Biomedical subjects

Z Guan

Publications and source records attributed to Z Guan.

At least 37 records · Page 2Linked to original sources

PubMed2001

Vagotomy attenuates tumor necrosis factor-alpha-induced sleep and EEG delta-activity in rats.

Much evidence suggests that tumor necrosis factor-alpha (TNF-alpha) is involved in the regulation of physiological sleep. However, it remains unclear whether peripheral administration of TNF-alpha induces sleep in rats. Furthermore, the role of the vagus nerve in the somnogenic actions of TNF-alpha had not heretofore been studied. Four doses of TNF-alpha were administered intraperitoneally just before the onset of the dark period. The three higher doses of TNF-alpha (50, 100, and 200 microg/kg) dose dependently increased nonrapid eye movement sleep (NREMS), accompanied by increases in electroencephalogram (EEG) slow-wave activity. TNF-alpha increased EEG delta-power and decreased EEG alpha- and beta-power during the initial 3 h after injection. In vagotomized rats, the NREMS responses to 50 or 100 microg/kg of TNF-alpha were attenuated, while significant TNF-alpha-induced increases in NREMS were observed in a sham-operated group. Moreover, the vagotomized rats failed to exhibit the increase in EEG delta-power induced by TNF-alpha intraperitoneally. These results suggest that peripheral TNF-alpha can induce NREMS and vagal afferents play an important role in the effects of peripheral TNF-alpha and EEG synchronization on sleep. Intraperitoneal TNF-alpha failed to affect brain temperature at the doses tested, thereby demonstrating that TNF-alpha-induced sleep effects are, in part, independent from its effects on brain temperature. Results are consistent with the hypothesis that a cytokine network is involved in sleep regulation.

Animals↗

PubMed2000

Mushroom body defect, a gene involved in the control of neuroblast proliferation in Drosophila, encodes a coiled-coil protein.

Neurogenesis relies on the establishment of the proper number and precisely controlled proliferation of neuroblasts, the neuronal precursor cells. A role for the mushroom body defect (mud) gene in both of these aspects of neuroblast behavior, as well as possible roles in other aspects of fruit fly biology, is implied by phenotypes associated with mud mutations. We have localized mud by determining the sequence change in one point mutant, identifying a predicted ORF affected by the mutation, and showing that an appropriate segment of the genome rescues mud mutant phenotypes. An analysis of mud cDNAs and a survey of mud transcripts by Northern blotting indicate that the gene is subject to differential splicing and is expressed primarily during embryogenesis but also, at lower levels, during subsequent developmental stages in a sexually dimorphic manner. The gene is predicted to encode a polypeptide without obvious homologs but with two prominent structural features, a long coiled coil that constitutes the central core of the protein and a carboxyl-terminal transmembrane domain.

Alternative Splicing↗

PubMed2000

Influence of lipid peroxidation on the nicotinic acetylcholine receptors in PC12 cells.

The expression of neuronal nicotinic acetylcholine receptors (nAChRs) influenced by lipid peroxidation has been investigated. The results showed that exposure of PC12 cells to a free radical insult (FeSO(4)) induced concentration-dependent increase in level of MDA (malondialdehyde), and a significant decline in MTT [3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide] reduction. In cultured cells exposed to FeSO(4), a significant dose-dependent decrease in [(3)H] epibatidine binding sites was detected and a significant reduction in B(max) value was observed in the high affinity epibatidine binding site. These results demonstrate that lipid peroxidation in cellular membranes can induce a reduction in numbers of neuronal nAChRs.

Animals↗

PubMed2000

[Role of interleukin-6 and platelet-activating factor in delaying neutrophil apoptosis].

