Single-walled carbon nanotubes as a photo-thermo-acoustic cancer theranostic agent: theory and proof of the concept experiment.

Theranostics is the emerging field of medicine that uniquely combines diagnostic techniques and active agents to diagnose and treat medical conditions simultaneously or sequentially. Finding a theranostic agent capable to cure the affected cells and being safe for the healthy ones is the key for successful treatment. Here, we demonstrate that agglomerated single-walled carbon nanotubes (SWCNTs) are promising theranostic agent that enables photo-activated 'cold' destruction of the cancer cells keeping their environment alive. The absorption of picosecond pulses by SWCNT agglomerates results in the mechanical (due to photoacoustic effect) rather than photothermal cancer cell destruction, which was visualized by micro-Raman and ultrafast near-infrared CARS. The developed theoretical model allows us to distinguish photothermal, photoacoustic, and photothermoacoustic regimes of the cancer cell destruction, and also to optimize SWCNT-based theranostics recipe.

Prevention and Reversion of Pancreatic Tumorigenesis through a Differentiation-Based Mechanism.

Activating mutations in Kras are nearly ubiquitous in human pancreatic cancer and initiate precancerous pancreatic intraepithelial neoplasia (PanINs) when induced in mouse acinar cells. PanINs normally take months to form but are accelerated by deletion of acinar cell differentiation factors such as Ptf1a, suggesting that loss of cell identity is rate limiting for pancreatic tumor initiation. Using a genetic mouse model that allows for independent control of oncogenic Kras and Ptf1a expression, we demonstrate that sustained Ptf1a is sufficient to prevent Kras-driven tumorigenesis, even in the presence of tumor-promoting inflammation. Furthermore, reintroducing Ptf1a into established PanINs reverts them to quiescent acinar cells in vivo. Similarly, Ptf1a re-expression in human pancreatic cancer cells inhibits their growth and colony-forming ability. Our results suggest that reactivation of an endogenous differentiation program can prevent and reverse oncogene-driven transformation in cells harboring tumor-driving mutations, introducing a potential paradigm for solid tumor prevention and treatment.

Carbon nanotube sponges as tunable materials for electromagnetic applications.

The microwave conductivity and permittivity of both single-walled and multi-walled carbon nanotube (SWCNT and MWCNT) sponges were measured while compressing the samples. Compression leads to a huge variation of the absorptance, reflectance, and transmittance of the samples. The dependence of the microwave conductivity on the sponge density follows a power-law relation with exponents 1.7 ± 0.1 and 2.0 ± 0.2 for MWCNT and SWCNT sponges, respectively. These exponents can be decreased slightly by the addition of a non-conducting component which partly electrically separates adjacent tubes within the samples. The conductivity of MWCNT sponge was measured in the terahertz range while heating in air from 300 to 513 K and it increased due to an increase of a number of conducting channels in MWCNTs.

Soft cutting of single-wall carbon nanotubes by low temperature ultrasonication in a mixture of sulfuric and nitric acids.

To decrease single-wall carbon nanotube (SWCNT) lengths to a value of 100-200 nm, aggressive cutting methods, accompanied by a high loss of starting material, are frequently used. We propose a cutting approach based on low temperature intensive ultrasonication in a mixture of sulfuric and nitric acids. The method is nondestructive with a yield close to 100%. It was applied to cut nanotubes produced in three different ways: gas-phase catalysis, chemical vapor deposition, and electric-arc-discharge methods. Raman and Fourier transform infrared spectroscopy were used to demonstrate that the cut carbon nanotubes have a low extent of sidewall degradation and their electronic properties are close to those of the untreated tubes. It was proposed to use the spectral position of the far-infrared absorption peak as a simple criterion for the estimation of SWCNT length distribution in the samples.

Hyperthermic effect of multi-walled carbon nanotubes stimulated with near infrared irradiation for anticancer therapy: in vitro studies.

