Man-machine interaction-based phenotyping preprocedurally identifies patients with severe aortic stenosis, who will not recover from cardiac damage following transcatheter aortic valve replacement

Background

Severe aortic stenosis (AS) can lead to left heart dysfunction, pulmonary hypertension (PH), and eventually right heart failure. Clinical phenotypes therefore appear heterogeneous, depending on disease progression and comorbidities.

Purpose

This study therefore sought to improve diagnostic and prognostic resolution in patients undergoing transcatheter aortic valve replacement (TAVR) for severe AS by developing a man-machine interaction-based phenotyping approach.

Methods

Unsupervised agglomerative clustering was applied to preprocedural data from echocardiography and right heart catheterization from 366 consecutively enrolled patients undergoing TAVR for severe AS. Echocardiographic follow-up data, obtained on day 147±75.1 after TAVR, were available from 247 patients (67.5%).

Results

Cluster analysis revealed four distinct phenotypes, reflecting various extents of disease severity, and hence differing in mortality.

Patients from cluster 1 presented with preserved left ventricular ejection fraction (LVEF; 57.2±6.4%) and with normal mean pulmonary artery pressure (mPAP) levels (21.2±6.5 mmHg).

In contrast, patients in cluster 2 suffered from postcapillary PH (mPAP: 34.2±7.8 mmHg).

Left heart failure (LVEF: 42.4±15.7%), severe PH (mPAP: 46.9±8.5 mmHg), and right heart dysfunction (tricuspid annular plane systolic excursion [TAPSE]: 16.1±4.57 mm) characterized patients in cluster 3.

Patients from cluster 4 showed mild postcapillary PH (mPAP: 27.5±9.2 mmHg), yet dilatation of all heart chambers, biventricular dysfunction (LVEF: 47.3±12.2%, TAPSE: 16.8±4.5 mm), and a high prevalence of both mitral and tricuspid regurgitation (12.5% and 14.8%, respectively).

Correction of severe AS by TAVR significantly reduced the proportion of patients suffering from concurrent severe mitral regurgitation (from 9.29% to 3.64%, p-value: 0.0015). Moreover, pulmonary artery pressures were ameliorated (estimated systolic pulmonary artery pressure: from 47.2±15.8 mmHg to 43.3±15.1 mmHg, p-value: 0.0079). However, right heart dysfunction as well as the proportion of patients with severe tricuspid regurgitation remained unchanged. Clusters 3 and 4 with persistent right heart dysfunction ultimately displayed 2-year survival rates of 69.2% (95% CI: 56.6–84.7%) and 74.6% (95% CI: 65.9–84.4%), which were significantly lower compared to clusters 1 and 2 with little or no persistent cardiopulmonary impairment (88.3% [95% CI: 83.3–93.5%] and 85.5% [95% CI: 77.1–94.8%]).

Conclusion

This phenotyping approach preprocedurally identifies patients with severe AS, who will not recover from extra-aortic valve cardiac damage following TAVR and whose survival is therefore significantly reduced. Importantly, not the degree of PH at initial presentation, but the irreversibility of right heart dysfunction determines prognosis.

Funding Acknowledgement

Type of funding sources: None.

Sub-phenotyping of patients with severe aortic stenosis undergoing transcatheter aortic valve replacement by unsupervised agglomerative clustering of echocardiographic and hemodynamic data

Background

Severe aortic stenosis (AS) can trigger a deleterious cascade of impairments including left heart dysfunction, pulmonary hypertension (PH), and eventually right heart failure. Clinical phenotypes therefore appear heterogeneous, depending on disease progression and comorbidities.

Purpose

This retrospective analysis aims to categorize patients with severe AS according to clinical presentation by applying unsupervised machine learning in combination with an artificial neural network (ANN).

Methods

Unsupervised agglomerative clustering was applied to pre-procedural data from echocardiography and right heart catheterization from 366 consecutively enrolled patients undergoing transcatheter aortic valve replacement (TAVR) for severe AS at two tertiary centers in Germany between 2014 and 2020. Association between cluster and 2-year all-cause mortality after TAVR was assessed, and an ANN was trained to open the avenue to prospectively predict cluster assignment in future patients.

Results

Cluster analysis revealed four distinct phenotypes, reflecting various extents of disease severity, and hence differing in mortality.

Patients from cluster 1, constituting the majority of cases and hereinafter referred to as reference, presented with regular cardiac function and without PH. Accordingly, estimated 2-year survival was 90.6% (95% CI: 85.8–95.6%).

