Rock music improvisation shows increased activity in Broca's area and its right hemisphere homologue related to spontaneous creativity

OBJECTIVE

The neural correlates of creativity are not well understood. Using an improvised guitar task, we investigated the role of Broca's area during spontaneous creativity, regardless of individual skills, experience, or subjective feelings.

RESULTS

Twenty guitarists performed improvised and formulaic blues rock sequences while hemodynamic responses were recorded using functional near-infrared spectroscopy. We identified a new significant response in Broca's area (Brodmann area [BA] 45L) and its right hemisphere homologue during improvised playing but not during formulaic playing. Our results indicate that bilateral BA45 activity is common during creative processes that involve improvisation across all participants, regardless of subjective feelings, skill, age, difficulty, history, or amount of practice. While our previous results demonstrated that the modulation of the neural network according to the subjectively experienced level of creativity relied on the degree of deactivation in BA46L, our current results independently show a common concurrent activity in BA45 in all participants. We suggest that this is related to the sustained execution of improvisation in "motor control," analogous to motor planning in speech control.

Association between Reaction Times in the Joint Simon Task and Personality Traits

Joint go and no-go effects (joint Simon effects; JSEs) are considered to have a stimulus-response compatibility effect on joint reaction time tasks (joint Simon task) caused by the presence of other people. Additionally, JSEs are known to be associated with various social factors and are therefore a potential clinical marker for communicative function; however, the relationship with the personality that is associated with communication skills remains unclear. In this study, we focused on the association between JSE and personality traits. Thirty Japanese participants (fifteen women) were recruited. First, personality trait scores were obtained using the Japanese version of the ten-item personality inventory before the experiment. Second, we measured reaction times in the joint Simon task and single go and no-go tasks with the go signal presented on the congruent and incongruent sides. At last, we analyzed the association between reaction times and personality traits by using Spearman's correlation analysis. As a result, we observed two pairs with significant correlations: JSE and neuroticism and short reaction times in the joint condition and agreeableness. In conclusion, we identified potential psychological markers associated with the joint Simon task. These findings may lead to an additional hypothesis regarding the neurobiological mechanisms of JSEs.

Mental arithmetic modulates temporal variabilities of finger-tapping tasks in a tempo-dependent manner

Background

Several psychiatric diseases impair temporal processing. Temporal processing is thought to be based on two domains: supra-second intervals and sub-second intervals. Studies show that temporal processing in sub-second intervals is mainly an automated process. However, the brain functions involved in temporal processing at each time scale remain unclear. We hypothesized that temporal processing in supra-second intervals requires several brain areas, such as the ventrolateral prefrontal cortex, intraparietal sulcus (IPS), and inferior parietal lobe, corresponding to various cognitions in a time scale-dependent manner. We focused on a dual-task paradigm (DTP) involving simultaneous performance of cognitive and motor tasks, which is an effective method for screening psychomotor functions; we then designed a DTP comprising finger tapping at various tempi as the temporal processing task and two cognitive tasks (mental arithmetic and reading) that might affect temporal processing. We hoped to determine whether task-dependent interferences on temporal processing in supra-second intervals differed depending on the cognitive tasks involved.

Methods

The study included 30 participants with no history of neuromuscular disorders. Participants were asked to perform a DTP involving right index finger tapping at varying tempi (0.33, 0.5, 1, 2, 3, and 4 s inter-tapping intervals). Cognitive tasks comprised mental arithmetic (MA) involving three-digit addition, mental reading (MR) of three- to four-digit numbers, and a control (CTL) task without any cognitive loading. For comparison between tasks, we calculated the SDs of the inter-tapping intervals. Participants' MA abilities in the three-digit addition task were evaluated.

Results

The MA and MR tasks significantly increased the SDs of the inter-tapping intervals compared to those of the CTL task in 2-3 s and 3-4 s for the MA and MR tasks, respectively. Furthermore, SD peaks in the finger-tapping tasks involving MA were normalized by those in the CTL task, which were moderately correlated with the participants' MA ability (r = 0.462, P = 0.010).

Discussion

Our results established that DTP involving the temporal coordination of finger-tapping and cognitive tasks increased temporal variability in a task- and tempo-dependent manner. Based on the behavioral aspects, we believe that these modulations of temporal variability might result from the interaction between finger function, arithmetic processing, and temporal processing, especially during the "pre-semantic period". Our findings may help in understanding the temporal processing deficits in various disorders such as dementia, Parkinson's disease, and autism.

BOLD signal response in primary visual cortex to flickering checkerboard increases with stimulus temporal frequency in older adults

Many older adults have difficulty seeing brief visual stimuli which younger adults can easily recognize. The primary visual cortex (V1) may induce this difficulty. However, in neuroimaging studies, the V1 response change to the increase of temporal frequency of visual stimulus in older adults was unclear. Here we investigated the association between the temporal frequency of flickering stimuli and the BOLD activity within V1 in older adults, using surface-based fMRI analysis. The fMRI data from 29 healthy older participants stimulated by contrast-reversing checkerboard at temporal flicker frequencies of 2, 4, and 8 Hz were obtained. The participants also performed a useful field of view (UFOV) test. The slope coefficient of BOLD activity regarding the temporal frequency of the visual stimulus averaged within V1 regions of interest was positive and significantly different from zero. Group analysis in the V1 showed significant clusters with positive slope and no significant clusters with a negative slope. The correlation coefficient between the slope coefficient and UFOV performance was not significant. The results indicated that V1 BOLD response to a flickering visual stimulus increases as the stimulus temporal frequency increases from 2 to 8 Hz in older adults.

