutants which were negative for the AA phenotype were analyzed. The TnphoA insertion site for each mutant was determined by junctional DNA sequencing. All 16 mutations occurred within a 4.6-kb span in region 1. Nucleotide sequence analysis of the region revealed four contiguous open reading frames, designated aggDCBA, in the same span. AA-negative TnphoA insertions into all open reading frames except aggB were obtained. On the basis of mutational analysis and protein homology data, it is inferred that aggA, aggC, and aggD are involved in biogenesis of AAF/I, encoding a major fimbrial subunit, outer membrane usher, and periplasmic fimbrial chaperone, respectively. By immunogold electron microscopy, polyclonal antiserum raised against the aggA gene product decorated AAF/I fimbriae, affirming that AggA encodes an AAF/I subunit.

Bacterial Adhesion↗

PubMed1994

Influence of pregnancy on ANF release from isolated atria.

Isolated perfused right atria were prepared from virgin cycling rats and from rats at 7, 14, and 21 days of pregnancy. Intraluminal pressure was raised from the basal control level (atmospheric) to 4, 6, and 10 cmH2O. Basal and stretch-induced release of atrial natriuretic factor (ANF) into the perfusate was measured by radioimmunoassay. When atria derived from unmated and from 7-day pregnant rats were distended, mean ANF secretion into the perfusion medium increased by 64 +/- 16 and 89 +/- 31 pg/ml at the highest distending pressure of 10 mmHg. (Mean basal secretion for the two groups was 196 +/- 104 and 181 +/- 63 pg/ml, respectively.) However, at 14 and 21 days, distension failed to elicit any significant increase in ANF release. There was no significant difference between the groups with respect to basal secretion of ANF, nor did pregnancy influence atrial compliance or volume. The slopes of the pressure-volume curves for atria derived from virgin, 7-, 14-, and 21-day-pregnant rats were 0.76 +/- 0.17, 0.623 +/- 0.178, 0.811 +/- 0.177, and 1.050 +/- 0.173, respectively. These results are in agreement with our findings in vivo that plasma ANF levels are elevated at 7 days of pregnancy but that, despite the progressive increase in intravascular volume, they decrease to control levels at 14 and 21 days. Our latest data suggest that this fall is a result of changes in the secretory characteristics of the atrial tissue itself and not necessarily of pregnancy-induced changes in atrial filling.

Analysis of Variance↗

PubMed1994

Tissue factor controls the balance of angiogenic and antiangiogenic properties of tumor cells in mice.

Meth-A sarcoma cells were stable transfected to overexpress (sense construct) or underexpress (antisense construct) tissue factor. In vitro, there was no difference in plating efficiency or growth between these cell lines. In vivo, tumor cells transfected to overexpress tissue factor grew more rapidly, and established larger and more vascularized tumors than control transfectants. Antisense transfectants grew the slowest and were the least vascularized. Anticoagulation of mice with warfarin did not alter the difference between these tumor lines. Tumor cells over-expressing tissue factor released more (compared with control transfectants) mitogenic activity for endothelial cells in parallel with enhanced transcription of vascular permeability factor/vascular endothelial cell growth factor (VEGF/VPF), and diminished transcription of thrombospondin (TSP2), a molecule with anti-angiogenic properties. Antisense tissue factor transfectants, while releasing the lowest amount of mitogenic activity, had increased thrombospondin and decreased VEGF/VPF transcription compared with control transfectants or wild-type cells. Experiments with these sense, antisense, truncated sense, or vector tumor lines gave comparable results in complete medium, serum free medium or in the presence of hirudin, indicating that the activation of the coagulation mechanism was not likely to be responsible for changes in tumor cell properties. These results suggest that tissue factor regulates angiogenic properties of tumor cells by altering the production of growth regulatory molecules of endothelium by a mechanism distinct from tissue factor activation of the coagulation mechanism.

Animals↗

PubMed1994

Antitumor activity of immunoconjugates composed of boanmycin and monoclonal antibody.

Boanmycin (bleomycin A6, BM), an antitumor antibiotic, was conjugated to monoclonal antibodies including R19, H111 and CCT2. The immunoconjugates exhibited selective cytotoxicity to related target cells including cecum cancer Hce-8693 cells, liver cancer BEL-7402 cells and leukemia CEM cells. They were highly effective against related human tumor xenografts in nude mice, and the inhibition rates by the conjugates were much higher than those by free BM. The inhibition rate by R19-BM conjugate against human cecum cancer xenografts reached 90%. BY immunoelectron microscopy, CCT2-BM conjugate showed specific binding and internalization in leukemia CEM cells. The results indicate that boanmycin-monoclonal antibody immunoconjugates are highly active both in vitro and in vivo.

Adenocarcinoma↗

PubMed1994

Electro-oculogram of retinal vein occlusion.

