Caveolin-1 null mice are viable but show evidence of hyperproliferative and vascular abnormalities

Caveolin-1 is the principal structural protein of caveolae membranes in fibroblasts and endothelia. Recently, we have shown that the human CAV-1 gene is localized to a suspected tumor suppressor locus, and mutations in Cav-1 have been implicated in human cancer. Here, we created a caveolin-1 null (CAV-1 -/-) mouse model, using standard homologous recombination techniques, to assess the role of caveolin-1 in caveolae biogenesis, endocytosis, cell proliferation, and endothelial nitric-oxide synthase (eNOS) signaling. Surprisingly, Cav-1 null mice are viable. We show that these mice lack caveolin-1 protein expression and plasmalemmal caveolae. In addition, analysis of cultured fibroblasts from Cav-1 null embryos reveals the following: (i) a loss of caveolin-2 protein expression; (ii) defects in the endocytosis of a known caveolar ligand, i.e. fluorescein isothiocyanate-albumin; and (iii) a hyperproliferative phenotype. Importantly, these phenotypic changes are reversed by recombinant expression of the caveolin-1 cDNA. Furthermore, examination of the lung parenchyma (an endothelial-rich tissue) shows hypercellularity with thickened alveolar septa and an increase in the number of vascular endothelial growth factor receptor (Flk-1)-positive endothelial cells. As predicted, endothelial cells from Cav-1 null mice lack caveolae membranes. Finally, we examined eNOS signaling by measuring the physiological response of aortic rings to various stimuli. Our results indicate that eNOS activity is up-regulated in Cav-1 null animals, and this activity can be blunted by using a specific NOS inhibitor, nitro-l-arginine methyl ester. These findings are in accordance with previous in vitro studies showing that caveolin-1 is an endogenous inhibitor of eNOS. Thus, caveolin-1 expression is required to stabilize the caveolin-2 protein product, to mediate the caveolar endocytosis of specific ligands, to negatively regulate the proliferation of certain cell types, and to provide tonic inhibition of eNOS activity in endothelial cells.

Detecting the inseparability and distillability of continuous variable states in Fock space

The partial transposition (PT) operation is an efficient tool in detecting the inseparability of a mixed state. We give an explicit formula for the PT operation for the continuous variable states in Fock space. We then give the necessary and sufficient condition for the positivity of Gaussian operators. Based on this, a number of criteria on the inseparability and distillability for the multimode Gaussian states are naturally drawn. We finally give an explicit formula for the state in a subspace of a global Gaussian state. This formula, together with the known results for Gaussian states, gives the criteria for the inseparability and distillability in a subspace of the global Gaussian state.

Effects of Tween-80 on the biodistribution of several lipophilic technetium-99m complexes

The effects of Tween-80 on the biodistributions in mice of (99m)Tc-TBI, (99m)Tc-MIBI, (99m)TcN-TBI and (99m)TcN-MIBI were reported. The studies resulted that liver and blood uptakes of Tween-80 added (TA) complexes significantly lower than that of corresponding non-Tween-80 added (NTA) complexes. And the clearance rate from blood of TA complexes faster than that of NTA complexes. The optimal concentration of Tween-80 was about 1%. It can decrease the lipophilicity of (99m)Tc-complexes and improve the biological properties of the lipophilic (99m)Tc-complexes for myocardial imaging. It's worthy for further studies.

[Age dependency of heart rate variability, blood pressure variability and baroreflex sensitivity]

Objective. To compare the cardiovascular autonomic regulatory function between young and middle-aged male subjects and to assess the effects of aging. Method. Spectral indices of short term heart rate variability (HRV), systolic blood pressure variability (SBPV), and baroreflex sensitivity (BRS) in both supine and upright positions were obtained by AR spectral analysis and the sequential method, respectively, for both groups. Result. HRV spectral indices in both supine and upright, and the BRS in supine were lower in the middle-aged subjects than in the young subjects (P< 0.05, or P< 0.01). From supine to upright position total power (TP), low frequency power (LF) and high frequency power (HF) of HRV spectrum did not show any significant changes in the middle-aged subjects, whereas in the young subjects typical changes were observed. SBPV spectral indices did not show significant differences between the two groups in both supine and upright positions. However, SBPV HF was an exception, being lower in supine position in the middle-aged than in the young subjects (P< 0.01). For the young subjects, in supine position, BRS was correlated with LF and HF of HRV, respectively, and the spectral indices of HRV in supine position were also correlated with their corresponding indices in upright position. For the middle-aged subjects these correlations did not exist. Conclusion. In the middle-aged, both HRV and BRS are reduced and the correlations between HRV indices and BRS are not existent. However, the short-term blood pressure variability seems to be not age-dependent. It suggests that different regulatory mechanisms might account for it and that under resting condition the feed forward regulation from HRV to SBPV might be unimportant.

[Alteration of sensitivity of supraoptic nucleus neurons to cytokine in the hypothalamic slices from the rat after lipopolysaccharide injection]

Using the whole cell patch clamp technique, the effects of interleukin 1beta (IL-1beta) and IL-2 on the membrane potential and spontaneous discharges in the supraoptic nucleus (SON) neurons from the rat hypothalamic slices in vitro were examined to determine the changes in sensitivity of supraoptic nucleus neurons to cytokine. The results obtained are as follows. IL-1beta (100 U/ml) hyperpolarized the SON neurons from the control rats (n=15) and the rats 9 d after i.p. lipopolysaccharide (LPS) (n=20), and decreased the rate of their spontaneous discharges. When 100 U/ml IL-2 was perfused, most SON neurons (n=14) from the control rats were hyperpolarized and the spontaneous firing decreased, but the rest (n=3) remained unchanged. When IL-2 (100 U/ml) was applied, 19 neurons out of the 45 SON neurons from the rats 9 days after i.p. LPS were depolarized accompanied with an increase of the discharges, 16 did not show significant changes in both membrane potential and spontaneous discharges, the rest 10 were hyperpolarized and their discharges were suppressed. These results show that the sensitivity of part of SON neurons from the immuned rat to cytokine IL-2 was altered, suggesting that IL-2 may be involved in modulation of the activity of SON neurons and thus play a role in modulation of the immune response.