UNLABELLED: It is proposed to use the novel paradigm of treating cancer with hyperthermic therapy using multi-walled carbon nanotubes (MWCNT) stimulated with near infrared (NIR) irradiation. AIM: To establish the capacity of MWCNT stimulated with NIR irradiation to destroy Erlich ascitic carcinoma (EAC) cells. MATERIALS AND METHODS: EAC cells suspension was irradiated with NIR heating lamp with a wavelength of 0.78-1.40 mm and power density of 3.5 W/cm2 over 1.5 min in the presence of MWCNT (0.1 mg/ml). The changes in the temperature of suspension with the NIR exposure time was measured using the differential cooper-constantan thermocouple. The viability of EAC cells was evaluated by trypan blue staining. RESULTS: The death of 95.2% of EAC cells in the presence of MWCNT was observed after 1.5 min of NIR light irradiation: thermal ablation temperature was approximately 50 degrees C. CONCLUSIONS: It was demonstrated that addition of MWCNT to EAC cell suspension results in the photo-ablative destruction of cells exposed to short time NIR irradiation.

[Effect of paxilline on Ca(2+)-dependent K+ current in smooth muscle cells isolated from rat vas deferens].

The properties of the outward Ca(2+)-dependent K+ current (KCa) were investigated in single smooth muscle cells (SMCs) isolated from epididymal part of the rat vas deferens (RVD) using amphotericin B perforated patch-clamp technique. The complex kinetic of the net outward current elicited by positive voltage steps from -80 mV to +40 mV suggested the presence of several components of this current. KCa current was separated from the net outward current by removal of Ca2+ from the external solution. KCa was characterized by slow kinetics of current activation and decay. Mycotoxin paxilline, the selective blocker of the large conductance KCa channels, inhibited KCa current in a dose-dependent manner. At the concentration of 70 nM paxilline evoked 50% inhibition of KCa and at 1 mkM complete suppression of KCa current was achieved. The blocking effect of low concentrations of a nonselective KCa channels inhibitor tetraethylammonium (TEA) was compared to that of paxilline. The external application of 0.3 mM TEA inhibited KCa current similarly to 1 mkM of paxilline. Finally, we studied the effect of paxilline on the resting membrane potential ofRVD SMCs. Paxilline (1 mkM) did not affect the membrane potential of SMCs with the resting potential in the range of -60 to -40 mV. However, at potentials more positive than -40 mV application of paxilline significantly (up to 15 mV) depolarized the membrane of SMCs. These results suggest that the large conductance KCa channels in RVD SMCs do not contribute to the resting membrane potential but could serve as a hyperpolarizing mechanism at the significant membrane depolarizations.

[Transfer factor of immune reactivity to diphtheria-tetanus anatoxin modulates the action of neurotransmitters in the intestinal smooth muscle].

Transfer factor (TF) of immune reactivity (10(-5) - 10(-3) mg/ml) to diphtheria-tetanus anatoxin modulates slow waves and spontaneous contractile activity of non-atropinized smooth muscle stripes (SMS) of guinea-pig taenia coli. TF (10(-4) mg/ml) transforms slow waves into stable depolarization and tonic contraction. After SMS atropinization, the substance acts in the same way. In the presence of methylene blue (10(-5) M), a guanylatecyclase blocker, FT induces transitory increase of SMS muscle tone, which is followed by their stable relaxation. ATP and UTP, purinoceptors agonists, evoke substantial hyperpolarization of smooth muscle cells membrane and their relaxation. FT enhances post-inhibitory excitation in SMS. In the presence of acetylcholine (10(-5) M) FT (10(-4) mg/ml) transforms the inhibitory ATP action on tonic contraction into excitative. This substance (10(-5), 10(-4) mg/ml) enhances Ca2+ mobilization from ryanodine-sensitive calcium store, inhibits the release of these cations from IP3-sensitive calcium store of sarcoplasmic reticulum. TF demolishes the inhibitory actions of sodium nitroprusside (nitric oxide donor), and noradrenaline in taenia coli smooth muscles.

[Effects of cell-binding protein A of Staphylococcus aureus on the level of intracellular calcium ions and actomyosin ATP-ase activity in the smooth muscles].

Immune-active substance of Staphylococcus aureus, cell-bound protein A (CBPA), enhances the acetylcholine- or hyperpotassium (K+) Krebs solution-evoked excitation in Taenia coli smooth muscles. CBPA increases caffeine- and carbachole-evoked Ca2+ signals in smooth muscle cells suspension, loaded with indo-1, and also caffeine- and acetylcholine-evoked contraction in smooth muscles slices. Against a background of CBPA-suppressed action of sodium nitroprusside, ATP evokes the membrane depolarization. CBPA in small concentrations potentiates ATPase (Mg2+,Ca2+-; Mg2+- and Mg2+- in the presence of EGTA) activity of actomyosin in the smooth muscles.