Contrarily, patients from smallest cluster 3 displayed most extensive disease characteristics, i.e. left and right heart dysfunction together with combined pre- and postcapillary PH, and their 2-year mortality was increased (2-year survival: 77.3% (95% CI: 65.2–91.6%), HR for 2-year mortality: 2.6 (95% CI: 1.1–6.2); p-value: 0.025).

Clusters 2 and 4 comprised patients suffering from postcapillary PH. Whilst patients from cluster 2 showed similar survival as cluster 1 (2-year survival: 85.8% (95% CI: 76.9–95.6%)), patients from cluster 4 with right atrial enlargement and high prevalence of severe tricuspid regurgitation (TR) deceased more often (2-year survival: 74.9% (95% CI: 65.9–85.2%), HR for 2-year mortality: 2.8 (95% CI: 1.4–5.5); p-value: 0.004).

After randomly dividing the study population into derivation and validation cohorts, an ANN could precisely predict cluster assignment (accuracy: 83.5%), significantly outperforming the no information rate (46.8%; p-value: 2.26e-15). Importantly, patients from high-risk clusters 3 and 4 were detected with high sensitivity (100.0% and 85.2%, respectively) and specificity (95.9% and 95.1%, respectively).

Conclusion

Expanding the analytical armamentarium by machine learning technology aids in capturing complex clinical presentations as observed in patients with severe AS. Assigning patients to clusters can thus facilitate a more sophisticated risk stratification in future clinical practice. Addressing irreversibility of PH and persistence of severe TR after TAVR should obtain paramount priority in order to improve long-term survival.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Mark Lachmann receives funding from Technical University of Munich (Clinician Scientist Grant).

P5411Prognostic communication with hospitalized heart failure patients; the patients' perspective

Background

Informing heart failure (HF) patients about their prognosis is an important part of clinical management, particularly at the time of hospitalization. Current European Society of Cardiology guidelines recommend communicating this information to HF patients at the time of hospitalization and with any change in clinical status. However, little is known about actual patient preferences, understanding, and attitudes towards prognostic communication with their treating physicians.

Methods

We surveyed 113 consecutive hospitalized HF patients in a single university hospital. We assessed patient understanding of prognosis (likelihood of survival beyond 2 years), and compared patient expectations to model predictions. Model-predicted 2-year survival rate was calculated by the Seattle Heart Failure Model (SHFM). We also assessed patient preferences for information disclosure using the Prognosis and Treatment Perception Questionnaire (PTPQ). The PTPQ assesses patient beliefs regarding 1) the importance of knowing about prognosis, 2) the importance of knowing about treatment option, and 3) frequency of having a conversation about prognosis during the hospital stay.

Results

Enrolled patients were predominantly male (65.5%), with a mean age of 73.6±9.6 years and mean left ventricular ejection fraction was 46.2±15.4%. Median SHFM-estimated 2-year survival rate was 89.2% (interquartile range: 83.8–92.9%). Overall, patient understanding about prognosis was suboptimal. Among patients with a guarded 2-year survival (SHFM <90%: N=60), 44% reported that their likelihood of 2-year survival was >90% (Figure; red box). However, among patients with favorable 2-year survival (>90%: N=53), 38% reported a likelihood of <90% (Figure; blue box). Regarding treatment options, most patients (98%) desired to learn as many details as possible. Responses varied with regard to information on individual prognosis; whereas 51% wanted to know more about prognosis than their present status alone, a significant number (28%) of subjects answered “never” or “less often” to a query on the frequency of discussion about prognosis. Patient preference for more information about prognosis was associated with female sex (odds ratio [OR]: 2.52; 95% confidence interval [CI]: 1.12–5.69), fewer symptoms of depression (1-point increase on Patient Health Questionnaire-2, OR: 0.66; 95% CI: 0.49–0.87), and previous stroke (OR: 2.92; 95% CI: 1.04–8.19), but not other social/demographic or clinical factors (e.g., age, education, caregiver support, HF phenotype and severity, and other comorbid conditions).

Figure 1

Conclusions

There were substantial discrepancies in patient understanding of prognosis and in desire for more information from physicians. Interventions to improve prognostic understanding are warranted for HF patients, and hospitalization for HF could represent an opportunity for optimization.

