Electrokinetic behavior of two touching inhomogeneous biological cells and colloidal particles: effects of multipolar interactions

We present a theory to investigate electrokinetic behavior, namely, electrorotation and dielectrophoresis under alternating current (ac) applied fields for a pair of touching inhomogeneous colloidal particles and biological cells. These inhomogeneous particles are treated as graded ones with physically motivated model dielectric and conductivity profiles. The mutual polarization interaction between the particles yields a change in their respective dipole moments, and hence in the ac electrokinetic spectra. The multipolar interactions between polarized particles are accurately captured by the multiple images method. In the point-dipole limit, our theory reproduces the known results. We find that the multipolar interactions as well as the spatial fluctuations inside the particles can affect the ac electrokinetic spectra significantly.

Electroacupuncture for Tension-type Headache on Distal Acupoints Only: A Randomized, Controlled, Crossover Trial

OBJECTIVE

To investigate the efficacy of electroacupuncture, applied to distal acupoints only, for tension-type headache.

BACKGROUND

Electroacupuncture is commonly used for tension-type headache, but when applied to distal acupoints only, evidence of its efficacy is lacking.

DESIGN

A randomized, single-blinded, sham-controlled, crossover clinical trial. Methods.-The trial had 5 stages: baseline (2 weeks), phases I and II (each 4 weeks), washout period (2 weeks), and follow-up (3 months after phase II). Forty patients were randomly assigned to either group A or group B. Group A received real electroacupuncture during phase I, then sham electroacupuncture in phase II. Group B received the treatments in reverse order. Outcome measures were headache frequency and duration, pain intensity using a visual analog scale, mechanical pain threshold, headache disability, and sickness impact. Data were analyzed by univariate 2-way analysis of variance.

RESULTS

Thirty-seven patients completed the trial. There were no significant differences between the 2 groups at baseline. At the end of phase I, group A, but not group B, demonstrated significant improvement in mean (standard error of the mean [SEM]) headache frequency (3.0 per month [0.3] versus 12.0 per month [1.7]), duration (13.3 hours [3.5] versus 32.0 hours [6.2]), pain intensity (32.8 mm [4.1] versus 47.5 mm [2.7]), pain threshold (right side, 2.9 kg/second [0.1] versus 0.9 kg/second [0.1]; left side, 2.4 kg/second [0.1] versus 1.1 kg/second [0.1]), headache disability score (6.0 [1.0] versus 16.3 [1.6]), and sickness impact score (288.7 [48.0] versus 687.1 [77.2]). For each parameter, significant differences also were demonstrated for both groups between baseline and phase II, and baseline and follow-up. There were no significant differences between the groups at the end of follow-up (P >.05).

CONCLUSION

Electroacupuncture to distal points alone is effective for short-term symptomatic relief of tension-type headache.

Expression of adherent molecule and cyclin by ligustrazine in bone marrow of mice with immune-induced aplastic anemia

Mice with immune-induced aplastic anemia (AA) were given 5 mg ligustrazine intraperitoneally twice a day. On the 14th day, the expression of CD49d, CD49c, cyclinD2 in bone marrow mononuclear cells (MNC) was examined by flow cytometry, and VCAM-1 on stromal cells was immunohistochemically measured by Strept Avidin-Biotin Complex (SABC). The expression of CD49d, CD49c, VCAM-1 and cyclinD2 in ligustrazine-treated group was significantly higher than that in AA group (P < 0.01), but the ratio of G0 + G1 phase cells was significantly lower than that in AA group (P < 0.01). The results showed that ligustrazine could improve the expression of adherent molecule and cyclin D2 in the bone marrow of mice with immune-induced aplastic anemia, thereby promoting the growth of hematopoietic cells.

Dielectrophoresis of charged colloidal suspensions

We present a theoretical study of dielectrophoretic (DEP) crossover spectrum of two polarizable particles under the action of a nonuniform ac electric field. For two approaching particles, the mutual polarization interaction yields a change in their respective dipole moments, and hence, in the DEP crossover spectrum. The induced polarization effects are captured by the multiple image method. Using spectral representation theory, an analytic expression for the DEP force is derived. We find that the mutual polarization effects can change the crossover frequency at which the DEP force changes sign. The results are found to be in agreement with recent experimental observation and as they go beyond the standard theory, they help to clarify the important question of the underlying polarization mechanisms.