Hemodynamic responses related to intrinsically photosensitive retinal ganglion cells in migraine

To clarify whether photoreception of intrinsically photosensitive retinal ganglion cells (ipRGCs) is related to migraine, we investigated the relationship between hemodynamic responses related to neural activity and visual stimulation of ipRGCs. It has been established that photoreception in ipRGCs is associated with photophobia in migraine. However, the relationship between visual stimulation of ipRGCs and hemodynamic responses in the visual cortex has not been clarified. Hemodynamic responses in the visual cortex were measured using functional near-infrared spectroscopy (fNIRS) as signals reflecting changes in oxygenated and deoxygenated hemoglobin concentrations. Different types of visual stimulation generated by a metamerism method were applied to the peripheral field of the eye of patients with migraine (N = 20) and healthy participants (N = 21). The stimulation intensity on the retina was controlled using an artificial pupil. In the primary visual cortex of patients with migraine, statistically significant changes in fNIRS signals dependent on visual stimulation intensity applied to ipRGCs were observed (p < 0.01), while no such changes were observed in healthy participants. These results reveal that visual stimulation of ipRGCs projecting to the primary visual cortex is involved in hemodynamic responses in patients with migraine, suggesting that ipRGCs, in addition to photometric values related to cones, are associated with migraine.

Dependence of behavioral performance on material category in an object-grasping task with monkeys

Material perception is an essential part of our cognitive function that enables us to properly interact with our complex daily environment. One important aspect of material perception is its multimodal nature. When we see an object, we generally recognize its haptic properties as well as its visual properties. Consequently, one must examine behavior using real objects that are perceived both visually and haptically to fully understand the characteristics of material perception. As a first step, we examined whether there is any difference in the behavioral responses to different materials in monkeys trained to perform an object grasping task in which they saw and grasped rod-shaped real objects made of various materials. We found that the monkeys’ behavior in the grasping task, which was measured based on the success rate and the pulling force, differed depending on the material category. Monkeys easily and correctly grasped objects of some materials, such as metal and glass, but failed to grasp objects of other materials. In particular, monkeys avoided grasping fur-covered objects. The differences in the behavioral responses to the material categories cannot be explained solely based on the degree of familiarity with the different materials. These results shed light on the organization of multimodal representation of materials, where their biological significance is an important factor. In addition, a monkey that avoided touching real fur-covered objects readily touched images of the same objects presented on a CRT display. This suggests that employing real objects is important when studying behaviors related to material perception.

NEW & NOTEWORTHY We tested monkeys using an object-grasping task in which monkeys saw and grasped rod-shaped real objects made of various materials. We found that the monkeys’ behavior differed dramatically across the material categories and that the behavioral differences could not be explained solely based on the degree of familiarity with the different materials. These results shed light on the organization of multimodal representation of materials, where the biological significance of materials is an important factor.

Abstract P6-15-05: Randomized controlled trial of neoadjuvant eribulin mesylate versus paclitaxel in women with operable breast cancer (JONIE-3 study)

Background:

Although treatment of eribulin mesylate (E) improved overall survival in metastatic breast cancer (BC) patients, little is known about the efficacy in early BC. The hypothesis of this study is that sequential administration of E followed by FEC would have less toxic, particularly peripheral neuropathy, and also have similar effect compared to paclitaxel (P) followed by FEC as primary systemic therapy (PST) for woman with operable BC.

Methods:

This is a phase II multicenter open label study (UMIN000012817). Patients (pts) were randomly assigned to either E (1.4mg/m2, d1 and d8, q21 days, 4 cycles) + FEC (fluorouracil 500 mg/m2, epirubicin 100 mg/m2, and cyclophosphamide 500 mg/m2) or P (80mg/m2, weekly, 12 cycles) + FEC as PST. HER2+ patients were allowed to receive trastuzumab. Stratification factors were ER, HER2, and menopausal status. Primary endpoint was the incidence of peripheral sensory and motor neuropathy (PSN and PMN) with Grade 1 or higher according to CTCAE ver.4.0. Secondary endpoints were pathological complete response (pCR) rates (ypT0/is/ypN0), clinical response rates (CR+PR), and adverse events. Safety was assessed in all pts who received at least one dose of the study drug.

Results:

Between 12/2013 to 3/2016, 121 pts were randomly assigned equally to E + FEC and P + FEC. Excluding 5 pts from the primary assessment, 116 pts (58 in each group) were included in the full analysis set. The characteristics of the pts were similar in the two arms. At the end of E or P administration, the incidences of PSN were 55.4% and 92.9% in E and P arm, respectively (p&lt;0.001). The incidences of PMN were 25.9% and 44.9% in E and P arm, respectively (p=0.049). At the end of E or P + FEC, PSN accounts for 38.9% in E arm and 85.2% in P arm (p&lt;0.001), and PMN accounts for 20.7% in E arm and 32.8% in P arm (p=0.201). The pCR rates in E and P arm were 20.7% and 29.8% (p=0.092). The clinical response rates in E and P arm were 82.2% and 91.0% (p=0.108). No statistical significant difference was found in efficacy of PST between E and P.