Temporal pattern recognition with delayed feedback spin-torque nano-oscillators

The recent demonstration of neuromorphic computing with spin-torque nano-oscillators has opened a path to energy efficient data processing. The success of this demonstration hinged on the intrinsic short-term memory of the oscillators. In this study, we extend the memory of the spin-torque nano-oscillators through time-delayed feedback. We leverage this extrinsic memory to increase the efficiency of solving pattern recognition tasks that require memory to discriminate different inputs. The large tunability of these non-linear oscillators allows us to control and optimize the delayed feedback memory using different operating conditions of applied current and magnetic field.

Vector network analyzer ferromagnetic resonance spectrometer with field differential detection

This work presents a vector network analyzer ferromagnetic resonance (VNA-FMR) spectrometer with field differential detection. This technique differentiates the S-parameter by applying a small binary modulation field in addition to the DC bias field to the sample. By setting the modulation frequency sufficiently high, slow sensitivity fluctuations of the VNA, i.e., low-frequency components of the trace noise, which limit the signal-to-noise ratio of the conventional VNA-FMR spectrometer, can be effectively removed, resulting in a very clean FMR signal. This paper presents the details of the hardware implementation and measurement sequence as well as the data processing and analysis algorithms tailored for the FMR spectrum obtained with this technique. Because the VNA measures a complex S-parameter, it is possible to estimate the Gilbert damping parameter from the slope of the phase variation of the S-parameter with respect to the bias field. We show that this algorithm is more robust against noise than the conventional algorithm based on the linewidth.

Enhancement of perpendicular magnetic anisotropy and its electric field-induced change through interface engineering in Cr/Fe/MgO

Recently, perpendicular magnetic anisotropy (PMA) and its voltage control (VC) was demonstrated for Cr/Fe/MgO. In this study, we shed light on the origin of large voltage-induced anisotropy change in Cr/Fe/MgO. Analysis of the chemical structure of Cr/Fe/MgO revealed the existence of Cr atoms in the proximity of the Fe/MgO interface, which can affect both magnetic anisotropy (MA) and its VC. We showed that PMA and its VC can be enhanced by controlled Cr doping at the Fe/MgO interface. For Cr/Fe (5.9 Å)/Cr (0.7 Å)/MgO with an effective PMA of 0.8 MJ/m³, a maximum value of the voltage-controlled magnetic anisotropy (VCMA) effect of 370 fJ/Vm was demonstrated due to Cr insertion.

Neuromorphic Computing through Time-Multiplexing with a Spin-Torque Nano-Oscillator

Fabricating powerful neuromorphic chips the size of a thumb requires miniaturizing their basic units: synapses and neurons. The challenge for neurons is to scale them down to submicrometer diameters while maintaining the properties that allow for reliable information processing: high signal to noise ratio, endurance, stability, reproducibility. In this work, we show that compact spin-torque nano-oscillators can naturally implement such neurons, and quantify their ability to realize an actual cognitive task. In particular, we show that they can naturally implement reservoir computing with high performance and detail the recipes for this capability.

Isolation and Characterization of Human Immunodeficiency Virus Type-1 Mutants Resistant to the Non-Nucleotide Reverse Transcriptase Inhibitor MKC-442

MKC-442, 6-benzy 1-1-ethoxymethyl-5-isopropyIuraciI (l-EBU), is a potent and selective non-nucleoside inhibitor of human immunodeficiency virus type-1 (HIV-1) reverse transcriptase (RT). Nevirapine, another non-nucleoside RT inhibitor (NNRTI), is associated with rapid emergence of drug-resistant variants during in vitro passages of HIV-1. The emergence of resistant viruses to MKC-442 or nevirapine was examined in vitro. MT-4 cells infected with a clinical isolate (HE) of HIV-1 were cultivated in medium containing excess concentrations of these drugs, and the drug susceptibilities of the breakthrough viruses recovered from the medium were measured. Although nevirapine lost its antiviral activity after six passages, a delay in the emergence of fully resistant viruses was observed for MKC-442. Two resistant clones for each drug were isolated and nucleotide sequences within the RT region were analysed. An amino acid substitution at position 181 (Tyr to Cys) was found, with additional substitutions at positions 103 (Lys to Arg) and 108 (Val to lle) in the MKC-442-resistant viruses. These clones showed various susceptibilities to MKC-442, and cross-resistance to other NNRTIs but not to AZT. These results suggest that the major binding site of MKC-442 on the HIV-1 RT is the tyrosine residue common to these NNRTIs, and that drug resistance to NNRTIs is dependent on both the quality and the quantity of mutations within the HIV-1 RT gene.

