Evaluation of magnetic micro- and nanoparticle toxicity to ocular tissues

PURPOSE

Magnetic nanoparticles (MNPs) may be used for focal delivery of plasmids, drugs, cells, and other applications. Here we ask whether such particles are toxic to ocular structures.

METHODS

To evaluate the ocular toxicity of MNPs, we asked if either 50 nm or 4 µm magnetic particles affect intraocular pressure, corneal endothelial cell count, retinal morphology including both cell counts and glial activation, or photoreceptor function at different time points after injection. Sprague-Dawley rats (n = 44) were injected in the left eye with either 50 nm (3 µl, 1.65 mg) or 4 µm (3 µl, 1.69 mg) magnetic particles, and an equal volume of PBS into the right eye. Electroretinograms (ERG) were used to determine if MNPs induce functional changes to the photoreceptor layers. Enucleated eyes were sectioned for histology and immunofluorescence.

RESULTS

Compared to control-injected eyes, MNPs did not alter IOP measurements. ERG amplitudes for a-waves were in the 100-250 µV range and b-waves were in the 500-600 µV range, with no significant differences between injected and non-injected eyes. Histological sectioning and immunofluorescence staining showed little difference in MNP-injected animals compared to control eyes. In contrast, at 1 week, corneal endothelial cell numbers were significantly lower in the 4 µm magnetic particle-injected eyes compared to either 50 nm MNP- or PBS-injected eyes. Furthermore, iron deposition was detected after 4 µm magnetic particle but not 50 nm MNP injection.

CONCLUSIONS

Intravitreal or anterior chamber injections of MNPs showed little to no signs of toxicity on retinal structure, photoreceptor function or aqueous drainage in the eye. Our results suggest that MNPs are safe for intraocular use.

Posterior fossa decompression and the cerebellum in Chiari type II malformation: a preliminary MRI study

OBJECTIVES

Chiari type II malformation (CII) is a congenital deformity of the hindbrain. The posterior fossa and cerebellum are small in CII. The cerebellar atrophy is associated with cognitive and motor deficits. Brainstem compression occurs in some patients with CII for whom posterior fossa decompression may be life saving. The aim was to determine whether posterior fossa decompression can prevent or reduce the cerebellar atrophy in CII.

METHODS

Cerebellar volumes and their tissue types (gray matter, white matter, and CSF volumes) from brain MRI were compared among four CII patients, aged 9.5 to 16.5 years, who had had posterior fossa decompression in infancy, 28 CII patients who had not had posterior fossa decompression, and ten age-matched normal controls. Parametric and non-parametric tests investigated group differences.

RESULTS

Compared to controls, mean cerebellar volume was significantly smaller in CII patients (p<0.0001). Mean CSF volume within the cerebellar fissures and fourth ventricle was significantly smaller in patients without posterior fossa decompression compared to the CII patients who had the decompression, p=0.043. Mean CSF volume of the latter group was similar to the controls. Other cerebellar volumetric measurements did not differ between the CII groups.

CONCLUSIONS

Posterior fossa decompression normalizes CSF spaces within the posterior fossa in CII but does not prevent the cerebellar atrophy. The author proposes that surgical expansion of the posterior fossa should be considered in infants with CII who have a significantly small posterior fossa, to prevent or reduce the deficits associated with the cerebellar atrophy.

Early microglial colonization of the human forebrain and possible involvement in periventricular white-matter injury of preterm infants

Amoeboid microglial subpopulations visualized by antibodies against ionized calcium-binding adapter molecule 1, CD68, and CD45 enter the forebrain starting at 4.5 postovulatory or gestational weeks (gw). They penetrate the telencephalon and diencephalon via the meninges, choroid plexus, and ventricular zone. Early colonization by amoeboid microglia-macrophages is first restricted to the white matter, where these cells migrate and accumulate in patches at the junctions of white-matter pathways, such as the three junctions that the internal capsule makes with the thalamocortical projection, external capsule and cerebral peduncle, respectively. In the cerebral cortex anlage, migration is mainly radial and tangential towards the immature white matter, subplate layer, and cortical plate, whereas pial cells populate the prospective layer I. A second wave of microglial cells penetrates the brain via the vascular route at about 12-13 gw and remains confined to the white matter. Two main findings deserve emphasis. First, microglia accumulate at 10-12 gw at the cortical plate-subplate junction, where the first synapses are detected. Second, microglia accumulate in restricted laminar bands, most notably around 19-30 gw, at the axonal crossroads in the white matter (semiovale centre) rostrally, extending caudally in the immature white matter to the visual radiations. This accumulation of proliferating microglia is located at the site of white-matter injury in premature neonates. The spatiotemporal organization of microglia in the immature white and grey matter suggests that these cells may play active roles in developmental processes such as axonal guidance, synaptogenesis, and neurodevelopmental apoptosis as well as in injuries to the developing brain, in particular in the periventricular white-matter injury of preterm infants.

