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Biomedical subjects

H Xie

Publications and source records attributed to H Xie.

At least 181 records · Page 10Linked to original sources
PubMed1997

Detection of Babesia bovis using a DIG-labeled DNA probe.

A plasmid DNA containing the inserted Babesia bovis cDNA clone designated c51A was used to prepare a DNA probe for B. bovis. The purified 0.6 kb specific DNA fragment was labeled by DIG DNA labeling. After denaturation, the probe was hybridised with the blotted target DNA extracted from bovine red blood cells infected with B. bovis or other protozoa or bovine red blood cells plus extra white blood cells. It was found that the probe produced from purified 0.6 kb DNA fragment could detect sample of B. bovis DNA equivalent to 0.015 microliter of 10% whole infected blood. Compared to the same DNA fragment labeled with photobiotin, this new probe is more sensitive giving a darker hybridization signal, a lighter hybridization background and without any non-specific reactions. These results indicated that this DIG-labeled B. bovis C5lA probe could provide a sensitive and specific method to diagnose clinically suspected B. bovis infections and distinguish B. bovis DNA from other haemoprotozoan infections.

Affinity Labels↗
PubMed1997

Properties of solutions for a chemotaxis system.

We investigate mathematically the system of equations proposed by Chaplain and Stuart, to describe the chemotactic response of endothelial cells under the angiogenesis stimulus. In particular, we characterize the steady state endothelial cell density function, and give conditions on the chemotactic parameter k and cell proliferation parameter b that ensure that migration/ proliferation either does or does not occur in steady state. The time dependent problem is also treated.

Angiogenesis Inducing Agents↗
PubMed1997

Cytokine rescue from glucocorticoid induced apoptosis in T cells is mediated through inhibition of IkappaBalpha.

We previously reported that dexamethasone (DEX), a synthetic glucocorticoid, causes apoptosis in mature Th cell lines, and that this induction of cell death is prevented by specific cytokines, namely, by IL-2 in Th1 cells and by IL-4 in Th2 cells. We now show that this differential rescue by specific cytokines in Th cells correlates with the level of IkappaBalpha that is regulated by DEX and cytokines. In both cell types the cellular levels of IkappaBalpha mRNA and protein were evaluated by DEX treatment. Interestingly, the DEX-mediated IkappaBalpha induction was completely inhibited by IL-2, but not IL-4, in Th1 cells, while the reverse profile was seen in Th2 cells. In both cell types, the cytokine that inhibits the induction of IkappaBalpha by DEX, also rescues these cells from DEX-induced apoptosis, although the rescue cytokine is different in Th1 and Th2 cells. Our results imply that T cells need to maintain a certain level of NF-kappaB transcriptional activity in order to survive; up- or down-regulation of nuclear NF kappaB through modulation of IkappaBalpha expression by cytokines or DEX may lead to cell survival or cell death, respectively.

Animals↗
PubMed1997

Alkoxy propane prodrugs of foscarnet: effect of alkyl chain length on in vitro antiviral activity in cells infected with HIV-1, HSV-1 and HCMV.

The identification of more effective and less toxic foscarnet (PFA) analogs for antiviral therapy would be useful. We recently synthesized 1-O-octadecyl-sn-glycero-3-phosphonoformic acid (ODG-PFA) and noted a 93-fold increase in its anti-HCMV activity relative to PFA. In addition, the antiviral activity of ODG-PFA in herpes simplex virus type-1 (HSV-1) and human immunodeficiency virus type-1 (HIV-1) infected cells was increased 40-fold relative to PFA (Hostetler et al., 1996. Antiviral Res. 31, 59). To evaluate structure-activity relationships further, we synthesized alkoxypropyl esters of foscarnet with varying alkyl chain lengths and degrees of saturation. These compounds were tested in vitro for activity and selectivity in comparison with PFA and ODG-PFA in cells infected with HCMV, HSV-1 or HIV-1. Antiviral activity was strongly dependent on chain length with alkyl ethers 14-18 carbon atoms long exhibiting the greatest antiviral activity against HCMV and HSV-1. In HIV-infected HT4-6C cells, optimal activity was observed at 18-22 carbon chain lengths. The antiviral activities of 1-octadecyloxypropane-3-PFA and 1-docosyloxypropane-3-PFA were 135- and 338-fold greater than that of PFA in HT4-6C cells infected with HIV-1. This also represents a 2.6-6-fold improvement in antiviral activity over ODG-PFA, the previously reported analog.