Spin-torque resonant expulsion of the vortex core for an efficient radiofrequency detection scheme

It has been proposed that high-frequency detectors based on the so-called spin-torque diode effect in spin transfer oscillators could eventually replace conventional Schottky diodes due to their nanoscale size, frequency tunability and large output sensitivity. Although a promising candidate for information and communications technology applications, the output voltage generated from this effect has still to be improved and, more pertinently, reduces drastically with decreasing radiofrequency (RF) current. Here we present a scheme for a new type of spintronics-based high-frequency detector based on the expulsion of the vortex core in a magnetic tunnel junction (MTJ). The resonant expulsion of the core leads to a large and sharp change in resistance associated with the difference in magnetoresistance between the vortex ground state and the final C-state configuration. Interestingly, this reversible effect is independent of the incoming RF current amplitude, offering a fast real-time RF threshold detector.

Abnormal neutrophil scattergram obtained using Pentra MS CRP in the patients with myelodysplastic syndrome showing dysgranulopoiesis

INTRODUCTION

Pentra MS CRP is an automated hematology analyzer capable of cytochemistry using Chlorazol black E, a lipid-staining agent, for white blood cell (WBC) differentials. Pentra MS CRP displays a WBC scattergram according to the cell volume obtained using flow impedance and light absorbance reflecting the Chlorazol black E (CBE)-positive lipid content.

METHOD

Neutrophil scattergrams obtained using Pentra MS CRP were compared between 5 patients with myelodysplastic syndrome (MDS) and normal controls. Sudan black B (SBB)-staining patterns of peripheral blood neutrophils were subdivided into four types (types I, II, III, and VI) based on their staining intensity and scored by counting 200 cells. Such SBB scores were also compared between the two groups.

RESULTS

Neutrophil scattergrams deviated downward in the MDS group, suggesting the decreased CBE positivity that seemed reflect the reduction of the lipid content in dysplastic neutrophils. SBB scores determined in this study were also decreased in the MDS group when compared with those in normal controls.

CONCLUSION

Pentra MS CRP might rapidly generate useful information on dysplastic neutrophils in patients with MDS based on its cytochemistry for WBC differentials during routine laboratory hematology.

Understanding of Phase Noise Squeezing Under Fractional Synchronization of a Nonlinear Spin Transfer Vortex Oscillator

We investigate experimentally the synchronization of vortex based spin transfer nano-oscillators to an external rf current whose frequency is at multiple integers, as well as at an integer fraction, of the oscillator frequency. Through a theoretical study of the locking mechanism, we highlight the crucial role of both the symmetries of the spin torques and the nonlinear properties of the oscillator in understanding the phase locking mechanism. In the locking regime, we report a phase noise reduction down to -90  dBc/Hz at 1 kHz offset frequency. Our demonstration that the phase noise of these nanoscale nonlinear oscillators can be tuned and eventually lessened, represents a key achievement for targeted radio frequency applications using spin torque devices.

Long-distance propagation of a surface plasmon on the surface of a ferromagnetic metal

A method for the reduction of the propagation loss of surface plasmons was proposed and experimentally demonstrated. A plasmonic structure, which contains a metal and two dielectric layers of different refractive indexes, is proposed in order to optimize the optical confinement and to reduce the propagation loss of the surface plasmons. Long-distance propagation of a surface plasmon on the surface of a ferromagnetic metal was demonstrated. A low propagation loss of 0.17 dB/μm for a surface plasmon in a Fe/MgO/AlGaAs plasmonic structure was achieved.

A ten-year survey of bacteriuria in the Osaka university hospital

10 consecutive years of observation of the laboratory data of quantitative urinary bacterial culture in the Central Clinical Laboratory of Osaka University Hospital was made. The marked rise of Pseudomonas and other Enterobacteriaceae was clearly demonstrated. The difference in bacterial species in bacteriuria between inpatients and outpatients strongly suggests that the origin of infection was quite different. The disappearance of Staph. aureus as a causative agent was also demonstrated.

Basic evaluation of Pentra MS CRP, a new automated hematology analyzer for rapid 5-part WBC differential and CRP using a small volume of whole blood

INTRODUCTION

Pentra MS CRP is a new automated hematology analyzer that can rapidly and reliably provide 5-part differential of leukocytes (5-Diff) and C-reactive protein (CRP) within approximately 3.5 min using a small volume of whole blood (35 μL).

METHODS

We evaluated the basic performance of Pentra MS CRP and correlations with Sysmex XN-3000, manual microscopic count, and Hitachi LABOSPECT.

