Semantic context-dependent neural representations of odors in the human piriform cortex revealed by 7T MRI

Olfactory perception depends not only on olfactory inputs but also on semantic context. Although multi-voxel activity patterns of the piriform cortex, a part of the primary olfactory cortex, have been shown to represent odor perception, it remains unclear whether semantic contexts modulate odor representation in this region. Here, we investigated whether multi-voxel activity patterns in the piriform cortex change when semantic context modulates odor perception and, if so, whether the modulated areas communicate with brain regions involved in semantic and memory processing beyond the piriform cortex. We also explored regional differences within the piriform cortex, which are influenced by olfactory input and semantic context. We used 2 × 2 combinations of word labels and odorants that were perceived as congruent and measured piriform activity with a 1-mm isotropic resolution using 7T MRI. We found that identical odorants labeled with different words were perceived differently. This labeling effect was observed in multi-voxel activity patterns in the piriform cortex, as the searchlight decoding analysis distinguished identical odors with different labels for half of the examined stimulus pairs. Significant functional connectivity was observed between parts of the piriform cortex that were modulated by labels and regions associated with semantic and memory processing. While the piriform multi-voxel patterns evoked by different olfactory inputs were also distinguishable, the decoding accuracy was significant for only one stimulus pair, preventing definitive conclusions regarding the locational differences between areas influenced by word labels and olfactory inputs. These results suggest that multi-voxel patterns of piriform activity can be modulated by semantic context, possibly due to communication between the piriform cortex and the semantic and memory regions.

Fabrication and electrochemical properties of electrode composites for oxide-type all-solid-state batteries through electrostatic integrated assembly

All-solid-state batteries, which use flame-resistant solid electrolytes, are regarded as safer alternatives to conventional lithium-ion batteries for various applications including electric vehicles. Herein, we report the fabrication of cathode composites for oxide-type all-solid-state batteries through an electrostatic assembly method. A polyelectrolyte is used to adjust the surface charge of the matrix particles to positive/negative, and the aggregation resulting from electrostatic interactions is utilized. Composites consisting of cathode active material particles (LiNi_1/3Mn_1/3Co_1/3O₂ (NMC) or LiNi_0.5Mn_1.5O₄ (LNMO)), solid electrolyte particles Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP), and electron conductive one-dimensional carbon nanotubes (CNT) are formed via an electrostatic integrated assembly of colloidal suspensions. Electrostatic integration increases the electronic conductivity by two orders of magnitude in the NMC-LATP-CNT composite (6.5 × 10^-3 S cm^-1/3.2 × 10^-5 S cm^-1) and by six orders of magnitude in the LNMO-LATP-CNT composite (6.4 × 10^-3 S cm^-1/2.3 × 10^-9 S cm^-1). The dispersion of CNTs in the cathode composite is enhanced, resulting in percolation of e^- path even at 1 wt% (approximately 2.5 vol%) CNT. This study indicates that an integrated cathode composite can be fabricated with particles uniformly mixed by electrostatic interaction for oxide-type all-solid-state batteries.

A Novel Controlled Fabrication of Hexagonal Boron Nitride Incorporated Composite Granules Using the Electrostatic Integrated Granulation Method

Despite the availability of nano and submicron-sized additive materials, the controlled incorporation and utilization of these additives remain challenging due to their difficult handling ability and agglomeration-prone properties. The formation of composite granules exhibiting unique microstructure with desired additives distribution and good handling ability has been reported using the electrostatic integrated granulation method. This study demonstrates the feasible controlled incorporation of two-dimensional hexagonal boron nitride (hBN) sheets with alumina (Al₂O₃) particles, forming Al₂O₃-hBN core-shell composite granules. The sintered artifacts obtained using Al₂O₃-hBN core-shell composite granules exhibited an approximately 28% higher thermal conductivity than those obtained using homogeneously hBN-incorporated Al₂O₃ composite granules. The findings from this study would be beneficial for developing microstructurally controlled composite granules with the potential for scalable fabrication via powder-metallurgy inspired methods.

Pupil diameter tracked during motor adaptation in humans

Pupil diameter, under constant illumination, is known to reflect individuals' internal states, such as surprise about observation and environmental uncertainty. Despite the growing use of pupillometry in cognitive learning studies as an additional measure for examining internal states, few studies have used pupillometry in human motor learning studies. Here we provide the first detailed characterization of pupil diameter changes in a short-term reach adaptation paradigm. We measured pupil changes in 121 human participants while they adapted to abrupt, gradual, or switching force field conditions. Sudden increases in movement error caused by the introduction/reversal of the force field resulted in strong phasic pupil dilation during movement accompanied by a transient increase in tonic pre-movement baseline pupil diameter in subsequent trials. In contrast, pupil responses were reduced when the force field was gradually introduced, indicating that large, unexpected errors drove the changes in pupil responses. Interestingly, however, error-induced pupil responses gradually became insensitive after experiencing multiple force field reversals. We also found an association between baseline pupil diameter and incidental knowledge of the gradually-introduced perturbation. Finally, in all experiments, we found a strong co-occurrence of larger baseline pupil diameter with slower reaction and movement times after each rest break. Collectively, these results suggest that tonic baseline pupil diameter reflects one's belief about environmental uncertainty, whereas phasic pupil dilation during movement reflects surprise about a sensory outcome (i.e., movement error), and both effects are modulated by novelty. Our results provide a new approach for non-verbally assessing participants' internal states during motor learning.