In the present study we investigated the role of platelet-activating factor (PAF) and interleukin-6 (IL-6) in delaying polymorphonuclear neutrophil (PMN) apoptosis. Isolation of PMN was performed by using the discontinuous plasma-Percoll gradient technique. PMN was cultured in enriched RPMI 1640 media at 2 x 10(7) PMN/ml for 24 h. Subgroups were treated with IL-6 or PAF or pretreated with PAF receptor antagonist BN52021 before IL-6 or PAF were added. Morphological assessment and quantitation of apoptosis were performed with acrodine/ethidium bromide stain and epifluorescent microscope. The results showed that both IL-6 and PAF suppressed PMN apoptosis. Pretreatment of PMN with BN52021 abrogated the effects of IL-6 and PAF. It is suggested that PAF may be a crucial cytokine in the suppression of PMN apoptosis. These observations may contribute to elucidating the mechanisms of IL-6 and PAF in mediating postinjury hyperinflammation and secondary organ dysfunction and provide a clue for the prevention and treatment of the conditions.

Apoptosis↗

PubMed2000

[Kinetics of plasma membrane and mitochondrial alterations in HL-60 cells undergoing apoptosis].

In the present study, VP16, an inhibitor of topoisomerase II, and NaN3, a chemical toxic substance, were used to induce apoptosis and necrosis of HL-60 cells, respectively. Cells were examined by transmission electron microscopy and by fluorescence microscopy after staining with Hoechst 33258 at 0, 2, 4, 8, 16 and 24 h of culture. Alterations of fluorescent intensity produced by FDA, Rh 123 and PI were measured by flow cytometry, which reflects sequential changes on plasma membrane permeability and the potential of mitochondrial membrane. The results indicated that the nuclear morphologic alteration of cells treated with VP-16 began at 4 hour of culture and the cells with condensed nucleus culminated at 8 h of culture and then reduced with no drop in cell counts, while the percentage of cells with fragmented nuclei reached its maximum at 24 h of culture accounting for some 80%. The potential of mitochondrial membrane of of apoptotic cells decreased gradually from 8 h of culture and showed obvious decline at 16 h of culture. In necrotic cells, the potential decreased by 50% at 4 h of culture which indicates an earlier and more rapid decline than that in apoptotic cells. Alteration of plasma membrane permeability appeared at 8 h of culture and showed a steady increase over time. It was concluded that plasma membrane permeability and mitochondrial membrane potential could reflect the development and degree of apoptosis, and the combination of these two criteria with nuclear morphology revealed by staining with Hoechst 33258 would be a simple and reliable assay for apoptosis and its progression.

Apoptosis↗

PubMed2000

[Ethanol-induced apoptosis in human HL-60 cells].

The purpose of this study was to examine the effect of ethanol on apoptosis of human promyelocytic leukemia cell line HL-60 cells and search for a possible reason for reduced PMNs, monocytes, lymphocytes in the blood of alcoholics. Human promyelocytic leukemia cell line HL-60 cells was used as a model of apoptosis, with ethanol being the interfering factor. Qualitative and quantitative detection was done by both electron microscopy and flow cytometry. Compared with the control treatment of HL-60 cells with ethanol at 50, 100, 150, 200, 250 mmol/L for 3 days increased apoptotic cells significantly (P < 0.01), and apoptosis was dose-dependent for ethanol. It suggest that ethanol can induce apoptosis of HL-60 cells. So as far as reduced PMNs, monocytes, phagocytes and lymphocytes of alcoholics are concerned, ethanol-induced apoptosis may well be an important reason.

Apoptosis↗

PubMed2000

Traumatic spinal cord injury produced by controlled contusion in mouse.

Previous work from this laboratory has described a rat spinal cord injury (SCI) model in which the mid-thoracic spinal cord is subjected to a single rapid and calibrated displacement at the site of a dorsal laminectomy. Injury is initiated at the tip of a vertical shaft driven by an electromagnetic shaker. Transducers arranged in series with the shaft record the patterns of displacement and force during the impact sequence. In the present study, this device and the relevant surgical procedures were adapted to produce a spinal contusion injury model in laboratory mice. The signal generator for the injury device has also been converted to a computer-controlled interface to permit extension of the model to other laboratories. Mice were subjected to SCI across a range of severities by varying the amplitude of displacement and the magnitude of measured preload force on the dural surface. A moderate injury produced by displacement of 0.5 mm over 25 msec resulted in initial paralysis and recovery of locomotion with chronic deficits in hindlimb function. The magnitude of the peak force, impulse, power, and energy generated at impact were correlated with behavioral outcome at 1 day postinjury, while peak displacement and impulse were the best predictors of behavioral outcome at 28 days postinjury. The shape of the force recording proved to be a highly sensitive measure of subtle variations in the spinal compartment that were otherwise difficult to detect in this small species. The results demonstrate that the electromagnetic spinal cord injury device (ESCID) can be used to produce a well-controlled contusion injury in mice. The unique features of controlled displacement and monitoring of the biomechanical parameters at the time of impact provide advantages of this model for reducing outcome variability. Use of this model in mice with naturally occurring and genetically engineered mutations will facilitate understanding of the molecular mechanisms of pathophysiology following traumatic spinal cord injury.