Tetrasomy 12p--unusual presentation in CVS

CVS direct preparations usually achieve limited resolution and are better at detecting numerical rather than structural abnormalities. A CVS direct preparation analyzed using G-banding revealed a 47,XY,+G karyotype in 5 of 11 cells and was reported as mosaic for trisomy 21. Subsequent analysis of the CVS culture found only normal male cells. Amniocentesis revealed both normal male cells and cells with an extra F-group chromosome. Fluorescence in situ hybridization (FISH) identified this chromosome to be an isochromosome from the short arm of chromosome 12 [i(12)(p10)]. The amniocyte karyotype was reported as 47,XY,+i(12)(p10)[12]/46,XY[8].ish i(12)(p10)(wcp12+), which is associated with Pallister-Killian syndrome. Reexamination of the CVS direct preparation by FISH with a chromosome 12 centromere probe confirmed the karyotype of this tissue to be 47,XY,+mar[5]/46,XY[6].nuc ish 12cen(D12Z3 x 3)/12cen(D12Z3 x 2). Thus, multiple studies, including amniocentesis and fluorescence in situ hybridization, may be required to fully and accurately evaluate abnormalities detected by CVS. This case also indicates that mosaicism for supernumerary isochromosomes may have a complex origin.

Ultrastructural observation on the transformation of the spermatozoon in spermatogenesis of Taeniid cestodes

AIM

To study the transformation of taeniid spermatozoon during spermatogenesis on the ultrastructure level.

METHODS

Transmission electronmicroscopy.

RESULTS

This paper was the second part of the ultrastructural observations on the spermatogenesis in Taeniid cestodes: The transformation of the spermatozoon. The 64-spermatid-plasmodium was generated from the secondary meiosis of the 32 rose-like secondary spermatocytes. The transformation of the spermatozoon was a complex process. Firstly, both the cytoplasm and nucleus of the spermatid elongated while the cytoplasm increased and connected to the cytoplasmic mass (cytophore). Secondly, the chromatins of nucleus polymerized to a thread-bundle-like structure. Finally, it detached from the cytoplasm mass and became a mature spermatozoon. The mature spermatozoon was a thread-like structure, about 16.2-18.6 microns in length and 0.35-0.45 micron in diameter. There were two structurally distinct parts: the part with the nucleus was the head and the part without the nucleus was the tail. The head measured about 5-6 microns in length, 1/3 of the total body length and contained an elongated nucleus which twined around the axoneme without mitochondria. The tail was about 11.2-16.6 microns in length. Throughout the core of the tail was an axoneme with typical "9 + 1" structure. The anterior of the tail, just behind the head, were some mitochondria, about 1.6-1.7 microns in total length which twined around the axoneme. The posterior of the tail contained only an axoneme. In cross-section of the spermatozoon, about 46 microtubules were beneath the plasma membrane.

CONCLUSION

The transformation of the spermatozoon is a very complex process.

Binding specificity of Escherichia coli trigger factor

The ribosome-associated chaperone trigger factor (TF) assists the folding of newly synthesized cytosolic proteins in Escherichia coli. Here, we determined the substrate specificity of TF by examining its binding to 2842 membrane-coupled 13meric peptides. The binding motif of TF was identified as a stretch of eight amino acids, enriched in basic and aromatic residues and with a positive net charge. Fluorescence spectroscopy verified that TF exhibited a comparable substrate specificity for peptides in solution. The affinity to peptides in solution was low, indicating that TF requires ribosome association to create high local concentrations of nascent polypeptide substrates for productive interaction in vivo. Binding to membrane-coupled peptides occurred through the central peptidyl-prolyl-cis/trans isomerase (PPIase) domain of TF, however, independently of prolyl residues. Crosslinking experiments showed that a TF fragment containing the PPIase domain linked to the ribosome via the N-terminal domain is sufficient for interaction with nascent polypeptide substrates. Homology modeling of the PPIase domain revealed a conserved FKBP(FK506-binding protein)-like binding pocket composed of exposed aromatic residues embedded in a groove with negative surface charge. The features of this groove complement well the determined substrate specificity of TF. Moreover, a mutation (E178V) in this putative substrate binding groove known to enhance PPIase activity also enhanced TF's association with a prolyl-free model peptide in solution and with nascent polypeptides. This result suggests that both prolyl-independent binding of peptide substrates and peptidyl-prolyl isomerization involve the same binding site.