Twenty five cases, including 26 eyes with retinal vein occlusion (RVO) were examined by means of the electro-oculogram. The results showed that 23 of the 26 eyes suffering from RVO exhibited abnormalities of the electro-oculogram (EOG). The potential difference and Arden ratio in the RVO eyes were lower than those in the normal eyes (P < 0.01). The more the visual acuity of ill eyes was decreased, the higher the abnormal rate of EOG in ill eyes was. 14 eyes had the visual acuity less than 0.1, whose EOGs were abnormal. Six eyes had the visual acuity from 0.2 to 0.4, in which the EOGs of 5 eyes were abnormal. Six eyes had the visual acuity more than 0.5, among which the EOGs of 4 eyes were abnormal. Based on the above observations, it may be considered that the circulatory disturbance resulting from RVO damages not only the internal layer but also the external layer of the retina. We suggest that EOG is a useful method for distinguishing lesions caused by RVO and may reflect the functional condition of the outer layer of the retina.

Adult↗

PubMed1993

Synthesis and antitumor activity of ammine/amine platinum(II) and (IV) complexes.

Dimeric platinum complexes, [Pt(RNH2)I2]2 (where R = H, methyl, ethyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl), have been synthesized by reactions of diiodoplatinum compounds with perchloric acid in water/ethanol solutions. The dimerization varies from several hours to a few days depending upon the length of the carbon chain in the alkylamines and the process can be conveniently monitored by 195Pt NMR spectroscopy. All these dimers exhibit two closely separated resonances around -4000 ppm (vs K2PtCl4 at -1620 ppm) in dimethylformamide. Reactions of [Pt(NH3)I2]2 with alkylamines do not yield the desired mixed ammine/amine complexes, which are obtained subsequently by treatment of the alkylamine dimer [Pt(RNH2)I2]2 with ammonium hydroxide in water. By using this latter procedure, a novel class of ammine/amine platinum complexes of the type PtII(NH3)(RNH2)Cl2, PtIV(NH3)(RNH2)X2A2, and PtIV(NH3)(RNH2)(CBDCA)A2.H2O, where X2 = chloro or 1,1-cyclobutanedicarboxylato (CBDCA), A = OH, Cl, or OCOCH3, have been synthesized and characterized by elemental analysis, infrared, and 195Pt NMR spectroscopic techniques. The alicyclic ammine/amine Pt(II) complexes, where R is C3-C6 were selected as representative of the class to undergo antitumor evaluations. The compounds had excellent activity against murine leukemic L1210/0 cells with cyclobutylamine-, cyclopentylamine- and cyclohexylamine-containing complexes demonstrating cytotoxicity superior to that of the clinically established cisplatin.

Amines↗

PubMed1993

Preparation, characterization, and antitumor activity of new ethylenediamine platinum(IV) complexes containing mixed carboxylate ligands.

A series of ethylenediamine platinum(IV) complexes of the type PtIV(en)XA2 and PtIV(en)X'2A2, where X = 1,1-cyclobutanedicarboxylato or malonato, X' = chloro, cyclobutanecarboxylato, cyclopentanecarboxylato, or cyclohexanecarboxylato, and A = acetato or trifluoroacetato were synthesized and characterized by elemental analysis, infrared, and NMR (13C and 195Pt) spectroscopic techniques. These compounds had good to excellent antitumor activity against murine leukemia L1210 cells. Complexes with axial trifluoroacetate groups were superior to those with acetate ligands. Those possessing both axial trifluoroacetate groups and monodentate bis-carboxylate ligands in the equatorial positions were the most active in the series investigated.

Animals↗

PubMed1993

The influence of reproductive hormones on ANF release by rat atria.

The effects of subcutaneous (sc) administration of estradiol (50 micrograms/100 microliters/day x 10 day) or testosterone (15 mg/100 microliters twice a week x 2 weeks) on ANF release were examined in isolated perfused rat atria. The concentration of ANF in the perfusate was measured by radioimmunoassay, under basal conditions (atrial wall unstressed), and during atrial distention (intraluminal pressure raised to 4, 6, and 10 cm water). In both male and female control (vehicle-injected) groups, increased atrial pressure resulting in distention of the atrium caused a significant increase in ANF release. Estradiol increased basal secretion of ANF but did not influence stretch-induced stimulation of ANF secretion. By contrast, although testosterone did not affect basal secretion, it completely abolished the stretch-induced increase in ANF secretion. Neither estradiol nor testosterone affected atrial compliance.

Animals↗

PubMed1993

Antigen processing: where tumor-specific T-cell responses begin.

It is well established that tumor-specific CD8+ T cells have the capacity to prevent and cure malignancies in animals under experimental conditions. This has raised expectations that it will prove possible to achieve similar successes with human cancers. CD8+ T cells recognize peptides of 8-10 residues derived from cytosolic proteins that are bound to the class I molecules of the major histocompatibility complex. To most effectively manipulate the T-cell response to tumor cells, it is essential to understand the means by which the peptide-class I complex is created in cells. An overview of this process is provided with an emphasis toward the recent findings made by our laboratory.

Animals↗

PubMed1993

Rapid inactivation of endothelin-1 by a carboxypeptidase-like enzyme purified from rat kidney.