Conclusion:

This randomized phase II study revealed that eribulin had favorable peripheral neuropathy profile with modest efficacy in the neoadjuvant setting, compared with paclitaxel.

Citation Format: Miura D, Hasegawa Y, Ishikawa T, Tachibana A, Horiguchi J, Hayashi M, Miyashita M, Kubota T, Narui K, Suzuki M, Akazawa K, Kohno N. Randomized controlled trial of neoadjuvant eribulin mesylate versus paclitaxel in women with operable breast cancer (JONIE-3 study) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-15-05.

A multicenter retrospective study of the risk factors associated with medication-related osteonecrosis of the jaw after tooth extraction in patients receiving oral bisphosphonate therapy: can primary wound closure and a drug holiday really prevent MRONJ?

Root amputation, extraction of a single tooth, bone loss or severe tooth mobility, and an unclosed wound were significantly associated with increased risk of developing medication-related osteonecrosis of the jaw (MRONJ). We recommend a minimally traumatic extraction technique, removal of any bone edges, and mucosal wound closure as standard procedures in patients receiving bisphosphonates.

INTRODUCTION

Osteonecrosis of the jaws can occur following tooth extraction in patients receiving bisphosphonate drugs. Various strategies for minimizing the risk of MRONJ have been advanced, but no studies have comprehensively analyzed the efficacy of factors such as primary wound closure, demographics, and drug holidays in reducing its incidence. The purpose of this study was to retrospectively investigate the relationships between these various risk factors after tooth extraction in patients receiving oral bisphosphonate therapy.

METHODS

Risk factors for MRONJ after tooth extraction were evaluated using univariate and multivariate analysis. All patients were investigated with regard to demographics; type and duration of oral bisphosphonate use; whether they underwent a discontinuation of oral bisphosphonates before tooth extraction (drug holiday), and the duration of such discontinuation; and whether any additional surgical procedures (e.g., incision, removal of bone edges, root amputation) were performed.

RESULTS

We found that root amputation (OR = 6.64), extraction of a single tooth (OR = 3.70), bone loss or severe tooth mobility (OR = 3.60), and an unclosed wound (OR = 2.51) were significantly associated with increased risk of developing MRONJ.

CONCLUSIONS

We recommend a minimally traumatic extraction technique, removal of any bone edges, and mucosal wound closure as standard procedures in patients receiving bisphosphonates. We find no evidence supporting the efficacy of a pre-extraction short-term drug holiday from oral bisphosphonates in reducing the risk of MRONJ.

A multi-centre retrospective study of mandibular fractures: do occlusal support and the mandibular third molar affect mandibular angle and condylar fractures?

This retrospective study was performed to investigate the influence of occlusal support and the presence, state, and position of mandibular third molars on the incidence of mandibular angle and condylar fractures. The following variables were investigated: age, sex, cause of fracture, presence and state (impaction, angulation, and the number of roots) of the mandibular third molars, site of the mandibular fracture, presence of occlusal support, duration of intermaxillary fixation, and postoperative complications. Various risk factors for mandibular angle and condylar fractures were investigated by univariate analysis. The risk of mandibular angle fracture was significantly higher in patients with occlusal support and mandibular third molars. The risk of condylar fracture was significantly higher in patients without occlusal support or mandibular third molars. The position and angulation of the mandibular third molars were not significant risk factors in mandibular angle and condylar fractures. This study demonstrated the influence of occlusal support and the presence of mandibular third molars on the incidence of mandibular angle and condylar fractures. The presence of occlusal support may be a more important factor affecting mandibular angle or condylar fractures than the position of the mandibular third molars.

Changes in Sympathetic Tone During Cooperative Game Play

We investigated the relationship between stress (specifically, sympathetic tone) and effective and efficient cooperation between partners using a cooperative version of a Tetris game as a model of limited resources in a shared environment. Participants were recruited from 2 distinct sociocultural orientations: individualism (Americans) and collectivism (Japanese). We compared the frequency domain of heart rate variability (HRV) and average scores on the short form of the Positive and Negative Affect Scale (I-PANAS-SF) for individuals and dyad partners. Japanese players cooperated more effectively and their scores on the positive subscale of the I-PANAS-SF for both self and partner were higher than those of American players. However, Japanese participants experienced more stress, as indicated by an increased low-to-high HRV frequency ratio. Our results suggest that sociocultural orientation affects the motivation to promote prosocial interactions that result in efficiency and effectiveness of cooperation.