Effects of signal transduction inhibitor 571 in acute myelogenous leukemia cells

STI571 is a 2-phenylalaminopyrimidine derivative that inhibits c-abl, Bcr-Abl, and platelet-derived growth factor receptor tyrosine kinases. Recently, inhibition of stem cell factor (SCF)-induced c-kit phosphorylation and cell proliferation by STI571 was reported in the human myeloid cell line MO7e. Because approximately 70% of acute myelogenous leukemia (AML) cases are c-kit positive, we evaluated in vitro effects of STI571 on c-kit-positive cell lines and primary AML blast cells. At concentrations >5 microM, the drug marginally inhibited SCF-independent proliferation of cell lines and most of AML blasts. Treatment of AML cells with cytarabine and STI571 showed synergistic effect at low concentrations. Western blotting analysis documented a distinct band of M(r) 145,000 specific for c-kit in cell lines and in AML samples. There was no correlation between the level of the c-kit expression evaluated by Western blotting and percentage of c-kit-positive blasts as measured by flow cytometry. Neither in cell lines nor in primary AML cells, c-kit autophosphorylation was detectable under standard growth conditions. SCF-induced phosphorylation of c-kit in MO7e cells was inhibited by STI571. In a c-kit-positive AML-4 cell line, as well as in AML samples, c-kit phosphorylation was not induced by SCF exposure, suggesting that in these cases, the receptor could not be functionally activated. In conclusion, with the exception of MO7e, SCF did not induce phosphorylation of c-kit, and cell proliferation was not modulated in the presence of STI571. We did not detect any SCF-independent c-kit phosphorylation in our experimental systems. Consequently, STI571 exerted only a limited inhibitory effect on the cell growth.

TCDD-inducible poly(ADP-ribose) polymerase: a novel response to 2,3,7,8-tetrachlorodibenzo-p-dioxin

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) causes pleotropic effects in mammalian species through modulating gene expression. Here we analyzed TCDD-induced mRNA expression by using mRNA differential display and report the cloning of a novel TCDD-inducible poly(ADP-ribose) polymerase (TiPARP). TiPARP cDNA contains an open reading frame of 657 amino acid residues; the carboxyl half shares sequence similarity to the catalytic domain of PARP, a family of enzymes that catalyze poly ADP-ribosylation of proteins. Expression of the cDNA by in vitro transcription/translation reveals a protein of approximately 75 kDa. The expressed TiPARP exhibits PARP activity toward histone. TiPARP is highly homologous to RM1 which is induced during long-term potentiation, a memory formation process, and to TIL which is induced in T cells infiltrating progressing tumors. TiPARP mRNA is expressed in a broad range of mouse tissues. Together, these data demonstrate that TiPARP is a novel target of TCDD that may contribute to multiple responses to TCDD by modulating protein function through poly ADP-ribosylation.

Research and prediction of coordination reactions between CPA-mA and some metal ions using artificial neural networks

The complex relationship between maximum absorption wavelength (lambda(max)), molar absorptivity (epsilon) of the coordination compounds formed from m-acetyl-chlorophosphonazo (CPA-mA) and the metal ions, the acidity of coordination reaction, some properties of metal ions and the properties of more than 20 coordination compounds were studied using artificial neural networks with extended delta-bar-delta EDBD back learning algorithms in this paper. Six parameters: the pH of coordination reactions, metal ion radius (R), relative atomic weight (Wt), ionic electronic energy (E), metal ion standard Gibbs' free energy (deltaG0) and hard-soft acid-base dual scale (f) were used as input parameters, to predict the lambda(max) and epsilon of the coordination compounds. The structures of networks and the learning times were optimized. The best networks structure is 6-7-2. The optimum number of learning times is about 160,196. It is shown that the maximum relative error is no more than 6% in the testing set. The trained networks are used to simulate the complicated relations between the metal ion properties, coordination reaction conditions and the properties of coordination compounds. This optimized networks have been used for the prediction of the lembda(max) and epsilon of coordination compounds formed from Tb3+, Ho3+ with CPA-mA separately and with satisfactory results.