Antiviral Agents↗
PubMed1997

A novel method for diabetes diagnosis based on electronic nose.

A novel non-invasive method for diabetes diagnosis based on an electronic nose is proposed in this paper. The principles of the method and results of clinical experiments are presented. These results show the convenience, painlessness and non-invasiveness of the method.

Algorithms↗
PubMed1997

Association of cortactin with developing neuromuscular specializations.

During the development of the neuromuscular junction (NMJ), motoneurons grow to the muscle cell and the nerve-muscle contact triggers the development of both presynaptic specialization, consisting of clusters of synaptic vesicles (SVs), and postsynaptic specialization, consisting of clusters of synaptic vesicles (SVs), and postsynaptic specialization, consisting of clusters of acetylcholine receptors (AChRs). Previous studies have shown that the activation of tyrosine kinases and the local assembly of an actin-based cytoskeletal specialization are involved in the development of both types of specializations. To understand the link between tyrosine phosphorylation and the assembly of the cytoskeleton, we examined the localization of cortactin in relationship to synaptic development. Cortactin is a 80/85 kD F-actin binding protein and is a substrate for tyrosine kinases. It contains a proline-rich motif and an SH3 domain and is localized at sites of active F-actin assembly. Using a monoclonal antibody against cortactin, its localization at developing NMJs in culture was observed. To understand the spatial and temporal relationship between cortactin and developing synaptic structures, cultured muscle cells and spinal neurons from Xenopus embryos were treated with beads coated with heparin-binding growth-associated molecule to induce the formation of AChR clusters and SV clusters and the localization of cortactin was followed by immunofluorescence. In untreated muscle cells, cortactin is often co-localized with spontaneously formed AChR clusters. After cells were treated with beads, cortactin became localized at bead-induced AChR clusters at their earliest appearance (1 h after the addition of beads). This association was most reliably detected at the early stage of the clustering process. On the presynaptic side, cortactin localization could be detected as early as 10 min after the bead-neurite contact was established. Cortactin-enriched contacts later showed concentration of F-actin (at 1 h) and clusters of SVs (at 24 h). These data suggest that cortactin mediates the local assembly of the cytoskeletal specialization triggered by the synaptogenic signal on both nerve and muscle.

Actins↗
PubMed1997

Ceramide selectively decreases tau levels in differentiated PC12 cells through modulation of calpain I.

Ceramide has been recently proposed to be a signal mediator in several important physiological processes including apoptosis, cellular growth, and differentiation. Because the microtubule-associated protein tau plays an important role in the establishment and maintenance of neuronal morphology, the effects of ceramide on tau were examined. Treatment of differentiated PC12 cells with the cell-permeable ceramide derivative N-acetylsphingosine (C2) resulted in a significant reduction in tau levels. Significant decreases in tau levels were also observed when the cells were treated with another ceramide derivative, N-hexanoylsphingosine (C6). In addition, C2 treatment increased the levels of a calpain-derived spectrin breakdown product but did not alter the levels of two cytoskeletal proteins, alpha-actin and alpha-tubulin. Because both tau and spectrin are proteolyzed in vitro by the calcium-activated cysteine protease calpain, the effects of ceramide analogues on the activity of this protease were examined. Treatment of PC12 cells with C2 enhanced calcium-stimulated proteolytic activity significantly, as revealed by monitoring the hydrolysis of the membrane-permeable calpain-selective fluorescence probe N-succinyl-L-leucyl-L-leucyl-L-valyl-L-tyrosine-7-amido-4-methylcoumarin . This activity increase was not due to a direct effect of C2 on calpains, because C2 did not alter the activities of purified calpain I or II. In addition, C2 treatment of PC12 cells resulted in a significant increase in the levels of calpain I and, to a lesser extent, the levels of calpastatin (an endogenous calpain inhibitor protein), whereas the levels of calpain II were not changed. Moreover, treatment of the cells with the synthetic calpain-specific inhibitor N-carbobenzoxy-L-leucyl-L-leucyl-L-tyrosine diazomethyl ketone blocked the C2-induced decreases in tau levels. These results indicate that tau levels are regulated in response to a physiological factor and, thus, have implications for ceramide-mediated changes in normal and pathological neuronal processes.