A survey of various rat tissues showed that the kidney had the highest endothelin degradation enzyme activity. An enzyme that effectively inactivated endothelin-1 was purified from soluble kidney extracts. This enzyme appeared to contain two subunits with molecular weights of 34 kDa and 21 kDa. It displayed carboxypeptidase-like properties and cleaved off the carboxyl terminal tryptophan of endothelin-1. These results agree with the findings that endothelin-1 is cleared efficiently by the kidney and suggest that this enzyme plays a role in the homeostasis of circulating endothelin-1.

Amino Acid Sequence↗

PubMed1993

Splenic control of intravascular volume in the rat.

1. We tested the hypothesis that hypervolaemia causes an increase in intrasplenic filtration of cell-free fluid out of the vasculature. To this end we developed a preparation in the anaesthetized rat whereby the splenic vein could be non-occlusively cannulated. 2. Haematocrit and plasma protein concentrations were measured in the splenic afferent and efferent blood supplies. 3. In response to volume loading with saline (1% body weight), there was a sustained increase in the arterial-venous differential of haematocrit, i.e. there was a relative increase in the haematocrit of the blood draining from the spleen. There was no such change in plasma protein concentration. By contrast, this degree of volume loading had no effect on the haematocrit of blood passing through the hindquarters of the animal. 4. Following volume expansion, there was no significant difference in the protein concentration of the plasma and the lymph fluid collected from the splenic lymphatic duct. 5. Distension of the superior vena caval-right atrial junction by means of a small inflatable balloon, caused a similar increase in the splenic venous haematocrit, and again, no change in plasma protein concentration. 6. We interpret these results to mean that, in response to expansion of the intravascular space, there is increased intrasplenic filtration of plasma out of the blood and into the lymphatic system.

Animals↗

PubMed1993

Renal response to atrial stretch during pregnancy in conscious rats.

Chronic indwelling balloons were placed at the junction of the right atrium and the right superior vena cava of virgin female rats. The renal response to discrete standardized atrial stretch was tested in the conscious animals. The rats were then mated, and the renal response was retested at days 7, 14, and 20 of pregnancy. On day 21, the rats were killed, and the pressure-volume relationship of the right atria was measured. In response to atrial stretch, there was an increase in urine volume, urine sodium output, and urine potassium output and a decrease in free water clearance in the virgin rats. Subsequent to mating, these responses were completely abolished at all stages of pregnancy. The renal responses to atrial stretch were also abolished during pseudopregnancy. Central venous pressure did not change when the intracardiac balloons were inflated; there were also no changes in resting central venous pressure during pregnancy. There were no significant changes in unstressed atrial volume or in atrial compliance during pregnancy.

Animals↗

PubMed1993

[Substance P is not involved in SII descending modulation of the nucleus centrum medianum of the thalamus in cats].

It was investigated that the effects of electrical stimulation of the somatosensory area II (SII) of the cerebral cortex and electroacupuncture on substance P (SP) concentration in the perfusate from the nucleus centrum medianum (CM) of the thalamus, in order to probe into if SP participates in the SII descending modulation of the nucleus CM and this mechanism of acupuncture analgesia. Adult cats were randomly divided into three groups: control, electroacupuncture and electrical stimulation of SII. Push-pull perfusion technique was used to collect the perfusate from the nucleus CM. SP contents in the perfusate were determined by radioimmunoassay. The results showed that SP contents in the perfusate have not statistically significant changes before and after the electrical stimulation of SII or electroacupuncture, suggesting that the SP release from the nucleus CM was not influenced by the stimulation of SII or electroacupuncture. It is indicated that SP may not associate with the SII descending modulation of the nucleus CM and this mechanism of acupuncture analgesia.

Acupuncture Analgesia↗

PubMed1993

[Effects of electroacupuncture at different frequencies on the nociceptive response and central contents of GABA and glutamic acid in arthritic rats].

It has been demonstrated that electroacupuncture (EA) produces analgesia in acute arthritic animal models, while the differential analgesic effects at different EA parameters remains to be discovered. In the present experiment, the effects of EA at 100 Hz and 15 Hz on bilateral Yanglingpuan acupoints of the arthritic rats was studied. The results showed: 1) 15Hz EA was more effective than 10Hz EA for analgesia; 2) spinal glutamic acid content of the 15-Hz EA group was significantly lower than that of the 100-Hz EA group, and 3) no significant difference in GABA contents between the two groups was found. The results suggest that spinal glutamic acid may be involved in the different analgesic effects of EA at different frequencies in arthritic rats.

Acupuncture Analgesia↗

PubMed1993

[Protective effects of combination of chlorpromazine and verapamil on ischemia-reperfusion induced injury in rat myocardium].

Combination of chlorpromazine (CPZ) and verapamil (Ver) was found to decrease the incidence of ventricular arrhythmias and ventricular fibrillation induced by myocardial ischemia and reperfusion, lower serum creatine phosphokinase (CPK) and decrease the content of malondialdehyde (MDA) in heart tissue homogenate especially in mitochondria; and increase the phospholipid content and the phospholipid/cholesterol ratio; and decrease the myocardial "cell calcium" content in the reperfused area. The effect of CPZ and Ver combination was better than either CPZ and Ver alone.

Animals↗