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Biomedical subjects

X Pei

Publications and source records attributed to X Pei.

At least 37 records · Page 2Linked to original sources
PubMed1999

[One-time operation in infant cleft lip and palate plus alveolar process].

OBJECTIVE: To improve safety and viability of one-time operation in the therapy of cleft lip and palate and cleft alveolar process. METHODS: Under the air-vein anesthesia, one-time operations were performed in 42 patients with complete cleft lip and palate plus cleft alveolar process. After rehabilitation in ICU, all patients were put into wards, and left hospital 4-7 days after operation. RESULTS: The situation during anesthesia and operation was good. There were no statistically significant changes in blood pressure, oxygen saturation of blood, heart rate and cardiac rhythm before, during and after operation. No anesthetic accident and no complication happened. The loss of blood was about 42.7 +/- 6.5 ml and the duration of operation was about 139.2 +/- 18.6 minutes. The rehabilitation was successful after operations. First intention took place in almost all patients' incisions, and palatal fistulas appeared in only 2 cases. CONCLUSION: Under the control of provisioned pediatric anesthesia and rehabilitation, one-time complete cleft lip and palate plus cleft alveolar process closure is safe and viable.

Alveolar Process↗
PubMed1998

Implications for function and therapy of a 2.9 A structure of binary-complexed antithrombin.

The crystal structure of a binary complex of human antithrombin with a peptide of the same sequence as its reactive loop (P14-P3) has been determined at 2.9 A. The peptide binds as the middle strand s4A in the A beta-sheet, homologously to that of the reactive loop in the latent and cleaved forms of antithrombin. Peptide binding results in the complete expulsion of the hinge region of the loop from the A beta-sheet although the conformation differs from that of heparin-activated antithrombin. The 36-fold increase in the rate of reaction of the binary complex with factor Xa indicates that full loop expulsion alone is not sufficient for complete heparin activation of antithrombin but that this is also dependent on the overall conformation of the molecule. Previous studies have demonstrated that reactive loop peptides can block or reverse the polymerisation of serpins associated with cirrhosis and thrombosis. The antithrombin binary complex structure defines the precise localisation of the blocking peptide in a serpin and provides the basis for rational drug design for mimetics that will prevent polymerisation in vivo and so ameliorate the associated disease.

Amino Acid Sequence↗
PubMed1998

[Expression of Wilms' tumor gene (WT1) in leukemias and its clinical implication].

OBJECTIVE: To elucidate the expression of Wilms' tumor gene (WT1) in leukemias and its clinical implication. METHODS: Expression of WT1 mRNA was detected in four leukemia cell lines, 25 AML patients, 11 ALL patients, 9 CML patients, 15 healthy subjects and 10 non-blood diseases patients by using RT-PCR. RESULTS: WT1 mRNA expression was revealed in K562, HL-60 and TF-1 cell lines, 21 of 25 (84%) AML patients, 8 of 11 (73%) ALL patients, 2 CML patients in blast crisis and 1 of 7 CML patients in accelerated and chronic phase. WT1 mRNA was undetectable in PBMNC from 15 healthy subjects and in bone marrow cells from 10 non-blood diseases patients. CONCLUSION: WT1 gene is expressed in the majority of acute leukemias and thus is involved in human leukemogenesis. WT1 is also a new important marker for monitoring MRD in acute leukemias.

Adolescent↗
PubMed1998

[Studies on the committed differentiation of CD34+ hematopoietic progenitor cells].

OBJECTIVE: To elucidate the capacity of different hematopoietic growth factors (HGFs) combinations for inducing CD34+ cells to proliferate and differentiate committedly to granulocytes, erythrocytes, megakaryocytes and dendritic cells (DC). METHODS: CD34+ cells were isolated from umbilical cord blood by using a high-gradient magnetic cell sorting system (MACS), and expanded with HGFs in a liquid culture system. Colony forming cells and antigen expression were studied by colony forming assays and FACS. RESULTS: Different combinations of HGFs, including SCF, IL-3, IL-6, GM-CSF, Epo and Tpo increased BFU-E, CFU-GM, CFU-MK and CD41a+ cells by 14.97 +/- 2.89 fold, 14.46 +/- 3.19 fold, 34.67 +/- 4.62 fold and 17.29 +/- 2.34 fold, respectively. Combination of HGFs allowed generation of a large number of DCs. Cultures of CD34+ cells with the combination of FLT-3 ligand + GM-CSF + IL-4 + TNF-alpha yielded 24.28% +/- 2.14% CD1a+ cells, while the control cultures did not. CONCLUSION: It is possible to induce CD34+ cells to proliferate and differentiate committedly to different lineage of hematopoietic cells and DC.

