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Biomedical subjects

Y Luo

Publications and source records attributed to Y Luo.

At least 307 records · Page 17Linked to original sources
PubMed1997

A complex containing two transcription factors regulates peroxisome proliferation and the coordinate induction of beta-oxidation enzymes in Saccharomyces cerevisiae.

Expression of the POX1 gene, which encodes peroxisomal acyl coenzyme A oxidase in the yeast Saccharomyces cerevisiae, is tightly regulated and can be induced by fatty acids such as oleate. Previously we have shown that this regulation is brought about by interactions between trans-acting factor(s) and an upstream activating sequence (UAS1) in the POX1 promoter. We recently identified and isolated a transcription factor, Oaf1p, that binds to the UAS1 of POX1 and mediates its induction. A screening strategy has been developed and used to identify eight S. cerevisiae mutants, from three complementation groups, that are defective in the oleate induction of POX1. Characterization of one such mutant led to the identification of Oaf2p, a protein that is 39% identical to Oaf1p. Oaf1p and Oaf2p form a protein complex that is required for the activation of POX1 and FOX3 and for proliferation of peroxisomes. We propose a model in which these two transcription factors heterodimerize and mediate this activation process. The mutants that we have isolated, and further identification of the corresponding defective genes, provide us with an opportunity to characterize the mechanisms involved in the coordinate regulation of peroxisomal beta-oxidation enzymes.

Acetyl-CoA C-Acetyltransferase↗
PubMed1997

A constitutively active version of the Ser/Thr kinase Akt induces production of the ob gene product, leptin, in 3T3-L1 adipocytes.

The expression of the ob gene product leptin in adipose tissues has been previously described to be regulated by insulin in vivo and vitro. Akt, a ser/thr kinase with a pleckstrin homology domain, has recently been identified to function in the insulin receptor signaling cascade. The aim of this study was to investigate the role of Akt in the production of leptin by adipocytes. Therefore, we examined leptin production by 3T3-L1 adipocytes stably expressing a myristoylated version of Akt which is constitutively active. Leptin levels in the supernatants of serum starved, nonstimulated 3T3-L1 adipocytes were determined by radioimmunoassay (RIA). Expression of the constitutively active Akt was found to induce a more than 20-fold increase in leptin levels whereas a control non-myristoylated Akt had no effect. Leptin mRNA levels as determined by either RNase protection assay or reverse transcriptase (RT)-polymerase chain reaction (PCR) were not elevated by the constitutively active Akt. These results indicate that Akt can induce leptin production in 3T3-L1 adipocytes via a non-transcriptional mechanism.

3T3 Cells↗
PubMed1997

A sensory axon repellent secreted from ventral spinal cord explants is neutralized by antibodies raised against collapsin-1.

During embryogenesis, different subclasses of sensory neurons extend central projections to specific locations in the spinal cord. Muscle and cutaneous afferents initially project to the same location in the dorsal cord. Later, specific muscle afferents leave other afferents behind and project into the ventral cord. Previous studies have shown that ventral spinal cord explants secrete a repellent for sensory neurites. We now find that antibodies to collapsin-1 neutralize this repellent activity. Additional data suggest that all afferents respond to collapsin-1 when they are first confined to the dorsal cord, but that ventrally projecting muscle afferents become collapsin-1 insensitive as they project into the ventral cord. Our results suggest that the transient dorsal expression of collapsin-1 prevents all efferents from entering the cord early and sustained ventral expression prevents dorsally terminating afferents from entering the ventral cord later.

Age Factors↗
PubMed1997

Mammalian two-hybrid system: a complementary approach to the yeast two-hybrid system.

Here we demonstrate the use of a mammalian two-hybrid system to study protein-protein interactions. Like the yeast two-hybrid system, this is a genetic, in vivo assay based on the reconstitution of the function of a transcriptional activator. In this system, one protein of interest is expressed as a fusion to the Gal4 DNA-binding domain and another protein is expressed as a fusion to the activation domain of the VP16 protein of the herpes simplex virus. The vectors that express these fusion proteins are cotransfected with a reporter chloramphenicol acetyltransferase (CAT) vector into a mammalian cell line. The reporter plasmid contains a cat gene under the control of five consensus Gal4 binding sites. If the two fusion proteins interact, there will be a significant increase in expression of the cat reporter gene. Previously, it was reported that mouse p53 antitumor protein and simian virus 40 large T antigen interact in a yeast two-hybrid system. Using a mammalian two-hybrid system, we were able to independently confirm this interaction. The mammalian two-hybrid system can be used as a complementary approach to verify protein-protein interactions detected by a yeast two-hybrid system screening. In addition, the mammalian two-hybrid system has two main advantages: (i) Assay results can be obtained within 48 h of transfection, and (ii) protein interactions in mammalian cells may better mimic actual in vivo interactions.