Age dependency and correlation of heart rate variability, blood pressure variability and baroreflex sensitivity

Simultaneous analysis of heart rate variability (HRV), blood pressure variability (BPV) and baroreflex sensitivity (BRS) with different types of measures may provide non-duplicative information about autonomic cardiovascular regulation. Therefore, a multiple signal analysis of cardiovascular time series will enhance the physiological understanding of neuro cardiovascular regulation with deconditioning in bedrest or related gravitational physiological studies. It has been shown that age is an important determinant of HRV and BRS in healthy subjects. Whereas in the case of BPV, the effect of aging seems to depend upon the activity status of the subjects. In view of the facts that most of the previous works were dealing with only the variability of one kind of cardiovascular parameters in one study with conventional time-domain and/or frequency-domain analysis, we therefore designed the present work to compare the HRV, BPV and BRS between young and middle-aged male healthy subjects in one study with the same subjects using various techniques, including the approximate entropy (ApEn) measurement, a statistic quantifying HRV "complexity" derived from non-linear dynamics.

[Study of the distribution feature of the endocrine cells of human islet and its relation to microvasculature]

Double immunohistochemical stain was used for the study of distribution feature of the endocrine cells of human islets and its relation to the microvasculature. The results were as follows (1) Sheath islet was found in human adult islets and the B cells situated the central part of the islets and arrounding it were the A and D cells which formed the sheath of the islets. (2) The identical distribution of the A and D cells was found. (3) Some islets were divided into several "subunite" by connective tissue in which the B cells and A(or D) cells situated the central and peripheral part respectively. (4) The A and D cells were near the microvasculature. These results will provide morphologic basis for the research of the functional relation among the endocrine cells.

Differential analysis of human leukocytes by dielectrophoretic field-flow-fractionation

The differential analysis of human leukocytes has many important biological and medical applications. In this work, dielectrophoretic field-flow-fractionation (DEP-FFF), a cell-separation technique that exploits the differences in the density and dielectric properties of cells, was used to separate the mixtures of the major human leukocyte subpopulations (T- and B-lymphocytes, monocytes, and granulocytes). The separation was conducted in a thin chamber equipped with an array of microfabricated interdigitated electrodes on the bottom surface, and the separation performance was characterized by on-line flow cytometry. To investigate optimal separation conditions for different leukocyte mixtures, elution fractograms at various DEP field frequencies were obtained for each leukocyte subtype. With appropriately chosen conditions, high separation performance was achieved in separating T- (or B-) lymphocytes from monocytes, T- (or B-) lymphocytes from granulocytes, and monocytes from granulocytes. DEP-FFF does not involve cell-labeling or cell-modification step, and provides a new approach to hematological analysis.

The removal of human breast cancer cells from hematopoietic CD34+ stem cells by dielectrophoretic field-flow-fractionation

Dielectrophoretic field-flow-fractionation (DEP-FFF) was used to purge human breast cancer MDA-435 cells from hematopoietic CD34+ stem cells. An array of interdigitated microelectrodes lining the bottom surface of a thin chamber was used to generate dielectrophoretic forces that levitated the cell mixture in a fluid flow profile. CD34+ stem cells were levitated higher, were carried faster by the fluid flow, and exited the separation chamber earlier than the cancer cells. Using on-line flow cytometry, efficient separation of the cell mixture was observed in less than 12 min, and CD34+ stem cell fractions with a purity >99.2% were obtained. The method of DEP-FFF is potentially applicable to many biomedical cell separation problems, including microfluidic-scale diagnosis and preparative-scale purification of cell subpopulations.

Neuronal localization of the Adenomatous polyposis coli tumor suppressor protein

Recent biochemical studies have demonstrated that the adenomatous polyposis coli gene, initially identified via its link to colon cancer, is expressed at high levels in the brain. Furthermore, the ability of this tumor suppressor protein to bind to Discs-Large and beta-catenin, proteins implicated in organizing synaptic structure, point to a role for APC in neuronal signalling. However, anatomical studies have provided conflicting results regarding its localization in brain. In situ hybridization studies predict neuronal expression of APC, while immunostaining studies performed with a panel of N-terminal antibodies detected staining of glial cells, especially oligodendrocytes. In this study, we have examined the basis for this discrepancy and provide evidence that the glial staining pattern detected in previous studies reflects cross-reactivity with an unrelated antigen rather than the localization of APC. Furthermore, we have performed immunohistochemical studies with a C-terminal APC antibody which reveal a neuronal pattern of staining closely matching that predicted by the in situ studies. For example, in the hippocampus APC immunostaining is detected in the pyramidal neurons and dentate granule cells, which fits well with the localization of APC mRNA. Examination of APC immunostaining in other regions revealed that particularly intense staining was displayed by large neurons, including layer V cortical pyramidal neurons, cerebellar Purkinje cells, and olfactory bulb mitral cells. Within labeled neurons, APC staining was apparent in the cytoplasm, as well as in dendritic and axonal processes. To help clarify the localization of APC in brain, we have conducted additional in situ hybridization and immunohistochemical studies. These results provide compelling evidence that APC is expressed predominantly in neurons rather than in glial cells as reported previously.