Actins↗
PubMed1997

Relationships between symptoms of schizophrenia and substance abuse.

Previous work posits that severity of substance abuse and severity of schizophrenic symptoms should be linked by either or both of two mechanisms: self-regulation of symptoms and drug-induced exacerbation of symptoms. Research on these relationships has yielded mixed results. We examined the interrelationships of schizophrenic symptoms and substance abuse in 172 patients with co-occurring disorders. Relationships were weak or nonexistent, without any consistent pattern. Our findings do not support the view that substances are used to self-regulate symptoms. In addition, our results suggest that substance abuse may lead to higher rates of institutionalization through mechanisms other than by exacerbating symptoms.

Adolescent↗
PubMed1997

Work and nonvocational domains of functioning in persons with severe mental illness: a longitudinal analysis.

In this study we sought to understand the relationship between obtaining competitive employment and changes in nonvocational domains of functioning (symptoms, substance abuse, hospitalizations, self-esteem, quality of life) in persons with severe mental illness. A group of 143 unemployed patients participating in a study of vocational rehabilitation programs were assessed in nonvocational areas of functioning at baseline and 6, 12, and 18 months later. Statistical analyses examined the relationship between work status at the follow-up assessments and nonvocational functioning, controlling for baseline levels of nonvocational variables. Patients who were working at follow-up tended to have lower symptoms (particularly thought disorder and affect on the Brief Psychiatric Rating Scale), higher Global Assessment Scores, better self-esteem, and more satisfaction with their finances and vocational services than unemployed patients. Employment is associated with better functioning in a range of different nonvocational domains, even after controlling for baseline levels of functioning.

Activities of Daily Living↗
PubMed1997

Environmental regulation of fimbrial gene expression in Porphyromonas gingivalis.

Porphyromonas gingivalis fimbriae are an important virulence factor involved in attachment and invasion. Fimbrillin, encoded by the fimA gene, is the major subunit protein of the fimbriae. To elucidate the influence of environmental signals on the expression of the fimA gene, a strain of P. gingivalis (designated PLE) containing a chromosomal transcriptional fusion between a promoterless lacZ gene and the fimA promoter region was constructed. Promoter activity was assessed by measurement of beta-galactosidase activity of PLE. An 11-fold increase in activity of fimA promoter was found as growth temperature declined from 39 to 34 degrees C. Promoter activity decreased by approximately 50% in response to hemin limitation and upon culture on solid medium. In addition, the presence of serum or saliva in the growth medium decreased fimA promoter activity by similar amounts. A correlation between fimA promoter activity and phenotypic properties dependent upon fimbriae was established. P. gingivalis grown at 34 degrees C, compared to 39 degrees C, showed an increased ability to adhere to Streptococcus gordonii and to invade primary cultures of gingival epithelial cells. These studies indicate that expression of the P. gingivalis fimA gene is regulated at the transcriptional level in response to several environmental conditions and that altered fimA expression can also modulate the adherence and invasion abilities of P. gingivalis.

Bacterial Proteins↗
PubMed1997

Housing status among formerly homeless dually diagnosed adults.

