[Clinical and laboratory characteristics in patients with myeloid neoplasms complicated with clonal T large granular lymphocyte proliferation]

Objective: To analyze the clinical manifestations and laboratory features in patients with myeloid neoplasms complicated with clonal T large granular lymphocyte (T-LGL) proliferation. Methods: The clinical data of 5 patients with myeloid neoplasms complicated with clonal T-LGL proliferation from November 2017 to November 2018 in Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College were analyzed retrospectively. Results: The median age was 60 years old. All patients had a history of abnormal peripheral blood cell counts for over 6 months. The absolute lymphocyte count in peripheral blood was less than 1.0×10(9)/L. In addition to the typical T-LGL phenotype, the immunophenotype was heterogenous including CD4(+)CD8(-) in 2 patients, the other 3 CD4(-)CD8(+). Four patients were αβ type T cells, the other one was γδ type. STAT3 mutation was detected in 1 patient by next-generation sequencing, the other 4 cases were negative. Conclusions: Clonal T-LGL proliferation with myeloid neoplasm develops in an indolent manner, mainly in elderly patients. Hemocytopenia is the most common manifestation. The diagnosis of T-LGL proliferation does not have specific criteria, that it should be differentiated from other T cell proliferative disorders, such as T-cell clones of undetermined significance. STAT3 or STAT5b mutation may help distinguish.

Size and shape of nanoclusters: single-shot imaging approach

A method of single-shot imaging via aberration-corrected scanning transmission electron microscopy equipped with high angle annular dark-field detector (STEM-HAADF) has been applied to size-selected gold model catalysts (Au(25) and Au(39) ) on hydroxyapatite. Through quantitative intensity analysis, the size, in terms of number of atoms as well as 3D shape of the clusters are obtained.

Mechanism and selectivity of the effects of halothane on gap junction channel function

Volatile anesthetics alter tissue excitability by decreasing the extent of gap junction-mediated cell-cell coupling and by altering the activity of the channels that underlie the action potential. In the present study, we demonstrate, using dual whole-cell voltage-clamp techniques, that coexpression of connexin (Cx) 40 and Cx43 rendered cells more sensitive to uncoupling by halothane than cells that express only Cx40 or only Cx43. The halothane-induced reduction in junctional conductance was caused by decreased channel mean open time and increased channel mean closed time. The magnitude of the effect of halothane on channel open time was least for Cx40-like channels and greatest for heteromeric channels. Thus, the data indicate that halothane gates gap junction channels to the closed state in a dose-dependent and connexin-specific manner. One consequence of the selectivity of halothane is that the profile of single-channel events observed in the presence of halothane may not be quantitatively representative of the population of channels contributing to macroscopic conductance in cells that express more than one connexin. In addition, in tissues that express multiple connexins, such as heart and blood vessels, the capacity of the gap junctions to transmit electrical and chemical signals in the presence of halothane could vary according to the pattern of connexin expression.

Formation of heteromeric gap junction channels by connexins 40 and 43 in vascular smooth muscle cells

Connexin (Cx) 43 and Cx40 are coexpressed in several tissues, including cardiac atrial and ventricular myocytes and vascular smooth muscle. It has been shown that these Cxs form homomeric/homotypic channels with distinct permeability and gating properties but do not form functional homomeric/heterotypic channels. If these Cxs were to form heteromeric channels, they could display functional properties not well predicted by the homomeric forms. We assessed this possibility by using A7r5 cells, an embryonic rat aortic smooth muscle cell line that coexpresses Cxs 43 and 40. Connexons (hemichannels), which were isolated from these cells by density centrifugation and immunoprecipitated with antibody against Cx43, contained Cx40. Similarly, antibody against Cx40 coimmunoprecipitated Cx43 from the same connexon fraction but only Cx40 from Cx (monomer) fractions. These results indicate that heteromeric connexons are formed by these Cxs in the A7r5 cells. The gap junction channels formed in the A7r5 cells display many unitary conductances distinct from homomeric/homotypic Cx43 or Cx40 channels. Voltage-dependent gating parameters in the A7r5 cells are also quite variable compared with cells that express only Cx40 or Cx43. These data indicate that Cxs 43 and 40 form functional heteromeric channels with unique gating and conductance properties.

Bio-battery signal predicts myocardial lesion formation and depth in vitro

AIMS

The aim of this study was to determine if the bio-battery signal can predict myocardial lesion formation and depth.