fMRI Validation of fNIRS Measurements During a Naturalistic Task

We present a method to compare brain activity recorded with near-infrared spectroscopy (fNIRS) in a dance video game task to that recorded in a reduced version of the task using fMRI (functional magnetic resonance imaging). Recently, it has been shown that fNIRS can accurately record functional brain activities equivalent to those concurrently recorded with functional magnetic resonance imaging for classic psychophysical tasks and simple finger tapping paradigms. However, an often quoted benefit of fNIRS is that the technique allows for studying neural mechanisms of complex, naturalistic behaviors that are not possible using the constrained environment of fMRI. Our goal was to extend the findings of previous studies that have shown high correlation between concurrently recorded fNIRS and fMRI signals to compare neural recordings obtained in fMRI procedures to those separately obtained in naturalistic fNIRS experiments. Specifically, we developed a modified version of the dance video game Dance Dance Revolution (DDR) to be compatible with both fMRI and fNIRS imaging procedures. In this methodology we explain the modifications to the software and hardware for compatibility with each technique as well as the scanning and calibration procedures used to obtain representative results. The results of the study show a task-related increase in oxyhemoglobin in both modalities and demonstrate that it is possible to replicate the findings of fMRI using fNIRS in a naturalistic task. This technique represents a methodology to compare fMRI imaging paradigms which utilize a reduced-world environment to fNIRS in closer approximation to naturalistic, full-body activities and behaviors. Further development of this technique may apply to neurodegenerative diseases, such as Parkinson’s disease, late states of dementia, or those with magnetic susceptibility which are contraindicated for fMRI scanning.

Is the useful field of view a good predictor of at-fault crash risk in elderly Japanese drivers?

AIM

Although age-related decline in the useful field of view (UFOV) is well recognized as a risk factor for at-fault crash involvement in elderly drivers, there is still room to study its applicability to elderly Japanese drivers. In the current study, we thus examined the relationship between UFOV and at-fault crash history in an elderly Japanese population. We also explored whether potential factors that create awareness of reduced driving fitness could be a trigger for the self-regulation of driving in elderly drivers.

METHODS

We measured UFOV and at-fault crash history from 151 community-dwelling Japanese aged 60 years or older, and compared UFOV of at-fault crash-free and crash-involved drivers. We also measured self-evaluated driving style using a questionnaire.

RESULTS

UFOV in crash-involved drivers was significantly lower than that in crash-free drivers. No significant difference was found in self-evaluated driving style between crash-free and crash-involved drivers. In addition, there was no significant association between UFOV and self-evaluated driving style.

CONCLUSIONS

The present study showed that UFOV is a good predictor of at-fault crash risk in elderly Japanese drivers. Furthermore, our data imply that it might be difficult for elderly drivers to adopt appropriate driving strategies commensurate with their current driving competence.

Effects of chewing on cognitive processing speed

In recent years, chewing has been discussed as producing effects of maintaining and sustaining cognitive performance. We have reported that chewing may improve or recover the process of working memory; however, the mechanisms underlying these phenomena are still to be elucidated. We investigated the effect of chewing on aspects of attention and cognitive processing speed, testing the hypothesis that this effect induces higher cognitive performance. Seventeen healthy adults (20-34 years old) were studied during attention task with blood oxygenation level-dependent functional (fMRI) at 3.0 T MRI. The attentional network test (ANT) within a single task fMRI containing two cue conditions (no cue and center cue) and two target conditions (congruent and incongruent) was conducted to examine the efficiency of alerting and executive control. Participants were instructed to press a button with the right or left thumb according to the direction of a centrally presented arrow. Each participant underwent two back-to-back ANT sessions with or without chewing gum, odorless and tasteless to remove any effect other than chewing. Behavioral results showed that mean reaction time was significantly decreased during chewing condition, regardless of speed-accuracy trade-off, although there were no significant changes in behavioral effects (both alerting and conflict effects). On the other hand, fMRI analysis revealed higher activations in the anterior cingulate cortex and left frontal gyrus for the executive network and motor-related regions for both attentional networks during chewing condition. These results suggested that chewing induced an increase in the arousal level and alertness in addition to an effect on motor control and, as a consequence, these effects could lead to improvements in cognitive performance.

Activation of dorsolateral prefrontal cortex in a dual neuropsychological screening test: an fMRI approach

Background

The Kana Pick-out Test (KPT), which uses Kana or Japanese symbols that represent syllables, requires parallel processing of discrete (pick-out) and continuous (reading) dual tasks. As a dual task, the KPT is thought to test working memory and executive function, particularly in the prefrontal cortex (PFC), and is widely used in Japan as a clinical screen for dementia. Nevertheless, there has been little neurological investigation into PFC activity during this test.

Methods

We used functional magnetic resonance imaging (fMRI) to evaluate changes in the blood oxygenation level-dependent (BOLD) signal in young healthy adults during performance of a computerized KPT dual task (comprised of reading comprehension and picking out vowels) and compared it to its single task components (reading or vowel pick-out alone).

Results

Behavioral performance of the KPT degraded compared to its single task components. Performance of the KPT markedly increased BOLD signal intensity in the PFC, and also activated sensorimotor, parietal association, and visual cortex areas. In conjunction analyses, bilateral BOLD signal in the dorsolateral PFC (Brodmann's areas 45, 46) was present only in the KPT.

Conclusions

Our results support the central bottleneck theory and suggest that the dorsolateral PFC is an important mediator of neural activity for both short-term storage and executive processes. Quantitative evaluation of the KPT with fMRI in healthy adults is the first step towards understanding the effects of aging or cognitive impairment on KPT performance.