[Cloning, sequencing of beagle E-selectin genomic DNA and comparison of it with other species]

OBJECTIVE

Selectins are a group of members of Cell Adhesion Molecular family; they play very important roles in inflammation and neovascularization. The aim of this study is to clone, sequence Beagle E-selectin genomic DNA and make homogeneous analyses to compare it with those of other animals.

METHODS

Twelve fragments of genomic DNA of Beagle E-selectin were obtained by PCR, and the 12 fragments were cloned in T-vector. At last, the genomic DNA sequences of Beagle E-selectin were obtained through gene sequencing, assembling and base calling, and the gene structure was analyzed.

RESULTS

The sequence of Beagle E-selectin genomic DNA that contained the whole open reading box was acgured. The results of homogeneous analyses showed a great extent of E-selectin gene homology among human, porcine and dog.

CONCLUSION

The demonstration of a large extent of the gene homology has substantiated in this connection the important roles of E-selectin in transplantation immunity and neoplasm development.

A method of simulating dynamic multileaf collimators using Monte Carlo techniques for intensity-modulated radiation therapy

A method of modelling the dynamic motion of multileaf collimators (MLCs) for intensity-modulated radiation therapy (IMRT) was developed and implemented into the Monte Carlo simulation. The simulation of the dynamic MLCs (DMLCs) was based on randomizing leaf positions during a simulation so that the number of particle histories being simulated for each possible leaf position was proportional to the monitor units delivered to that position. This approach was incorporated into an EGS4 Monte Carlo program, and was evaluated in simulating the DMLCs for Varian accelerators (Varian Medical Systems, Palo Alto. CA, USA). The MU index of each segment, which was specified in the DMLC-control data, was used to compute the cumulative probability distribution function (CPDF) for the leaf positions. This CPDF was then used to sample the leaf positions during a real-time simulation, which allowed for either the step-shoot or sweeping-leaf motion in the beam delivery. Dose intensity maps for IMRT fields were computed using the above Monte Carlo method, with its accuracy verified by film measurements. The DMLC simulation improved the operational efficiency by eliminating the need to simulate multiple segments individually. More importantly, the dynamic motion of the leaves could be simulated more faithfully by using the above leaf-position sampling technique in the Monte Carlo simulation.

[The follow-up of 12 pregnant women with anticoagulation therapy after mechanical heart valve replacement]

OBJECTIVE

The article discusses the effect of warfarin on pregnant women and their fetus, and the methods of anticoagulation therapy during pregnancy.

METHODS

The pregnancy, delivery, and anticoagulation therapy of 12 pregnant women with mechanical heart valve replacement were followed-up.

RESULTS

All the patients received oral anticoagulant therapy during pregnancy. The mean dose of imported warfarin was (2.71 +/- 1.24) mg/d (4 cases); domestic warfarin, (3.14 +/- 0.28) mg/d (6 cases); domestic acenocumarol tablet (3.14 +/- 1.08) mg/d (2 cases). No thromboembolism and major hemorrhage occurred. A total of 8 person/times had minor bleeding. Ten patients had term delivery, 2 had premature birth, No abnormal fetus was observed. Only 1 newborn had low birth weight (2,100 g).

CONCLUSION

The anticoagulation therapy with low dosage of warfarin (< 5 mg/d) is safe and convenient for the mothers during pregnancy following mechanical heart valve replacement and has low fetus abnormal rate.

