In vivo acute performance of the Cleveland Clinic self-regulating, continuous-flow total artificial heart

BACKGROUND

The purpose of this study was to evaluate the acute in vivo pump performance of a unique valveless, sensorless, pulsatile, continuous-flow total artificial heart (CFTAH) that passively self-balances left and right circulations without electronic intervention.

METHODS

The CFTAH was implanted in two calves, with pump and hemodynamic data recorded at baseline over the full range of pump operational speeds (2,000 to 3,000 rpm) in 200-rpm increments, with pulsatility variance, and under a series of induced hemodynamic states created by varying circulating blood volume and systemic and pulmonary vascular resistance (SVR and PVR).

RESULTS

Sixty of the 63 induced hemodynamic states in Case 1 and 73 of 78 states in Case 2 met our design goal of a balanced flow and maximum atrial pressure difference of 10 mm Hg. The correlation of calculated vs measured flow and SVR was high (R(2) = 0.857 and 0.832, respectively), allowing validation of an additional level of automatic active control. By varying the amplitude of sinusoidal modulation of the speed waveform, 9 mm Hg of induced pulmonary and 18 mm Hg of systemic arterial pressure pulsation were achieved.

CONCLUSIONS

These results validated CFTAH self-balancing of left and right circulation, induced arterial flow and pressure pulsatility, accurate calculated flow and SVR parameters, and the performance of an automatic active control mode in an acute, in vivo setting in response to a wide range of imposed physiologic perturbations.

Novel implantable device to detect cardiac allograft rejection

BACKGROUND

Allograft rejection remains the nemesis of solid organ transplantation. Soul Mate is a novel implantable wireless data transmission system that analyzes 9 intramyocardial electrogram parameters recorded from 4 or 6 configurations of 2 or 3 epicardial leads to detect allograft rejection. This study determined the ability of the Soul Mate to detect early rejection of transplanted hearts.

METHODS AND RESULTS

Five dogs underwent heterotopic cervical heart transplantation and simultaneous implantation of the Soul Mate's Cardiac Rejection Monitoring Device. Dogs were initially immunosuppressed, but subsequent drug discontinuation allowed allograft rejection to appear. Allograft biopsies were performed at regular intervals to determine rejection grade, which was compared to a calculated rejection score determined as percent change from baseline of values for each intramyocardial electrogram. There was significant correlation between the biopsy results and the evolution of 5 parameters. The strongest correlation (r=0.939; P<0.001) was obtained using the "general median" parameter from 4 configurations, assessed 1 day before the biopsy, with a sensitivity of 85.7% and a specificity of 100% compared to the myocardial biopsy results.

CONCLUSIONS

The Soul Mate allograft rejection monitoring system accurately detected transplanted heart rejection in a canine model noninvasively with continuous sampling. This proof-of-concept study suggests that the Soul Mate could be used to more intensely and more frequently monitor cardiac allografts for rejection.

Spin-related current suppression in a semiconductor quantum dot spin-diode structure

We experimentally study the transport features of electrons in a spin-diode structure consisting of a single semiconductor quantum dot (QD) weakly coupled to one nonmagnetic and one ferromagnetic (FM) lead, in which the QD has an artificial atomic nature. A Coulomb stability diamond shows asymmetric features with respect to the polarity of the bias voltage. For the regime of two-electron tunneling, we find anomalous suppression of the current for both forward and reverse bias. We discuss possible mechanisms of the anomalous current suppression in terms of spin blockade via the QD-FM interface at the ground state of a two-electron QD.