Petersen's hernia as a complication of bariatric surgery: CT findings

Referrals for bariatric surgery have currently increased due to the need for more effective interventions in the management of severely obese patients. The Roux-en-Y gastric bypass is currently one of the preferred procedures, and internal hernias are the main causes of late postoperative complication. Petersen's hernia is a less common finding in most published papers compared to transmesocolic hernia, however, it seems to be increasing in incidence (in our service, eight cases which have been tomographic diagnosed in 2 years, were confirmed by laparoscopic surgery). The clinical findings are not specific, usually with abdominal pain, associated or not with abdominal distention and vomiting. In this context, imaging exams have an important role in the early diagnosis and surgery of this condition, with multislice computed tomography being the most accurate method. The aim of this pictorial essay is to the demonstrate the main CT findings associated with Petersen's hernia in patients who underwent Roux-en-Y gastric bypass.

The changing pattern of referral in acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is not only managed by nephrologists, but also by several other subspecialists. The referral rate to nephrologists and the factors influencing it are unknown.

AIMS

To determine the referral rate, factors affecting referral and outcomes across the spectrum of AKI in a population based study.

METHODS

We identified all patients with serum creatinine concentrations ≥150 µmol/l (male) or ≥130 µmol/l (female) over a 6-month period. AKI was defined according to the RIFLE classification (risk, injury, failure, loss, end stage renal disease [ESRD]). Clinical information and outcomes were obtained from each patient's case records.

RESULTS

A total of 562 patients were identified as having AKI (incidence 2147 per million population/year [pmp/y]). One hundred and sixty-four patients (29%) were referred to nephrologists-referral rate 627 pmp/y. Forty-nine percent of patients whose serum creatinine rose to >300 µmol/l were referred compared with 22% in our previous study of 1997. Forty-eight patients required renal replacement therapy-incidence 184 pmp/y in comparison to 50 pmp/y in our previous study of 1997. Patients had higher odds of referral if they were male, of younger age and were in the F category of the RIFLE classification. Patients had lower odds of referral if they had multiple co-morbid conditions or if they were managed in a hospital without a nephrology service.

CONCLUSION

There has been a significant rise in the referral rate of patients with AKI to nephrologists but even during our period of study only one-third of such patients were being referred. With rising incidence and increased awareness, the referral rate will certainly rise putting a significant burden on the nephrology services.

Increased sensitivity to sparsely ionizing radiation due to excessive base excision in clustered DNA damage sites inEscherichia coli

PURPOSE

In order to clarify the cellular processing and repair mechanisms for radiation-induced clustered DNA damage, we examined the correlation between the levels of DNA glycosylases and the sensitivity to ionizing radiation in Escherichia coli.

MATERIALS AND METHODS

The lethal effects of gamma-rays, X-rays, alpha-particles and H2O2 were determined in E. coli with different levels of DNA glycosylases. The formation of double-strand breaks by post-irradiation treatment with DNA glycosylase was assayed with gamma-irradiated plasmid DNA in vitro.

RESULTS

An E. coli mutM nth nei triple mutant was less sensitive to the lethal effect of sparsely ionizing radiation (gamma-rays and X-rays) than the wild-type strain. Overproduction of MutM (8-oxoguanine-DNA glycosylase), Nth (endonuclease III) and Nei (endonulease VIII) increased the sensitivity to gamma-rays, whereas it did not affect the sensitivity to alpha-particles. Increased sensitivity to gamma-rays also occurred in E. coli overproducing human 8-oxoguanine-DNA glycosylase (hOgg1). Treatment of gamma-irradiated plasmid DNA with purified MutM converted the covalently closed circular to the linear form of the DNA. On the other hand, overproduction of MutM conferred resistance to H2O2 on the E. coli mutM nth nei mutant.

CONCLUSIONS

The levels of DNA glycosylases affect the sensitivity of E. coli to gamma-rays and X-rays. Excessive excision by DNA glycosylases converts nearly opposite base damage in clustered DNA damage to double-strand breaks, which are potentially lethal.

Obstacle clearance and prevention from falling in the bipedally walking Japanese monkey, Macaca fuscata

BACKGROUND

studies are needed which consider CNS-controlled strategies for accommodating perturbed bipedal (Bp) posture and walking.

OBJECTIVE

to demonstrate the suitability of the Japanese monkey, Macaca fuscata, for the above purpose.

SETTING AND SUBJECTS

three adult monkeys were operantly trained to use Bp-walking on a moving treadmill belt. On one side of the belt, a rectangular adjustable-height obstacle confronted the ipsilateral leg every 4-6 steps, as determined by belt speed.

METHODS

animal posture and walking patterns were captured and digitized by two high-speed video systems. Frame-by-frame analyses of side- and back-view kinematics were obtained.

RESULTS

the monkeys learned quickly to proactively clear the in-coming obstacles by use of a flexible hip-knee-ankle flexion strategy. This featured an appropriate postural adjustment and leg trajectory. In cases where a monkey failed to clear the obstacle, it promptly adopted a defensive posture to avoid falling. There was then a quick return to a posture that allowed the resumption of a Bp gait.

