Effects of energy controllable steep pulses on intracellular calcium concentration and cell membrane potential

BACKGROUND AND OBJECTIVES

Our previous experiments showed that steep pulses could kill tumor cells, but the mechanism is unclear yet. This study was to probe the effects of different dosages of energy controllable steep pulses on intracellular concentration of dissociative calcium ion ([Ca2+]i) and cell membrane potential.

MATERIALS AND METHODS

The mammary carcinoma cells MDA-MB-231 were divided into control group and 5 different dosages of Energy Controllable Steep Pulses (ECSP) treatment groups. The calcium ion in each group was labeled by Fluo-3/AM individually and the cell membrane potential was labeled by DiBAC4 (3). The mean fluorescence intensity of fluorescent probe in mammary carcinoma cells was observed in quiet state by laser confocal microscopy after ECSP treatment The changes of calcium concentration and cell membrane potential in cells after ECSP treatment were analyzed. The changes of intracellular [Ca2+]i after ECSP treatment were also observed with and without calcium ion outside of the cells.

RESULTS

The calcium ion outside of cells influx with lower dosage of pulse in quiet state. With the dosage increase, the intracellular calcium ion outflow. In real time kinetic detection, the mean fluorescence intensity of intracellular calcium ion was increased with the pulse electric field intensity raised in the lower ECSP. When the voltage was 285V, frequency was 100Hz, the [Ca2+]i decreased. The increase of intracellular calcium ion concentration was decreased without calcium ion than with calcium ion outside of cells, but still raised gradually. The lower dosage of ECSP could induce the fluorescence intensity of DiBAC4 (3) in cells increase, which showed that the lower dosage of ECSP could induce the depolarization of cells. With the dosage raised, the fluorescence intensity of DiBAC4 (3) in cells attenuated. This dosage of ECSP could induce the superpolarization of cell membrane.

CONCLUSIONS

The lower dosage of ECSP can induce the depolarization of cell membrane and induce the inter flow of calcium ion outside of cell membrane. The higher dosage of ECSP can directly destroy the cell membrane and induce the superpolarization of cell membrane, then induce the outflow of intracellular calcium ion which causes the necrosis of tumor cells.

Modulation of K(v)7 potassium channels by a novel opener pyrazolo[1,5-a]pyrimidin-7(4H)-one compound QO-58

BACKGROUND AND PURPOSE

Modulation of K(v)7/M channel function represents a relatively new strategy to treat neuronal excitability disorders such as epilepsy and neuropathic pain. We designed and synthesized a novel series of pyrazolo[1,5-a] pyrimidin-7(4H)-one compounds, which activate K(v)7 channels. Here, we characterized the effects of the lead compound, QO-58, on K(v)7 channels and investigated its mechanism of action.

EXPERIMENTAL APPROACH

A perforated whole-cell patch technique was used to record K(v)7 currents expressed in mammalian cell lines and M-type currents from rat dorsal root ganglion neurons. The effects of QO-58 in a rat model of neuropathic pain, chronic constriction injury (CCI) of the sciatic nerve, were also examined.

KEY RESULTS

QO-58 increased the current amplitudes, shifted the voltage-dependent activation curve in a more negative direction and slowed the deactivation of K(v)7.2/K(v)7.3 currents. QO-58 activated K(v)7.1, K(v)7.2, K(v)7.4 and K(v)7.3/K(v)7.5 channels with a more selective effect on K(v)7.2 and K(v)7.4, but little effect on K(v)7.3. The mechanism of QO-58's activation of K(v)7 channels was clearly distinct from that used by retigabine. A chain of amino acids, Val(224)Val(225)Tyr(226), in K(v)7.2 was important for QO-58 activation of this channel. QO-58 enhanced native neuronal M currents, resulting in depression of evoked action potentials. QO-58 also elevated the pain threshold of neuropathic pain in the sciatic nerve CCI model.

CONCLUSIONS AND IMPLICATIONS

The results indicate that QO-58 is a potent modulator of K(v)7 channels with a mechanism of action different from those of known K(v)7 openers. Hence, QO-58 shows potential as a treatment for diseases associated with neuronal hyperexcitability.