Dielectric properties of human leukocyte subpopulations determined by electrorotation as a cell separation criterion

The separation and purification of human blood cell subpopulations is an essential step in many biomedical applications. New dielectrophoretic fractionation methods have great potential for cell discrimination and manipulation, both for microscale diagnostic applications and for much larger scale clinical problems. To discover whether human leukocyte subpopulations might be separable by such methods, the dielectric characteristics of the four main leukocyte subpopulations, namely, B- and T-lymphocytes, monocytes, and granulocytes, were measured by electrorotation over the frequency range 1 kHz to 120 MHz. The subpopulations were derived from human peripheral blood by magnetically activated cell sorting (MACS) and sheep erythrocyte rosetting methods, and the quality of cell fractions was checked by flow cytometry. Mean specific membrane capacitance values were calculated from the electrorotation data as 10.5 (+/- 3.1), 12.6 (+/- 3.5), 15.3 (+/- 4.3), and 11.0 (+/- 3.2) mF/m2 for T- and B-lymphocytes, monocytes, and granulocytes, respectively, according to a single-shell dielectric model. In agreement with earlier findings, these values correlated with the richness of the surface morphologies of the different cell types, as revealed by scanning electron microscopy (SEM). The data reveal that dielectrophoretic cell sorters should have the ability to discriminate between, and to separate, leukocyte subpopulations under appropriate conditions.

Cell separation on microfabricated electrodes using dielectrophoretic/gravitational field-flow fractionation

Dielectrophoretic/gravitational field-flow fractionation (DEP/G-FFF) was used to separate cultured human breast cancer MDA-435 cells from normal blood cells mixed together in a sucrose/dextrose medium. An array of microfabricated, interdigitated electrodes of 50 microns widths and spacings, and lining the bottom surface of a thin chamber (0.42 mm H x 25 mm W x 300 mm L), was used to generate DEP forces that levitated the cells. A 10-microL cell mixture sample containing approximately 50,000 cells was introduced into the chamber, and cancerous and normal blood cells were levitated to different heights according to the balance of DEP and gravitational forces. The cells at different heights were transported at different velocities under the influence of a parabolic flow profile that was established in the chamber and were thereby separated. Separation performance depended on the frequency and voltage of the applied DEP field and the fluid-flow rate. It took as little as 5 min to achieve cell separation. An analysis of the DEP/G-FFF results revealed that the separation exploited the difference in dielectric and density properties between cell populations. The DEP/G-FFF technique is potentially applicable to many biological and biomedical problems, especially those related to microfluidic systems.

Membrane dielectric responses of human T-lymphocytes following mitogenic stimulation

Human peripheral blood T-lymphocytes, normally resting at the G0 phase, were stimulated with phytohemagglutinin (PHA) and interleukin-2 (IL-2) to induce the cell division cycle. The cells were examined at 24-h intervals for up to 96 h by flow cytometry to determine cell cycle distributions and by electrorotation to determine dielectric properties. The average membrane specific capacitance was found to vary from 12 (+/-1.5) mF/m2 prior to stimulation to 10 (+/-1.5) and 16 (+/-3.5) mF/m2 at 24 and 48 h after stimulation, respectively, and to remain unchanged up to 96 h after stimulation. Scanning electron microscopy studies of the cells revealed an increased complexity in cell membrane morphology following stimulation, suggesting that the observed change in the membrane capacitance was dominated by the alteration of cell surface structures. The average electrical conductivity of the cell interior decreased from approximately 1.1 S/m prior to stimulation to approximately 0.8 S/m at 24 h after stimulation and showed little change thereafter. The average dielectric permittivity of the cell interior remained almost unchanged throughout the course of the cell stimulation. The percentage of T-lymphocytes in the S and G2/M phases increased from approximately 4% prior to stimulation to approximately 11 and approximately 34% at 24 and 48 h after stimulation, respectively. The large change in membrane specific capacitance between the 24 and 48 h time period coincided with the large alteration in the cell cycle distribution where the S and G2/M populations increased by approximately 23%. These data, together with an analysis of the variation of the membrane capacitance during the cell cycle based on the cell cycle-dependent membrane lipid accumulation, show that there is a correlation between membrane capacitance and cell cycle phases that reflects alterations in the cell plasma membrane.

[Effects of mild and moderate hypoxia on event-related potentials and the comparison of different stimulus paradigms]

OBJECTIVE

To investigate the effects of mild and moderate hypoxia on event-related potentials (ERP), and to compare the sensitivity of different stimulus paradigms to hypoxia.

METHODS

Twelve subjects performed visual Oddball and memory set size (MSET) 1 and MSET 3 of Sternberg tasks on the ground and at the simulated altitudes of 2500 m and 4300 m by breathing low oxygen mixtures. P3 latency and amplitude of ERP, reaction time (RT) and response error rate (ER) were recorded.

RESULTS

During hypoxia at the altitude of 4300 m, P3 latency significantly delayed, and ER was high when the difficulty of task increased (Sternberg paradigm with MSET 3). In contrast, at the altitude of 2500 m no changes were observed. Sternberg paradigm with MSET 1, in comparison with others, could elicit clearer ERP waves, and P3 latency was slower during hypoxia.

CONCLUSION

Hypoxia at the altitude of 4300 m has strong influence on ERP. P3 latency can be used as a sensitive index in evaluating the decrement of brain cognitive capacity during hypoxia. ERP elicited by Sternberg paradigm with MSET 1 was more sensitive to hypoxia.

