Neural and musculoskeletal contributions to the development of stance balance control in typical children and in children with cerebral palsy

Studies on the development of automatic postural responses in both typically developing children and children with cerebral palsy were performed. With the appearance of "pull-to-stand" behavior, typically developing children first began to show muscle responses to platform movements in mainly the ankle muscles. With increased development, additional agonist muscles were added to the response pattern and a consistent distal to proximal sequence began to emerge. Well-organized responses were seen with the onset of independent stance and walking, along with the reduction of antagonist muscle co-activation. The older children with cerebral palsy who were pre-walkers had immature muscle activation patterns like those seen in the typically developing children at the pull-to- stand stage of development. These included disorganized muscle responses and increased frequency of coactivation of both proximal–distal and agonist–antagonist muscles. In order to determine if musculoskeletal constraints contributed to these response patterns, normal children were asked to stand in a crouched posture similar to that of children with CP. This caused postural muscle response patterns to more closely approximate those of children with spastic diplegia.     

Induction of long-term depression is associated with decreased dendritic length and spine density in layers III and V of sensorimotor neocortex

Long-term potentiation (LTP) and long-term depression (LTD) are currently the most widely investigated models of the synaptic mechanisms underlying learning and memory. Previous research has shown that induction of LTP increases measures of pyramidal cell dendritic morphology in the hippocampus and layers III and V of the neocortex. However, to date there are no reports on the direct effects of LTD induction on dendritic morphology. Here, we investigated the effects of LTD induction on sensorimotor pyramidal cell dendritic morphology. Rats carried a stimulating electrode in the corpus callosum (midline) and a recording electrode in the right sensorimotor cortex. Each rat received low-frequency stimulation composed of 900 pulses at 1 Hz or handling daily for a total 15 days. Evoked potentials (EPs) of the transcallosal pathway were recorded in the right hemisphere before and after the 15 days of stimulation or handling. The rats were then perfused with saline and the brains were immediately processed for Golgi-Cox staining. Our results show that LTD induction is related to decreases in dendritic length and spine density both in layers III and V as well as a decrease in dendritic branch complexity in layer V of the sensorimotor cortex. Thus, neuronal alterations following modifications in neocortical synaptic efficacy may provide a general mechanism for the physical instantiation of learning and memory.     

Differential neuroplastic changes in neocortical movement representations and dendritic morphology in epilepsy-prone and epilepsy-resistant rat strains following high-frequency stimulation

The epileptogenic-prone (FAST) and epileptogenic-resistant (SLOW) rat strains have become a valuable tool for investigating the neurochemical and neurophysiological basis of epilepsy. This study examined the two strains with respect to their neocortical movement representations and cortical layer III pyramidal cell dendritic morphology in both control and potentiated conditions. FAST and SLOW rats received high-frequency stimulation of the corpus callosum in order to induce long-term polysynaptic potentiation of the transcallosal pathway to the sensorimotor neocortex. Baseline-evoked potentials of this pathway were recorded in the left hemisphere before stimulation, and following 5, 10, 15 and 20 days of high-frequency stimulation. All rats then underwent high-resolution intracortical microstimulation (ICMS) in order to assess functional movement representations of the left caudal forelimb area of the sensorimotor cortex. Immediately following ICMS, the brains were stained with the Golgi-Cox method, and the length, branching and spine density of frontal and occipital neocortical layer III pyramidal neurons were measured. We observed that high-frequency stimulation induced similar increases in polysynaptic potentiation in both rat strains; however, only the FAST strain showed an increase (doubling) in the size of their motor maps. We also observed decreases in dendritic length and branching in the FAST rats, and the opposite profile in the SLOW rats. The potentiated FAST rats also showed an increase in spine density. Our results suggest that differences in susceptibility to epileptogenesis may result in a differential response to stimulation-induced plasticity.     

Dynamic holographic imaging of the beating human heart

Background--Currently, the reporting and archiving of echocardiographic data suffer from the difficulty of representing heart motion on printable 2-dimensional (2D) media. Methods and Results--We studied the capability of holography to integrate motion into 2D echocardiographic prints. Images of normal human hearts and of a variety of mitral valve function abnormalities (mitral valve prolapse, systolic anterior motion of the mitral leaflets, and obstruction of the mitral valve by a myxoma) were acquired digitally on standard echocardiographic machines. Images were processed into a data format suitable for holographic printing. Angularly multiplexed holograms were then printed on a prototype holographic "laser" printer, with integration of time in vertical parallax, so that heart motion became visible when the hologram was tilted up and down. The resulting holograms displayed the anatomy with the same resolution as the original acquisition and allowed detailed study of valve motion with side-by-side comparison of normal and abnormal findings. Comparison of standard echocardiographic measurements in original echo frames and corresponding hologram views showed an excellent correlation of both methods (P<0.0001, r2=0.979, mean bias=2.76 mm). In this feasibility study, both 2D and 3D holographic images were produced. The equipment needed to view these holograms consists of only a simple point-light source. Conclusions--Holographic representation of myocardial and valve motion from echocardiographic data is feasible and allows the printing on a 2D medium of the complete heart cycle. Combined with the recent development of online holographic printing, this novel technique has the potential to improve reporting, visualization, and archiving of echocardiographic imaging.     

7-(4,7-二取代香豆素-3-乙酰氨基)头孢菌素的合成

本文根据构效关系,设计并合成了17个7-(4,7-二取代香豆素-3-乙酰氨基)头孢菌素衍生物。其缩合方法采用酰氯法、Vilsmeier试剂法及混合酐法。初步体外抑菌试验表明,化合物对革兰氏阳性菌和少数革兰氏阴性菌有较强的抗菌作用。进一步药理试验尚在进行。     

O等位基因引起ABO基因型与表现型定型差异

保证输血时血清学方面的安全,首要的是对受血者与献血者ABO血型定型,血清学检查通常分两个步骤.正定型通常使用鼠源单克隆抗体检测红细胞表面是否存在A或B抗原.互补的实验即反定型,利用当红细胞上缺乏A或B抗原时,人群可天然产生相对应的抗体的原理,检测血清中是否存在抗-A或者抗-B抗体.确定了受血者红细胞表面的ABO抗原以及血浆中的抗体,便能确定血型,为其提供相合的血液.