Antigens, CD34↗
PubMed1997

Low-dimensional dynamics in sensory biology. 1: Thermally sensitive electroreceptors of the catfish.

We report the results of a search for evidence of periodic unstable orbits in the electroreceptors of the catfish. The function of these receptor organs is to sense weak external electric fields. In addition, they respond to the ambient temperature and to the ionic composition of the water. These quantities are encoded by receptors that make use of an internal oscillator operating at the level of the membrane potential. If such oscillators have three or more degrees of freedom, and at least one of which also exhibits a nonlinearity, they are potentially capable of chaotic dynamics. By detecting the existence of stable and unstable periodic orbits, we demonstrate bifurcations between noisy stable and chaotic behavior using the ambient temperature as a parameter. We suggest that the technique developed herein be regarded as an additional tool for the analysis of data in sensory biology and thus can be potentially useful in studies of functional responses to external stimuli. We speculate that the appearance of unstable orbits may be indicative of a state of heightened sensory awareness by the animal.

Animals↗
PubMed1997

[Analysis of causes of drug resistance and therapeutic effects on 27 multi-drug resistant pulmonary tuberculosis patients].

OBJECTIVE: To analyse the causes of multi-drug resistant tuberculosis (MDR-TB) and to evaluate the effects of chemotherapy with ofloxacin and other antituberculosis drugs. METHOD: 27 cases with MDR-TB were treated with the regimen of 3KPTHOX/PTHOX. Changes of sputum convesion, X-ray manifestations and side effects after the treatment were also evaluated. RESULTS: 67% of the MDR-TB patients were due to irregular treatment, and 18% were caused by improper treatment. The sputum culture conversion rate at end of treatment was 89%. The bacteriological relapse rate of converted cases during 2 year follow-up was 8%. CONCLUSIONS: MDR-TB might be prevented by a combination of health education and rational use of short-course chemotherapy. Ofloxacin and other second-line anti-tuberculosis drugs are effective and were tolerated in treating patients with MDR-TB.

Adult↗
PubMed1997

[Studies on peripheral blood stem cells mobilization by short course and high-dose G-CSF].

OBJECTIVE: To explore the effect of short-course, high dose granulocyte-colony stimulating factor (G-CSF) on peripheral blood stem cell (PBSC) mobolization. METHODS: G-CSF 5microg/kg was injected subcutaneously twice daily for 3 consecutive days. On the first day and the fourth day the peripheral blood and bone marrow were collected for CFU-GM, BFU-E, CFU-mix assays and CD34/CD38 detection. A single apheresis of over 8000ml blood processing was performed with CS-3000 blood cell separator. The mononuclear cells were prepared for hematopoietic colony assays and CD34/CD38 detection before and after freezing. RESULTS: After adminitration of G-CSF, the white blood cell count increased significantly. The CFU-GM, BFU-E, CFU-mix yields and CD34+ CD38+ cell and CD34+ CD38- cells also increased significantly (P<0.05). The median of mononuclear cells was 1.56 x 10(8)/kg. After one week freezing, the recovery of mononuclear cells, CFU-GM, BFU-E yields and CD34+ CD38+ cells were about 80% (P>0.05) and CFU-mix yields was 60%; The CD34+ CD38- cells were decreased compared with that of pre-freezing (P<0.05). The median of the reinfused mononuclear cells was 1.27 x 10(8)/kg,CFU-GM 6. 7 x 10(4)/kg, BFU-E 1.6 x 10(4)/kg, CFU-mix 0.32 x 10(4)/kg, CD34- CD38+ cells 1.6 x 10(6)/kg and CD34+ CD38- cells 0.23 x 10(6)/kg. CONCLUSION: Short course and high-dose G-CSF can effectively mobilize the peripheral stem cells. The mononuclear cells, hematopoietic colonies and CD34/CD38 cells were satisfied for the peripheral stem cells rescue.