The effect of dietary sulfur-containing amino acids on calcium excretion

The relationships between dietary protein and sulfur amino acid (methionine and cystine or taurine) intakes and urinary calcium excretion were examined both in animals and in young men. Thirty-two adult Wistar rats were divided into 4 groups, i.e., basal diet (group I), supplemented with albumin (II), methionine and cystine (III), or taurine (IV). During the 5-week feeding period, food consumption was recorded and 48 h urine samples were collected 4 times for each rat. Urinary calcium, creatinine and sulfate were measured. The results showed that the calcium and sulfate excretion in rats in group II and III were significantly higher than rats in the basal diet group. In contrast, supplementing a basal diet with taurine did not increase sulfate excretion and failed to induce hypercalciuria. The same result was also observed in the study carried out in Chinese young men. An increase in protein intake from 67 g to 107 g caused an increase in urinary calcium and sulfate. Supplementation with methionine and cystine in an amount to simulate those in the high protein diet had a similar effect. Adding taurine to the diet had no effect on urinary calcium and sulfate excretion. About 60 percent of the supplemented taurine in the diet was detected in the urine.

Separation of polystyrene microbeads using dielectrophoretic/gravitational field-flow-fractionation

The characterization of a dielectrophoretic/gravitational field-flow-fractionation (DEP/G-FFF) system using model polystyrene (PS) microbeads is presented. Separations of PS beads of different surface functionalization (COOH and none) and different sizes (6, 10, and 15 microm in diameter) are demonstrated. To investigate the factors influencing separation performance, particle elution times were determined as a function of particle suspension conductivity, fluid flow rate, and applied field frequency and voltage. Experimental data were analyzed using a previously reported theoretical model and good agreement between theory and experiment was found. It was shown that separation of PS beads was based on the differences in their effective dielectric properties. Particles possessing different dielectric properties were positioned at different heights in a fluid-flow profile in a thin chamber by the balance of DEP and gravitational forces, transported at different velocities under the influence of the fluid flow, and thereby separated. To explore hydrodynamic (HD) lift effects, velocities of PS beads were determined as a function of fluid flow rate in the separation chamber when no DEP field was applied. In this case, particle equilibrium height positions were governed solely by the balance of HD lift and gravitational forces. It was concluded that under the experimental conditions reported here, the DEP force was the dominant factor in controlling particle equilibrium height and that HD lift force played little role in DEP/G-FFF operation. Finally, the influence of various experimental parameters on separation performance was discussed for the optimization of DEP/G-FFF.

Subtracted differential display: genes with amphetamine-altered expression patterns include calcineurin

Genes whose expression changes with administration of abused substances provide candidate biochemical mechanisms for drug-induced long-term brain changes. To identify such genes, and to avoid the false-positive results frequently obtained from differential display PCR, we applied a subtracted differential display (SDD) approach. We subtracted single-stranded cDNA prepared from drug-treated animals with excess mRNA from saline-treated animals, and visa versa, prior to differential display amplifications. Two of initial amphetamine-regulated cDNAs identified in this fashion encoded calcineurin A, a neuron-specific protein phosphatase catalytic subunit whose striatal expression was upregulated ca. 1.5-fold. SDD may enhance the utility of differential display approaches to identifying regulated genes in tissues in which mRNA complexities are high.

rGbeta1: a psychostimulant-regulated gene essential for establishing cocaine sensitization

Repeated doses of cocaine or amphetamine lead to long-lasting behavioral manifestations that include enhanced responses termed sensitization. Although biochemical mechanisms that underlie these manifestations currently remain largely unknown, new protein synthesis has been implicated in several of these neuroadaptive processes. To seek candidate biochemical mechanisms for these drug-induced neuroplastic behavioral responses, we have used an approach termed subtracted differential display (SDD) to identify genes whose expression is regulated by these psychostimulants. rGbeta1 is one of the SDD products that encodes a rat G-protein beta subunit. rGbeta1 expression is upregulated by cocaine or amphetamine treatments in neurons of the nucleus accumbens shell region, a major center for psychostimulant effects in locomotor control and behavioral reward. Antisense oligonucleotide treatments that attenuate rGbeta1 expression in regions including the nucleus accumbens abolish the development of behavioral sensitization when they are administrated during the repeated cocaine exposures that establish sensitization. These treatments fail to alter acute behavioral responses to cocaine, and they do not block the expression of cocaine sensitization when it is established before oligonucleotide administrations. Full, regulated rGbeta1 expression is a biochemical component essential to the establishment of a key consequence of repeated cocaine administrations, sensitization.

Introducing dielectrophoresis as a new force field for field-flow fractionation

We present the principle of cell characterization and separation by dielectrophoretic field-flow fractionation and show preliminary experimental results. The operational device takes the form of a thin chamber in which the bottom wall supports an array of microelectrodes. By applying appropriate AC voltage signals to these electrodes, dielectrophoretic forces are generated to levitate cells suspended in the chamber and to affect their equilibrium heights. A laminar flow profile is established in the chamber so that fluid flows faster with increasing distance from the chamber walls. A cell carried in the flow stream will attain an equilibrium height, and a corresponding velocity, based on the balance of dielectrophoretic, gravitational, and hydrodynamic lift forces it experiences. We describe a theoretical model for this system and show that the cell velocity is a function of the mean fluid velocity, the voltage and frequency of the signals applied to the electrodes, and, most significantly, the cell dielectric properties. The validity of the model is demonstrated with human leukemia (HL-60) cells subjected to a parallel electrode array, and application of the device to separating HL-60 cells from peripheral blood mononuclear cells is shown.