Xenopus sonic hedgehog guides retinal axons along the optic tract

The role of classic morphogens such as Sonic hedgehog (Shh) as axon guidance cues has been reported in a variety of vertebrate organisms (Charron and Tessier-Lavigne [2005] Development 132:2251-2262). In this work, we provide the first evidence that Xenopus sonic hedgehog (Xshh) signaling is involved in guiding retinal ganglion cell (RGC) axons along the optic tract. Xshh is expressed in the brain during retinal axon extension, adjacent to these axons in the ventral diencephalon. Retinal axons themselves express Patched 1 and Smoothened co-receptors during RGC axon growth. Blocking Shh signaling causes abnormal ventral pathfinding, and targeting errors at the optic tectum. Misexpression of exogenous N-Shh peptide in vivo also causes pathfinding errors. Retinal axons grown in culture respond to N-Shh in a dose-dependent manner, either by decreasing extension at lower concentrations, or retracting axons in the presence of higher doses. These data suggest that Shh signaling is required for normal RGC axon pathfinding and tectal targeting in the developing visual system of Xenopus. We propose that Shh serves as a ventral optic tract repellent that helps to define the caudal boundary for retinal axons in the diencephalon, and that this signaling is also required for initial target recognition at the optic tectum.

Amniotic fluid levels of glial fibrillary acidic protein in fetal rats with retinoic acid induced myelomeningocele: a potential marker for spinal cord injury

OBJECTIVE

The objective of this study was to determine whether amniotic fluid levels of glial acidic fibrillary protein (GFAP) would reflect myelomeningocele-related neurodegeneration in the rat model of retinoic acid-induced myelomeningocele, which is a model that is very similar to human myelomeningocele and develops the entire spectrum of disease severity including features of the Chiari II malformation.

STUDY DESIGN

Time-dated (embryonic day 10) pregnant Sprague-Dawley rats were gavage fed 60 mg/kg/bodyweight retinoic acid that had been dissolved in olive oil or olive oil alone. Myelomeningocele, retinoic acid-exposed no myelomeningocele, and control fetuses were harvested at specific time points throughout gestation. A standard set of pinching tests was performed to interrogate the sensorimotor reflex arc of hindpaws and tails. Amniotic fluid-GFAP levels were analyzed by standard enzyme-linked immunosorbent assay techniques.

RESULTS

Amniotic fluid-GFAP levels were similar between groups at embryonic days 14, 16, and 18, respectively. Compared with control fetuses, amniotic fluid GFAP levels were significantly increased in myelomeningocele fetuses at embryonic days 20 and 22 (P < .001). Defect size (P < .001), presence of clubfoot deformity (P = .0004), and absence of sensorimotor function (P < .01) at embryonic day 22 correlated with amniotic fluid-GFAP levels.

CONCLUSION

Amniotic fluid-GFAP levels appear to correlate with spinal cord injury as gestation proceeds in fetal rats with myelomeningocele.