RESULTS

Pentra MS CRP demonstrated good repeatability and linearity without any significant carryover for all parameters examined (WBC, RBC, HGB, Hct, PLT, 5-Diff, and CRP). Complete blood cell count (CBC) data examined by Pentra MS CRP correlated well with those evaluated by Sysmex XN-3000 (R ≥ 0.9880). Absolute number of NEU, LYM, and EOS also showed the good correlation (R ≥ 0.9866) between the two analyzers. The correlation with the manual microscopic count was within acceptable criteria. Furthermore, when CRP was examined in hemolyzed whole blood by Pentra MS CRP and converted to plasma concentrations according to Hct, it correlated well (R = 0.9964) with serum CRP examined by Hitachi LABOSPECT.

CONCLUSION

Pentra MS CRP is a convenient and reliable analyzer especially in the emergency unit of hospitals in which the prompt and simultaneous measurement of CBC including 5-Diff and CRP is often necessary.

Highly sensitive nanoscale spin-torque diode

Highly sensitive microwave devices that are operational at room temperature are important for high-speed multiplex telecommunications. Quantum devices such as superconducting bolometers possess high performance but work only at low temperature. On the other hand, semiconductor devices, although enabling high-speed operation at room temperature, have poor signal-to-noise ratios. In this regard, the demonstration of a diode based on spin-torque-induced ferromagnetic resonance between nanomagnets represented a promising development, even though the rectification output was too small for applications (1.4 mV mW(-1)). Here we show that by applying d.c. bias currents to nanomagnets while precisely controlling their magnetization-potential profiles, a much greater radiofrequency detection sensitivity of 12,000 mV mW(-1) is achievable at room temperature, exceeding that of semiconductor diode detectors (3,800 mV mW(-1)). Theoretical analysis reveals essential roles for nonlinear ferromagnetic resonance, which enhances the signal-to-noise ratio even at room temperature as the size of the magnets decreases.

Local and retrograde gene transfer into primate neuronal pathways via adeno-associated virus serotype 8 and 9

Viral vector-mediated gene transfer has become increasingly valuable for primate brain research, in particular for application of genetic methods (e.g. optogenetics) to study neuronal circuit functions. Neuronal cell tropisms and infection patterns are viable options for obtaining viral vector-mediated transgene delivery that is selective for particular neuronal pathways. For example, several types of viral vectors can infect axon terminals (retrograde infections), which enables targeted transgene delivery to neurons that directly project to a particular viral injection region. Although recent studies in rodents have demonstrated that adeno-associated virus serotype 8 (AAV8) and 9 (AAV9) efficiently transduce neurons, the tropisms and infection patterns remain poorly understood in primate brains. Here, we constructed recombinant AAV8 or AAV9, which expressed an enhanced green fluorescent protein (EGFP) gene driven by a ubiquitous promoter (AAV8-EGFP and AAV9-EGFP, respectively), and stereotaxically injected it into several brain regions in marmosets and macaque monkeys. Immunohistochemical analyses revealed almost exclusive colocalization of EGFP fluorescence via AAV9-mediated gene transfer with a neuron-specific marker, indicating endogenous neuronal tropism of AAV9, which was consistent with our previous results utilizing AAV8. Injections of either AAV8-EGFP or AAV9-EGFP into the marmoset striatum resulted in EGFP expression in local striatal neurons as a result of local infection, as well as expression in dopaminergic neurons of the substantia nigra via retrograde transport along nigrostriatal axonal projections. Retrograde infections were also observed in the frontal cortex and thalamus, which are known to have direct projections to the striatum. These local and retrograde gene transfers were further demonstrated in the geniculocortical pathway of the marmoset visual system. These findings indicate promising capabilities of AAV8 and AAV9 to deliver molecular tools into a range of primate neural systems in pathway-specific manners through their neuronal tropisms and infection patterns.

Large microwave generation from current-driven magnetic vortex oscillators in magnetic tunnel junctions

Spin-polarized current can excite the magnetization of a ferromagnet through the transfer of spin angular momentum to the local spin system. This pure spin-related transport phenomenon leads to alluring possibilities for the achievement of a nanometer scale, complementary metal oxide semiconductor-compatible, tunable microwave generator that operates at low bias for future wireless communication applications. Microwave emission generated by the persistent motion of magnetic vortices induced by a spin-transfer effect seems to be a unique manner to reach appropriate spectral linewidth. However, in metallic systems, in which such vortex oscillations have been observed, the resulting microwave power is much too small. In this study, we present experimental evidence of spin-transfer-induced vortex precession in MgO-based magnetic tunnel junctions, with an emitted power that is at least one order of magnitude stronger and with similar spectral quality. More importantly and in contrast to other spin-transfer excitations, the thorough comparison between experimental results and analytical predictions provides a clear textbook illustration of the mechanism of spin-transfer-induced vortex precession.