Dielectrophoretic manipulation of cells with spiral electrodes

Electrokinetic responses of human breast cancer MDA-MB-231 cells were studied in suspensions of conductivities 18, 56, and 160 mS/m on a microelectrode array consisting of four parallel spiral electrode elements energized with phase-quadrature signals of frequencies between 100 Hz and 100 MHz. At low frequencies cells were levitated and transported toward or away from the center of the spiral array, whereas at high frequencies cells were trapped at electrode edges. The frequencies of transition between these characteristic cell behaviors increased with increasing suspension conductivity. Levitation heights and radial velocities were determined simultaneously for individual cells as a function of the applied field magnitude and frequency. Results were compared with theoretical predictions from generalized dielectrophoresis theory applied in conjunction with cell dielectric parameters and simulated electric field distributions corrected for electrode polarization effects. It was shown that the conventional and traveling-wave dielectrophoretic force components dominated cell levitation and radial motion, respectively. Both theoretical predictions and experimental data showed that the cell radial velocity was very sensitive to the field frequency when the in-phase component of the field-induced polarization was close to zero. Applications of spiral electrode arrays, including the isolation of cells of clinical relevance, are discussed.

Role of transchelation in the uptake of 99mTc-MAb in liver and kidney

High radioactivity in liver and kidney after administration of 99mTc-labeled antibodies is a major detriment to the use of radiolabeled antibodies for diagnosis and therapy. In the present study, the uptake mechanism of radioactivity by liver and kidney involving 99mTc moiety was investigated. The data of in vitro and in vivo thiol transchelation studies, biodistribution alteration of 99mTc-MAb after specific modulation of endogenous thiol containing compounds, and the finding of 99mTc-labeled cysteine and GSH in bile, urine and kidney after administration of 99mTc-MAb demonstrated that transchelation by thiols (cysteine and GSH) played an important role in the localization of radiotracer from 99mTc MAb in normal tissues such as liver and kidney.

AP-1 DNA-binding activation by methamphetamine involves oxidative stress

Methamphetamine (METH) caused dose-dependent increases in AP-1 DNA-binding activity in both nontransgenic (Non-Tg) and CuZn-SOD transgenic (SOD-Tg) mice. However, the increases in SOD-Tg mice were less prominent than those observed in Non-Tg animals. The time-course of METH-induced AP-1 changes was similar in both strains of mice. AP-1 binding activity showed an initial increase at 1 h, peaked at 3 h, and then gradually declined. AP-1 binding activity was back to normal by the 72-h time point. Regional analyses of METH effects revealed increases in the caudate putamen and cerebellum, with the striatum showing relatively higher METH-induced AP-1 DNA-binding activation. These regional effects were also attenuated in the SOD-Tg mice. These data indicate that METH-induced stimulation of AP-1 DNA-binding depends on cellular redox status. These results are consistent with in vitro studies that have reported that several transcription factors are regulated through redox mechanisms.

Methamphetamine-induced neurotoxicity is associated with increased striatal AP-1 DNA-binding activity in mice

Multiple injections of methamphetamine (METH) produce long-lasting neurotoxic effects on the nigrostriatal dopamine (DA) system. The drug also causes increases in AP-1 DNA-binding activity in mice. In the present study, we tested the idea that toxic doses of METH might cause long-term increases in AP-1 DNA-binding. Mice were given 10 mg/kg of METH 2, 3 or 4 times at a 2 h interval in 1 day. Striatal DA levels were markedly decreased at 3 h and 24 h in all injection groups. After 1 week, striatal DA level recovered to near control in the METH x2 group, but were still significantly decreased in the METH x3 and x4 groups. Similar drug administration schedules caused increases in AP-1 DNA-binding activity at the 3 h time point in all groups. The AP-1-binding activity almost returned back to control level in the x2 and x3 injection groups at the 24 h and 1 week time point, but there were still increased levels of AP-1-binding activity in the METH x4 group. These findings raise the possibility that METH-induced neurotoxicity might involve prolonged activation of AP-1 transcription factor. This might be related to the report that c-fos or c-jun activation may be important in some models of neurodegeneration.

Interference in spin tunnelling of small magnetic particles

A previously studied (Enz and Schilling 1986 J. Phys. C: Solid State Phys. 19 1765) magnetocrystalline anisotropic Hamiltonian with a magnetic field applied along the medium axis is reconsidered, with emphasis on the topological phase effect. A quantum inteference effect is revealed.

[Effects of tangshenkang capsule on diabetic nephropathy]

To study the effects of Chinese herbal medicine Tangshenkang (TSK) capsule on diabetic nephropathy (DN), 57 patients with DN were randomly divided into two groups, the treated group and the control group, they were treated with TSK capsule and the conventional therapy respectively. There were serious disorders of metabolism in DN patients, that showed the TXB 2/6-keto-PGF1 alpha ratios and lipid peroxidase (LPO) levels were higher than that of healthy people. After 6 weeks treated with TSK capsule the albuminuria levels reduced obviously (decreased 51%), renal plasma flow (RPF) increased, glomerular filtration rate and the LPO levels decreased and a positive correlation was observed between albuminuria levels and TXB 2/6-keto-PGF1 alpha ratios while the clearance rate of creafinin didn't improve significantly. There were no significant difference in the above-mentioned parameters in the control group before and after treatment. These results suggested that TSK capsule possessed a significant effect in improving albuminuria and glomerular function. And the effect of TSK might be due to its adjusting TXB 2/6-keto-PGF1 alpha ratios and its lipid-peroxidation in DN patients.