Profiles of serotonin receptors in the developing human thalamus

The critical importance of the thalamus and its serotonergic innervation with respect to neuropsychiatric syndromes is increasingly recognized. This study investigates the localization of serotonin (5-hydroxytryptamine; 5-HT) receptors by immunohistochemistry in the thalamic nuclei of human fetuses aged 21 to 32 weeks of gestation. Results indicate that, already at 21 weeks of gestation, two 5-HT receptors are present in the dorsomedial nucleus of the developing thalamus: 5-HT2A receptors are localized in neurons and 5-HT2C receptors in fibers. By 31 and 32 weeks of gestation, 5-HT1A and 5-HT4 receptors are also detected in neuronal fibers of the same nucleus. At this later developmental stage, the percentage of 5-HT2A labeled neurons has significantly increased in the dorsomedial nucleus, and 5-HT2C positive neurons are observed in the centromedian and lateroventral thalamic nuclei as well. In contrast, neither neuronal cells nor fibers display any immunoreactivity for 5-HT3 or 5-HT6 receptors at any of the ages examined. Our observation that 5-HT1A, 5-HT2A, 5-HT2C and 5-HT4 receptors are present in the human thalamus prenatally indicates that 5-HT may play a role during fetal development. Disrupted development of the thalamic serotonergic system during this gestational period may contribute to the pathophysiology of neuropsychiatric disorders.

Mechanisms of vestibular compensation: recent advances

PURPOSE OF REVIEW

This article reviews recent studies that have provided experimental evidence for mechanisms of neural and synaptic plasticity in the brain during vestibular compensation, the behavioural recovery that takes place following peripheral vestibular lesions.

RECENT FINDINGS

First, experimental evidence from animal studies indicates that an unbalanced vestibular commissural system is a fundamental cause of the syndrome of oculomotor and postural deficits after unilateral labyrinthectomy. Second, recent studies suggest the involvement of both GABAergic and glycinergic commissural neurons. In addition gliosis and reactive neurogenesis in the ipsilesional vestibular nuclei appear to be involved in compensation. Third, evidence from cerebellar-deficient mutant mice demonstrates an important role for cerebellum-dependent motor learning in the longer term. Factors such as stress steroids and neuromodulators such as histamine influence these plasticity mechanisms and may thus contribute to the development of compensation in patients.

SUMMARY

Vestibular compensation involves multiple, parallel plastic processes at various sites in the brain. Experimental evidence suggests that adaptive changes in the sensitivity of ipsilesional vestibular neurons to the inhibitory neurotransmitters GABA and glycine, changes in the electrophysiological excitability of vestibular neurons, changes in the inhibitory control of the brainstem vestibular networks by the cerebellum, gliosis and neurogenesis in the ipsilesional vestibular nuclei, and activity-dependent reorganization of the synaptic connectivity of the vestibular pathways are mechanisms involved in compensation.

Olfactory ensheathing cells as putative host cells for Streptococcus pneumoniae: evidence of bacterial invasion via mannose receptor-mediated endocytosis

Olfactory ensheathing cells (OECs) are a special glia that ensheath olfactory receptor axons that enter the brain via olfactory phila, thus, providing a potential route for access of pathogens. Streptococcus pneumoniae (Sp), that has a capsule rich in mannosyl residues, is the most common cause of rhinosinusitis that may evolve to meningitis. We have tested whether OECs in vitro express the mannose receptor (MR), and could internalize Sp via MR. Cultures were infected by a suspension of Sp (ATCC 49619), recognized by an anti-Sp antibody, in a 100:1 bacteria:cells ratio. Competition assays, by means of mannan, showed around a 15-fold reduction in the number of internalized bacteria. To verify whether MR could be involved in Sp uptake, OECs were reacted with an antibody against the MR C-terminal peptide (anti-cMR) and bacteria were visualized with Sytox Green. Selective cMR-immunoreaction was seen in perinuclear compartments containing bacteria whereas mannan-treated cultures showed an extremely low percentage of internalized bacteria and only occasional adhered bacteria. Our data suggest the involvement of MR in adhesion of bacteria to OEC surface, and in their internalization. Data are also coherent with a role of OECs as a host cell prior to (and during) bacterial invasion of the brain.