ADP-ribosyl Cyclase 1↗
PubMed1997

[Experimental studies on the expansion of cord blood CD34+ cells and the improvement of their grafting efficiency].

OBJECTIVE: To elucidate the expanding response of cord blood CD34+ cells to human hematopoietic growth factors (HGFs) and evaluate their grafting efficiency. METHODS: CD34+ cells were isolated from umbilical cord blood by using a high-gradient magnetic cell sorting system (MACS), expanded with HGFs in a liquid culture system and evaluated of grafting efficiency with a panning assay on an adult bone marrow stroma. RESULTS: The percentage of CD34+ CD38- subset in cord blood was much higher than that in bone marrow or peripheral blood. Treatment with a combination of HGFs, including SCF, IL-3, IL-6, G-CSF,and Epo increased hematopoietic progenitor cells by nearly 100 fold and nucleated cells by more than 500 fold. 68.0%-89.6% of the CD34+ cells treated with HGFs (GM-CSF or IL-3, alone or in combination) seeded in the pre-irradiated marrow stroma, whereas only 36% of the untreated ones did. CONCLUSION: It is possible to expand cord blood CD34+ cells ex vivo and to improve their grafting efficiency with HGFs.

Antigens, CD34↗
PubMed1997

[In vitro effects of hematopoietic growth factors on CD34+ cell from patients with myelodysplastic syndromes].

OBJECTIVE: To investigate the role of recombinant human hematopoietic growth factors (HGFs) in the treatment of myelodysplastic syndromes (MDS) patients. METHODS: CD34+ cells from 16 MDS patients were purified up to 96% approximately 99% by means of a immunomagnetic beads sorting system. The effects of individual and combination of HGFs on the proliferation and differentiation of the CD34+ cells were studied in semi -solid cultures. RESULTS: CD34+ cells were impaired and none of the individual HGF (GM-CSF, IL-3, SCF) could effectively support their proliferation and differentiation. rh-SCF combined with GM-CSF, IL-3 or Epo could partly increase the colony forming capacity of MDS hematopoietic progenitor, however, an increase of undifferentiated blast cells colonies occurred in some high-risk MDS patients at the same time. CONCLUSION: Proper combination of HGFs was essential for improving hematopoiesis in MDS patients.

Animals↗
PubMed1997

[Studies on the engraftment of human mixed cord blood in severe combined immunodeficient mice].

OBJECTIVE: To evaluate the engrafting characteristics of human mixed cord bloods. METHODS: Single or double human cord bloods were transplanted into sublethally irradiated severe combined immunodeficient (SCID) mice. Engrafting rate, hematopoiesis reconstitution and immunologic functions between the two groups were compared. RESULTS: The survival rates of both transplanted groups were equivalent (P > 0.05) while the total volume of transfused cord bloods had no statistical differences. But the engrafting rate of mixed cord blood transplant (MCBT) group was lower than that of single cord blood transplant (SCBT) group. The lymphocyte transformation rate of MCBT group was also lower than that of SCBT group. In MCBT group, only one of the two mixed cord bloods was engrafted in SCID mice as shown by HLA-DPB gene detection. CONCLUSION: Two HLA-mismatched human cord bloods transplanted in SCID mice could reconstitute hematopoietic and immunologic functions, but only one cord blood with the higher proliferation potential was engrafted.

Animals↗
PubMed1996

A linear model fails to predict orientation selectivity of cells in the cat visual cortex.

1. Postsynaptic potentials (PSPs) evoked by visual stimulation in simple cells in the cat visual cortex were recorded using in vivo whole-cell technique. Responses to small spots of light presented at different positions over the receptive field and responses to elongated bars of different orientations centred on the receptive field were recorded. 2. To test whether a linear model can account for orientation selectivity of cortical neurones, responses to elongated bars were compared with responses predicted by a linear model from the receptive field map obtained from flashing spots. 3. The linear model faithfully predicted the preferred orientation, but not the degree of orientation selectivity or the sharpness of orientation tuning. The ratio of optimal to non-optimal responses was always underestimated by the model. 4. Thus non-linear mechanisms, which can include suppression of non-optimal responses and/or amplification of optimal responses, are involved in the generation of orientation selectivity in the primary visual cortex.