METHODS

Fresh bovine ventricular myocardium was immersed in a temperature-controlled bath of circulating blood. RF energy was delivered with a custom generator to a catheter electrode. RF energy, electrode temperature, bio-battery signal and tissue impedance were displayed and recorded. A copper return plate was placed in the bath.

RESULTS

When 50 volts of constant RF energy was terminated at a 20, 40, or 60% decline from the maximum bio-battery signal, the lesion depth was 4 +/- 0.4 mm. When RF energy application was terminated later, at a point characterized by a brief change of slope of the bio-battery signal, the lesions measured 7.8 +/- 1.4 mm in depth. This "bump" occurred before a rapid impedance rise.

CONCLUSION

The depth of lesions created at the "bump" point was almost two-fold deeper than those at the termination points of 20, 40 and 60% bio-battery decrease (p = 0.0001). When RF energy was terminated at the rapid impedance rise the lesions were similar in depth, 8.2 +/- 0.9 mm, to those obtained when RF energy was stopped at the "bump" (p = 0.28). The bio-battery signal provides a unique marker that might be useful to obtain maximum lesion depth while avoiding rapid impedance rise.

Cylindrical ultrasonic transducers for cardiac catheter ablation

This study was designed to evaluate the feasibility of using cylindrical ultrasound transducers mounted on a catheter for the ablation of cardiac tissues. In addition, the effects of ultrasound frequency and power was evaluated both using computer simulations and in vitro experiments. Frequencies of 4.5, 6, and 10 MHz were selected based on the simulation studies and manufacturing feasibility. These transducers were mounted on the tip of 7-French catheters and applied in vitro to fresh ventricular canine endocardium, submerged in flowing degassed saline at 37 degree C. When the power was regulated to maintain transducer interface temperature at 90-100 degree C, the 10-, 6-, and 4.5-MHz transducers generated a lesion depth of 5.9 +/- 0.2 mm, 4.6 +/- 1.0 mm, and 5.3 +/- 0.9 mm, respectively. The 10-MHz transducer was chosen for the in vivo tests since the maximum lesion depth was achieved with the lowest power. Two dogs were anesthetized and sonications were performed in both the left and right ventricles. The 10-MHz cylindrical transducers caused an average lesion depth of 6.4 +/- 2.5 mm. In conclusion, the results show that cylindrical ultrasound transducers can be used for cardiac tissue ablation and that they may be able to produce deeper tissue necrosis than other methods currently in use.

Simultaneous multipolar radiofrequency ablation in the monopolar mode increases lesion size

Delivery of radiofrequency (RF) energy from the distal tip of electrophysiology catheters produces lesions that may be too small to ablate arrhythmogenic sites during a single application of RF energy. To produce larger lesions, we delivered RF energy via a quadripolar catheter in which all four electrodes were connected in unipolar fashion. The catheter (Webster Labs) had a 4-mm tip, 2-mm ring electrodes, and 2-mm interelectrode distance. Lesion size was compared using RF energy delivered in a multipolar configuration with that delivered only to the distal tip using fresh bovine ventricular tissue. In vivo, RF lesions were made in dogs using the distal tip as well as all four poles of the same catheter inserted percutaneously. RF energy was delivered using a constant voltage at a frequency of 400 kHz. Preliminary experiments were conducted to determine the maximum power deliverable without coagulation using each electrode configuration. The use of simultaneous multipolar RF ablation produced significantly larger lesions both in vitro and in vivo. The length of the lesion was increased by a factor of approximately 2 in both the in vitro and in vivo experiments. There was a trend toward an increasing depth of the lesion by simultaneously applying RF energy to all four electrodes. Lesion width was significantly increased in the in vivo studies. We concluded that simultaneous multipolar delivery of RF energy produces larger lesions than can be obtained with delivery of RF energy to the distal tip alone. This technique may offer a means of increasing lesion size, leading to a decrease in the number of applications of RF energy necessary for ablation of arrhythmias.