Developmental origins of precocial forelimbs in marsupial neonates

Marsupial mammals are born in an embryonic state, as compared with their eutherian counterparts, yet certain features are accelerated. The most conspicuous of these features are the precocial forelimbs, which the newborns use to climb unaided from the opening of the birth canal to the teat. The developmental mechanisms that produce this acceleration are unknown. Here we show that heterochronic and heterotopic changes early in limb development contribute to forelimb acceleration. Using Tbx5 and Tbx4 as fore- and hindlimb field markers, respectively, we have found that, compared with mouse, both limb fields arise notably early during opossum development. Patterning of the forelimb buds is also accelerated, as Shh expression appears early relative to the outgrowth of the bud itself. In addition, the forelimb fields and forelimb myocyte allocation are increased in size and number, respectively, and migration of the spinal nerves into the forelimb bud has been modified. This shift in the extent of the forelimb field is accompanied by shifts in Hox gene expression along the anterior-posterior axis. Furthermore, we found that both fore- and hindlimb fields arise gradually during gastrulation and extension of the embryonic axis, in contrast to the appearance of the limb fields in their entirety in all other known cases. Our results show a surprising evolutionary flexibility in the early limb development program of amniotes and rule out the induction of the limb fields by mature structures such as the somites or mesonephros.

Applications and bioefficacy of the functional food supplement fermented papaya preparation

Fermented papaya preparation (FPP) (a product of yeast fermentation of Carica papaya Linn) is a food supplement. Studies in chronic and degenerative disease conditions (such as thalassemia, cirrhosis, diabetes and aging) and performance sports show that FPP favorably modulates immunological, hematological, inflammatory, vascular and oxidative stress damage parameters. Neuroprotective potential evaluated in an Alzheimer's disease cell model showed that the toxicity of the β-amyloid can be significantly modulated by FPP. Oxidative stress trigger apoptotic pathways such as the c-jun N-terminal kinase (JNK) and p38-mitogen activated protein kinase (MAPK) are preferentially activated by pro-inflammatory cytokines and oxidative stress resulting in cell differentiation and apoptosis. FPP modulated the H₂O₂-induced ERK, Akt and p38 activation with the reduction of p38 phosphorylation induced by H₂O₂. FPP reduces the extent of the H₂O₂-induced DNA damage, an outcome corroborated by similar effects obtained in the benzo[a]pyrene treated cells. No genotoxic effect was observed in experiments with FPP exposed to HepG2 cells nor was FPP toxic to the PC12 cells. Oxidative stress-induced cell damage and inflammation are implicated in a variety of cancers, diabetes, arthritis, cardiovascular dysfunctions, neurodegenerative disorders (such as stroke, Alzheimer's disease, and Parkinson's disease), exercise physiology (including performance sports) and aging. These conditions could potentially benefit from functional nutraceutical/food supplements (as illustrated here with fermented papaya preparation) exhibiting anti-inflammatory, antioxidant, immunostimulatory (at the level of the mucus membrane) and induction of antioxidant enzymes.

Electrophysiological properties of morphologically-identified medial vestibular nucleus neurons projecting to the abducens nucleus in the chick embryo

Neurons in the medial vestibular nucleus (MVN) show a wide range of axonal projection pathways, intrinsic firing properties, and responses to head movements. To determine whether MVN neurons participating in the vestibulocular reflexes (VOR) have distinctive electrophysiological properties related to their output pathways, a new preparation was devised using transverse brain slices containing the chicken MVN and abducens nucleus. Biocytin Alexa Fluor was injected extracellularly into the abducens nucleus so that MVN neurons whose axons projected to the ipsilateral (MVN/ABi) and contralateral (MVN/ABc) abducens nuclei were labeled selectively. Whole-cell, patch-clamp recordings were performed to study the active and passive membrane properties, sodium conductances, and spontaneous synaptic events in morphologically-identified MVN/AB neurons and compare them to MVN neurons whose axons could not be traced (MVN/n). Located primarily in the rostral half of the ventrolateral part of the MVN, MVN/AB neurons mainly have stellate cell bodies with diameters of 20-25 μm. Compared to MVN/n neurons, MVN/ABi and MVN/ABc neurons had lower input resistances. Compared to all other MVN neuron groups studied, MVN/ABc neurons showed unique firing properties, including type A-like waveform, silence at resting membrane potential, and failure to fire repetitively on depolarization. It is interesting that the frequency of spontaneous excitatory and inhibitory synaptic events was similar for all the MVN neurons studied. However, the ratio for miniature to spontaneous inhibitory events was significantly lower for MVN/ABi neurons compared to MVN/n neurons, suggesting that MVN/ABi neurons retained a larger number and/or more active inhibitory presynaptic neurons within the brain slices. Also, MVN/ABi neurons had miniature excitatory postsynaptic currents (mEPSCs) with slower decay time and half width compared to MVN/n neurons. Altogether, these findings underscore the diversity of electrophysiological properties of MVN neuron classes distinguished by axonal projection pathways. This represents the first study of MVN/AB neurons in brain slice preparations and supports the concept that the in vitro brain slice preparation provides an advantageous model to investigate the cellular and molecular events in vestibular signal processing.

