Effect of middle ear infection upon the pneumatization of the mastoid: An experimental study in pigs

The suppression of the temporal bone's pneumatized cavities is commonly observed in chronic middle ear inflammatory disease, but this fact has not been explained in respect to its etiology, i.e., whether the poorly pneumatized cavity induces chronic middle ear infection or middle ear inflammatory condition suppresses the pneumatization of cellulae. We studied the effect of middle ear infection and eustachian tubal dysfunction in the early stage of life upon the development of pneumatization of the mastoid using 13 pigs, whose mastoid is comparable to that of man. We used two methods, the eustachian tube stenosis test and the tympanic membrane paraffin infusion test. The present study indicated that in six pigs infection of the middle ear in the early stage of life suppressed the normal development of pneumatization of the mastoid bone in pigs.     

Advanced Colorectal Carcinomas Measuring 20 mm or Less Exhibit Markedly Higher Invasiveness Despite Their Size

To analyze the biology of small (20 mm or less) advanced colorectal carcinomas (SAC), 24 cases, 22 small early colorectal carcinomas (SEC) of similar size, and 52 advanced colorectal carcinomas (AC) were studied. The proliferative (Ki-67) labeling index for SAC was 65.9+/-17.1%, significantly higher than those for SEC (30.9+/-13.7%) or AC (43.0+/-17.1%) (P < 0.01). Matrix metalloproteinase (MMP)-9 and tissue inhibitors of metalloproteinase (TIMP)-2 expressions for SAC were 62.5 and 79.2%, respectively, significantly higher than those for SEC (4.5, 13.6%) or AC (21, 33%) (P < 0.01). Small advanced carcinomas have higher invasiveness than SEC or AC and may represent a different type of cancer.     

Lower rhombic lip-derived cells undergo transmedian tangential migration followed by radial migration in the chick embryo brainstem

Migration behaviour and fate of cells originated from the lower rhombic lip (LRL) was examined in the chick embryo hindbrain. LRL-derived cells tangentially migrate along the pial surface of the brainstem and form a transient subpial migratory stream. In the initial stages of migration, LRL-derived cells appose each other or axon-like processes, which is indicative of mode of homophilic chain migration and/or axophilic migration. Some LRL-derived cells relocate rostroventrally towards the pontine region, although the majority of them migrate circumferentially to the ventral medulla oblongata. Depending on the stage of generation, LRL-derived cells undergo transmedian migration; late-generated LRL-derived cells preferentially colonize the contralateral brainstem compared with early generated cells. Thus, latecomer neuron precursors may migrate past their predecessors in the migratory stream. When LRL-derived cells leave the subpial migratory stream, they change their migratory direction to a radial one and relocate inwardly, with a profile that resembles a tangential-to-radial change seen in cerebellar granule cell precursors. After they enter the parenchymal region of the brainstem, they exhibited morphological differentiation, and some differentiate into excitatory neurons. The present results suggest that LRL-derived cells migrate across boundaries such as midline or rhombomere, which may facilitate to build up cellular and functional architectures of the hindbrain.     

Cortical processing of tactile language in a postlingually deaf-blind subject

We compared neural activation detected by magnetoencephalography (MEG) during tactile presentation of words and non-words in a postlingually deaf-blind subject and six normal volunteers. The left postcentral gyrus, bilateral inferior frontal gyri, left posterior temporal lobe, right anterior temporal lobe, bilateral middle occipital gyri were activated when tactile words were presented to the right hand of the deaf-blind subject. This set of activated regions was not observed in the normal volunteers, although activation of several combinations of these regions was detected. Positron emission tomography confirmed the location of the MEG-activated areas in the deaf-blind subject. Our results demonstrated that the deaf-blind subject is heavily involved in interpreting tactile language by enhancing cortical activation of cognitive and semantic processing.     

Electroporation-mediated gene transfer system applied to cultured CNS neurons

Electroporation is effective in transferring foreign genes into immature neurons in intact brain tissue. We utilized this approach to transfect genes into developing rodent hippocampi. Transfected hippocampi were subsequently dissociated and allowed to differentiate in culture. By optimizing developmental stage of the hippocampus, promoters to drive the marker cDNA, and culture conditions, neurons kept strong expression of multiple marker genes for more than two weeks after electroporation. We could also induce transient expression in mature neurons by combining electroporation of plasmids containing loxP-flanked stopper sequences and infection of Cre-producing recombinant adenoviruses. The system described here is useful in analyzing biological roles of multiple genes in specific stages of neuronal development.     

Independent inputs by VGLUT2- and VGLUT3-positive glutamatergic terminals onto rat sympathetic preganglionic neurons

To characterize glutamatergic axon terminals onto sympathetic preganglionic neurons (SPNs), we visualized immunohistochemically three vesicular glutamate transporters (VGLUTs) in the intermediolateral cell column (IML) of rat thoracic spinal cord. VGLUT2 and VGLUT3 immunoreactivities but not VGLUT1 immunoreactivity were distributed in the IML and found in terminals making asymmetric synapses and apposed to dendrites immunopositive for choline acetyltransferase, an SPN marker. VGLUT2 and VGLUT3 immunoreactivities were not co-localized with each other. A population of VGLUT2-immunoreactive but not VGLUT3-immunoreactive terminals were adrenergic or noradrenergic. Some of VGLUT3-immunoreactive but not VGLUT2-immunoreactive terminals contained serotonin. These results indicate at least two independent glutamatergic terminal populations, which include a distinct monoaminergic subpopulation, making excitatory inputs onto SPNs.     

Alzheimer disease: evidence for a central pathogenic role of iron-mediated reactive oxygen species

Free radical formation, abnormalities in iron and copper distribution, and metal-catalyzed oxidation have all been noted in Alzheimer disease and are thought to play an important role in disease pathogenesis. Metal-catalyzed hydroxyl radical formation results in damage to every category of macromolecule found in the vulnerable neuronal populations in Alzheimer disease. In fact, redox activity resides within the cytosol of vulnerable neurons. Since oxidative damage represents one of the earliest pathological changes in Alzheimer disease, it is likely that aberrant redox activity is among the earliest changes in the transition to the disease state. In this review, we consider the wealth of evidence implicating a central role for metals in Alzheimer disease.     

Three-dimensional probabilistic anatomical cranio-cerebral correlation via the international 10-20 system oriented for transcranial functional brain mapping

The recent advent of multichannel near-infrared spectroscopy (NIRS) has expanded its technical potential for human brain mapping. However, NIRS measurement has a technical drawback in that it measures cortical activities from the head surface without anatomical information of the object to be measured. This problem is also found in transcranial magnetic stimulation (TMS) that transcranially activates or inactivates the cortical surface. To overcome this drawback, we examined cranio-cerebral correlation using magnetic resonance imaging (MRI) via the guidance of the international 10-20 system for electrode placement, which had originally been developed for electroencephalography. We projected the 10-20 standard cranial positions over the cerebral cortical surface. After examining the cranio-cerebral correspondence for 17 healthy adults, we normalized the 10-20 cortical projection points of the subjects to the standard Montreal Neurological Institute (MNI) and Talairach stereotactic coordinates and obtained their probabilistic distributions. We also expressed the anatomical structures for the 10-20 cortical projection points probabilistically. Next, we examined the distance between the cortical surface and the head surface along the scalp and created a cortical surface depth map. We found that the locations of 10-20 cortical projection points in the standard MNI or Talairach space could be estimated with an average standard deviation of 8 mm. This study provided an initial step toward establishing a three-dimensional probabilistic anatomical platform that enables intra- and intermodal comparisons of NIRS and TMS brain imaging data.