Antigens, Polyomavirus Transforming↗
PubMed1997

[Effect of superoxide dismutase on membrane fluidity and functions of lymphocytes in traumatized mice].

Effect of superoxide dismutase (SOD) on membrane fluidity and functions of lymphocytes in traumatized mice was studied. The results showed that in vivo administration of SOD (10,000 U/kg.d, from 0 to 3 days posttrauma) could significantly decrease malondialdehyde (MDA) contents in serum, lymphatic tissues from spleen, thymus, mesenteric lymph nodes and T cells plasmalemma, mitochondria, microsome, restore decreased T lymphocytes and T cells in traumatized mice, elevate membrane fluidity of lymphocytes transformation (TLT), reduce interleukin 2 (IL-2) production, supprssed IL-2 receptor (IL-2R) expression and depress IL-2 mediated lymphocyte proliferation response (IL 2MLPR) after trauma in various degress. It is suggested that SOD may protect lymphocytes post trauma from damage of oxygen free radical, and elevate lymphocytes functions.

Animals↗
PubMed1997

[Medicine S inhibits class II MHC expression of intragraft renal in rats].

The Purpose of this study was to address the mechanism of medicine S which has anti-rejection effects of renal allografts in rats. Kidney transplantations were performed from SD to Wistar strain (allogeneic) and from Wistar to Wistar (Isograft) using the same modified technigue described by Fabre and kamada. Experimental rats were divided into five groups. Group I (Isograft group) and group II (allograft group) as controls were not treated with medicine. The others were allograft groups which received medicine S, Cyclosporine A, and low-dose Cyclosporine combined with medicine S, respectively. Renal function and resultant morphology changes were assessed 2, 4 weeks after transplantation. All sections of kidney grafts were stained with monoclonal antibody class II MHC (OX6), and then the surface densities of positive staining were quantified by computer image analysis. The level of molecular expression in group II was significantly increased (7.61 +/- 0.57 vs 0.51 +/- 0.2 of group I, P < 0.01). In groups I and IV, the molecule of expression was reduced, compared with the groups II, III and V (P < 0.05). The results suggest that medicine S decreases the level of class II MHC expression and medicines combined with lowe-dose cyclosporine is more effective than cyclosporine alone.

Animals↗
PubMed1997

[Measurement and clinical significance of inspiratory drive efficacy in patients with chronic obstructive pulmonary disease].

To study the relationship between VT/P0.1 and the function of inspiratory muscles, we performed the measurement of VT/P0.1 (inspiratory drive efficacy), MIP (maximal inspiratory mouth pressure) and MMIF (maximal midinspiratory flow) in 15 normal subjects and 60 patients with chronic obstructive pulmonary disease(COPD). The results indicated that VT/P0.1 decreased with the deterioration of COPD and it correlated highly and positively with MIP and MMIF. These suggest that VT/P0.1 can reflect the function of inspiratory muscles as well as MIP and MMIF can.

Aged↗
PubMed1997

[Effect of methylphenidatum on inspiratory muscles function in patients with chronic obstructive pulmonary disease and its mechanism].

To have a better understanding of the effect of methylphenidatum on inspiratory muscles function, we studied the respiratory force parameters of 70 patients with chronic obstructive pulmonary disease by intravenous infusion methylphenidatum in a randomized controlled clinical trial. The indices of respiratory force parameter included maximal inspiratory mouth pressure (MIP), maximal midinspiratory flow (MMIF), forced inspiratory capacity (FIC), maximal works of inspiration (Wimax) and airway occlusion pressure (P0.1), etc. Aminophylline and Nikethamidi were chosen as controls. The results showed that MIP, MMIF, FIC, Wimax, P0.1 and minute ventilation (Vr) were significantly increased after administration of methylphenidatum and aminophylline. There were no significant differences in MIP, MMIF, FIC and Wimax after administration of Nikethamidi, but P0.1 was significantly increased and the increase was higher than that after administration of methylphenidatum and aminophylline groups. We conclude that methylphenidatum can significantly improve the function of inspiratory muscles as aminophylline can do.