Clinical role of regulatory T cell in intraductal papillary mucinous neoplasms

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Background: Intraductal papillary mucinous neoplasms of pancreas (IPMNs) have malignant potential and exhibit a broad histologic spectrum, ranging from adenoma to invasive carcinoma. Recently, several investigators have reported that regulatory T cells (Foxp3+CD4+ T cells including CD4+CD25+ T cells and CD4+CD25- T cells) play important roles in anti-tumor immunity. We previously reported clinical role of increased populations of Foxp3+CD4+ T cells (Treg) in peripheral blood from advanced pancreatic cancer patients (Pancreas 2006). This study was conducted to clarify the clinical role of Treg for surveillance of IPMNs. Methods: Thirty-five patients with IPMNs (IPMC: n=8, IPMB: n=2, IPMA: n=5) and pancreas cancer (n=20) who underwent surgical resection were included in this study. Peripheral blood was withdrawn from IPMN patients (IPMC: n=5, IPMA: n=2) and PC patients (n=20), as well as healthy volunteer donors (n=20) as controls. The peripheral blood mononuclear cells (PBMCs) were subjected to FACScan analysis after labeling with anti-CD4, anti-CD25, and anti-Foxp3 antibodies. Immunohistochemical expression of Foxp3 (abcam: FOXP3 antibody, 236A/E7), Fascin (Dako: Fascin antibody, 55K-2) and TGF-β (Santa Cruz: TGF-β1 antibody, SC146) in main tumor was assessed in all IPMN patients. Results: The Treg population among the PBMCs was significantly increased in IPMC patients (median: 4.50%) and PC patients (median: 3.06%) compared with healthy donors (median: 1.30%). No significant difference in the Treg population among the PBMCs was observed between IPMC and PC patients. On the other hand, in IPMA patients (n=2), the Treg population among the PBMCs was equivarent to healthy donors (2.40 and 1.85% respectively). In immnohistochemical staining, the positive expression of Foxp3 was 87.5% (7 of 8) in IPMC patients, while in IPMA and IPMB patients, the expression of Foxp3 was not observed. The expression of Fascin and TGF-β was not correlated to malignant potential of IPMNs Conclusions: Increase of Foxp3+CD4+ T cells in the PBMCs is a new promising marker for malignant potential in IPMNs patients.

No significant financial relationships to disclose.

Quantitative estimation of exchange interaction energy using two-electron vertical double quantum dots

We use Pauli-spin blockade in two-electron vertical double quantum dots to quantitatively estimate the exchange energy J in a wide range of interdot level detuning Delta and fully compare it with calculations. Pauli-spin blockade is lifted via a singlet- (S-)triplet (T) transition mediated by hyperfine coupling, which abruptly occurs in our devices when the S-T transition energy or J is compensated by the Zeeman energy. We use this feature to derive J depending on Delta between the S-S and T-T resonances. The obtained J versus Delta including the resonance effect is perfectly reproduced by Hubbard model calculations.

Design of high-Q photonic crystal microcavities with a graded square lattice for application to quantum cascade lasers

A high-Q photonic crystal (PC) microcavity for TM-like modes, which can be applied to quantum cascade lasers (QCLs), was successfully designed in an air-hole based PC slab with semiconductor cladding layers. In spite of no photonic badgaps for TM-like modes in air-hole based PC slabs, cavity Q reached up to 2,200 by utilizing a graded square lattice PC structure. This is approximately 18 times higher than those previously reported for PC defect-mode microcavities for QCLs. This large improvement is attributed to a suppression of the coupling between the cavity mode and the leaky modes thanks to the dielectric perturbation in the graded structure. We also predicted a dramatic reduction of the threshold current in the designed cavity down to one-fifteenth of that of a conventional QCL, due to a decreased optical volume.

The bite-raised condition enhances the aging process in the dorsal and ventral hippocampus

The bite raised condition decreases the number of neurons and increases the amount of glial fibrillary acidic protein in the hippocampus of aged SAMP8 mice. In the present study, we examined whether these effects differ between the dorsal and ventral hippocampus. In bite-raised SAMP8 mice, the number of neurons was significantly lower in the hippocampal CA1 and dentate gyrus (DG) subfields compared to control mice. In the bite raised condition, the number of neurons was significantly lower in both the dorsal and ventral CA3 subfields, and the number of glial fibrillary acidic protein-labeled astrocytes was increased in the CA1, CA3, and DG subfields, compared to control mice. These data suggest that in aged SAMP8 mice, the bite-raised condition enhanced aging processes in both the dorsal and ventral hippocampus.

Median sternotomy approach for chronic bovine experiments

Lateral thoracotomy is the traditional surgical approach for preclinical animal testing of various ventricular assist devices. Median sternotomy, however, is regarded from a functional standpoint as the most appropriate approach for cardiac surgical procedures, particularly for device implantation. The purpose of this study was to evaluate the outcomes of performing a median sternotomy in chronic bovine studies. Three chronic studies using the sternotomy approach were performed. Surgical access was compared to the lateral thoracotomy approach used in three other animal experiments. Postoperative speed of recovery, pain management, sternotomy incision, and monitoring line exit site healing and infection were also evaluated. With sternotomy, better surgical access to all cardiac chambers and great vessels and more room for device placement were achieved. The recovery time was similar to that using the lateral thoracotomy approach, with no additional difficulties observed in standing or recumbency and no need for increased pain management. At the time of autopsy, the sternum was well healed without any sign of infection. In conclusion, these studies showed that a median sternotomy can be used successfully for chronic bovine studies. This approach will be used for our future biventricular assist device implantation surgeries.

Plical resection in pre-temporal approach for basilar bifurcation aneurysms: preliminary surgical experience and cadaveric study

OBJECT

Although a pre-temporal approach (PA) can provide a wide space for preservation of thalamoperforating atrteries in direct surgery for basilar bifurcation aneurysms (BBAs), it cannot always secure adequate proximal control. The authors described the advantages of plical resection added to PA for BBAs.