FasL-induced apoptosis in bovine oocytes via the Bax signal

The factor associated suicide (Fas) and its ligand (FasL) signaling is an important regulatory pathway of apoptosis in mammalian follicles. However, whether apoptosis in bovine oocytes is regulated by the Fas-FasL signaling pathway remains unknown. In this study, localization of Fas and FasL in immature oocytes and FasL in cumulus cells were examined using immunofluorescence staining. In addition, exogenous FasL was added to an in vitro culture system to investigate apoptotic changes in bovine oocytes, using annexin-V and terminal uridine nick-end labeling staining, and real-time quantitative polymerase chain reaction. In this study, Fas was expressed in immature oocytes, whereas FasL was expressed in cumulus cells, but not in immature oocytes; annexin-V- and terminal uridine nick-end labeling-positive rates of oocytes treated with 2, 10, or 50 ng/mL FasL were higher than those of control oocytes (P < 0.05); and oocytes from the three treatment groups had higher expression levels of Fas and B cell lymphoma/leukemia-2 associated X than those in the control group (P < 0.05). Taken together, we concluded that the Fas-FasL signaling pathway was involved in regulation of bovine oocyte apoptosis, perhaps related to B cell lymphoma/leukemia-2 associated X upregulation.

High-intensity electric pulses induce mitochondria-dependent apoptosis in ovarian cancer xenograft mice

Human ovarian cancer models were established in nude mice by transplanting SKOV(3) cells, and then tumors were exposed to high-intensity electric pulses with a voltage 1000 V, frequency of 1000 Hz, and duration of 250 ns for 1 min. Mitochondria permeability transition pore (PTP) was inspected by cofocal microscope; cytochrome C (Cyt C) and apoptosis-induced factor (AIF) were determined by immunohistochemistry; and voltage-dependent anion channel (VDAC) was measured by immunofluorescence. High-intensity electric pulses exposure led to increases of PTP, Cyt C, and AIF and a decrease of VDAC. These findings revealed that high-intensity electric pulses activated mitochondria electroporation, apoptosis was realized via mitochondria pathway.

ZD6474 reverses multidrug resistance by directly inhibiting the function of P-glycoprotein

P-glycoprotein (P-gp) pumps multiple types of drugs out of the cell, using energy generated from ATP, and confers multidrug resistance (MDR) on cancer cells. ZD6474 is an orally active, selective inhibitor of the vascular endothelial growth factor receptor, epidermal growth factor receptor, and rearranged during transfection tyrosine kinases. This study was designed to examine whether ZD6474 reverses P-gp-mediated MDR in cancer cells. Here, we show that clinically achievable levels of ZD6474 reverse P-gp-mediated MDR of the P-gp-overexpressing cell lines derived from breast cancer, MCF-7/adriamycin (ADR), and human oral epidermoid carcinoma, KBV200 to ADR, docetaxel, and vinorelbine. This ability to reverse the P-gp-mediated resistance is comparable to that of another frequently used reversal agent known as verapamil. ZD6474 itself moderately inhibits the proliferation of both MCF-7 and MCF-7/ADR cells with almost equal activity, but its inhibitory effect is not altered by co-incubation with verapamil, suggesting that ZD6474 may not be a substrate of P-gp. In addition, ZD6474 increases the intracellular accumulation of the P-gp substrate, rhodamine-123, and ADR, by enhancing the uptake and/or decreasing the efflux of these compounds in resistant cells. Further studies show that ZD6474 stimulates ATPase activity in a dose-dependent manner, which is required for the proper function of P-gp. In contrast, ZD6474 does not inhibit the expression level of P-gp. Our results suggest that ZD6474 is capable of reversing MDR in cancer cells by directly inhibiting the function of P-gp, a finding that may have clinical implications for ZD6474.