[Effects of Staphylococcus aureus cell-bound protein A on adenosine triphosphate and nitric oxide inhibitory actions in smooth muscles].

Cell-bound protein A (CBPA), an immune-active substance of Staphylococcus aureus was ascertained to depolarize membrane of taenia coli smooth muscle (SM) cells, depress ATP inhibiting action (or uridinetriphosphate (UTP)) and sodium nitroprusside (SNP). ATP or UTP-induced membrane hyperpolarization increased during first minutes of CBPA exposure. Bacterial substance enhanced and then inhibited fast component of nicotine-induced relaxation of histamine-activated smooth muscles. This enhancement was inhibited by N(omega)-nitro-Larginine, a NO-syntase blocker. CBPA decreased ATP inhibiting action upon histamine-induced contraction, but enhanced cholinergic SM excitation. All these processes are reversible.

[Molecular mechanisms of receptor-dependent signaling in the cells of the longitudinal and circular intestinal smooth muscles].

The G-protein-dependent intracellular signal cascades of excitation in longitudinal and circular intestinal smooth muscles (SM) are compared and summarized in the present review. The key mechanism of excitation in longitudinal SM is an activation of electro-mechanical coupling, in that G-proteins, phospholipase A2, arachidonic acid, membrane-bound cyclic adenosine diphosphoribose and Ca2+ are involved. We observed the role of arachidonic acid-activated chorine and voltage-dependent Ca2+ -channels (L-type) in Ca2+ mobilization in these muscle cells. In contrast to longitudinal, the main mechanism of agonist-induced excitation in circular SM is connected with activation of key methabotropical processes. The role of Rho-kinase in mechanisms of Ca2+ --sensitization of contractile apparatus in SM is also shown in this review. A comparative analysis of involvement of different links of signal cascades in initial and sustained phases of contraction in longitudinal and circular SM are also reviewed.

[Modulation of molecular signaling mechanisms in excitable cells by toxins and bacterial substances].

The mechanisms of bacterial substances (protein A, peptidoglican Staphylococcus aureus), bacterium toxins (St. aureus, Corynebacterium diphtheriae, Shigella dysenteriae, Clostridium botulinum, Clostridium tetani, Vibrio choleral), transfer factor of immune reactivity to Staphylococcus aureus upon the key link (acetylcholine-, ATP-, inositol-1,4,5-triphosphate-, ryanodin-sensitive receptors, G-proteins, Ca2+, K(+)-transporting systems, second messengers) in the chain of signal conduction of excitatory and inhibitory agonists in excitable cells were examined. The action of these immune-active substances upon contractile proteins ATP-ase activity and protein synthesis was also discussed.

[Single nonselective cation channels activated by muscarinic agonists in smooth muscle cells of the guinea-pig small intestine]. / Poodynoki neselektyvni kationni kanaly, aktyvovani muskarynovymy ahonistamy hladen'kom'iazovykh klityn tonkoho kyshechnyka mors'koï svynky.

The carbachol-evoked inward cationic current in guinea-pig ileum smooth muscle cells is comprised of three types nonselective cationic channels (NSCC) with small (10 +/- 2 pS), medium (56 +/- 8pS) and large (135 +/- 14 pS) unitary conductance. All three types of NSCC could be activated by external application of carbachol as well as by internal application of GTPgS. It was found that behavior of carbachol- and GTPgammaS-evoked whole-cell current is mainly determined by the properties of medium conductance channels. The U-shaped I-V relationship of the whole-cell cationic current at negative potentials range arrives from voltage-dependence of its Po of this channel.

The effects of H2O2 on electromechanical activity of the ileum longitudinal muscle.