Membrane changes associated with the temperature-sensitive P85gag-mos-dependent transformation of rat kidney cells as determined by dielectrophoresis and electrorotation

Conventional dielectrophoresis (cDEP) and electrorotation (ROT) measurements have been used to determine the dielectric properties of a clone of normal rat kidney cells, designated 6m2, that exhibits a transformed phenotype at 33 degrees C and a non-transformed phenotype at 39 degrees C. cDEP measurements of the crossover frequencies at which individual 6m2 cells experienced zero cDEP force performed as a function of the conductivity of the suspension medium revealed that, in response to a temperature shift from 33 degrees C to 39 degrees C for 24 h, the mean specific cell membrane capacitance and conductance fell significantly (P < 0.01) from 42.3 (+/-1.3) to 30.3 (+/-2.9) mF/m2 and 743 (+/-422) to 567 (+/-326) S/m2, respectively. ROT analyses demonstrated a similar reduction for the membrane capacitance from 37.2 (+/-7.3) to 27.4 (+/-6.1) mF/m2, and also showed that accompanying changes in the mean internal electrical conductivity and dielectric permittivity of the cells were insignificant. Scanning electron microscopy was used to examine the surface morphology of the cells and, in agreement with our previous reports for leukemia cells, the observed membrane capacitance values correlated closely with the morphological complexity of the cell membrane surface. The observed changes in the membrane dielectric properties are discussed in terms of their biological significance and their relationship to previously-detected changes in cell surface charge.

Electrorotational studies of the cytoplasmic dielectric properties of Friend murine erythroleukaemia cells

Electrorotation (ROT) spectra of Friend murine erythroleukaemia DS19 cells were measured in the frequency range 10 kHz-100 MHz as a function of suspension osmolality and cell differentiation treatment with hexamethylene bisacetamide (HMBA). A minimization program was employed to curve-fit the measured spectra using a single-shell dielectric model, allowing the derivation of cellular interior conductivity and permittivity (valid for the frequency range 10-100 MHz) and the cytoplasmic membrane capacitance (its dependence on the cell differentiation state and suspension osmolality having been reported earlier). Following HMBA treatment, DS19 cells exhibited a slight increment in average interior permittivity and a decrement in interior conductivity, although the changes were not statistically significant. For both untreated and HMBA treated samples, the average interior conductivity increased and permittivity decreased with increasing suspension osmolality. Of significance was that the average permittivity of cell interiors was larger than that of pure water. The electrorotation spectra of freshly prepared cell nuclei were measured, and the derived nuclear dielectric parameters were employed in numerical simulations to investigate the effects of nuclei on the ROT spectra of intact cells. Other cellular internal structures such as mitochondria were also analysed using theoretical simulations. It was concluded that the derived large permittivity values did not result from cell nuclei or mitochondria, and, instead, we suggest that they may arise from the combined effects of several cytoplasmic organelles.

Non-uniform spatial distributions of both the magnitude and phase of AC electric fields determine dielectrophoretic forces

It is well known that the conventional dielectrophoretic force acting on a polarised particle in a non-uniform AC electric field is proportional to the in-phase component of the induced dipole moment and the non-uniformity of the field strength. In contrast, the travelling-wave-dielectrophoretic force that acts on a particle subjected to a travelling electric field is proportional to the out-of-phase component of the induced dipole moment. We derive a theory that unifies the description and interpretation of conventional dielectrophoretic and travelling-wave-dielectrophoretic forces. We show that a particle in a non-uniform AC electric field experiences a dielectrophoretic force due to spatial non-uniformities of the magnitude and the phase of the field interacting, respectively, with the in-phase and out-of-phase components of the induced dipole moment. The theory is used to explain the translational effects observed for particles in the presence of standing, travelling and rotating fields in several experimental electrode configurations. The good agreement found between the experimental observations and the theoretical predictions validate the theory.

Separation of human breast cancer cells from blood by differential dielectric affinity

Electrorotation measurements were used to demonstrate that the dielectric properties of the metastatic human breast cancer cell line MDA231 were significantly different from those of erythrocytes and T lymphocytes. These dielectric differences were exploited to separate the cancer cells from normal blood cells by appropriately balancing the hydrodynamic and dielectrophoretic forces acting on the cells within a dielectric affinity column containing a microelectrode array. The operational criteria for successful particle separation in such a column are analyzed and our findings indicate that the dielectric affinity technique may prove useful in a wide variety of cell separation and characterization applications.

Decrease in CRE binding activity by chronic morphine administration in mouse brain

Recent studies have suggested that opiate addiction is associated with transcriptional changes. We developed a novel method, in situ DNA-protein binding (ISDB), for investigating the distribution and changes of DNA binding activity of transcription factors in the brain. Using this method, we found that cAMP response element (CRE) binding activity was decreased by chronic morphine treatment in specific regions including the amygdala complex, thalamus, cerebral cortex and hypothalamus in mouse brain. This effect persisted for at least 14 days after the cessation of morphine. These data suggest that chronic morphine treatment elicits a long-term change in cAMP-mediated gene expression in the brain.