Magnetization-dependent loss in an (Al,Ga)As optical waveguide with an embedded Fe micromagnet

The dependence of waveguiding loss on the magnetization of a Fe micromagnet embedded into the (Al,Ga)As optical waveguide was examined as a possible readout method for the spin-photon memory. The optical detection of the magnetization direction of a Fe micromagnet was demonstrated for the micromagnet sizes of 3 microm x 4 microm and 3 microm x 8 microm with signal-to-noise ratios of 4.8 and 6 dB, respectively. In the case of smaller sizes, the use of spin injection from the micromagnet into a semiconductor optical amplifier was proposed for the optical detection of the magnetization.

Surface morphology of epitaxial magnetic tunnel junctions

The surface morphology of epitaxial Fe(001)/MgO(001)/Fe(001) magnetic tunnel junctions, which show the giant tunneling magnetoresistance effect, was investigated by in situ scanning tunneling microscopy. It was observed that an epitaxial MgO barrier layer forms flat surface structures. The surface was flatter with distinct steps and terraces after annealing, which would lead to an increase of the tunneling magnetoresistance ratio. Examination of the local electronic structures of 1.05-nm-thick MgO barrier layers by scanning tunneling spectroscopy revealed no pinholes in the layers, so they would be perfect barriers in magnetic tunnel junctions.

Spin-torque diode effect in magnetic tunnel junctions

There is currently much interest in the development of 'spintronic' devices, in which harnessing the spins of electrons (rather than just their charges) is anticipated to provide new functionalities that go beyond those possible with conventional electronic devices. One widely studied example of an effect that has its roots in the electron's spin degree of freedom is the torque exerted by a spin-polarized electric current on the spin moment of a nanometre-scale magnet. This torque causes the magnetic moment to rotate at potentially useful frequencies. Here we report a very different phenomenon that is also based on the interplay between spin dynamics and spin-dependent transport, and which arises from unusual diode behaviour. We show that the application of a small radio-frequency alternating current to a nanometre-scale magnetic tunnel junction can generate a measurable direct-current (d.c.) voltage across the device when the frequency is resonant with the spin oscillations that arise from the spin-torque effect: at resonance (which can be tuned by an external magnetic field), the structure exhibits different resistance states depending on the direction of the current. This behaviour is markedly different from that of a conventional semiconductor diode, and could form the basis of a nanometre-scale radio-frequency detector in telecommunication circuits.

[Acute type A aortic dissection combined with surgical treatment with acute myocardial infarction]

Acute myocardial infarction, as a result of coronary malperfusion caused by acute type A aortic dissection, has been identified as one of significant factors relating to operative mortality. This complication could be diagnosed with a combination of electrocardiography and echocardiography in acute phase. However, the indication of coronary angiography and/or intervention has been controversial as it is time-consuming and renders additional stress to a critical patient requiring an emergency operation. We report a case of myocardial infarction successfully treated with percutaneous transluminal coronary angioplasty (PTCA) at first, after that, recognition of dissection of aorta necessitated subsequent surgical therapy. In this particular case, coronary intervention in advance proved to be mandatory.

Spin-dependent tunneling in magnetic tunnel junctions with a layered antiferromagnetic Cr(001) spacer: role of band structure and interface scattering

The tunnel magnetoresistance effect (TMR), which is intrinsically determined by the interface monolayer of an electrode, was realized by using magnetic tunnel junctions (MTJs) with a single-crystal Cr(001) layer inserted between a tunnel barrier and an electrode. The MTJs showed an oscillation of the TMR ratio as a function of the thickness of the Cr(001) layer with a period of 2 monatomic layers, which corresponds to the layered antiferromagnetic structure of Cr(001). These oscillations originate from electron scattering at the interface, due to the mismatching of the symmetry of the wave functions and band structure in Cr(001).