Effect of pattern topology on the self-cleaning properties of textured surfaces

The water contact angle and self-cleaning property of microfabricated surface textures possessing different topologies are compared. In one kind of surface textures, the protruded regions form a connected square network. In the other kind of surface textures, the protruded regions form a regular array of square posts. We find that the water apparent contact angle of the connected textures agrees with the Cassie equation [Discuss. Faraday Soc. 3, 11 (1948)], but that of the disconnected textures is much larger. Nevertheless, the disconnected textures exhibit inferior self-cleaning property, contrary to conventional conception. We discuss the possible reasons for these observations.

Indoor molds, bacteria, microbial volatile organic compounds and plasticizers in schools--associations with asthma and respiratory symptoms in pupils

We investigated asthma and atopy in relation to microbial and plasticizer exposure. Pupils in eight primary schools in Uppsala (Sweden) answered a questionnaire, 1014 (68%) participated. Totally, 7.7% reported doctor-diagnosed asthma, 5.9% current asthma, and 12.2% allergy to pollen/pets. Wheeze was reported by 7.8%, 4.5% reported daytime breathlessness, and 2.0% nocturnal breathlessness. Measurements were performed in 23 classrooms (May-June), 74% had <1000 ppm CO(2) indoors. None had visible mold growth or dampness. Mean total microbial volatile organic compound (MVOC) concentration was 423 ng/m(3) indoors and 123 ng/m(3) outdoors. Indoor concentration of TMPD-MIB (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, Texanol) and TMPD-DIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate, TXIB), two common plasticizers, were 0.89 and 1.64 microg/m(3), respectively. MVOC and plasticizer concentration were correlated (r = 0.5; P < 0.01). Mold concentration was 360 cfu/m(3) indoors and 980 cfu/m(3) outdoors. At higher indoor concentrations of total MVOC, nocturnal breathlessness (P < 0.01) and doctor-diagnosed asthma (P < 0.05) were more common. Moreover, there were positive associations between nocturnal breathlessness and 3-methylfuran (P < 0.01), 3-methyl-1-butanol (P < 0.05), dimethyldisulfide (P < 0.01), 2-heptanone (P < 0.01), 1-octen-3-ol (P < 0.05), 3-octanone (P < 0.05), TMPD-MIB (P < 0.05), and TMPD-DIB (P < 0.01). TMPD-DIB was positively associated with wheeze (P < 0.05), daytime breathlessness (P < 0.05), doctor-diagnosed asthma (P < 0.05), and current asthma (P < 0.05). In conclusion, exposure to MVOC and plasticizers at school may be a risk factor for asthmatic symptoms in children.

PRACTICAL IMPLICATIONS

Despite generally good ventilation and lack of visible signs of mold growth, we found an association between respiratory symptoms and indoor MVOC concentration. In addition, we found associations between asthmatic symptoms and two common plasticizers. The highest levels of MVOC, TMPD-MIB, and TMPD-DIB were found in two new buildings, suggesting that material emissions should be better controlled. As MVOC and plasticizers concentrations were positively correlated, while indoor viable molds and bacteria were negatively correlated, it is unclear if indoor MVOC is an indicator of microbial exposure. Further studies focusing on health effects of chemical emissions from indoor plastic materials, including PVC-floor coatings, are needed.

Current asthma and respiratory symptoms among pupils in relation to dietary factors and allergens in the school environment

The aim was to study asthma and allergy in relation to diet and the school environment. Pupils (5-14 years) in eight schools received a questionnaire, 1014 participated (68%). Settled dust was collected on ALK-filters and analyzed for allergens from cat (Fel d 1), dog (Can f 1), horse (Equ cx), house dust mites (Der p 1, Der f 1), and cockroach (Bla g 1) by ELISA. In total, 6.8% reported cat allergy, 4.8% dog allergy, 7.7% doctor's diagnosed asthma and 5.9% current asthma, and 7.8% reported wheeze. Current asthma was less common among those consuming more fresh milk (P < 0.05) and fish (P < 0.01). Poly-unsaturated fatty acids was associated with more wheeze (P < 0.05), olive oil was associated with less doctors' diagnosed asthma (P < 0.05). Totally, 74% of the classrooms had mean CO(2) <1000 ppm. The median concentration per gram dust was 860 ng/g Fel d 1, 750 ng/g Can f 1 and 954 U/g Equ cx. Horse allergen was associated with more wheeze (P < 0.05), daytime breathlessness (P < 0.05), current asthma (P < 0.05) and atopic sensitization (P < 0.05). Dog allergen was associated with wheeze (P < 0.05) and daytime breathlessness (P < 0.05). The associations between allergens and respiratory symptoms were more pronounced among those consuming margarine, not consuming butter, and with a low intake of milk. In conclusion, cat, dog and horse allergens in schools could be a risk factor for asthma and atopic sensitization, and dietary factors may interact with the allergen exposure.