Changes in Friend murine erythroleukaemia cell membranes during induced differentiation determined by electrorotation

We used electrorotation measurements to investigate alterations in the plasma membranes of DS19 murine erythroleukaemia cells that accompanied erythropoietic differentiation induced by hexamethylene bisacetamide (HMBA). Following 3 days of HMBA treatment, the mean cell membrane specific capacitance determined from electrorotation spectra of individual, viable cells at physiological tonicity (300 mosmol/kg) fell from 1.74 to 1.53 microF/cm2, in agreement with trends observed earlier by dielectrophoretic measurements on bulk cell populations. Scanning and transmission electron microscopy revealed that the relatively high values found for cell membrane capacitance (> 1 microF/cm2) reflected the large area of plasma membrane associated with complex surface morphology including numerous microvilli. Furthermore, it demonstrated that the fall in membrane capacitance during HMBA treatment correlated with a reduction in the density of these complex surface features. Differences in the mechanical characteristics of the cell membranes of untreated and treated cells were then examined by exposing cells to osmotic stress. The intricacy of membrane morphology intensified with increasing osmolality of the suspending medium and this was reflected in higher specific capacitance values. When the osmolality was increased from 210 to 450 mosmol/kg, the mean membrane capacitance of untreated DS19 cells changed from 1.58 to 2.05 microF/cm2 while that for HMBA-treated cells changed from 1.47 to 1.72 microF/cm2, a significantly smaller response. This demonstrated that cells exposed to 72 h of differentiation treatment had an enhanced mechanical resilience as compared with their untreated counterparts, evidencing the early stages of the development of the membrane skeleton which becomes fully developed in mature erythrocytes. Our findings demonstrate the value of electrorotation measurements as a method for the non-invasive characterisation of viable leukaemic cells and their responses to stimuli and show that the membrane capacitance values so derived reflect membrane morphology.

[Involvement of gene expression in drug tolerance and dependence]

The development of drug tolerance and dependence are thought to be associated with gene expression. Our studies showed that the binding activity of nuclear factors to several DNA sequences is altered by long-term treatment with methamphetamine, cocaine and morphine: 1) the binding activity of AP-1 increased markedly in the mouse brain after administration of methamphetamine and cocaine, 2) CRE-binding activity was decreased by chronic morphine treatment in the amygdala complex, cerebral cortex and hypothalamus of the mouse brain, and 3) the binding activity of single-stranded CRE binding proteins was decreased by chronic morphine treatment in the mouse cerebellum. These data suggest that the changes of DNA binding proteins can be involved in the development of drug tolerance and dependence.

Modulation by chronic morphine administration of single-stranded cAMP response element (ssCRE) binding proteins in the mouse cerebellum

The development of opiate tolerance and dependence are thought to be associated with gene expression. Our previous studies have shown that the binding activity of nuclear factors to a single-stranded oligo-DNA containing cAMP response element (ssCRE) is altered by long term treatment with morphine in cultured neuronal cells. In the present experiments, the effects of acute and chronic treatments with morphine on the binding of nuclear proteins to single- and double-stranded oligo-DNAs of the cAMP response element were studied in the mouse brains by using gel shift assay. The activity of single-stranded CRE binding proteins (ssCRE-BP) was decreased by chronic morphine treatment to about 40% of control in the cerebellum. The effect of chronic morphine treatment on the binding activity persisted for at least 2 weeks after morphine withdrawal. The activity of double-stranded CRE binding proteins was also detected in the cerebellum, but it was insensitive to the morphine treatment. The activity of ssCRE-BP was also decreased by acute morphine treatment in 5 h, but it returned to control level in 24 h. These data suggest that the change of ssCRE-BP can be involved in the development of tolerance and dependence.

Muscarinic receptors stimulate Ca2+ influx via phospholipase A2 pathway in ileal smooth muscles

Receptor-mediated changes in intracellular Ca2+ in ileal longitudinal smooth muscles of guinea pig were studied. Stimulation of muscarinic receptors by carbachol induced both Ca(2+)-influx through plasma membranes and Ca(2+)-release from intracellular stores. Pretreatment of the muscle with an inhibitor of phospholipase A2 abolished the Ca2+ influx but not the Ca(2+)-release, whereas an inhibitor of phospholipase C showed opposite effects. The inhibitors of cyclooxygenase and lipoxygenase enhanced the muscarinic receptor-induced Ca(2+)-influx. Addition of arachidonic acid mimic the receptor-induced Ca(2+)-influx. Treatment of muscles with pertussis toxin abolished the receptor-induced release of arachidonic acid as well as Ca(2+)-influx, but was less effective on the IP3 formation and the Ca(2+)-release. Taken together, our results suggest that phospholipase A2 but not phospholipase C pathway is involved in the muscarinic receptor-induced Ca(2+)-influx in ileal smooth muscle.

Nutritional efficacy of a fortified weaning rusk in a rural area near Beijing

A micronutrient-fortified rusk for weanling children was tested in a rural area near Beijing. Two hundred twenty-six children aged 6-13 mo were randomly assigned by village to either a micronutrient-fortified or an unfortified rusk, daily for 3 mo. The fortified rusk contained extra zinc; iron; calcium; vitamins A, D, and B-12; thiamin, riboflavin, niacin, and folic acid. Infants receiving the fortified rusk exhibited no decline in hemoglobin concentrations during the study whereas those receiving the unfortified rusk exhibited a significant decline. Improvements were also seen in erythrocyte porphyrin, plasma vitamin A, and riboflavin status, but these improvements were seen in both of the groups. Micronutrient fortification was probably beneficial for iron status and the fortified rusk promises to be an effective vehicle for supplementation.

In situ DNA-protein binding: a novel method for detecting DNA-binding activity of transcription factor in brain

A novel method, in situ DNA-protein binding (in situ DPB), was developed to detect the distribution and DNA-binding activity of AP-1 and Sp1 binding proteins in situ. The regional distribution of AP-1 binding protein in mouse brain was different from that of Sp1. Antibody against the DNA-binding domain of Jun protein markedly reduced the AP-1 but not the Sp1 binding activity. The binding activity of AP-1 probe increased markedly in the brain after administration of methamphetamine. These results suggest that the in situ DPB is convenient and sensitive for detecting the distribution and the DNA-binding activity of transcription factors in situ.