Animals↗

PubMed2000

T-cell activation and receptor downmodulation precede deletion induced by mucosally administered antigen.

The fate of antigen-specific T cells was characterized in myelin basic protein (MBP) T-cell receptor (TCR) transgenic (Tg) mice after oral administration of MBP. Peripheral Th cells are immediately activated in vivo, as indicated by upregulation of CD69 and increased cytokine responses (Th1 and Th2). Concurrently, surface TCR expression diminishes and internal TCR levels increase. When challenged for experimental autoimmune encephalomyelitis during TCR downmodulation, Tg mice are protected from disease. To characterize Th cells at later times after antigen feeding, it was necessary to prevent thymic release of naive Tg cells. Therefore, adult Tg mice were thymectomized before treatment. TCR expression returns in thymectomized Tg mice 3 days after MBP feeding and then ultimately declines in conjunction with MBP-specific proliferation and cytokine responses (Th1-type and Th2-type). The decline correlates with an increase in apoptosis. Collectively, these results demonstrate that a high dose of fed antigen induces early T-cell activation and TCR downmodulation, followed by an intermediate stage of anergy and subsequent deletion.

Administration, Oral↗

PubMed2000

A new assay for the genetic study of general anesthesia in Drosophila melanogaster: use in analysis of mutations in the X-chromosomal 12E region.

We describe a new measure of the influence of general anesthetics on Drosophila that uses the robust tendency of fruit flies to briskly walk upwards after being tapped down. We expose flies to a fixed concentration of anesthetic gas in a 50 ml tube for a period of up to 1 h and then test the distribution of flies in the tube shortly after tapping them to its bottom. By measuring the effect of a series of anesthetic concentrations on the fraction of flies that fail to climb, we derive quantitative descriptors of the potency of the drug. This "distribution test" is superior to previous assays of anesthetic potency in terms of ease and reliability. We have used the assay to further the genetic analysis of several mutations that cluster on the X chromosome and are known to influence both neural function and anesthesia sensitivity. The results establish complementation patterns between the mutations, refine their genetic map positions, and open the way for the molecular identification of the relevant gene(s).

Anesthetics, Inhalation↗

PubMed2000

A study of hemorheological behaviour for patients with Alzheimer's disease at the early stages.

To evaluate the change of hemorheological indexes for patients with Alzheimer's disease (AD) at the early stages and to discuss effects of these changes on AD, high shear value of whole blood viscosity (etabh), reduced high shear value of whole blood viscosity (retabh), low shear value of whole blood viscosity (etabl), reduced low shear, value of whole blood viscosity (retabl), KT value of whole blood viscosity, hematocrit (HCT) and blood plasma viscosity (etaP) were measured in 31 patients with probable AD at the early stages and 33 age-matched healthy subjects. There were significant differences of all hemorheological indexes between AD group and control group except HCT. Step discriminant analysis revealed 81.25% of overall group-classified accuracy in a hemorheological discriminant function consisting of etabl, retabl, retabh and HCT. Significant difference of hemorheological indexes existed between AD and age-matched healthy control subjects. The results showed that measurement of hemorheological indexes could be used as one of reference standards of diagnosis in AD.

Aged↗

PubMed2000

[The clinical application of the reverse island skin flap supplied by the superficial sural artery].

