[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.

[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.

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.

[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.

[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.

[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.

[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.

[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.

A study on detection of serum fasting total bile acid and choloyglycin in neonate for cholestasis

Enzyme-linked colorimetric analysis and radioimmunoassay were employed to detect serum fasting total bile acids (FBA) and choloyglycin (CG) respectively in cases of 32 neonatal hepatitis, 33 cases of neonatal unconjugated hyperbilirubinemia and 34 cases of breast milk jaundice (BMJ). FBA and CG in acute period of neonatal hepatitis were obviously elevated and decreased gradually in convalescent and recovered period. The difference was significant for each stage as compared with controls. Acute FBA correlated strongly with the course. Both neonatal unconjugated hyperbilirubinemia and BMJ differed significantly from controls in FBA and CG. The results suggested that serum FBA and CG were helpful in judging the course and state of neonatal hepatitis, and cholestasis might existed in neonatal unconjugated hyperbilirubinemia.

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.

Light enhances hydrodynamic signaling in the multimodal caudal photoreceptor interneurons of the crayfish

1. The caudal photoreceptor (CPR) interneurons in the sixth abdominal ganglion of the crayfish are complex, multi-modal interneurons. These cells respond directly to light with tonic spike discharges, and they integrate synaptic input from an array of fili-form mechanoreceptors on the tailfan. They also provide input to rostral command centers, inducing backward walking at high firing frequencies, and thus directly influence behavior. 2. We recorded CPR activity in response to weak hydrodynamic stimulation of the tailfan mechanoreceptors while under varying intensities of light shined on the sixth ganglion. Spike trains were characterized according to the mean discharge rate (MDR) and the power spectrum from which the signal-to-noise ratio (SNR) was calculated. 3. Illumination of the CPR enhances the efficiency of transmitting mechanosensory signals. It does so by increasing the SNR of mechanosensory input received from tailfan receptors. A sevenfold, nonlinear increase in the SNRs was observed with increasing light intensity, an effect especially pronounced for weak hydrodynamic stimuli. In comparison with the dark, illumination of the ganglion lowered the hydrodynamic threshold and heightened the response to suprathreshold stimulation. Unlike the SNR, the MDR is little affected by mechanosensory input. 4. These results are compared with simulated electronic activity from an analogue threshold model and are discussed with respect to the mechanism of stochastic resonance.

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.

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.

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.

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.

Comparison of purity and enrichment of CD34+ cells from bone marrow, umbilical cord and peripheral blood (primed for apheresis) using five separation systems

Interest in the isolation and characterization of primitive hemopoietic cells in both the clinical and research fields has rapidly increased. In parallel, different purification systems have been developed to isolate these cells. We have compared five different methods for separation of CD34+ cells from human umbilical cord blood, normal bone marrow and apheresis harvests and analyzed purity, recovery, yield and enrichment of colony forming cells (CFC) for each individual system. Our results indicate that the most reliable methods of purification for all samples were fluorescence activated cell sorting (FACS) and magnetic activated cell sorting (MACS) which consistently yielded high purities (> 70%) and enrichment of CFC. In this respect the enrichment of CFC from the MACS was superior to all the other systems including FACS. Similar results (> 70%) for purity were obtained using avidin affinity columns and a biotinylated antibody but neither yield nor CFC enrichment approached the values achieved with MACS. On average CFC enrichment using these affinity columns was greater than that observed for FACS while the purity was comparable. Both CELLector flasks and immunomagnetic beads coated with CD34 antibodies were less effective in our hands in separating purified populations of progenitor cells. Both purity and CFC enrichment of CD34+ cells using these methods were at least 50% lower than obtained with either FACS, MACS or affinity columns.

Bone marrow purging with dibutyl phthalate--experimental basis and a preliminary clinical application

It has been found recently that di-n-butyl phthalate (DBP) possesses a new pharmacological activity in the selective elimination of tumor cells from marrow. In combination with long-term liquid culture of marrow cells in vitro, DBP purged autologous bone marrow transplantation has first been applied to a case of acute myeloid leukemia at the first complete remission with successful reconstitution of hematopoiesis.

Dynamics of the orientation tuning of postsynaptic potentials in the cat visual cortex

We evaluated the dynamic aspects of the orientation tuning of the input to cat visual cortical neurons by analyzing the postsynaptic potentials (PSPs) evoked by flashing bars of light. The PSPs were recorded using in vivo whole-cell technique, and we analyzed the orientation tuning during subsequent temporal windows after stimulus onset and offset. Our results show that the amplitudes of the postsynaptic potential are reliably tuned to orientation and matching that of the spike responses only during certain temporal windows. During the first 100 ms after stimulus presentation, orientation tuning of the membrane potential underwent regular changes. Within particular intervals, orientation tuning of the input was much sharper than that estimated according to the whole response. In most cells, optimal orientation was usually stable over the whole period. In several cells which had a second hump of EPSPs in the response, this second hump was tuned to the same orientation as the first one, but always showed sharper tuning. Estimation of the integration time revealed sufficient delay between the appearance of EPSPs and spikes, to let inhibition influence spike generation. These results show that orientation selectivity of the input to cortical cells is a dynamic function, and also indicate the possibility of temporal coding in the visual system.

[Mesenteric vein thrombosis after devasculation for portal hypertension]

Six patients with mesenteric vein thrombosis (MVT) after devasculation for portal hypertension were treated by intestinal resection. Two patients had recurrence of thrombosis after the initial operations. Among 6 patients 2 survived and 4 (66.7%) died. MVT is an underappreciated, patentially lethal complication after revasculation. Three pathogenic factors after the operation may lead to thrombus formation of the portal vein, portal congestion, hypercoaguble state, and extensive ligation of portal branches. The complication commonly occurs in the recent period after devasculation. It is a characteristic manifestation of MVT that abdominal pain is out of proportion to physical findings. The most effective method is resection of infarcted bowel with sufficient length of normal bowel and its mesentery. In order to avoid a recurrence of thrombosis, postoperative anticoagulation treatment should be given.

Receptive field analysis and orientation selectivity of postsynaptic potentials of simple cells in cat visual cortex

Postsynaptic potentials (PSPs) were recorded from cat striate cortical cells by the whole-cell in vivo recording technique using patch-clamp electrodes. EPSPs and IPSPs evoked by flashing bars on the receptive field at different positions and orientations revealed the spatial structure of the excitatory and inhibitory inputs. The elongation of the excitatory input field (length:width ratio) was found to be minimal (mean ratio of 1.7) and much lower than those reported for spike discharges. Two-dimensional receptive field response profiles of early PSPs were recorded by flashing a small spot of light over a square matrix covering the receptive field. These recordings also showed only mild degrees of elongations of the receptive field. Such elongations could be the result of either an excitatory input from the geniculate that is already biased for orientation or an excitatory convergence from a limited number of LGN fields arranged in a row. In most first-order cells, we found that inhibition was contributing significantly to orientation selectivity. Often prominent IPSPs could be evoked by stimuli of nonoptimum orientations. Presence of inhibition could also be inferred by the way that EPSPs were sharply cut off by inhibition. When the amplitude of an EPSP was measured at different latencies after its onset, the EPSP was found to be very broadly tuned to orientation at the beginning, but showing increasing orientation selectivity with time. It is proposed that this progressive development of orientation selectivity is due to (1) inhibitory inputs arriving after the first wave of excitation, (2) intracortical excitatory inputs from other cells tuned to similar orientations, and (3) voltage-sensitive mechanisms such as NMDA channels.