OBJECTIVE: Residential outcomes of homeless adults with severe mental illness and a substance use disorder were studied over 18 months during which participants received integrated dual diagnosis services and housing supports based on a continuum model. METHODS: Interviews with 158 participants at baseline and at six-, 12-, and 18-month follow-ups assessed housing status, residential history, substance abuse and progress toward recovery, psychiatric symptoms, and quality of life. Complete data were available for 122 participants. If participants lived continuously in high-quality housing with no housing loss or nights of homelessness during the final six months of the study, they were classified as having stable housing. RESULTS: Of the 122 participants for whom complete data were available, 64 (52 percent) achieved stable housing. Most participants who achieved stable housing first entered staffed and supervised housing and then moved to independent arrangements by the end of the study. Stable housing during the final evaluation period was associated with lower substance use, greater progress toward substance abuse recovery, and higher quality of life. Final housing status was not predicted by baseline variables but was predicted by progress toward recovery during months 0 to 6 and 6 to 12 and by less severe drug use during months 6 to 12. Participants who abused no illicit drugs during months 6 to 12 were almost three times as likely to achieve stable housing as those who abused illicit drugs. CONCLUSIONS: Housing stability is strongly mediated by substance abuse and progress toward recovery. Nevertheless, when formerly homeless persons with dual diagnoses are provided integrated dual diagnosis treatment, they can gradually achieve stable housing.

Adult↗
PubMed1997

Flow relaxation is not ATP-mediated in the rabbit ear artery.

ATP has been proposed to play a role in flow-induced dilation of blood vessels. Changes in flow would alter the concentration of ATP at lumenal endothelial P2Y receptors, occupation of which results in dilation. We tested the hypothesis that the lumenal release of ATP close its receptors on the endothelium and the subsequent influence of flow rate on its concentration at such receptors acts as a flow sensing system. The effect of the selective P2Y-purinoceptor antagonist reactive blue 2 on relaxation of the isolated rabbit ear resistance artery to flow, ATP and ACh was studied. We found that reactive blue 2 (100 micromol/L) significantly inhibited ATP-induced relaxation, but had no effect on equivalent relaxation induced by intraluminal flow (10-40 microl/min). It reduced ACh-induced relaxation to a less extent. These findings strongly suggest that flow-induced relaxation of the rabbit ear resistance artery can occur without the mediation of locally released ATP.

Acetylcholine↗
PubMed1997

[Effects of different components of serum from radiation, burn and combined radiation-burn injury on L-type calcium channel of cultured myocardial cells].

The effects of different components of serum from radiation, burn and combined radiation-burn injury on the activity of L-type calcium channel in cultured myocardial cells were investigated in this study. The results revealed that the serum from different injury groups could all activate the L-type calcium channel of cultured myocardial cells. These changes altered the calcium level in cells, which might be an important cause of dysfunction in cardiovascular system. Among the components of postinjury serum, the effect of high molecular components (> 8-10 kD) was not significant, whereas low molecule (< 8-10kD) and lipid components were the major effective components. The low molecule of postinjury serum affected not only on the opening activity of L-type channel, but also on the state of molecular movement in the membrane. The effect of serum lipids from injury groups could be depressed by SOD, which suggests that there may be free radical reactions during the serum lipids effect on calcium channel. The effects of serum and its components from combined radiation-burn group were the most intensive, and those from radiation injury were the weakest. The nature of the toxic material in serum remains to be further investigated.

Animals↗
PubMed1997

[Inclusion body myositis: clinical and myopathological features].

Inclusion body myositis has been recognized as a major form of idiopathic inflammatory myopathy. An old male patient with insidious onset and slowly progressive muscular weakness and artrophy has been reported in this article. The duration of symptom before biopsy was 23 years. The first symptom was dysphagia, and muscular weakness developed seven years later. Muscular atrophy was predominant symmetrically and proximally, particularly the quadriceps femoris muscles. Cervical and abdominal muscles were also affected. Myalgia was absent. Electromyogrophy showed myopathic alterations. Erythrocyte sedimentation rate, creatine kinase, immunoglobulins G increased slightly or moderately. Rheumatoid factor was positive, and he had been diagnosed as having rheumatoid arthritis for 23 years. Inclusion body myositis was ultimately diagnosed based on the muscle biopsy which showed mononuclear cell invasion of nonnecrotic muscle fibers, the characteristic rimmed vacuoles in cryostat sections and cytoplasmic inclusion bodies consisted of plenty of tubulofilaments by electron microscope.