METHODS

Between October 1998 and April 2000, eight consecutive patients with BBAs were treated in the neurosurgical department of Kurashiki Central Hospital. Among them, five patients received direct clipping using this method. There were four females and one male, ages ranging from 61 to 77 (mean 70.8 years). Mean aneurysmal size and distance between the in"terclinoidal line and the aneurysmal neck was 4.5 and 9.5 mm, respectively. The operative procedures consisted of the following components; 1) fronto-temporal craniotomy with translocation of orbito-zygomatico-malar bone for PA, 2) preservation of lateral branches of the superficial sylvian veins, 3) resection of plica dural folds to increase the operative field up to the oculomotor nerve (OMN).

RESULTS

Complete clipping was achieved without thalamic infarction or temporal contusion in all patients. Three of the five patients suffered from transient right OMN palsy which recovered within two months after surgery.

CONCLUSION

Plical resection in the pre-temporal approach might be beneficial in the surgical treatment of BBAs when proximal control seems difficult.

The bite-raised condition in aged SAMP8 mice reduces the expression of glucocorticoid receptors in the dorsal and ventral hippocampus

In the present study, we examined whether the effects induced by the bite-raised condition on glucocorticoid receptor (GR) expression differ between the dorsal and ventral hippocampus in SAMP8 mice. In the bite-raised condition, the number of GR-immunoreactive cells was significantly decreased in both the dorsal and ventral CA1 and dentate gyrus (DG) subfields of the hippocampus compared to control mice, as revealed by immunohistochemical analysis. The decrease in the number of GR-immunoreactive cells tended to be greater in the dorsal hippocampus than in the ventral hippocampus. Only in the DG subfield was there a significant difference in the number of GR-immunoreactive cells between the dorsal and ventral hippocampus. These findings suggest that in aged SAMP8 mice, the bite-raised condition decreases the number of GR-immunoreactive cells in both the dorsal and ventral hippocampus.

Increase of Q-factor in photonic crystal H1-defect nanocavities after closing of photonic bandgap with optimal slab thickness

We investigate the dependence of quality factor Q of dipole modes in photonic crystal H1-defect nanocavity on the slab thickness and observe an increase of Q even after closing of the photonic bandgap both in numerical simulation and experimentation. This counter intuitive behavior results from the weak coupling between the cavity mode and the 2nd-guided mode in the photonic crystal slab. This is confirmed by computing the overlap between them in the momentum space.

Molecular analysis of Clostridium difficile at a university teaching hospital in Japan: a shift in the predominant type over a five-year period

Clostridium difficile isolates recovered from patients admitted to a teaching hospital in Japan over a 5-year period were analyzed. Two molecular typing systems, PCR ribotyping and pulsed-field gel electrophoresis (PFGE) analysis, were used. Twenty-six PCR ribotypes were found among the 148 isolates. The predominant type at our hospital appeared to shift during the study period, from PCR ribotype a in 2000 (15/33, 45%) to PCR ribotype f in 2004 (18/28, 64%). By using PFGE with thiourea added to both the gel and running buffer, all 148 Clostridium difficile isolates were successfully classified into 37 types and 61 subtypes. The PCR ribotype f isolates were further classified into four types and 11 subtypes by PFGE. The PFGE patterns of the 11 subtypes differed from each other by only 1 to 4 bands, suggesting that these differences might reflect genetic changes during patient-to-patient transmission over the 5-year period analyzed, and that PCR ribotype f isolates might be outbreak-related. In addition, the PCR ribotype f was identical to the PCR ribotype designated smz, which is reported to have caused multiple outbreaks in Japan. These results confirmed that PCR ribotype f (type smz) has specific virulence or survival factors that make it more likely to cause nosocomial outbreaks at Japanese hospitals. PCR ribotype 027, which has been reported to have caused recent outbreaks in North America and Europe, was recovered from one patient in this study; however, this strain was community-acquired. Our findings emphasize the importance of monitoring specific strains to control and prevent nosocomial infection.

Duration-dependent effects of the bite-raised condition on hippocampal function in SAMP8 mice

We evaluated the effect of the duration of occlusal disharmony induced chronic stress on hippocampal function by examining spatial memory in the Morris water maze and on the number of hippocampal neurons in aged senescence-accelerated prone (SAMP8) mice. The bite of SAMP8 mice was raised 0.1 mm using dental adhesive. Groups of mice were tested in the Morris water maze 8, 11, or 22 d after raising the bite. The results indicated that the longer the duration of the bite-raised condition, the greater the impairment in spatial learning ability and the greater the decrease in the number of neurons in the hippocampal CA3 subfield. Thus, behavioral and morphologic deficits induced by the bite-raised condition in aged SAMP8 mice are influenced by the duration of the occlusal disharmony.