Origin of the tunnel anisotropic magnetoresistance in Ga(1-x)Mn(x)As/ZnSe/Ga(1-x)Mn(x)As magnetic tunnel junctions of II-VI/III-V heterostructures

We investigated spin-dependent transport in magnetic tunnel junctions made of III-V Ga(1-x)Mn(x)As electrodes and II-VI ZnSe tunnel barriers. The high tunnel magnetoresistance (TMR) ratio up to 100% we observed indicates high spin polarization at the barrier/electrodes interfaces. We found anisotropic tunneling conductance having a magnitude of 10% with respect to the direction of magnetization to linearly depend on the magnetic anisotropy energy of Ga(1-x)Mn(x)As. This proves that the spin-orbit interactions in the valence band of Ga(1-x)M(x)As are responsible for the tunnel anisotropic magnetoresistance (TAMR) effect.

Development of the amygdalohypothalamic projection in the mouse embryonic forebrain

The amygdalohypothalamic projection, a major component of the stria terminalis, is involved in the conduction of emotional and olfactory information integrated in the amygdala to the hypothalamus to elicit emotional reactions. Despite the extensive studies on functional aspects of the amygdaloid complex, developmental mechanisms of the amygdala and related structures are still poorly understood. To investigate the development of the amygdalohypothalamic projection in the mouse embryonic brain, carbocyanine dye was applied to the amygdala to label the growing axons anterogradely and to the hypothalamus to label the amygdaloid neurons retrogradely. The initial outgrowth of the stria terminalis was found to be as early as E11.5. The pathway crossed in a saddle over the internal capsule, another prominent connection in the developing forebrain of the mammalian embryo. Bipolar immature neurons were distributed along the stria terminalis at the telencephalo-diencephalic boundary, and the internal capsule was also surrounded by these cells. These cells expressed immunoreactivities to calretinin and the lot-1 antigen which has been shown to be involved in guidance of the developing lateral olfactory tract. Ultrastructural analysis revealed an adherens-like junction between the stria terminalis and the apposed cells, implying contact-mediated guidance. These results suggest that, in the development of the stria terminalis, the axonal outgrowth is guided by a mechanism similar to that of the developing lateral olfactory tract, a major amygdalopetal connection.

Reduced inflammatory pain in mice deficient in the differential screening-selected gene aberrative in neuroblastoma

Differential screening-selected gene aberrative in neuroblastoma (Dan) protein is produced in small neurons of dorsal root ganglia. Thermal and mechanical allodynia and Fos expression in the spinal dorsal horn evoked by inflammation and neuropathic pain were investigated using Dan-deficient mice. Mice showed pain reactions induced by the introduction of complete Freund's adjuvant (CFA) into their hind paw (inflammatory pain model) and after sciatic nerve ligation (neuropathic pain model). In the inflammatory pain model, thermal and mechanical pain thresholds in Dan-deficient mice were significantly higher than those of wild-type mice. The number of Fos-immunoreactive cells in the dorsal horn during the inflammatory period was significantly less in Dan-deficient mice. However, in the neuropathic pain model, no differences in thermal hypersensitivity, mechanical allodynia, or the number of Fos-immunoreactive cells in the dorsal horn were observed between the mice. These data suggest that Dan may be a neuromodulator in inflammatory pain.

Long-term evaluation of nutritional status using dual-energy X-ray absorptiometry in chronic hemodialysis patients

BACKGROUND

Hemodialysis patients very often suffer from malnutrition with net loss of body muscle and fat stores. Since protein-calorie malnutrition has been considered to be highly associated with increased morbidity and mortality, it is important that the nutritional status is evaluated accurately and that long-term evaluation of the nutritional status is performed to obtain good outcome.

PATIENTS AND METHODS

Forty-six patients (28 men and 18 women) undergoing maintenance hemodialysis were studied. Nutritional status of the patients was examined by dual-energy X-ray absorptiometry (DXA) and anthropometry measurements after a hemodialysis session and 4 years after the initial measurement.

RESULTS

Percent fat, the ratio of body fat (BF) to weight, determined by DXA correlated positively with body mass index (BMI) calculated from weight and height. There was also a significant positive correlation between lean body mass (LBM) determined by DXA and arm muscle circumference (AMC) calculated using the anthropometric method. In the study period of 4 years, LBM and bone mineral content (BMC) observed at the end point were significantly lower than those at the start. In contrast, BF and %fat at the end point were significantly higher as compared with those at the initial measurement.

CONCLUSION

These results indicate that DXA is a reliable method for body composition analysis in chronic hemodialysis patients. Because the detection of early alterations in body composition may provide an early indication of the development of malnutrition, serial evaluation of body composition using DXA should be valid for assessment of the nutritional status.