Intravenous vagal stimulation catheter, JOHAKU, rapidly decreases heart rate and myocardial oxygen consumption without worsening hemodynamics

Background

Rapid reduction of heart rate (HR) is the most evident physiological response of vagal nerve stimulation (VNS). Since HR reduction is the most potent factor to decrease myocardial oxygen consumption rate (MVO2), the appropriate VNS can exert cardio-protective effects. It is also known that VNS reduces inflammation, oxidative stress, and sympathetic overload. In addition, the VNS during ischemia-reperfusion is known to attenuate myocardial damage by studies in various animal species. Despite the presence of preclinical evidence of VNS benefits, the lack of the device has limited the translation of this technology to clinical practice. We have recently developed an intravenous VNS catheter (JOHAKU, Neuroceuticals Inc.) that can stimulate the right vagal nerve via superior vena cava (SVC) (Figure 1) on temporary basis.

Purpose

We aimed to confirm the feasibility of JOHAKU as a device to modulate heart rate and MVO2 rapidly by a canine experiment.

Methods

In eight beagle dogs, JOHAKU was inserted from the right femoral vein and placed at the SVC level. The stimulation intensity was adjusted to 10–20 V (20 Hz). We simultaneously recorded electrocardiogram and intraarterial blood pressure (BP). In three of eight dogs, we measured the left anterior descending coronary artery flow and oxygen saturations of arterial and coronary sinus blood to calculate MVO2. We compared HR, BP, and MVO2 during JOHAKU stimulation to ones at baseline.

Results

As shown in Figure 2, JOHAKU attenuated HR immediately after stimulation. Compared with baseline, JOHAKU significantly reduced HR (baseline: 135±13 vs. 5 min on stimulation: 107±13 bpm, p<0.05), and did not affect mean BP significantly (96.2±22.8 vs. 89.4±26.6 mmHg, P=0.59). HR promptly recovered to baseline level after JOHAKU stopped. JOHAKU also reduced MVO2 (0.57±0.43 vs. 0.48±0.38 ml/min, p<0.05).

Conclusion

JOHAKU rapidly attenuated cardiac metabolism burden via the rapid HR reduction. The controllability of HR by JOHAKU without affecting BP enables us to apply the VNS even for patients with hemodynamic instability, such as heart failure and acute myocardial infarction.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Japan Agency for Medical and Research Development

Controlled formation of carbon nanotubes incorporated ceramic composite granules by electrostatic integrated nano-assembly

Controlled incorporation of carbon nanotubes (CNT) with alumina (Al₂O₃) and zirconia (ZrO₂) nanoparticles using an electrostatic nano-assembly method for the fabrication of homogeneous CNT-incorporated Al₂O₃-ZrO₂ and CNT-incorporated shell-layer Al₂O₃-ZrO₂ composite granules is demonstrated. The spark-plasma-sintered CNT-incorporated shell-layer Al₂O₃-ZrO₂ artifact exhibited approximately 15 times higher electrical conductivity than a homogeneous CNT-incorporating artifact. This novel composite granule fabrication method using an electrostatic integrated assembly of colloidal nanomaterials would be beneficial for the development of multiscale and multicomponent composite materials.

Improved green body strength using PMMA–Al2O3 composite particles fabricated via electrostatic assembly

In additive manufacturing, indirect laser sintering is used to process and fabricate ceramic materials using a polymer–ceramics green body. The mechanical strength of the green body is important to hold the shape and to enable the use of laser with low power density during the laser sintering process. Because the microstructure of the green body will considerably affect the density of the final product, this study demonstrated a feasible controlled formation of Poly (methylmethacrylate) (PMMA)–Al2O3 composite particles by an electrostatic assembly method that was used for the fabrication of the green body with improved mechanical properties, which were determine using an indentation test. The controllable homogeneous decoration of desired submicron-sized PMMA particles on Al2O3 particles allowed an effective use of PMMA additives while exhibiting considerable mechanical property improvement of the green body compared to poly(vinyl alcohol)-bonded Al2O3. The findings of this study show good potential of green body formation with improved strength for ceramics fabrication via indirect laser sintering.