OBJECTIVE: To conform the reliability of the reverse island skin flap supplied by the superficial sural artery in clinical applications. METHODS: The distally based superficial sural artery flap was designed on the posterior aspect of the leg. 15 patients were treated with this flap, who had soft-tissue shortage of the lower third of the leg, the foot or the heel. The size of the flap ranged from 10 cm x 8 cm to 5 cm x 4 cm. RESULTS: All flaps survived. The results were satisfactory after 6 to 18 months' postoperative follow-up. CONCLUSIONS: The blood supply of this flap is reliable without sacrificing the major arteries. Flap elevation is easy and quick. This flap may provide a new method in reconstructioning the soft-tissue shortage of the lower leg, the foot and the heel.

Adolescent↗

PubMed2000

[Risk factors for nosocomial infections after total knee replacement].

OBJECTIVE: To investigate prevalence and risk factors of nosocomial infections in patients with total knee replacement. METHODS: From August 1993 to October 1998, total knee replacement was performed on 363 patients (503 knees). The difference of nosocomial infection rates was statistically analyzed in comparison with different age, primary disease, and associated disease groups. RESULTS: No statistically significant difference was observed in nosocomial infection when compared rheumatoid arthritis with osteoarthritis, bilateral total knee replacement (TKR) with unilateral TKR and different ages. However, the higher nosocomial infection rate was related to the following factors: revision surgery, steroid administration and diabetes urinary infection. 28 female patients demonstrated higher urinary infection rate than that in other systems. CONCLUSIONS: Nosocomial infection rate of TKR in rheumatoid cases is related to steroid administration, accompanying diabetes mellitus, previous knee surgery, aged women and retention of urinary catheter. It is feasible to prevent nosocomial infection by controlling the above-mentioned risk factors.

Adult↗

PubMed2000

[Reconstruction of hip, knee, and ankle bony fused in non-functional position of ankylosing spondylitis patients].

OBJECTIVE: To evaluate the reconstruction of hip, knee and ankle joints with bony fusion at non-functional positions for patients with severe late-stage ankylosing spondylitis (AS). METHODS: From January 1996 to May 1997, simultaneous ipsilateral total hip, knee and ankle replacement was performed under single anesthesia on 2 patients (3 sides) with multiple joint deformity including bony fusion at non-functional positions. They were followed for 29 months on average. RESULTS: Satisfactory range of motion and function were observed. HSS knee score on average was improved by 45 points and Harris hip score by 37.7 points. There were no wound healing problems or late infection. No aseptic loosening was found. CONCLUSIONS: Simultaneous ipsilateral total hip, knee and ankle replacement not only reduced cost for hospitalization, but also facilitated early rehabilitation. To our knowledge, this is the first report on this type of surgery, named ipsilateral tri-arthroplasty.

Adult↗

PubMed2000

[Study on the genetic difference of SEO type Hantaviruses].

OBJECTIVE: To understand the genetic type of Hantaviruses and the difference between them caused by rodents in Beijing and to furhter explore the source of the infectious factors. METHODS: Hantavirus RNA, isolated from lungs of rodents captured in Beijing and positive with Hantavirus antigens with frozen sectioning and Immunofluorescent assay, were reverse-transcribed and amplified with PCR with Hantavirus-specific primers. RESULTS: Five of the PCR amplifications were discovered and sequenced with 300 bp sequence data of M segments (from 2003 - 2302nt according cDNA of seoul 8039 strain). Nucleotide sequence homology showed that they were sequences of SEO-type Hantavirus. Compared with SEO type Hantavirus, the nucleotide sequence homology of these samples was more than 94% while the homology of amonia acid sequence was more than 98%. When compared with HNT type Hantavirus, the homology of nucleotide sequence became less than 72% with the homology of amonia acid sequence less than 81%. Similar to other Hantavirus of SEO type, their nucleotide sequences and deduced amino acid sequences were highly preserved. Phylogenetic tree analysis showed that the five viruses could be divided into at least 4 branches. CONCLUSION: It was quite likely that there were at least two sub-type SEO viruses with 4 branches that were circulating in Beijing.

DNA, Viral↗

PubMed2000

[Influence of free radical inducer on the level of oxidative stress in brain of rats with fluorosis].