Comparison of gold versus platinum electrodes on myocardial lesion size using radiofrequency energy

During radiofrequency (RF) catheter ablation of arrhythmias, temperatures that approach 100 degrees C cause a coagulum to form on the ablation electrode that results in an increase in electrical impedance and prevents further energy delivery. Since gold has nearly four times the thermal conductivity as platinum, the metal commonly used, it was postulated that gold tip electrodes could deliver more power and produce deeper lesions because of its greater heat dissipation from the electrode-tissue interface to the circulating blood. To test this hypothesis, RF energy was applied to fresh bovine ventricular myocardium using 6 French catheters with 2-mm long distal electrodes made from gold or platinum. Similar studies were also conducted using 7 French catheters with 4-mm long distal electrodes. Maximum lesion depth was defined as that produced with the level of energy just below that causing an impedance rise. A maximum lesion depth of 6.2 +/- 0.7 mm (mean +/- SD) was obtained with the gold 2-mm electrode and 4.7 +/- 0.5 mm with the platinum electrode (P = 0.003). The 4-mm gold electrode produced a maximum lesion depth of 7.2 +/- 1.4 mm, while a catheter with a 4-mm platinum electrode caused a maximum lesion depth of 5.8 +/- 0.7 mm (P = 0.05). We conclude that deeper lesions should be able to be made when RF energy is delivered to a gold rather than platinum tip electrode.

The feasibility of using ultrasound for cardiac ablation

The feasibility of using ultrasound to induce cardiac tissue necrosis for the treatment of arrhythmias was investigated. A theoretical model was used to optimize the operating frequency for necrosis of highly perfused muscle tissue. From these simulations it appeared that frequencies from 10-15 MHz produce the deepest lesions at ultrasound intensities between 15 and 30 W/cm2. Test catheters with a planar ultrasound transducer (diameter 2.3 mm = 7 F) were also constructed and in vitro and in vivo tests with canine heart muscle were performed. Both of these tests showed that the ultrasound catheters could deliver adequate energy to necrose cardiac tissue. The in vivo lesion depths of 5-9 mm indicated that ultrasound has significant potential for cardiac ablation for the treatment of arrhythmias.

Application of ultrasound energy for intracardiac ablation of arrhythmias

Ultrasound is a potential energy source for cardiac ablation. Small ultrasound applicators were tested for their ability to create lesions in cardiac tissue. Ultrasound applicators were designed, constructed and tested in canine cardiac tissue in degassed normal saline, and both in vitro and in vivo, lesions were produced by using transducers with frequencies of about 10 MHz. Lesion depth increased with longer duration of energy delivery from 15-60 s, and there was a linear relationship between increasing power and depth of lesions. Seven in vivo experiments in open-chest dogs were performed, and the ultrasound transducers were mounted on the tip of 7-French angiographic catheters. On the epicardium the maximum lesion depth was 9 mm. When the transducer was inserted into the left ventricle, lesions of 8.7 +/- 2.9 mm (n = 4) were produced. It is concluded that an ultrasound transducer mounted on a cardiac catheter can produce lesions that may be useful for ablation of cardiac arrhythmias.

Oxotremorine-M activates single nicotinic acetylcholine receptor channels in cultured Xenopus myocytes

Oxotremorine methiodide (oxotremorine-M) is the quaternary amine derivative of oxotremorine and is known to be a potent and oft-reported pure, muscarinic receptor agonist. We report here, for the first time, that oxotremorine-M also has strong nicotinic actions at the single channel level. Although previous reports have suggested that oxotremorine-M has mixed cholinergic properties, its nicotinic actions have only been reported in systems which contain both muscarinic and nicotinic receptors, or in skeletal neuromuscular systems where the site of action of oxotremorine-M may have been ambiguous. We tested the possibility that oxotremorine-M is a nicotinic receptor agonist by examining the responses of single nicotinic acetylcholine receptors in primary cultures of myocytes from skeletal myotomes of Xenopus larvae. Myotomal myocytes are known to express the nicotinic acetylcholine receptor and no evidence exists that muscarinic receptors are expressed in these progenitors of the skeletal musculature. Furthermore, because we used aneural myocyte cultures, the effects of oxotremorine-M cannot be attributed to action on presynaptic receptors. Using cell-attached patches, we compared the responses of the nicotinic acetylcholine receptors to suberyldicholine and oxotremorine-M. Our results show that (1) both agonists activate the receptor channel in nanomolar concentrations; (2) the mean channel open-time is significantly smaller in oxotremorine-M; and (3) activation of the nicotinic acetylcholine receptor by oxotremorine-M is accompanied by a large percentage of short openings and a high frequency of event flickering. We conclude that oxotremorine-M is a mixed function agonist, showing partial blocking behavior, which effectively activates pure nicotinic acetylcholine receptors.