The effects of H2O2 on electrical and mechanical activity of the longitudinal layer from the guinea-pig ileum were studied using sucrose-gap technique and the influence of H2O2 on ionic current was investigated in single smooth muscle cells by the patch-clamp method. In most of the preparations tested, the spontaneous activity observed was composed of slow waves with superimposed action potentials (APs). Both were resistant to tetrodotoxin and atropine. H2O2 (1 mmol/l) evoked sustained 3-5 mV membrane depolarisation, doubled the amplitude of the slow waves and increased their frequency, augmented the APs and reduced their splitting. These changes were accompanied with significant contraction, which had an amplitude comparable to that of the tonic component of 50 mmol/l K+-induced contraction. Calcium-free solution caused membrane depolarisation, reduction of the slow wave amplitude and frequency, disappearance of APs and decreased the mechanical tension of the preparations. Application of H2O2 (1 mmol/l) into the zero-calcium bath solution recovered the APs, which was accompanied by a low amplitude contraction. H2O2 (up to 1 mmol/l) increased the L-type calcium current (I(Ca)) both under conventional whole-cell patch-clamp configuration and under amphotericin-perforated patches by 16 +/- 3%. These data demonstrated that contractile response of the ileum longitudinal smooth muscle preparation evoked by H2O2 was mainly due to the enhanced electrical activity.

[Transfer factor modulates inhibitory action of neurotransmitters on intestinal smooth muscles]. / Faktor perenosu moduliuie hal'mivnu diiu neiromediatoriv na hladen'ki m'iazy kyshechnyka.

It has been shown that Transfer factor (TF) to Staphilococcus aureus antigens blocked ATP-induced component of the inhibitory junction potential in taenia coli smooth muscle from guinea-pig, and converted an inhibitory action of exogenous ATP into an exciting one (instead of the hyperpolarization of the smooth muscle, TF induced its depolarization). TF at 10-6 mg/ml converted the relaxing effects of sodium nitroprusside (nitric oxide donor) into exciting ones in smooth muscle strips. Higher concentrations (10-5-10-3 mg/ml) of TF slightly amplified the relaxing effect of sodium nitroprusside. Both a- and b-adrenergic activation in taenia coli smooth muscle were not sensitive to that agent.

[Spontaneous transient outward currents in smooth muscle cells of the rat tail artery]. / Spontanni vykhidni strumy gladen'kom'iazovykh klityn khvostovoi arteriï shchura.

Spontaneous transient outward currents (STOCs) were studied in the rat tail artery smooth muscle cells using standard patch-clamp recording techniques in the whole-cell configuration. STOCs evoked by membrane depolarization from -30 to 20 mV varied in size from 50 to 1000 pA, their amplitude increased with membrane depolarization. These currents were inhibited by 1 mM TEA+. Both the frequency and the transferred charge (Q) were decreased in the absence of the extracellular Ca2+ or in the presence of the selective blocker of voltage-gated L-type Ca2+ channels nifedipine. Application of caffeine at 1 mM increased both Q and the frequency of STOCs generation. These results indicate that STOCs are carried by large conductance Ca(2+)-dependent K+ channels and Ca2+ influx plays an important role in their activation.

[The role of voltage gated K(+) channels in the modulation of resting membrane potential of myocytes isolated from rat resistance arteries]. / Rol' potentsialkerovannykh kaliievykh kanaliv u formuvanni membrannoho potentsialu spokoiu miotsytiv rezystyvnykh arteriï shchura.

K+ current which take part in the controlling of membrane potential in myocytes isolated from rat resistance mesenteric arteries have been investigated using conventional patch clamp method. The mean resting potential of myocytes was--37 mV. Charybdotoxin (200 nM)--selective blocker of large conductance Ca(2+)-activated K+ (KCa) channels--inhibited transmembrane outward K+ current by 60%. 1 mM of tetraethylammonium inhibited outward K+ current same as 200 nM of charybdotoxin, also it inhibited spontaneous spike-like hyperpolarizations and did not affect the membrane potential. Transmembrane current had a 4 aminopyridine (4-AP) sensitive component of delayed rectifier current (KV). Addition of 5 mM of 4-AP evoked membrane depolarization with mean significance of 12.0 +/- 1.5 mV in 5 from 7 single myocytes which had resting potential in the range of -50 ... -35 mV. The obtained results suggest that large conductance KCa channels do not determine the resting potential, but may serve as a negative feedback mechanism at the considerable membrane depolarization. In contrast, 4-AP sensitive KV current take part in the controlling of the resting membrane potential of single myocytes from rat resistance mesenteric arteries.