PRACTICAL IMPLICATIONS

Previous school studies performed by us in mid-Sweden, showed that most classrooms did not fulfill the ventilation standards. In this study, most of the classrooms fulfilled the ventilation standard, but despite that had widespread allergen contamination. Most previous studies have focused on cat allergen, but our study has shown that also dog and horse allergens can be risk factors for asthma and allergy in schools. As allergens are transported from other environments, mainly the home environment, the main prevention should be to minimize transfer of allergens. This could be achieved by reducing contacts with furry pets and horses, or using different clothes at home and at school (e.g. school uniforms). Increased cleaning in the schools may reduce allergen levels, but the efficiency of this measure must be evaluated in further intervention studies. Finally, our study supports the view that dietary habits among pupils should not be neglected and interaction between dietary factors and indoor allergen exposure needs to be further investigated.

[A study of the relationship among interleukin-8, cortisol and idiopathic preterm labor]

OBJECTIVE

To assess the effect of interleukin-8 and cortisol on the onset of idiopathic preterm labor (PL).

METHODS

In 35 women with preterm labor and 17 controls, maternal serum and urine samples were collected. Interleukin-8 concentration was measured by enzyme-linked immunosorbant assay, serum cortisol level was measured by radioimmunoassay.

RESULTS

The concentration of interleukin-8 in maternal serum and urine and cortisol in serum were significantly higher in PL group than those in the control [(0.26 +/- 0.13) microg/L vs (0.16 +/- 0.08) microg/L, (0.16 +/- 0.15) x 10(-2) g/mol Cr vs (0.04 +/- 0.02) x 10(-2) g/mol Cr, (765.83 +/- 408.55) microg/L vs (512.41 +/- 142.65) microg/L; P < 0.05, P < 0.01, P < 0.01, respectively]. A strong correlation was found ammong interleukin-8 and cortisol concentration in maternal serum in PL (r = 0.448; P < 0.05).

CONCLUSIONS

There is a strong relationship between interleukin-8 and cortisol in the onset of preterm labor. Immune system and endocrine system might be involved in the mechanisms of idiopathic preterm labor.

[Preliminary study on postremission therapy courses in acute myeloid leukemia]

OBJECTIVE

To explore the optimum postremission therapy courses in acute myeloid leukemia (AML).

METHODS

Data from medical records of AML patients in our hospital in 7 year were analyzed with SPSS 8.0 system software.

RESULTS

One hundred and ninety one untreated de novo AML patients received different induction chemotherapy regimens: HA, DA, AA and HAD. The complete remission (CR) rate was 81.4%, 89.9% for one to two courses. The median disease free survival (DFS) in 144 CR patients whose survival time could be analyzed was 9.6 months. The probability of survival was 21.6% at 3 year and 12.9% at 5 year. For the patients received less than 6 courses of post-remission therapy, the median DFS was 7.1 months and the probability of survival was 11.4% at 3 year and 6.3% at 5 years, Whereas for patients received 6 or more courses of post-remission therapy, they were 35.3 months, 43.2% and 27.0%, respectively. The differences between the two groups were statistically significant. For patients received 8 or more courses of post-remission therapy, the median DFS was 48.8 months and the probability of survival was 57.9% at 3 year and 31.6% at 5 year.

CONCLUSION

AML patients should at least receive 6 courses of post-remission therapy, and 8 courses therapy seems better.