Aged↗
PubMed1997

[Interleukin-8, a regulator of inflammation in gingival crevicular fluid].

The role of interleuking-8 (IL-8), a neutrophil-attracting and-activating cytokine, was investigated in gingival crevicular fluid (GCF). ELISA was used to detect the levels of IL-8 in GCF collected from 54 adult periodontitis (AP) patients (105 teeth) and 24 healthy subjects (54 teeth). The results showed that 1. The role of IL-8 was dependent upon the concentration of IL-8 in GCF. IL-8, in the low concentration (< or = 30 micrograms/L), was positively correlated with bleeding index (r = 0.36, P < 0.01). While in the high concentration (> 30 micrograms/L), was negatively correlated with bleeding index and probing depth (r = -0.54 and r = -0.65 respectively, P < 0.01). In the majority of periodontitis sites (91%), the concentration of IL-8 in GCF were lower than 30 microliters/L. IL-8 most likely acted as pro-inflammatory factor in these teeth. 2. IL-8 was a two-way regulator of inflammation, pro-inflammation and anti-inflammation. The threshold of IL-8 between inducing and suppressing inflammation was approximately 30 micrograms/L. Within the confined range, IL-8 concentration greater than 30 micrograms/L could be inflammation suppressive, while a less-than-30 micrograms/L concentration of IL-8 might become inflammation inducing.

Adult↗
PubMed1997

[Preventive effect of gubao on hydrocortisone-induced osteoporosis in rats].

The antagonistic effect of Gubao (consisting of Herba Epimedii, Radix Astragali, etc.) on hydrocortisone-induced osteoporosis in rats was observed in quantitative bone histomorphometry study with stereological method. The results of experiment show that Gubao helps to reduce trbecular bone resorption and increase bone formation in ratsuith hydrocortisone-induced osteoporosis. It is suggested that Gubao is useful in preventing glucocorticoid-induced osteoporosis.

Animals↗
PubMed1997

[The evidence for existence of interleukin 8 inhibitor and its biological activity in gingival crevicular fluid].

In order to confirm the existence of Interleukin-8 (IL-8) inhibitor and its biological activity in gingival crevicular fluid (GCF), this study examined the GCF taken from 7 adult periodontitis (AP) patients. In neutralization test of IL-8, the results showed that the mean level of IL-8 was less than 1 ng/ml, which had been added into the GCF before ELESAs was performed to measure the amount of IL-8 in GCF. The mean level of IL-8 in the GCF of AP group was significantly lower than that of healthy group (P < 0.001). In biological activity test of IL-8 inhibitor, using pooled GCF taken from 8 AP patients (23 teeth), the results showed that the GCF (without recombinant human IL-8, rhIL-8) caused more white blood cell (WBC) migration than blank control group (physiological saline) did. When the amount of rhIL-8 increased in GCF from 0.1 microgram to 1 microgram, the WBC count increased by 18.6% which was less than the increase rate (49.1%) in control group with same dose of IL-8. In the saline group containing rhIL-8, the WBC chemotactic response appeared as an inverted "V"-shape curve. All these data suggested that 1. Certain kinds of IL-8 inhibitor exist in GCF which can "cleave" IL-8. 2. The level of IL-8 inhibitor(s) increases significantly in the GCF from periodontitis sites. 3. The GCF of adult periodontitis patient has strong chemotactic effects on WBC. IL-8 inhibitor(s) in GCF can slightly suppress the chemotactic effect induced by IL-8. When assessing the role of IL-8 in pathophysiology, the high and low dose of IL-8 might have different sense.

Adult↗