Endogenous nitric oxide enhances the light-response of cones during light-adaptation in the rat retina

The electroretinogram (ERG) is a non-invasive indicator of retinal function. Light flashes evoke a cornea-negative a-wave followed by a cornea-positive b-wave. Light-adaptation is known to increase the amplitude of cone-dependent b-waves. To identify the underlying mechanism, we recorded rat cone photoresponses in situ, using intravitreally-injected glutamate to block synaptic transmission and intense paired-flash stimuli to isolate cone a-waves. Steady adapting illumination caused a progressive increase in cone a-wave amplitude, which was suppressed in a dose-dependent manner by intravitreal CPTIO, a nitric oxide scavenger. We conclude that light-adaptation causes release of nitric oxide, which enhances the cone photoresponse.

The effects of aging and chronic fluoxetine treatment on circadian rhythms and suprachiasmatic nucleus expression of neuropeptide genes and 5-HT1B receptors

Age-related changes in circadian rhythms, including attenuation of photic phase shifts, are associated with changes in the central pacemaker in the suprachiasmatic nucleus (SCN). Aging decreases expression of mRNA for vasoactive intestinal peptide (VIP), a key neuropeptide for rhythm generation and photic phase shifts, and increases expression of serotonin transporters and 5-HT(1B) receptors, whose activation inhibits these phase shifts. Here we describe studies in hamsters showing that aging decreases SCN expression of mRNA for gastrin-releasing peptide, which also modulates photic phase resetting. Because serotonin innervation trophically supports SCN VIP mRNA expression, and serotonin transporters decrease extracellular serotonin, we predicted that chronic administration of the serotonin-selective reuptake inhibitor, fluoxetine, would attenuate the age-related changes in SCN VIP mRNA expression and 5-HT(1B) receptors. In situ hybridization studies showed that fluoxetine treatment does not alter SCN VIP mRNA expression, in either age group, at zeitgeber time (ZT)6 or 13 (ZT12 corresponds to lights off). However, receptor autoradiographic studies showed that fluoxetine prevents the age-related increase in SCN 5-HT(1B) receptors at ZT6, and decreases SCN 5-HT(1B) receptors in both ages at ZT13. Therefore, aging effects on SCN VIP mRNA and SCN 5-HT(1B) receptors are differentially regulated; the age-related increase in serotonin transporter sites mediates the latter but not the former. The studies also showed that aging and chronic fluoxetine treatment decrease total daily wheel running without altering the phase of the circadian wheel running rhythm, in contrast to previous reports of phase resetting by acute fluoxetine treatment.

Effect of the method of conception and embryo transfer procedure on mid-gestation placenta and fetal development in an IVF mouse model

BACKGROUND

Abnormal placentation is a potential mechanism to explain the increased incidence of low birthweight observed after IVF. This study evaluates, in a mouse model, whether the method of conception and embryo transfer affect placentation and fetal development.

METHODS

IVF blastocysts (CF1 x B6D2F1/J) were cultured in Whitten's medium (IVF(WM), n = 55) or K modified simplex optimized medium with amino acids (IVF(KAA), n = 56). Embryos were transferred to the uteri of pseudo-pregnant recipients. Two control groups were created: unmanipulated embryos produced by natural mating (in vivo group, n = 64) and embryos produced by natural mating that were flushed from uterus and immediately transferred to pseudo-pregnant recipients (flushed blastocysts, FB group, n = 57). At gestation age 12.5 days, implantation sites were collected and fixed; fetuses and placentas were weighed and their developmental stage (DS) evaluated. Placental areas and vascular volume fractions were calculated; parametric statistics were applied as appropriate.