Clinical evaluation of 99Tcm-MIBI SPECT in the assessment of coronary artery disease

To evaluate the clinical efficacy of 99Tcm-MIBI myocardial tomography for detecting coronary artery disease (CAD) 115 consecutive patients who underwent both 99Tcm-MIBI single photon emission computed tomography (SPECT) and coronary arteriography were studied. Thirty-three patients without and 82 with significant coronary artery disease were documented by coronary arteriography. The overall sensitivity and specificity of 99Tcm-MIBI SPECT for detecting coronary artery disease were 96 and 87.9%, respectively. The sensitivity for identifying patients with CAD without myocardial infarction was 88%. The sensitivity of 99Tcm-MIBI SPECT for detecting individual coronary artery lesions was 86% for left anterior descending artery (LAD), 69% for left circumflex artery (Lcx) and 86% for right coronary artery (RCA), lesions respectively. In conclusion, 99Tcm-MIBI SPECT provides a reliable method for detecting CAD.

Differences in the AC electrodynamics of viable and non-viable yeast cells determined through combined dielectrophoresis and electrorotation studies

An electrode system is described for the near-simultaneous application and measurement of translational, levitational and rotational forces induced by AC electric fields, and this has been used to investigate the differences in the AC electrodynamics of viable and non-viable yeast cells. A new approach to the theoretical modelling of the experimental data has enabled these differences to be quantified in terms of changes in the conductivity of the cytoplasmic membrane and cell interior. The results are considered to have potentially important biomedical and biotechnological applications.

Different pathways for Ca2+ influx and intracellular release of Ca2+ mediated by muscarinic receptors in ileal longitudinal smooth muscle

Muscarinic receptor-mediated elevations in intracellular Ca2+ concentration ([Ca2+]i) in the longitudinal smooth muscle of guinea pig ileum were studied by the use of fura-2 fluorescence. Dose-response analysis indicated a difference in the potencies of carbachol (CCh) to increase [Ca2+]i in the presence and absence of extracellular Ca2+. For the increase in [Ca2+]i due to Ca2+ release from intracellular stores in the absence of extracellular Ca2+, the ED50 value of CCh was 3 x 10(-5) M. On the other hand, in the presence of Ca2+, the ED50 value was 2.5 x 10(-7) M, indicating that a low concentration of CCh (less than 10(-7) M) caused influx of extracellular Ca2+ without Ca2+ release. Oxotremorine and pilocarpine induced Ca2+ influx, but were less potent inducers of Ca2+ release. CCh also stimulated the formation of inositol trisphosphates (IP3) with an ED50 value of (4.5 x 10(-5) M), which was similar to that for Ca2+ release from intracellular stores. Treatment of the smooth muscle with neomycin (1 mM), a phospholipase C inhibitor, abolished both CCh-induced IP3 formation and Ca2+ release from intracellular stores, but did not affect CCh-induced Ca2+ influx. These results suggest that the pathway for muscarinic stimulation of Ca2+ influx through plasma membranes is different from that for Ca2+ release from intracellular stores, which seems to be coupled with IP3 formation.

Medium hyperosmolarity inhibits prolactin secretion induced by depolarizing K+ in GH4C1 cells by blocking Ca2+ influx

Medium hyperosmolarity between 300 (normal medium osmolarity) and 600 mOsm inhibited in a concentration-correlated fashion (r greater than 0.97, p less than 0.001) the rise in intracellular Ca2+ concentration ([Ca2+]i) and prolactin (PRL) secretion induced in GH4C1 cells by depolarizing 30 mM K+. [Ca2+]i concentration and PRL secretion were tightly related between 300 and 600 mOsm (r = 0.976, p less than 0.001); 50% inhibition of both occurred at 450 mOsm. Medium hyperosmolarity slowed the rate of Ca2+ influx. At 600 mOsm the rise in both [Ca2+]i and PRL secretion was abolished but PRL secretion induced by 1 microM phorbol 12-myristate 13-acetate was not significantly reduced. Our data suggest that inhibition of Ca2+ influx may be the primary mechanism by which extracellular hyperosmolarity inhibits PRL secretion induced by high medium K+ in GH4C1 cells. Depression of the Ca2+ intracellular transduction system may play a pathophysiological role in vivo in conditions such as dehydration and hypertonic coma.

Different natures of supersensitivity of adenylate cyclase stimulated by calcitonin gene-related peptide and isoproterenol in rat diaphragm after denervation and reserpine treatment

In skeletal muscles, calcitonin gene-related peptide (CGRP) released from motor nerve terminals and humoral catecholamines stimulate adenylate cyclase (AC) and enhance muscle contraction. The effects of denervation and treatment with reserpine on twitch contraction and the AC system in rat diaphragm were investigated. The basal levels of twitch contraction and AC activity of the diaphragm of rats were both increased 2 weeks after phrenic nerve denervation but were not altered by treatment with reserpine. Reserpine treatment provoked supersensitivity of AC to isoproterenol, without affecting the response to CGRP. On the other hand, denervation decreased the activation of AC and enhancement of twitch contraction by CGRP, without affecting the responses to isoproterenol. These data suggest that denervation causes up-regulation of AC as a result of loss of CGRP release from nerve terminal and that depletion of catecholamines by reserpine treatment supersensitizes the responses at the beta-adrenoceptor level. Thus, nervous and humoral factors regulate the AC system in striated muscle by different mechanisms.