Edg-1, the G protein-coupled receptor for sphingosine-1-phosphate, is essential for vascular maturation

Sphingolipid signaling pathways have been implicated in many critical cellular events. Sphingosine-1-phosphate (SPP), a sphingolipid metabolite found in high concentrations in platelets and blood, stimulates members of the endothelial differentiation gene (Edg) family of G protein-coupled receptors and triggers diverse effects, including cell growth, survival, migration, and morphogenesis. To determine the in vivo functions of the SPP/Edg signaling pathway, we disrupted the Edg1 gene in mice. Edg1(-/-) mice exhibited embryonic hemorrhage leading to intrauterine death between E12.5 and E14.5. Vasculogenesis and angiogenesis appeared normal in the mutant embryos. However, vascular maturation was incomplete due to a deficiency of vascular smooth muscle cells/pericytes. We also show that Edg-1 mediates an SPP-induced migration response that is defective in mutant cells due to an inability to activate the small GTPase, Rac. Our data reveal Edg-1 to be the first G protein-coupled receptor required for blood vessel formation and show that sphingolipid signaling is essential during mammalian development.

Buckwheat allergy and reports on asthma and atopic disorders in Taiyuan City, Northern China

Allergy to common buckwheat (Fagopyrum esculentum) has been reported from Europe and Japan, and a 24 kDa globulin protein has been identified as one of the major allergens. In China also another type, tartary buckwheat (Fagopyrum tartaricum) is grown and consumed. Three groups of individuals in Shanxi province, China, were investigated for buckwheat allergy using skin prick test. The groups were: agricultural researchers with occupational exposure to buckwheat (N = 16); workers in a food industry producing buckwheat noodles (N = 25), and patients with diabetes or cardiovascular disease consuming buckwheat as functional food (N = 20). Information on atopic disorders and adverse food reactions were collected by a doctors-administered questionnaire. One male industrial worker had a positive skin prick test to buckwheat, but no symptoms while eating or handling buckwheat products. In total, 34% consumed buckwheat food at least every week, and 23% had a weekly consumption of tartary buckwheat. The prevalence of doctor's diagnosed asthma was low (1.6%). Four subjects (6.6%) reported a history of allergic rhinitis, with allergy to cedar pollen, carnation and peach.

[Study on the clinical characteristics of biphenotypic acute leukemia]

OBJECTIVE

To analyze the biological characteristics and the treatment outcome of adult biphenotypic acute leukemia.

METHODS

Immunophenotypes were examined using indirect immunofluorescence method. Biphenotypic acute leukemia (BAL) was diagnosed according to EGIL scoring system.

RESULTS

(1) The incidence of BAL in acute leukemia was 3.4%. Percentage for coexpression of B lymphoid and myeloid antigens was 68.4%, for T lymphoid and myeloid antigens 21.1%, for B, T lymphoid and myeloid antigens 10.5%. (2) CD(34) was expressed in 43.75% of the BAL cases. (3) Cytogenetic analysis revealed normal and abnormal karyotypes in 41.7% and 58.3% of the BAL cases, respectively. (4) Six of 19 patients achieved completed remission (CR), but the disease free survivals were all less than 6 months. Treatment outcomes were negatively related to the expression of CD(34) antigen and cytogenetic findings. The BAL patients were poorly responded to therapeutic regimens directed to AML.

CONCLUSION

Coexpression of B/M antigens is the commonest subtype in BAL. BAL had a poor prognosis, especially treated with induction regimen directed to AML.

Retinoic acid resistance at late stages of human papillomavirus type 16-mediated transformation of human keratinocytes arises despite intact retinoid signaling and is due to a loss of sensitivity to transforming growth factor-beta