Female↗
PubMed1997

[Different chemotherapy protocols for intermediate and high grade malignant non-Hodgkin's lymphoma].

OBJECTIVE: To assess the optinums chemotherapeutic protocols for higher CR rate in the treatment of intermediate and high grade malignant non Hodgin's lyphoma(NHL). METHODS: Seventy-four patients with pathological intermediate and high grade malignant NHL were tried randomly with revised ProMACE-CytaBOM(treatment group) and CHOP(control group). RESULTS: The CR rate was 56.8% in the treatment group and 35.0% in the control group (P > 0.05). In patients with high grade maliganat NHL, the CR rate of ProMACE-CytaBOM was 60.0% as compared with 32.0% of the CHOP (P < 0.05). Patients in both group suffered from similar side effects with tolerable bone marrow supression and gastric irritation. CONCLUSION: ProMACE-CytaBOM is a safe regimen with relative high CR rate for high grade malignant NHL, but further research is indicated for remote results.

Adolescent↗
PubMed1997

[A systematic screening and identification method for 29 central nervous system drugs in body fluid by high performance capillary electrophoresis].

A systematic screening method has been developed for the detection of 29 central nervous system (CNS) drugs in human plasma, urine and gastric juice by high performance capillary electrophoresis (HPCE). The first step is sample preparation. The patient's or normal human plasma (0.5 ml) spiked with CNS drugs was extracted with 2 x 4 ml dichloromethane, while 2 ml of patient's or spiked urine was extracted with 2 x 6 ml chloroform. The combined extract from plasma or urine was evaporated to dryness in a rotation evaporator at 35 degrees C. The residue was dissolved in 100 microliters methanol and subsequently 400 microliters of redistilled water was added. The patient gastric juice (3 ml) was centrifuged at 2,000 r.min-1 for 5 min. The supernatant was filtered through 0.45 micron microporous membrane for injection onto capillary columns. The second step was to perform CZE separation in acidic buffer composed of 30 mmol.L-1(NH4)3PO4(pH 2.50) and 10% acetonitrile (condition A). Most of the benzodiazepines (diazepam, nitrazepam, chlordiazepoxide, flurazepam, extazolam, alprazolam) and methaqualone were baseline separated and detected at 5-13 min, while thiodiphenylamines showed group peaks at 3-5 min and barbiturates migrate with electroosmotic fluid (EOF) together. The third step is to separate the drugs in basic buffer constituted of 70 mmol.L-1 Na2HPO4(pH 8.60) and 30% acetonitrile (condition B). The thiodiphenylamines and some other basic drugs could be well separated, which include thihexyphenidyl, imipramine, amitriptyline, diphenhydramine, chlorpromazine, doxepin, chlorprothixene, promethazine and flurazepam, while the rest of the CNS drugs did not interfere with the separation. The last step was to separate the drugs by micellar electrokinetic chromatography (MEKC) in such a buffer as 70 mmol.L-1 SDS plus 15 mmol.L-1 Na2HPO4 (pH 7.55) and 5% methanol (condition C). Barbiturates (barbital, phenobarbital, methylphenobarbital, amobarbital, thiopental, pentobarbital, secobarbital) and some hydrophobic drugs (glutethimide, alprazolam, clonazepam, carbamazepine, trifluoperazine, oxazepam) could be well separated. These drugs might be identified by both the relative migration time (rtm = tdrug/tEOF) and the ratios of peak heights (rh) monitored at different wavelength, since the ratios are characteristic of the spectrum of a drug. This method has been used in several real clinical samples of intoxication. For example, perphenazine and doxepin were detected in the gastric juice and phenobarbital in blood and gastric juice of an intoxicated patient.

Central Nervous System Agents↗
PubMed1997

[Quantitative analysis of soporific sedative drugs and local anesthetic drugs with unidentical standard substance by GC-AED].

According to the principle of GC-AED (gas chromatography-atomic emission detector), the possibility of quantitative determination of samples by different substances as internal standard was studied. The element C was determined at wavelength of 496 nm. The relative response factors of 17 soporific sedative and local anesthetic drugs were analyzed with an internal standard of proadifen hydrochloride under optimized analytical conditions. Oven temp.: 45 degrees C (0.5 min)-35 degrees C.min-1--120 degrees C-15 degrees C.min-1--220 degrees C-5 degrees C.min-1--250 degrees C; Cool on column injector temp: 60 degrees C-50 degrees C.min-1--250 degrees C (0.2 min); inject volume: 1 microliter; column head pressure: 145 kPa. The results show that the element C(496) in identical or unidentical substances has similar relative response factor. The RSD is 10.21%, which means that a sample can be quantitatively determined by a different substance when the analysis condition and the selected internal standard are suitable. An amobarbital sample of 109.0 micrograms.ml-1 was quantitatively determined by using methylphenobarbitone, pramoxine, lidocaine and itself as internal standard. The results are 117.6, 115.6, 110.0 and 102.14 micrograms.ml-1, respectively. They can be quantitatively determined by each other.