Voltage-dependent inhibition of the muscarinic cationic current in guinea-pig ileal cells by SK&F 96365.

The effects of SK&F 96365 on cationic current evoked either by activating muscarinic receptors with carbachol or by intracellularly applied GTPgammaS (in the absence of carbachol) were studied using patch-clamp recording techniques in single guinea-pig ileal smooth muscle cells. SK&F 96365 reversibly inhibited the muscarinic receptor cationic current in a concentration-, time- and voltage-dependent manner producing concomitant alteration of the steady-state I-V relationship shape which could be explained by assuming that increasing membrane positivity increased the affinity of the blocker. The inhibition was similar for both carbachol- and GTPgammaS-evoked currents suggesting that the cationic channel rather than the muscarinic receptor was the primary site of the SK&F 96365 action. Increased membrane positivity induced additional rapid inhibition of the cationic current by SK&F 96365 which was more slowly relieved during membrane repolarization. Both the inhibition and disinhibition time course could be well fitted by a single exponential function with the time constants decreasing with increasing positivity for the inhibition (e-fold per about 12 mV) and approximately linearly decreasing with increasing negativity for the disinhibition. At a constant SK&F 96365 concentration, the degree of cationic current inhibition was a sigmoidal function of the membrane potential with a potential of half-maximal increase positive to about +30 mV and a slope factor of about -13 mV. Increasing the duration of voltage steps at -80 or at 80 mV, increased the percentage inhibition; the degree of inhibition was almost identical at both potentials providing evidence that the same cationic channel was responsible for the cationic current both at negative and at positive potentials. It is concluded that the distinctive and unique mode of SK&F 96365 action on the muscarinic receptor cationic channel is a valuable tool in future molecular biology studies of this channel.

[Transmembrane ionic currents in smooth muscle cells of rat tail artery]. / Transmembranni ionni strumy hladen'kom'iazovykh klityn khvostovoï arteriï shchura.

Whole-cell currents in single smooth muscle cells freshly isolated from the rat tail artery have been studied using patch-clamp recordings techniques. Outward current evoked by depolarizing steps from -70 mV consisted of the initial fast and subsequent sustained components. The former was inhibited by 10 mM nifedipine and Ca(2+)-free solution application whereas the latter decreased by only 16% under these conditions. Caffeine at 4 mM abolished the fast component and only slightly reduced the sustained component. Both component were inhibited by 1 mM TEA+. Adding 10 mM EGTA to the pipette solution abolished the fast outward current. In the presence of 10 mM TEA+ and 4 mM 4-AP an inward current was unmasked. These results suggest that the outward current in these cells is carried mainly via delayed rectifier and Ca(2+)-activated K(+)-channels. 4-AP inhibited the sustained component and had no effect on the initial fast outward current, thus A-current is apparently absent.

TTX-sensitive Na(+) and nifedipine-sensitive Ca(2+) channels in rat vas deferens smooth muscle cells.

The inward currents in single smooth muscle cells (SMC) isolated from epididymal part of rat vas deferens have been studied using whole-cell patch-clamp method. Depolarising steps from holding potential -90 mV evoked inward current with fast and slow components. The component with slow activation possessed voltage-dependent and pharmacological properties characteristic for Ca(2+) current carried through L-type calcium channels (I(Ca)). The fast component of inward current was activated at around -40 mV, reached its peak at 0 mV, and disappeared upon removal of Na ions from bath solution. This current was blocked in dose-dependent manner by tetrodotoxin (TTX) with an apparent dissociation constant of 6.7 nM. On the basis of voltage-dependent characteristics, TTX sensitivity of fast component of inward current and its disappearance in Na-free solution it is suggested that this current is TTX-sensitive depolarisation activated sodium current (I(Na)). Cell dialysis with a pipette solution containing no macroergic compounds resulted in significant inhibition of I(Ca) (depression of peak I(Ca) by about 81% was observed by 13 min of dialysis), while I(Na) remained unaffected during 50 min of dialysis. These data draw first evidence for the existence of TTX-sensitive Na(+) current in single SMC isolated from rat vas deferens. These Na(+) channels do not appear to be regulated by a phosphorylation process under resting conditions.