The effect of instruction on motor skill learning

Many motor skills are learned with the help of instructions. In the context of complex motor sequences, instructions often break down the movement into chunks that can then be practiced in isolation. Thus, instructions shape an initial cognitive representation of the skill, which in turn guides practice. Are there ways of breaking up a motor sequence that are better than others? If participants are instructed in a way that hinders performance, how much practice does it take to overcome the influence of the instruction? To answer these questions, we used a paradigm in which participants were asked to perform finger sequences as fast and accurately as possible on a keyboard-like device. In the initial phases of training, participants had to explicitly remember and practice two- or three-digit chunks. These chunks were then combined to form seven 11-digit sequences that participants practiced for the remainder of the study. Each sequence was broken up into chunks in a way such that the instruction was either aligned or misaligned with the basic execution-level constraints. We found that misaligned chunk instruction led to an initial performance deficit compared with the aligned chunk instruction. Overall, instructions still influenced the temporal pattern of performance after 10 days of subsequent training, with shorter interpress intervals within a chunk compared with between chunks. However, for the misaligned instructed sequences, this temporal pattern was altered more rapidly, such that participants could overcome the induced performance deficit in the last week. At the end of training, participants found idiosyncratic, but interindividually stable, ways of performing each sequence.NEW & NOTEWORTHY Instructions often break down motor sequences into smaller parts, such that they can be more easily remembered. Here, we show that different ways of breaking down a finger sequence can subsequently lead to better or worse performance. The initial instruction still influenced the temporal performance pattern after 10 days of practice. The results demonstrate that the initial cognitive representation of a motor skill strongly influences how a skill is learned and performed.

Micro- and Nano-assembly of Composite Particles by Electrostatic Adsorption

This work reports on a novel controlled nanocomposite fabrication technique which is applicable for material design via a micro- and nano-assembly method. The principle is based on the use of electrostatic adsorption of the surface charge-modified particles via layer-by-layer assembly. The polarity and the zeta potential of the surface charge was controlled using polycation and polyanion, while the zeta potential strength was controlled via the number of alternating coating layers which was determined using zeta potential measurement. A systematic study was conducted to demonstrate the feasibility of composite material assembly via electrostatic adsorption using alumina (Al2O3) and silica (SiO2) composite as a study model, which was carried out as a function of surface zeta potential, surface coverage percentage, and processing time. The considerable potential of this technique for composite material design is also further demonstrated with controlled assembly involving different materials in various structural forms such as fiber, whisker, nanosheets, and even irregular-shaped foam-like structured urethane. The composite materials designed using this EA method possess good potentials to be utilized for various applications such as mechanical property control, composite ceramic films formation, selective laser sintering, and rechargeable metal-air battery.

Correction to: Controlled Microstructure and Mechanical Properties of Al2O3-Based Nanocarbon Composites Fabricated by Electrostatic Assembly Method

Please note that in the original article [1] the name of the second author, Norio Hakiri, was erroneously ordered; the name was ordered with the given and family names the wrong way around, as 'Hakiri Norio'.

Controlled microstructure and mechanical properties of Al2O3-based nanocarbon composites fabricated by electrostatic assembly method

This work reports on the microstructure-controlled formation of interconnected carbon-layered Al₂O₃ ceramics using carbon nanoparticles (CNP)-alumina (Al₂O₃) composite particles. The Al₂O₃ micro-particles used in this study were obtained by granulation of nano-sized Al₂O₃ nanoparticles with an average diameter of 150 nm. Then, CNP-Al₂O₃ composite was fabricated using an electrostatic assembly method using the granulated Al₂O₃ and CNP. The decoration of CNP on the surface of granulated Al₂O₃ was investigated as a function of primary particle size and coverage percentage using a fixed amount of CNP. Notably, an interconnected layer of carbon particles at the interface of Al₂O₃ that resemble the grain boundaries was obtained. The mechanical properties of the samples obtained with different particle size and CNP coverage on Al₂O₃ particles were also investigated which presented the possibility to control the mechanical properties through microstructural design of composite ceramic materials.

Neural Organization of Hierarchical Motor Sequence Representations in the Human Neocortex

Although it is widely accepted that the brain represents movement sequences hierarchically, the neural implementation of this organization is still poorly understood. To address this issue, we experimentally manipulated how participants represented sequences of finger presses at the levels of individual movements, chunks, and entire sequences. Using representational fMRI analyses, we then examined how this hierarchical structure was reflected in the fine-grained brain activity patterns of the participants while they performed the 8 trained sequences. We found clear evidence of each level of the movement hierarchy at the representational level. However, anatomically, chunk and sequence representations substantially overlapped in the premotor and parietal cortices, whereas individual movements were uniquely represented in the primary motor cortex. The findings challenge the common hypothesis of an orderly anatomical separation of different levels of an action hierarchy and argue for a special status of the distinction between individual movements and sequential context.