Animals↗
PubMed1996

Characterization of low-dimensional dynamics in the crayfish caudal photoreceptor.

Attempts to detect and characterize chaos in biological systems are of considerable interest, especially in medical science, where successful demonstrations may lead to new diagnostic tools and therapies. Unfortunately, conventional methods for identifying chaos often yield equivocal results when applied to biological data, which are usually heavily contaminated with noise. For such applications, a new technique based on the detection of unstable periodic orbits holds promise. Infinite sets of unstable periodic orbits underlie chaos in dissipative systems; accordingly, the new method searches a time series only for rare events characteristic of these unstable orbits, rather than analysing the structure of the series as a whole. Here we demonstrate the efficacy of the method when applied to the dynamics of the crayfish caudal photoreceptor (subject to stimuli representative of the animal's natural habitat). Our findings confirm the existence of low-dimensional dynamics in the system, and strongly suggest the existence of deterministic chaos. More importantly, these results demonstrate the power of methods based on the detection of unstable periodic orbits for identifying low-dimensional dynamics--and, in particular, chaos--in biological systems.

Action Potentials↗
PubMed1996

Dibutyl phthalate purged autologous bone marrow transplant in the treatment of leukemia.

It has been proved that di-N-butyl phthalate (DBP) is singular in killing leukemic cells selectively or accelerating the deterioration of residual leukemic cells in long-term marrow culture in vitro. Based on this principle, the DBP-purged autologous bone marrow transplant has been applied to the treatment of a group of 14 patients suffering from acute nonlymphocytic leukemia. After 5-10 days of in vitro co-culture of marrow cells with DBP at a concentration of 50 micrograms/ml, the recovery of total nucleated cells and the amount of CFU-GM were 67.5% and 68.1%, respectively. In all patients, the reconstitution of hematopoiesis was observed after pre-conditioning and transfusion of purged marrow cells. Among these, two patients had a relapse, two patients died from complications of transplant, one patient died from non-leukemic disease, and the others are all alive and free of disease; the mean survival time as calculated recently was 15 months. These preliminary clinical data support that marrow culture in the presence of DBP is a safe and effective measure for treating leukemia in purged autologous bone marrow transplant.

Adolescent↗
PubMed1996

Multiple mechanisms underlying the orientation selectivity of visual cortical neurones.

For over three decades, the mechanism of orientation selectivity of visual cortical neurones has been hotly debated. While intracortical inhibition has been implicated as playing a vital role, it has been difficult to observe it clearly. On the basis of recent findings, we propose a model in which the visual cortex brings together a number of different mechanisms for generating orientation-selective responses. Orientation biases in the thalamo-cortical input fibres provide an initial weak selectivity either directly in the excitatory input or by acting via cortical interneurones. This weak selectivity of postsynaptic potentials is then amplified by voltage-sensitive conductances of the cell membrane and excitatory and inhibitory intracortical circuitry, resulting in the sharp tuning seen in the spike discharges of visual cortical cells.

Models, Biological↗
PubMed1996

Detecting low dimensional dynamics in biological experiments.

We discuss the well-known problems associated with efforts to detect and characterize chaos and other low dimensional dynamics in biological settings. We propose a new method which shows promise for addressing these problems, and we demonstrate its effectiveness in an experiment with the crayfish sensory system. Recordings of action potentials in this system are the data. We begin with a pair of assumptions; that the times of firings of neural action potentials are largely determined by high dimensional random processes or "noise"; and that most biological files are non stationary, so that only relatively short files can be obtained under approximately constant conditions. The method is thus statistical in nature. It is designed to recognize individual "events" in the form of particular sequences of time intervals between action potentials which are the signatures of certain well defined dynamical behaviors. We show that chaos can be distinguished from limit cycles, even when the dynamics is heavily contaminated with noise. Extracellular recordings from the crayfish caudal photoreceptor, obtained while hydrodynamically stimulating the array of hair receptors on the tailfan, are used to illustrate the method.

Action Potentials↗