Development of the blood-testis barrier in the mouse is delayed by neonatally administered diethylstilbestrol but not by beta-estradiol 3-benzoate

A group of newborn mice were treated with 1 micro g dose-1 individual-1 of diethylstilbestrol (DES) on alternate days, from days 1 to 11 postnatally. Another group of mice were treated similarly with 125 ng dose-1 individual-1 of beta-estradiol 3-benzoate (E2B). The testes were sequentially examined up to 84 days of age using light and electron microscopy. Spermatogenic cells in the DES-treated mice differentiated normally from birth until 17 days of age, when they differentiated into pachytene spermatocytes and remained at this meiotic prophase for the next 10 days approximately. The cells then began to differentiate further, ultimately forming spermatozoa by 49 days of age. Confocal and electron microscopy showed that the blood-testis barrier did not form until 28 days of age in the DES-treated mice, and a delay in the functional maturation of this structure, as the blood-testis barrier, was confirmed by intercellular tracer experiments. The arrest of spermatogenesis at the meiotic prophase may have been attributable to the DES-induced defective formation of the blood-testis barrier. No delay of the blood-testis barrier formation was detected in the E2B-treated mice. Thus, DES and E2B, both of which are known as potent oestrogenic compounds, had different effects on the Sertoli cells.

Spin-polarized resonant tunneling in magnetic tunnel junctions

Insertion of a thin nonmagnetic copper Cu(001) layer between the tunnel barrier and the ferromagnetic electrode of a magnetic tunnel junction is shown to result in the oscillation of the tunnel magnetoresistance as a function of the Cu layer thickness. The effect is interpreted in terms of the formation of spin-polarized resonant tunneling. The amplitude of the oscillation is so large that even the sign of the tunnel magnetoresistance alternates. The oscillation period depends on the applied bias voltage, reflecting the energy band structure of Cu. The results are encouraging for the development of spin-dependent resonant tunneling devices.

A case of systemic lupus erythematosus presenting with rectal ulcers as the initial clinical manifestation of disease

Gastrointestinal involvement is often seen in patients with systemic lupus erythematosus (SLE). All parts of the gastrointestinal tract may be affected. However, rectal involvement at onset is rare. We describe here a case of SLE in which rectal ulcers due to vasculitis occurred as the initial manifestation of the disease without involvement of any other organ. The ulcers worsened, along with the appearance of lupus nephritis 5 years later When steroid therapy was initiated, there was rapid clinical and radiographic improvement. Our case suggests that rectal ulcer is a rare but important complication of SLE and can represent the initial and sole clinical manifestation of the disease.

Disruption of the midkine gene (Mdk) resulted in altered expression of a calcium binding protein in the hippocampus of infant mice and their abnormal behaviour

BACKGROUND

Midkine (MK) is a growth factor implicated in the development and repair of various tissues, especially neural tissues. However, its in vivo function has not been clarified.

RESULTS

Knockout mice lacking the MK gene (Mdk) showed no gross abnormalities. We closely analysed postnatal brain development in Mdk(-/-) mice using calcium binding proteins as markers to distinguish neuronal subpopulations. Intense and prolonged calretinin expression was found in the dentate gyrus granule cell layer of the hippocampus of infant Mdk(-/-) mice. In infant Mdk(+/+) mice, calretinin expression in the granule cell layer was weaker, and had disappeared by 4 weeks after birth, when calretinin expression still persisted in Mdk(-/-) mice. Furthermore, 4 weeks after birth, Mdk(-/-) mice showed a deficit in their working memory, as revealed by a Y-maze test, and had an increased anxiety, as demonstrated by the elevated plus-maze test.

CONCLUSION

Midkine plays an important role in the regulation of postnatal development of the hippocampus.

Direct determination of interfacial magnetic moments with a magnetic phase transition in Co nanoclusters on Au(111)

The spin, in-plane and out-of-plane orbital and magnetic dipole moments of almost purely interfacial Co atoms were directly determined for Au/2-monolayer Co nanoclusters/Au(111) by angle-dependent magnetic circular x-ray dichroism (MCXD) measurements. The field- and temperature-dependent MCXD evidences a ferromagnetic(FM)-to-superparamagnetic phase transition in single-domain clusters with decreasing size. The interfacial moments are remarkably enhanced as compared with bulk values, verifying theoretical predictions. The FM clusters show strong perpendicular magnetic anisotropy, providing promise of applications for nanoscale magnetic bits.