Stability of representational geometry across a wide range of fMRI activity levels

Fine-grained activity patterns, as measured with functional magnetic resonance imaging (fMRI), are thought to reflect underlying neural representations. Multivariate analysis techniques, such as representational similarity analysis (RSA), can be used to test models of brain representation by quantifying the representational geometry (the collection of pair-wise dissimilarities between activity patterns). One important caveat, however, is that non-linearities in the coupling between neural activity and the fMRI signal may lead to significant distortions in the representational geometry estimated from fMRI activity patterns. Here we tested the stability of representational dissimilarity measures in primary sensory-motor (S1 and M1) and early visual regions (V1/V2) across a large range of activation levels. Participants were visually cued with different letters to perform single finger presses with one of the 5 fingers at a rate of 0.3-2.6 Hz. For each stimulation frequency, we quantified the difference between the 5 activity patterns in M1, S1, and V1/V2. We found that the representational geometry remained relatively stable, even though the average activity increased over a large dynamic range. These results indicate that the representational geometry of fMRI activity patterns can be reliably assessed, largely independent of the average activity in the region. This has important methodological implications for RSA and other multivariate analysis approaches that use the representational geometry to make inferences about brain representations.

Pattern component modeling: A flexible approach for understanding the representational structure of brain activity patterns

Representational models specify how complex patterns of neural activity relate to visual stimuli, motor actions, or abstract thoughts. Here we review pattern component modeling (PCM), a practical Bayesian approach for evaluating such models. Similar to encoding models, PCM evaluates the ability of models to predict novel brain activity patterns. In contrast to encoding models, however, the activity of individual voxels across conditions (activity profiles) are not directly fitted. Rather, PCM integrates over all possible activity profiles and computes the marginal likelihood of the data under the activity profile distribution specified by the representational model. By using an analytical expression for the marginal likelihood, PCM allows the fitting of flexible representational models, in which the relative strength and form of the encoded feature spaces can be estimated from the data. We present here a number of different ways in which such flexible representational models can be specified, and how models of different complexity can be compared. We then provide a number of practical examples from our recent work in motor control, ranging from fixed models to more complex non-linear models of brain representations. The code for the fitting and cross-validation of representational models is provided in an open-source software toolbox.

A network meta-analysis of the clinical properties of various types of supraglottic airway device in children

We conducted both conventional pairwise and Bayesian network meta-analyses to compare the clinical properties of supraglottic airway devices in children. We searched six databases for randomised clinical trials. Our primary end-points were oropharyngeal leak pressure, risk of insertion failure at first attempt, and blood staining risk. The risk of device failure, defined as the abandonment of the supraglottic airway device and replacement with a tracheal tube or another device, was also analysed. Sixty-five randomised clinical trials with 5823 participants were identified, involving 16 types of supraglottic airway device. Network meta-analysis showed that the i-gel™, Cobra perilaryngeal airway™ and Proseal laryngeal mask airway (LMA^® -Proseal) showed statistically significant differences in oropharyngeal leak pressure compared with the LMA^® -Classic, with mean differences (95% credible interval, CrI) of 3.6 (1.9-5.8), 4.6 (1.7-7.6) and 3.4 (2.0-4.8) cmH₂ O, respectively. The i-gel was the only device that significantly reduced the risk of blood staining of the device compared with the LMA-Classic, with an odds ratio (95%CrI) of 0.46 (0.22-0.90). The risk (95%CI) of device failure with the LMA-Classic, LMA^® -Unique and LMA-Proseal was 0.36% (0.14-0.92%), 0.49% (0.13-1.8%) and 0.50% (0.23-1.1%), respectively, whereas the risk (95%CI) of the i-gel and PRO-Breathe was higher, at 3.4% (2.5-4.7%) and 6.0% (2.8-12.5%), respectively. The risk, expressed as odds ratio (95%CrI), of insertion failure at first attempt, was higher in patients weighing < 10 kg at 5.1 (1.6-20.1). We conclude that the LMA-Proseal may be the best supraglottic airway device for children as it has a high oropharyngeal leak pressure and a low risk of insertion. Although the i-gel has a high oropharyngeal leak pressure and low risk of blood staining of the device, the risk of device failure should be evaluated before its routine use can be recommended.

Restricted transfer of learning between unimanual and bimanual finger sequences

When training bimanual skills, such as playing piano, people sometimes practice each hand separately and at a later stage combine the movements of the two hands. This poses the critical question of whether motor skills can be acquired by separately practicing each subcomponent or should be trained as a whole. In the present study, we addressed this question by training human subjects for 4 days in a unimanual or bimanual version of the discrete sequence production task. Both groups were then tested on trained and untrained sequences on both unimanual and bimanual versions of the task. Surprisingly, we found no evidence of transfer from trained unimanual to bimanual or from trained bimanual to unimanual sequences. In half the participants, we also investigated whether cuing the sequences on the left and right hand with unique letters would change transfer. With these cues, untrained sequences that shared some components with the trained sequences were performed more quickly than sequences that did not. However, the amount of this transfer was limited to ∼10% of the overall sequence-specific learning gains. These results suggest that unimanual and bimanual sequences are learned in separate representations. Making participants aware of the interrelationship between sequences can induce some transferrable component, although the main component of the skill remains unique to unimanual or bimanual execution.NEW & NOTEWORTHY Studies in reaching movement demonstrated that approximately half of motor learning can transfer across unimanual and bimanual contexts, suggesting that neural representations for unimanual and bimanual movements are fairly overlapping at the level of elementary movement. In this study, we show that little or no transfer occurred across unimanual and bimanual sequential finger movements. This result suggests that bimanual sequences are represented at a level of the motor hierarchy that integrates movements of both hands.