CONCLUSIONS

when Bp posture and gait are perturbed in a non-human primate model, the prompt adjustment of a flexible hip-knee-ankle flexion strategy and a defensive postural adjustment act together to prevent a fall and enable the speedy resumption of normal Bp posture and gait.

Coordination of fore and hind leg stepping in cats on a transversely-split treadmill

To gain insight into the mechanism of coordination of stepping in the fore and hind legs of quadrupeds, we examined the kinematics of leg movements and the motor patterns in fore and hind leg flexor muscles in decerebrate walking cats when the two pairs of legs stepped on separate treadmills running at different speeds. When the front treadmill was slowed progressively from 0.6 to 0.3 m/s with the rear treadmill running at 0.6 m/s, the rate of stepping in both the fore and hind legs decreased and a 1:1 stepping ratio was maintained. The decrease in the rate of stepping in the hind legs was due primarily to an increase in the duration of the swing phase. Slowing the speed of the rear treadmill while keeping the front treadmill speed at 0.6 m/s decreased the rate of stepping of the hind legs, but had relatively little influence on the average rate of stepping in the forelegs. In this situation stepping in the fore and hind legs was uncoupled and the time of stepping in one hind leg relative to the ipsilateral foreleg progressively shifted during a walking sequence. Analysis of the timing of electromyographic (EMG) recordings from flexor muscles of the hip and elbow joints yielded insight into the neuronal mechanisms underlying the asymmetry in slowing either the front or rear treadmill. We propose that ipsilateral pattern generating networks are asymmetrically coupled via descending inhibitory pathways and an ascending excitatory pathway. We discuss how the characteristics of these linkages are functionally appropriate for establishing the normal timing of stepping in the hind and forelegs during slow walking.

A Role for Hip Position in Initiating the Swing-to-Stance Transition in Walking Cats

In this investigation, we obtained data that support the hypothesis that afferent signals associated with hip flexion play a role in initiating the swing-to-stance transition of the hind legs in walking cats. Direct evidence came from observations in walking decerebrate cats. Assisting the flexion of the hip joint during swing advanced the onset of activity in ankle extensor muscles, and this advance was strongly correlated with a reduction in the duration of hip flexor muscle activity. The hip angle at the time of onset of the flexion to extension transition was similar during assisted and unassisted steps. Additional evidence for the hypothesis that sensory signals related to hip flexion are important in regulating the swing-to-stance transition came from four normal animals trained to walk in a variety of situations designed to alter the coordination of movements at the hip, knee, and ankle joints during the swing phase. Although there were exceptions in some tasks and preparations, the angle of the hip joint at the time of onset of extensor activity was generally less variable than that of the knee and ankle joints. We also found no clear relationships between the angle of the limb and body axes, or the length of the limb axis, and the time of onset of extensor activity. Finally, there were no indications that the stretching of ankle extensor muscles during swing was a factor in regulating the transition from swing-to-stance.

Recruitment of gastrocnemius muscles during the swing phase of stepping following partial denervation of knee flexor muscles in the cat

In walking cats, the biarticular medial and lateral gastrocnemius (MG-LG) muscles act to produce extension and flexion torques at the ankle and knee, respectively, and they usually display only one burst of activity beginning just before ground contact and ending near the end of the stance phase. Currently, the MG-LG muscles are considered to function primarily to control extension movements around the ankle joint during the stance phase. However, their flexion action at the knee means that they have the capacity to regulate rotations at the knee, but this role has not yet been clearly defined. Following partial denervation of the other muscles that normally act to flex the knee during swing, we observed that the MG-LG muscles, but not the Soleus muscle (a pure ankle extensor), often generated strong bursts of activity during early swing. These bursts were enhanced following mechanical stimulation of the paw, and they were especially prominent when the leg trailed over an object. They were absent when the leg led over an object. During treadmill walking the swing-related bursts in MG and LG had little influence on ankle flexion at the beginning of swing, but they were associated with slowing of ankle flexion when the leg trailed over an object. We hypothesized that the recruitment of these bursts functions to partially compensate for the reduction in knee torque resulting from the denervation of other knee flexors. Consistent with this hypothesis was our finding that the magnitude of the swing-related activity in the MG-LG muscles was linearly correlated to the extent of the knee flexion and to the peak angular velocity of knee flexion, and that the timing of the bursts was similar to that in the denervated muscles prior to denervation. Our findings suggest that an excitatory pathway exists from the flexor half-center of the central pattern-generating network to MG-LG motoneurons, and that this pathway is strongly regulated by central and/or peripheral signals.