Partial purification and biochemical characterization of a heteromeric protein phosphatase 2A holoenzyme from maize (Zea mays L.) leaves that dephosphorylates C4 phosophoenolpyruvate carboxylase

The activity and allosteric properties of plant phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) are controlled posttranslationally by specific reversible phosphorylation of a strictly conserved serine residue near the N-terminus. This up/down-regulation of PEPC is catalyzed by a dedicated and highly regulated serine/threonine (Ser/Thr) kinase (PEPC-kinase) and an opposing type-2A Ser/Thr phosphatase (PP2A). In marked contrast to PEPC-kinase, the PP2A holoenzyme from photosynthetic tissue has been virtually unstudied to date. In the present investigation, we have partially purified and characterized the native form of this PP2A from illuminated leaves of maize (Zea mays L.), a C4 plant, using maize [32P]PEPC as substrate. Various conventional chromatographic matrices, together with thiophosphorylated C4 PEPC-peptide and microcystin-LR affinity-supports, were exploited for the enrichment of this PP2A from soluble leaf extracts. Biochemical and immunological results indicate that the C4-leaf holoenzyme is analogous to other eukaryotic PP2As in being a approximately 170-kDa heteromer comprised of a core PP2Ac-A heterodimer (approximately 38- and approximately 65-kDa subunits, respectively) complexed with a putative, approximately 74-kDa B-type regulatory/targeting subunit. This heterotrimer lacks any strict substrate specificity in that it dephosphorylates C4 PEPC, mammalian phosphorylase a, and casein in vitro. This activity is independent of free Me2+, insensitive to levamisole and the Inhibitor-2 protein that targets PP1, activated by several polycations such as protamine and poly-L-lysine, and highly sensitive to inhibition by microcystin-LR and okadaic acid (IC50 approximately 30 pM), all of which are diagnostic features of yeast and mammalian PP2As. In addition, this C4-leaf PP2A holoenzyme (i) is inhibited in vitro by physiological concentrations of certain C4 PEPC-related metabolites (L-malate, PEP, glucose 6-phosphate, but not the activator glycine) when either 32P-labeled maize PEPC or rabbit muscle phosphorylase a is used as substrate, suggesting a direct effect on this Ser/Thr phosphatase; and (ii) displays, at best, only modest light/dark effects in vivo on its apparent molecular mass, component core subunits and activity against C4 PEPC, in marked contrast to the opposing activity of PEPC-kinase in C4 and Crassulacean acid metabolism leaves. This report represents one of the few studies of a heteromeric PP2A holoenzyme from photosynthetic tissue that dephosphorylates a known target enzyme in plants, such as PEPC, sucrose-phosphate synthase or nitrate reductase.

[Difference of T helper cell subsets and B7 co-stimulatory molecule expressions by alveolar macrophages in bronchoalveolar lavage fluid between patients with allergic asthma and chronic obstructive pulmonary disease]

OBJECTIVE

To elucidate the differences of T helper cell subsets and expressions of B7 co-stimulatory molecules by alveolar macrophages (AM) between patients with allergic asthma and chronic obstructive pulmonary disease (COPD).

METHODS

Bronchoalveolar lavage fluid (BALF) cells were obtained from 16 normal control volunteers, 16 patients with allergic asthma and 16 patients with COPD. IFN-gamma and IL-4 levels in the supernatant of BLAF lymphocytes cultured with PHA were determined using sandwich ELISA and the CD80 (B7-1) and CD86 (B7-2) expressed by AM stimulated with LPS were determined using avdin-biotin complex technique.

RESULTS

In COPD group, IFN-gamma level was significantly higher than those of the control group and asthma group (P < 0.01). IFN-gamma in asthma group was lower than that of the control group (P < 0.01). IL-4 level and the ratio of AM expressing CD86 in asthma group were higher than those of the control group and COPD group (P < 0.01). The IL-4 level and ratio of AM expressing CD86 showed no significantly difference between COPD and control group (P > 0.05). The IL-4 levels in 3 groups were significantly positively correlated with the ratio of AM expressing CD86 (r = 0.61, P < 0.05). No difference of the ratio of AM expressing CD80 was found among three groups (P < 0.05).

CONCLUSION

Asthma is characterized by a predominance of Th2-type response in BALF T cells, and COPD of Th1-type response in BALF T cells. The increased expression of co-stimulation of CD86 in AM is probably involved in Th2-type response in the airway inflammation in allergic asthmatics.