Anesthetics, Local↗
PubMed1997

[The change of serotonin of venous blood in pregnancy induced hypertension].

OBJECTIVE: To provide evidence to the hypothesis that the involvement of serotonin (5-HT) takes part in the pathogenesis of pregnancy induced hypertension (PIH). METHOD: 31 pregnant women with PIH and 20 normotensive pregnant women were studied in the present study. Venous plasma 5-HT and platelet 5-HT from all subjects were measured with spectrometry. RESULTS: The mean platelet 5-HT level in PIH group (24.69 +/- 17.79 micrograms/L) was less than that in normotensive group (91.06 +/- 47.77 micrograms/L) (P < 0.01). The mean plasma 5-HT level in PIH group (48.65 +/- 19.29 micrograms/L) was significantly higher than that in normotensive group (35.39 +/- 12.88 micrograms/L) (P < 0.01). CONCLUSION: Plasma levels of 5-HT in PIH were elevated significantly, this might be largely caused by the increased release of 5-HT by platelet. The results show that elevated level of 5-HT in patients with PIH might take part in the pathogenesis of PIH.

Adult↗
PubMed1997

[Clinical application of retrograde island flap carrying plantar metatarsal arteries as pedicle].

The skin and soft tissue defects or ulceration of the wight-bearing part of the sole was difficult to repair with medial plantar island flap, but would be treated with retrograde island flap carrying plantar metatarsal arteries as pedicle. Ten flaps were applied in 9 patients. They had either indolent ulcer or skin defect secondary to excision of painful corn or callosities of the front part of the sole. The flaps were 3 cm to 5 cm long and 3 cm to 4 cm wide, and they all survived following retrograde transfer. The patients were followed up for 1 to 10 years. It was found that the patients could bear weight on the operated foot and could walk without pain or lameness. The flaps were resistant to abrasion from long-time walking. It was concluded that this kind of flap was best suitable to repair the ulcers and defects over the front part of the sole despite there were some minor shortcomings such as the size of the flaps available was small and the donor site required split skin graft for coverage.

Adolescent↗
PubMed1997

[Preliminary investigation of treatment of ulnar nerve defect by end-to-side neurorrhaphy].

In the repair of the defect of peripheral nerve, it was necessary to find an operative method with excellent therapeutic effect but simple technique. Based on the experimental study, one case of old injury of the ulnar nerve was treated by end-to-side neurorraphy with the intact median nerve. In this case the nerve defect was over 3 cm and unable to be sutured directly. The patient was followed up for fourteen months after the operation. The recovery of the sensation and the myodynamia was evaluated. The results showed that: the sensation and the motor function innervated by ulnar nerve were recovered. The function of the hand was almost recovered to be normal. It was proved that the end-to-side neurorraphy between the distal stump with the intact median nerve to repair the defect of the ulnar nerve was a new operative procedure for nerve repair. Clinically it had good effect with little operative difficulty. This would give a bright prospect to repair of peripheral nerve defect in the future.

Adult↗
PubMed1997

[Clinical application of implantation of vascular bundle into silicone tube to bridge the peripheral nerve defect].

In order to improve the therapeutic effect of non-neural tissue in bridging the peripheral nerve defect and increase the blood supply of the implant, the silicone tube was chosen to bridge the gap, and the vessel bundle was inserted into the tube. The procedures were performed as following: resected the pseudoneuroma and enveloped the proximal and the distal ends in a silicone tube, and then sutured the epineurium and the tube wall with 7/0 stitch. In patients, eleven cases with fifteen nerves were treated, including seven median nerves, five ulnar nerves and three radial nerves. The lengths of the nerve defects were within 3 cm in 13 nerves and 3 cm-5 cm in 2 nerves. They were followed up from one to five years and the result was excellent (M4S4) in 8 nerves, good (M3S3) in 3 and poor (M1S1) in 2. It was discussed that the indication for the procedure should be included: the nerve defect could not be sutured directly, and the patient would not agree to use his own nerve for graft.

Adolescent↗