Tagging motor memories with transcranial direct current stimulation allows later artificially-controlled retrieval

We demonstrate that human motor memories can be artificially tagged and later retrieved by noninvasive transcranial direct current stimulation (tDCS). Participants learned to adapt reaching movements to two conflicting dynamical environments that were each associated with a different tDCS polarity (anodal or cathodal tDCS) on the sensorimotor cortex. That is, we sought to determine whether divergent background activity levels within the sensorimotor cortex (anodal: higher activity; cathodal: lower activity) give rise to distinct motor memories. After a training session, application of each tDCS polarity automatically resulted in the retrieval of the motor memory corresponding to that polarity. These results reveal that artificial modulation of neural activity in the sensorimotor cortex through tDCS can act as a context for the formation and recollection of motor memories.

DOI:http://dx.doi.org/10.7554/eLife.15378.001

Memory is strongly affected by the context in which a particular memory is formed and remembered. For example, visiting a familiar place can often trigger memories associated or “tagged” with that place. Such tagging also exists for memories related to movement: for instance, distinct motor memories for a limb movement are formed depending on whether the other limb is stationary or moving. However, little is known about how the tagging of such motor memories takes place.

Nozaki et al. have now used a technique known as transcranial direct current stimulation to generate artificial “tags” for motor memories. In the experiments, volunteers tried to move a robotic arm towards a goal while the robot pushed their hand off-course. Sometimes the robot pushed the participant’s hand to the left, and sometimes to the right. This makes the task difficult to learn, even when the cue for the direction is provided, as the motor memories that are made to counteract each push overwrite each other.

Nozaki et al. used transcranial stimulation to alter the background electrical activity in the sensorimotor regions of the participants’ brains as they performed the robotic arm task. Artificially generating a different pattern of background brain electrical activity for each push direction caused the motor memories associated with leftward and rightward pushes to be tagged differently. Once this association had been learnt, applying the artificial brain stimulation pattern associated with one of the pushes resulted in the participants unconsciously compensating for a push in that direction, even when it was not there.

Overall, the results presented by Nozaki et al. suggest that the background electrical activity seen in the brain can influence how a motor memory is created and later recalled. A future challenge is to investigate whether this technique could be used to help athletes improve their performance or to treat people with movement disorders. Further experiments are also needed to test whether the same approach can influence the formation and recollection of other kinds of memories, such as those related to fear.

DOI:http://dx.doi.org/10.7554/eLife.15378.002

Combined therapeutic application of botulinum toxin type A, low-frequency rTMS, and intensive occupational therapy for post-stroke spastic upper limb hemiparesis

BACKGROUND

For spastic upper limb hemiparesis after stroke, we developed triple-element protocol of botulinum toxin type A (BoNTA) injection, low-frequency repetitive transcranial magnetic stimulation (LF-rTMS), and intensive occupational therapy (OT). Aim. To investigate the safety and feasibility of the protocol. Design. A preliminary study. Setting. At a university hospital. Population. Fourteen post-stroke patients with spastic upper limb hemiparesis (mean age: 54.9±9.2 years, time after onset: 87.1±48.2 months, ±SD).

METHODS

In all patients, BoNTA was injected into spastic muscles of the affected upper limb (maximum total dose: 240 units). Four weeks later, they were hospitalized to receive 22 sessions of 20-min LF-rTMS and 120-min intensive OT daily over 15 days. Motor function of the affected upper limb was evaluated mainly using Fugl-Meyer Assessment (FMA), Wolf Motor Function Test (WMFT), motor activity log (MAL), and the severity of spasticity was measured with modified Ashworth scale (MAS) at BoNTA injection, discharge and four weeks post-discharge.

RESULTS

All patients completed the protocol without any adverse effects. The FMA score and MAL scores, but not WMFT performance time, improved significantly at discharge. The MAS score of all examined muscles decreased significantly between BoNTA and discharge. The beneficial effect of the protocol on motor function and spasticity was almost maintained until four weeks after discharge.

CONCLUSION

The protocol is safe and feasible, although further larger studies are needed to confirm its efficacy.

CLINICAL REHABILITATION IMPACT

The protocol is a potentially useful neurorehabilitative approach for this patient population.