Recombination repair pathway in the maintenance of chromosomal integrity against DNA interstrand crosslinks

DNA interstrand crosslinks (ICL) present a major threat to cell viability and genome integrity. In eukaryotic cells, the ICLs have been suggested to be repaired by a complex process involving Xpf/Ercc1-mediated endonucleolytic incision and homologous recombination (HR). However, the entire feature of the ICL tolerating mechanism is still poorly understood. Here we studied chromosome aberrations (CA) and sister chromatid exchanges (SCE) by the use of the crosslinking agent mitomycin C (MMC), in chicken DT40 cells with the HR genes disrupted by targeted replacement. The disruption of the Rad54, Rad51B, Rad51C, Rad51D, Xrcc2 and Xrcc3 genes resulted in a dramatic reduction of spontaneous and MMC-induced SCEs. Interestingly, while HR-deficient cells were hypersensitive to cell killing by MMC, MMC-induced CAs were also suppressed in the HR-deficient cells except for Rad51D-, Xrcc2- and Xrcc3-deficient cells. These observations indicate that DNA double strand breaks (DSB) at stalled replication forks and those arising as repair intermediates present strong signals to cell death but can be tolerated by the HR repair pathway, where Rad54, Rad51B and Rad51C have an initiative role and repair can be completed by their paralogs Rad51D, Xrcc2 and Xrcc3. The impairment of the HR pathway, which otherwise leads to cell death, may be somewhat substituted by an alternative mechanism such as the Mre11/Rad50/Nbs1 pathway, resulting in reduced frequencies of SCEs and CAs.

Reactive and anticipatory control of posture and bipedal locomotion in a nonhuman primate

Bipedal locomotion is a common daily activity. Despite its apparent simplicity, it is a complex set of movements that requires the integrated neural control of multiple body segments. We have recently shown that the juvenile Japanese monkey, M. fuscata, can be operant-trained to walk bipedally on moving treadmill. It can control the body axis and lower limb movements when confronted by a change in treadmill speed. M. fuscata can also walk bipedally on a slanted treadmill. Furthermore, it can learn to clear an obstacle attached to the treadmill's belt. When failing to clear the obstacle, the monkey stumbles but quickly corrects its posture and the associated movements of multiple motor segments to again resume smooth bipedal walking. These results give indication that in learning to walk bipedally, M. fuscata transforms relevant visual, vestibular, proprioceptive, and exteroceptive sensory inputs into commands that engage both anticipatory and reactive motor mechanisms. Both mechanisms are essential for meeting external demands imposed upon posture and locomotion.

Acquisition of operant-trained bipedal locomotion in juvenile Japanese monkeys (Macaca fuscata): a longitudinal study

This study investigated developmental aspects of the acquisition of operant-trained bipedal (Bp) standing and Bp walking in the normally quadrupedal (Qp) juvenile Japanese monkey (M. fuscata). Four male monkeys (age: 1.6 to 2.4 years, body weight: 3.3 to 4.6 kg) were initially operantly trained to stand upright on a smooth floor and a stationary treadmill belt (width = 60 cm, walking length = 150 cm). They were then trained to walk bipedally on the moving treadmill belt (speed: 0.4-0.7 m/s). A regular training program (5 days/week; 30-60 min/day) was given to each monkey for the first 40 to 60 days, followed by less intensive training. After the beginning of locomotor training, upright postural stability and Bp walking capability were assessed kinematically for 592, 534, 526, and 537 days on monkeys A, B, C, and D, respectively. Left side- and back-views of the walking monkey were photographed (10 frames/s) and videotaped (250 frames/s). Stick figures of the head, body, and hindlimbs were drawn with reference to ink-marks positioned in front of the ear and over the pivot points of hindlimb joints. All kinematic data were digitized and analyzed using image-analyzing software. After sufficient physical growth and locomotor training, all the monkeys gradually acquired: (a) a more upright and a more stable posture with a constant body axis orientation during Bp locomotion; (b) a more stable and a stronger functional coupling between the body and hindlimb movements with a less anterior (A)-posterior (P) fluctuation of a body axis; (c) a smaller leftward (Lt)-rightward (Rt) displacement of the midline pelvic position, allowing the monkey to walk along a straight course; (d) a more coordinated relationship among hip-knee, knee-ankle, and ankle-metatarsophalangeal (MTP) joints; and finally (e) the acquisition of well-coordinated Bp walking even at high treadmill belt speeds up to 1.5 m/s. All of these results demonstrated the capability of the physically developing monkey to integrate the neural and musculoskeletal mechanisms required for sufficient coordination of upper (head, neck, trunk) and lower (hindlimbs) motor segments so that Bp standing and Bp walking could be elaborated.

Radiation-induced apoptosis in the scid mouse spleen after low dose-rate irradiation

PURPOSE

To elucidate the process of radioadaptation, the role of DNA-PK activity was examined using the scid mouse defective in DNA-PKcs.

MATERIALS AND METHODS

The induction of apoptosis in the spleens of the C.B-17 Icr scid mouse and the parental mouse was studied after chronic irradiation with gamma-rays at 1.5 Gy (0.001 Gy min(-1) for 25 h) followed by challenge irradiation with X-rays at 3.0 Gy (1.0 Gy min(-1) for 3 min).

RESULTS

When the wild-type mouse was previously exposed to chronic irradiation (1.5 Gy) at a low dose-rate (0.001 Gy min(-1)), apoptosis induced by acute irradiation (3.0 Gy, 1.0 Gy min(-1)) was significantly suppressed, especially in the splenic white pulp. There was no change by acute irradiation after chronic irradiation in the scid mouse, although an effect was detected in the spleen after acute irradiation alone.

CONCLUSIONS

These data suggest that DNA-PK activity might play a major role in the radioadaptive response following pre-irradiation at a low dose-rate.