In our in vitro model of human cell carcinogenesis, normal human foreskin keratinocytes (HKc) transfected with human papillomavirus type 16 DNA (HKc/HPV16) progress toward malignancy through several phenotypically defined and reproducible "steps" that include immortalization, growth factor independence (HKc/GFI), differentiation resistance (HKc/DR), and ultimately malignant conversion. While HKc/HPV16 are very sensitive to growth inhibition by all-trans-retinoic acid (RA) at early passages, they lose their sensitivity to RA during progression in culture. However, gel mobility shift assays using the retinoid response elements DR1 and DR5 showed no changes in binding activity of nuclear extracts obtained from HKc/HPV16 at different stages of in vitro progression. Similarly, Western blot analyses for retinoic acid receptor gamma-1 and the retinoid X receptors failed to reveal any decreases in the levels of these retinoid receptors throughout progression. In addition, luciferase activity driven by the SV40 promoter with a DR5 enhancer element was activated following RA treatment of HKc/DR that were resistant to growth inhibition by RA. Since RA induces transforming growth factor-beta2 (TGF-beta2) in normal HKc and HKc/HPV16, we investigated whether this response changed during progression. Again, RA induced TGF-beta2 mRNA in early and late passage HKc/HPV16, HKc/GFI, and HKc/DR approximately to the same extent, confirming that the RA signaling pathways remained intact during in vitro progression despite the fact that the cells become resistant to growth inhibition by RA. We then investigated the sensitivity of HKc/HPV16 to growth inhibition by TGF-beta. While early passage HKc/HPV16 were as sensitive as normal HKc to growth inhibition by TGF-beta1 and TGF-beta2, the cells became increasingly resistant to both TGF-beta isotypes during in vitro progression. In addition, while both RA and TGF-beta produced a decrease in the levels of mRNA for the HPV16 oncogenes E6 and E7 in early passage HKc/HPV16, this effect was also lost at later stages of progression. Finally, blocking anti-TGF-beta antibodies partially prevented RA inhibition of growth and E6/E7 expression in early passage HKc/HPV16. Taken together, these data strongly suggest that inhibition of growth and HPV16 early gene expression in HKc/HPV16 by RA is mediated by TGF-beta and that a loss of RA sensitivity is linked to TGF-beta resistance rather than alterations in RA signaling.

Loss of transforming growth factor-beta (TGF-beta) receptor type I mediates TGF-beta resistance in human papillomavirus type 16-transformed human keratinocytes at late stages of in vitro progression

Human keratinocytes (HKc) immortalized by human papillomavirus type 16 DNA (HKc/HPV16) progress toward malignancy through growth factor-independent (HKc/GFI) and differentiation-resistant stages (HKc/DR). This progression is associated with a loss of sensitivity to growth inhibition by both all-trans-retinoic acid (RA) and transforming growth factor-beta (TGF-beta). In the accompanying article (Borger et al., 2000, Virology 270, 397-407), we demonstrate that RA resistance in HKc/HPV16 arises despite functional nuclear retinoid receptors and that TGF-beta mediates growth inhibition by RA. To investigate the basis for the loss of TGF-beta sensitivity during in vitro progression of HKc/HPV16, we explored the expression of TGF-beta receptors type I and type II in independently derived HKc/HPV16 lines and their corresponding HKc/GFI and HKc/DR derivatives. While TGF-beta receptor type II mRNA levels were unchanged during progression, mRNA levels for TGF-beta receptor type I decreased dramatically as the cells became TGF-beta resistant. At the HKc/DR stage, loss of TGF-beta receptor type I mRNA, compared to low-passage cells, ranged from 55 to 87% in four HKc/HPV16 lines examined. Immunohistochemistry, using anti-TGF-beta receptor type I antibodies, confirmed a loss of TGF-beta receptor type I expression in HKc/DR. Reintroduction of the TGF-beta-receptor type I into TGF-beta-resistant HKc/DR completely restored growth inhibition by TGF-beta. Southern blot analysis of DNA extracted from normal HKc, HKc/HPV16, and HKc/DR ruled out any gross changes in the TGF-beta receptor type I gene. The activity of the TGF-beta receptor type I promoter, cloned upstream of a luciferase reporter gene, was decreased in HKc/DR, to an extent comparable to the decrease in mRNA levels for the TGF-beta receptor type I. Thus, TGF-beta resistance at late stages of HPV16-mediated transformation of HKc is the result of a loss of expression of TGF-beta receptor type I.