Reduced neuropeptide Y mRNA levels in the frontal cortex of people with schizophrenia and bipolar disorder

To study the change of gene expression in the brain tissues of schizophrenia, we used the gene expression monitoring technology and compared two sets of pools each containing four RNA samples of frontal cortex that were randomly selected from the control or schizophrenia group. We found that the expression of two genes were commonly altered in four pairwise comparisons; the expression of DEAD-box protein p72 (p72) gene was increased and neuropeptide Y (NPY) gene expression was decreased in the schizophrenia group compared with the control group. To substantiate these results, we estimated their mRNA levels by the real time TaqMan method in the 15 samples of each frontal or temporal cortex of four matched groups of schizophrenia, bipolar disorder, major depression and normal controls. A statistically significant decrease was observed for NPY in the frontal, but not in the temporal cortex, in the schizophrenia group (P=0.003). A decrease was also observed in the frontal cortex of the bipolar disorder group (P=0.031). In contrast, p72 gene expression showed no significant difference among the four groups. In conclusion, by novel technology of DNA array and TaqMan PCR analyses, we found that neuropeptide Y mRNA levels were significantly reduced in the frontal cortex in both schizophrenia and bipolar disorder.

Living donor liver transplantation in Kyoto, 2001

The living-donor liver transplant program at Kyoto University Hospital entered its 12th year in 2001. The rapid increase in adult patients that occurred with active use of right hemi-liver grafts is now reaching its plateau, limited by OR facilities and bed capacity. Graft selection is now being polarized to the left lateral section and right hemi-liver, and disease indications are becoming more similar to those for Western cadaveric programs, including a program for hepatocellular carcinoma. With the active introduction of right hemi-liver grafts, donor selection requires more multifactorial attention. Although most anatomical variants are managed surgically without significant risk, small-for-size grafts combined with high-risk patients are often a continuing problem even with the use of right hemi-liver grafts. Solutions for small-for-size syndrome with or without persistent portal hypertension and massive ascites are urgent targets of research. It will take some more time in Japan until the final establishment of a mutual compensatory system between cadaveric and living donor programs covering medical and socioeconomical aspects is achieved.

Novel use of an established agent: Topotecan is anti-angiogenic in experimental Wilms tumor

BACKGROUND/PURPOSE

Antiangiogenic agents offer a new approach to the treatment of aggressive neoplasms, yet very few agents are available for current use. The authors have shown previously the efficacy of antiangiogenic therapy in experimental Wilms tumor, using an investigative antibody. They hypothesized that topotecan, administered in a regimen targeting endothelial cells, would suppress tumor growth and angiogenesis in experimental Wilms tumor.

METHODS

Experimental tumors were induced in the left kidneys of athymic mice by injection of cultured Wilms tumor cells. Topotecan (0.36, 0.6, 1.0, 2.0, and 3.0 mg/kg) or vehicle was injected intraperitoneally in 2 cycles over a 6-week period. Fluorescein angiograms and platelet endothelial cell adhesion molecule-1 staining of primary tumors were performed to ascertain vascular architecture. Endothelial apoptosis was assessed by TdT-mediated dUTP nick end labeling assay.

RESULTS

Tumor weights were reduced significantly in treated versus control animals, even in the lowest-dose group. Endothelial cell staining and angiography results showed relatively sparse vascularity in treated xenografts. Endothelial apoptosis was observed in treated but not control tumors.

CONCLUSIONS

Topotecan, delivered in an "antiangiogenic" regimen, even at very low doses, significantly inhibited growth of experimental Wilms tumors. No adverse effects were noted at low doses. Thus, the established chemotherapy agent topotecan may be useful in a novel role: as antiangiogenic therapy. J Pediatr Surg 36:1781-1784.

Combination antiangiogenic therapy: increased efficacy in a murine model of Wilms tumor

BACKGROUND/PURPOSE

Antibody to vascular endothelial growth factor (anti-VEGF) suppresses tumor growth and metastasis in experimental Wilms tumor. However, tumor growth accelerates if antibody is withdrawn. As recently shown, low-dose, frequently administered topotecan, a topoisomerase-1 inhibitor, has anti-angiogenic activity. The authors hypothesized that combined topotecan/anti-VEGF therapy would suppress tumor growth and metastasis more durably than either agent alone.

METHODS

Xenografts were induced by intrarenal injection of human Wilms tumor cells in athymic mice (n = 59). Mice were divided into control (n = 10), anti-VEGF (n = 16), topotecan (n = 17), and topotecan plus anti-VEGF (n = 16) groups. All control and half the treated mice were killed at week 6. Remaining ("rebound") mice were maintained without treatment until week 8. Tumor vasculature was mapped by fluorescein angiography/PECAM immunostaining. Endothelial apoptosis was assessed by TUNEL assay.

RESULTS

6 weeks: Tumor weights were reduced significantly in treated mice (P <.003 v control). Seven of ten control and 1 of 25 treated mice displayed lung metastases (P <.003). Rebound tumors were largest in topotecan-only, intermediate in antibody-treated, and smallest in combination-treated mice. Immunostaining and angiography results showed sparse vascularity in treated xenografts. Endothelial apoptosis was observed only in treated tumors.