Bipedal locomotion by the normally quadrupedal Japanese monkey, M. Fuscata: strategies for obstacle clearance and recovery from stumbling

This study explored how the normally quadrupedal Japanese monkey adjusts to treadmill perturbations, when trained to walk bipedally. The monkey was required to use the left hindlimb to clear an obstacle that was fixed on the left side of a treadmill belt. The monkey either cleared the obstacle (CL: cleared locomotion), or stumbled over it (SL: stumbled locomotion). For CL, it changed its left hind limb's kinematics according to the obstacle's height and position relative to the left foot. In SL, the monkey used a "defensive posture", which included a rapid lowering of the right foot and forelimb movements, to stabilize the perturbed posture and thereby prevent falling. Then, with powerful extensions of its lower limb joints, the monkey raised its center-of-mass to the appropriate level for continuation of normal bipedal walking. The results show that M. Fuscata recruited both anticipatory and reactive neural mechanisms to accommodate to the obstacle.

High frequency of deletions at the hypoxanthine-guanine phosphoribosyltransferase locus in an ataxia-telangiectasia lymphoblastoid cell line irradiated with gamma-rays

The molecular nature of gamma-ray-induced mutations at the hypoxanthine-guanine phosphoribosyltransferase (HPRT) locus in an ataxia-telangiectasia (A-T) lymphoblastoid cell line was investigated. Twelve of 15 gamma-ray-induced HPRT-deficient mutants showed deletions. Eight of them had lost the entire HPRT gene, one showed a 1.9-kb deletion, and three had deletions of about 40-150 base pairs. Of the eight mutants that lost the entire gene, five had also lost both DXS79 and DXS86, flanking markers of the HPRT locus. The spectrum of mutations induced by gamma-irradiation in the A-T cells showed a high frequency of deletions in comparison with that in a control cell line, WIL2-NS. Sequence analysis of breakpoint junctions in four mutants revealed that three of them had junctions between short identical sequences at each breakpoint, leaving one copy at the junction. These results suggest that non-homologous end-joining is the major mechanism for deletion formation in A-T cells.

Radiation response of apoptosis in C57BL/6N mouse spleen after whole-body irradiation

PURPOSE

Primary conditioning low dose irradiation suppresses the molecular responses against secondary challenge high dose irradiation; this phenomenon has been termed the radioadaptive response. The mechanism of the radioadaptive response is not yet clear. This study was undertaken to elucidate the radiation response of apoptosis in mouse spleen after whole-body irradiation.

MATERIALS AND METHODS

The induction of apoptosis was analysed in the spleens of C57BL/6N mice after chronic irradiation with gamma-rays at 1.5 Gy (0.001 Gy/min for 25 h) followed by challenge irradiation with X-rays at 3.0Gy (1 Gy/min).

RESULTS

Accumulation of p53 and Bax, and the induction of apoptosis were observed dose-dependently in mouse spleen 12 h after acute irradiation at a high dose-rate. However, it was found that there was significant suppression of the accumulation of p53 and Bax, and induction of apoptosis 12 h after challenge irradiation at 3.0Gy at a high dose-rate following chronic preirradiation at 1.5Gy at a low dose-rate. In addition, the combination of pre-irradiation at 1.5Gy at a high dose-rate and challenge irradiation at 3.0Gy at a high dose-rate could not suppress the accumulation of p53 and Bax or the induction of apoptosis.

CONCLUSIONS

Chronic pre-irradiation at a low dose-rate suppressed Bax-mediated apoptosis. These findings suggest that the radioadaptive response in mouse spleen may be due to a suppression of p53-mediated apoptosis.

Stereoselective synthesis of the axially chiral A-B ring system of vancomycin utilizing a planar chiral arene chromium complex

[reaction: see text] The axial biaryl ring system of vancomycin was stereoselectively synthesized by utilizing a planar chiral tricarbonyl(arylhalide)chromium complex. Both enantiomers of the planar chiral (arylbromide)chromium complexes, (+)-9 and ent-(-)-9, can be stereoselectively transferred to an absolutely identical key intermediate 23 for the vancomycin A-B ring system by the diastereoselective Suzuki-Miyaura cross-coupling reaction as key step.

Neonatal thrombocytosis resulting from the maternal use of non-narcotic antischizophrenic drugs during pregnancy

Neonatal thrombocytosis can result from maternal narcotic drug abuse. The case of a male infant is reported who was born to a woman with schizophrenia treated with non-narcotic psychotropic drugs during pregnancy; he developed severe prolonged thrombocytosis. The platelet count reached 1310 x 10(9)/l on day 15. This thrombocytosis persisted for three months. The patient was treated with dipyridamole. A bone marrow aspirate showed normal myeloid and erythroid precursors with an increased number of megakaryocytes. Plasma concentrations of interleukin 6 and thrombopoietin were suppressed. No obvious complications from the thrombocytosis occurred, and the platelet count fell to within the upper limit of normal after 3 months of age. This case indicates that thrombocytosis may occur in infants born to mothers treated with non-narcotic psychopharmaceutical drugs during pregnancy. The thrombocytosis in this case may have been induced by factors other than interleukin 6 or thrombopoietin.