OBJECTIVE: To study changes in content of lipid peroxide and composition of fatty acids in the brain of rats affiliated with chronic fluorosis after treatment with free radical inducer (ferric ion). METHODS: Thirty-six Wistar rats were divided into three groups, fed with similar fodder and varied concentrations of fluoride in drinking water, and were killed five months after treatment. Lipid peroxidation was induced by ferric ions. Malondialdehyde content in brain was analysed by high-performance liquid chromatography; oxygen consumption was determined with an oxygen electrode and fatty acid composition was measured by gas chromatography in brain tissues of the rats. RESULTS: In the brain tissues, content of malondialdehyde and oxygen consumption increased, composition of polyunsaturated fatty acids decreased and that of saturated fatty acids decreased after treatment with free radical inducer in the treated group, as compared with those in control group. CONCLUSION: Over uptake of fluoride for a long term could cause potential increase in the level of oxidative stress in the brain tissue.

Animals↗

PubMed2000

[The research progress of using electromagnetic technology in treatment of bone diseases].

In these years, the study of the bioeffects of electromagnetic fields (EMFs) has been listed as the national important task in the field of biological physics. Using EMFs to treat bone diseases is associated with electric technology, biology and medicine. Previous medical studies have shown that EMFs can stimulate healing in bone fractures. But the effects are still controversial and the mechanism is not yet clear. Therefore, it is necessary to carry out experiments in vitro at cellular and molecular levels. Research workers have been exploring the effects of EMFs on bone formation and metabolism. The suggestion of using EMFs in the treatment of osteoporosis and other osseous diseases has been put forward.

Animals↗

PubMed1999

Both p38alpha(MAPK) and JNK/SAPK pathways are important for induction of nitric-oxide synthase by interleukin-1beta in rat glomerular mesangial cells.

Interleukin 1beta (IL-1beta) induces expression of the inducible nitric-oxide synthase (iNOS) with concomitant release of nitric oxide (NO) from glomerular mesangial cells. These events are preceded by activation of the c-Jun NH(2)-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38(MAPK). Our current study demonstrates that overexpression of the dominant negative form of JNK1 or p54 SAPKbeta/JNK2 significantly reduces the iNOS protein expression and NO production induced by IL-1beta. Similarly, overexpression of the kinase-dead mutant form of p38alpha(MAPK) also inhibits IL-1beta-induced iNOS expression and NO production. In previous studies we demonstrated that IL-1beta can activate MKK4/SEK1, MKK3, and MKK6 in renal mesangial cells; therefore, we examined the role of these MAPK kinases in the modulation of iNOS induced by IL-1beta. Overexpression of the dominant negative form of MKK4/SEK1 decreases IL-1beta-induced iNOS expression and NO production with inhibition of both SAPK/JNK and p38(MAPK) phosphorylation. Overexpression of the kinase-dead mutant form of MKK3 or MKK6 demonstrated that either of these two mutant kinase inhibited IL-1beta-induced p38(MAPK) (but not JNK/SAPK) phosphorylation and iNOS expression. Interestingly overexpression of wild type MKK3/6 was associated with phosphorylation of p38(MAPK); however, in the absence of IL-1beta, iNOS expression was not enhanced. This study suggests that the activation of both SAPK/JNK and p38alpha(MAPK) signaling cascades are necessary for the IL-1beta-induced expression of iNOS and production of NO in renal mesangial cells.

Animals↗

PubMed1999

[Relationship between unhealthy dietary behavior and blood lipids and lipid peroxides in coronary heart disease patients].

The effects of unhealthy dietary behavior on blood lipids(TC, TG, HDL-C, LDL-C) and lipid peroxides (LPO) and the occurrence of coronary heart disease(CHD) were measured in 97 CHD patients and 97 controls without any clinical appearance of cardiovascular or cerebrovascular diseases. The results showed that the serum level of TC, TG, HDL-C, LDL-C and LPO were significantly higher in CHD group than control group. More unhealthy dietary behavior was observed in CHD group than in control group. The odds ratio of the population with more than 3 items of unhealthy dietary behavior was 3.88. The results of this study suggested that unhealthy dietary behavior might play an important role in increasing the risk of CHD.

Adult↗