CONCLUSION

Combination low-dose topotecan and anti-VEGF antibody therapy is antiangiogenic and suppresses tumor growth and metastasis in experimental Wilms tumor more durably than either agent alone.

A novel single-nucleotide polymorphism in the 3'-untranslated region of the human dihydrofolate reductase gene with enhanced expression

A novel single-nucleotide polymorphism (SNP), 829C-->T in the 3'-untranslated region of the human dihydrofolate reductase (DHFR) gene transcript, was identified in the study population of 37 patients with childhood leukemias/lymphomas and 83 healthy Japanese children. Frequencies of the DHFR 829C/C, 829C/T, and 829T/T genotypes were 83.8, 10.8, and 5.4%, respectively, in the cases and 74.7, 19.3, and 6.0% in the controls, showing no significant difference in genotype frequencies between the cases and controls. When determined by real-time quantitative reverse transcription-PCR analysis, the highest expression of the DHFR transcript was demonstrated in the samples with a DHFR 829T/T polymorphism (P < 0.001). Direct association of the presence of the SNP with methotrexate-related adverse events in each patient was not demonstrated in this limited analysis. These data suggest that the novel DHFR 829 polymorphism is associated with a positive role in gene expression and provide evidence of a functional SNP in the 3' regulatory region of the gene.

Selective expression and function of granzyme D in lymphohematopoietic stromal cells

Granzymes are a family of serine proteases exclusively detected in the granules of cytotoxic lymphocytes, and in mice at least eight granzymes, A to G and K, have been identified. Except for granzymes A and B, which activate the apoptotic pathway, little is known about the exact functions of the other granzymes. We have found that the granzyme D transcript is selectively expressed in functional hematopoietic stromal lines as well as primary stromal cells. Stromal lines supported growth of a pre-T lymphoma clone BTK at an efficiency proportional to the expression level of granzyme D, while a stromal line lacking granzyme D failed to do so. When the defective stromal line was transfected with granzyme D cDNA, it could efficiently support the growth of BTK cells. The results indicate that granzyme D expressed in the stromal cells plays an important role in stromal cell-lymphocyte interaction.

Structures of mouse Rep-8 cDNA and genomic clones

A mouse homologue of the human Rep-8 gene was cloned by PCR methods using degenerate oligonucleotide primers corresponding to highly conserved regions between human and mouse genes, and by the Marathon-Ready cDNA amplification method. The full-length mouse Rep-8 contains 1422 nucleotides and codes for a protein of 277 amino acids with a calculated mol. wt. of 31,519. The overall amino acid sequence homology between mouse and human Rep-8 proteins was 73%, and the overall nucleic acid sequence similarity was 65%. The predicted amino acid sequence of mouse Rep-8 has leucine zipper-like motifs in the N-terminal region, similar to the human Rep-8 protein. Rep-8 exists as a single-copy gene and is expressed in both the early and late embryonic stages of mouse development, suggesting that the Rep-8 gene product has an important role in embryogenesis. The genomic structure of the mouse Rep-8 gene was characterized extensively so that a gene targeting strategy could be used to develop an understanding of the biological function(s) of this interesting gene and its product.

Mapping of eight testis-specific genes to mouse chromosomes

We previously identified eight testis-specific genes using antibodies raised against testicular germ cells. They are expressed during spermatogenesis and are presumed to be involved in testicular germ cell differentiation and sperm formation. We have mapped the genomic loci for these testis-specific genes using restriction fragment length variants in interspecific backcross mice. The calmegin gene (Clgn) was mapped to Chr 8. The synaptonemal complex protein gene 1 (Sycp1) probe hybridized with two sequences on different chromosomes; Sycp1-rs2 was mapped to Chr 3, whereas Sycp1-rs3 was mapped to Chr 7. The relaxin-like factor gene (Rlnl) was mapped to Chr 8, and collapsin response mediator protein 1 (Crmp1) was mapped to Chr 5. Three novel genes encoding testis-specific proteins A2 (Tsga2), A8 (Tsga8), and A12 (Tsga12) were mapped to chromosomes 3, X, and 10, respectively.

A supernumerary cusp in the human pulmonary valve

A supernumerary cusp of the valve of the pulmonary trunk was found in a 75-year old, male Japanese. The valve was composed of 4 cusps of different size and shape. The supernumerary cusp was located between the right and left cusps. We found this case from a series of 1,100 consecutive necropsies.