Development of a two-dimensional dual pendulum thrust stand for Hall thrusters

A two-dimensional dual pendulum thrust stand was developed to measure thrust vectors [axial and horizontal (transverse) direction thrusts] of a Hall thruster. A thruster with a steering mechanism is mounted on the inner pendulum, and thrust is measured from the displacement between inner and outer pendulums, by which a thermal drift effect is canceled out. Two crossover knife-edges support each pendulum arm: one is set on the other at a right angle. They enable the pendulums to swing in two directions. Thrust calibration using a pulley and weight system showed that the measurement errors were less than 0.25 mN (1.4%) in the main thrust direction and 0.09 mN (1.4%) in its transverse direction. The thrust angle of the thrust vector was measured with the stand using the thruster. Consequently, a vector deviation from the main thrust direction of +/-2.3 degrees was measured with the error of +/-0.2 degrees under the typical operating conditions for the thruster.

Occlusal disharmony attenuates glucocorticoid negative feedback in aged SAMP8 mice

To evaluate the mechanism underlying impaired cognitive function due to occlusal disharmony, we examined the effect of the bite-raised condition on spatial performance and hippocampal expression of glucocorticoid receptors (GR) and glucocorticoid receptor messenger ribonucleic acid (GRmRNA) using behavioral, immunohistochemical, and in situ hybridization techniques. Learning ability in the water maze test was significantly impaired in aged bite-raised mice compared with age-matched control mice. There was no difference between control and bite-raised young and middle-aged mice. Also, immunohistochemical and in situ hybridization analysis showed that the bite-raised condition enhanced the age-related decrease in GR and GRmRNA expression in the hippocampus. In particular, GR and GRmRNA expressions were significantly decreased in aged bite-raised mice compared to age-matched control mice. These findings suggest that the bite-raised condition in aged SAMP8 mice decreases GR and GRmRNA, which impairs the hypothalamic-pituitary-adrenal feedback inhibition, thereby leading to memory deficits.

Microfiberscope coaxial technique in neuroendoscopic surgery

Exploration in neuroendoscopic surgery is occasionally insufficient because of the structural limitations in endoscope. It is not easy to identify the precise position of the endoscope during an operation. We here show a coaxial technique for neuroendoscopic exploration with monitoring by means of a microfiberscope. The endoscopic coaxial technique consists of two scopes. The microfiberscope has a diameter of 0.75 mm, flexible body and high-quality image system. We tested its ability to visualize the subject at several distances and applied this coaxial technique in neuroendoscopic surgery. The microfiberscope not only visualizes the object but also magnifies it by a distance. The scope was easy to handle with monitoring of its movement in the endoscopic view. The technique allowed us to safely explore details which are difficult to approach with an ordinary fiberscope or rigid-rod scope. The microfiberscope also adjusts to the neuronal anatomy and many clinical situations. Taken together, the microfiber coaxial technique might offer new advantages to modern neuroendoscopic surgery.

First isolation of Clostridium difficile 027 in Japan

We report the first isolation of a variant strain of Clostridium difficile from a patient with pseudomembranous colitis in Japan. The strain was chararacterised as North American pulsed field gel electrophoresis type 1 (NAP1), PCR ribotype 027, toxinotype III.

Transformation of Acinetobacter sp. BD413 with DNA from commercially available genetically modified potato and papaya

AIM

To estimate the likelihood of transfer of kanamycin-resistance gene (nptII) from commercially available genetically modified (GM) plants.

METHODS AND RESULTS

Acinetobacter sp. BD413 carrying a plasmid containing an inactivated nptII gene was treated with DNA derived from GM potato and GM papaya. Kanamycin-resistant transformants were obtained at a frequency of 10-30 microg(-1) DNA. Calculation of the results suggested that 6-9 x 10(4) molecules of genomic DNA from GM plants were needed to obtain one transformant. However, such transformation events were not detectable in the absence of the plasmid in the host strain.

CONCLUSIONS

Acinetobacter sp. BD413 was transformed with DNA derived from GM potato and GM papaya, in the presence of an inactivated nptII gene on a plasmid. However, the frequency of such events in the natural environment on wild-type strains, while evidently low, remains unknown.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results may help to evaluate potential risks associated with the use of antibiotic-resistance determinants as genetic markers in GM plants. Complete risk assessment must consider factors other than transformation frequency alone, including the natural background of antibiotic resistance present in bacterial populations, and the spectrum and clinical use of the antimicrobial agents in question.