The fine structure and elemental analysis of keratinized epithelium of the filiform papillae analysis on the dorsal tongue in the American alligator (Alligator mississippiensis)

The filiform papillae of subadult alligator (120 cm-260 cm total length) tongues are examined by scanning electron microscopy and electron microprobe analysis. The filiform papillae form cone-like structures and are observed over the entire dorsal surface of a relatively long tongue with a round tip. The filiform papillae are composed of four layers; outer, upper intermediate, lower intermediate, and basal layer. The keratinized epithelial cells are analysed by the sulphur (S), and nitrogen (N) content levels. The S content is higher than that of N. In the anterior side of the filiform papillae, this content is lower than that in the posteriors. The S content is highest of all at about 2 microns in depth from the surface. These results suggest that the use of S concentration measurements may serve to be an effective tool for a simple, offhand evaluation of keratinization.

Glutathione conjugation of styrene 7,8-oxide enantiomers by major glutathione transferase isoenzymes isolated from rat livers

Male Sprague-Dawley rat liver cytosol mediated regioselective conjugation of styrene 7,8-oxide (STO) enantiomers with glutathione in completely trans-ring-opening manner to afford (1S)-S-(1-phenyl-2-hydroxyethyl)glutathione and (2R)-S-(2-phenyl-2-hydroxyethyl)glutathione in the ratio 22:1 for (R)-STO and also to afford (1R)-S-(1-phenyl-2-hydroxyethyl)glutathione and (2S)-S-(2-phenyl-2-hydroxyethyl)glutathione in the ratio 12:1 for (S)-STO. In the above cytosolic reactions, (R)-STO was conjugated 1.8 times faster than (S)-STO, while the (R)- to (S)-ratio in rate of the conjugation was 2.7 when racemic STO was used as a substrate. A kinetic study, carried out by using six major glutathione transferase (GST) isoenzymes isolated from the cytosol, indicated that GSTs 3-3, 3-4 and 4-4 (class mu enzymes) had much higher Kcat/Km values towards both STO enantiomers than the other three major isoenzymes, GSTs 1-1, 1-2 and 2-2 (class alpha enzymes). All the class mu enzymes mediated preferential glutathione conjugation of (R)-STO to (S)-STO. On the contrary, the class alpha enzymes catalysed the conjugation of (S)-STO preferentially to (R)-STO. The kinetic study strongly suggested that GSTs determining the higher enantioselectivity towards (R)-STO in the rat liver cytosol were the class mu enzymes, especially GST 3-3, which had the highest Kcat/Km value towards (R)-STO as well as the highest (R) to (S) ratio in the enantioselectivity among the six isoenzymes examined. GST 7-7, isolated as a major enzyme from the liver cytosol of the animals bearing hepatic hyperplastic nodules which were induced by chemical carcinogens, catalysed preferential GSH conjugation of (S)-STO to (R)-STO.

Glutathione conjugation of the fluorophotometric epoxide substrate, 7-glycidoxycoumarin (GOC), by rat liver glutathione transferase isoenzymes

The fluorophotometric substrate, 7-glycidoxycoumarin (GOC), was examined for the assay of epoxide-glutathione (GSH)-conjugating activities of seven major GSH transferases (GSTs) isolated from rat liver cytosols. GST 7-7 (GST-P), isolated from the liver cytosol of rats bearing hepatic hyperplastic nodules, catalysed the GSH conjugation of GOC at a higher rate than any other examined GST isolated from the normal rat liver cytosol. GSTs 3-3, 3-4 and 4-4 (group 3-4 enzymes) had specific activities towards GOC by one fifth to one third of that of GST 7-7. GSTs 1-1, 1-2 and 2-2 (group 1-2 enzymes) had very low activities towards this epoxide. A kinetic study indicated that GST 7-7 showed the largest kappa cat/Km value for the catalytic reaction of GOC-GSH conjugation among the GSTs. In spite of their much smaller kappa cat values, group 3-4 enzymes showed much larger kappa cat/Km values for GOC than the group 1-2 enzymes, because GOC had a much higher affinity for group 3-4 enzymes than for group 1-2 enzymes. A comparative study was also done with GSH conjugations of styrene 7,8-oxide (STO) and 1-chloro-2,4-dinitrobenzene by the GSTs. Unlike GOC, the conjugation of STO was mediated at rates about twice as high by group 3-4 enzymes than by GST 7-7. STO was also a very poor substrate for group 1-2 enzymes.

Effects of ajmaline on right precordial Q waves simulating myocardial infarction

Seven patients with right precordial Q waves (RPQs) simulating anterior myocardial infarction (MI), but without a previous history of either MI or other underlying diseases showing RPQ, were injected intravenously with ajmaline. The RPQs were abolished in 5 patients. Two patients displayed a transient, spontaneous abolition of RPQ, and 2 patients had false positive ST responses to the exercise test. Ajmaline injection in patients with documented MI and in patients with normal electrocardiograms did not produce any notable changes in the initial part of QRS complex. The RPQs abolished by ajmaline were probably a result of a mild pre-excitation, induced by Mahaim fiber conduction, because the PR and QRS intervals were normal and low amplitude delta waves were found in some patients. It is important to note that altered intraventricular conduction, probably a mild preexcitation, can markedly deform electrocardiograms and mimic myocardial infarction.