RESULTS

IVF fetuses showed a modest but significant delay in development compared with FB mice (P < 0.05). In addition, IVF conceptuses were consistently smaller than FB (P < 0.05). Importantly, these differences persisted when analyzing fetuses of similar DS. The placenta/fetus ratio was larger in the IVF group (IVF(WM) 0.95; IVF(KAA) = 0.90) than the FB group (0.72) (P < 0.05 for all comparisons). Gross morphology of the placenta and ratio labyrinth/fetal area were equivalent in the IVF and FB groups, as were percentage of fetal blood vessels, maternal blood spaces and trophoblastic components.

CONCLUSIONS

In vitro embryo culture affects fetal and placental development; this could explain the lower birthweight in IVF offspring.

Seizures beget seizures: a lack of experimental evidence and clinical relevance fails to dampen enthusiasm

Three Brief Epileptic Seizures Reduce Inhibitory Synaptic Currents, GABAACurrents, and GABAA-Receptor Subunits. Evans MS, Cady CJ, Disney KE, Yang L, LaGuardia JJ. Epilepsia 2006;4710):1655–1664. PURPOSE: Cellular mechanisms activated during seizures may exacerbate epilepsy. γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in brain, and we hypothesized that brief epileptic seizures may reduce GABA function. METHODS: We used audiogenic seizures (AGSs) in genetically epilepsy-prone rats (GEPRs) to investigate effects of seizures on GABA-mediated inhibition in the presence of epilepsy. GEPRs are uniformly susceptible to AGSs beginning at 21 postnatal days. AGSs are brief convulsions lasting 20 s, and they begin in inferior colliculus (IC). We evoked three seizures in GEPRs and compared the results with those in seizure-naive GEPRs and nonepileptic Sprague-Dawley (SD) rats, the GEPR parent strain. RESULTS: Whole-cell recording in IC slices showed that GABA-mediated monosynaptic inhibitory postsynaptic currents (IPSCs) were reduced 55% by three brief epileptic seizures. Whole-cell recording in IC neuronal cultures showed that currents elicited by GABA were reduced 67% by three seizures. Western blotting for the alpha1 and alpha4 subunits of the GABAA receptor showed no statistically significant effects. In contrast, three brief epileptic seizures reduced gamma2 subunit levels by 80%. CONCLUSIONS: The effects of the very first seizures, in animals known to be epileptic, in an area of brain known to be critical to the seizure network, were studied. The results indicate that even brief epileptic seizures can markedly reduce IPSCs and GABA currents and alter GABAA-receptor subunit protein levels. The cause of the reductions in IPSCs and GABA currents is likely to be altered receptor subunit composition, with reduced gamma2 levels causing reduced GABAA-receptor sensitivity to GABA. Seizure-induced reductions in GABA-mediated inhibition could exacerbate epilepsy.

MRI findings in the young infant with brainstem disconnection and extracerebral features. Report of one case and review of the literature

We present the young infant with the extremely rare brain abnormality-brainstem disconnection. Additionally, several extracerebral abnormalities were diagnosed: bilateral anotia, micrognatia, hypertelorism, scoliosis, ribs and vertebral anomalies. MR brain examination precisely demonstrated absence of the pons, with disruption between midbrain and hypoplastic medulla oblongata. The thin strands connecting the medulla with the midbrain and medulla with both cerebellar hemispheres were revealed. The large hamartoma of the tuber cinereum was found. In this study we review case reports published previously.

Preschool neurodevelopmental outcome of children following fetal myelomeningocele closure

OBJECTIVE

We sought to investigate the preschool neurodevelopmental outcomes of children following fetal myelomeningocele (fMMC) surgery.

STUDY DESIGN

Prior to the Management of Myelomeningocele Study trial, 54 children underwent fMMC closure at our institution. Thirty (56%) returned at 5 years of age for standardized neurocognitive examination. Scores were grouped as high-average, average, mildly delayed, and severely delayed by SD intervals.

RESULTS

Mean verbal intelligence quotient (VIQ), performance intelligence quotient (PIQ), and full intelligence quotient (FIQ) scores were within normal population range. High-average or average scores for VIQ, PIQ, FIQ, and processing speed were found in 93%, 90%, 90%, and 60%, respectively. Mean FIQ and processing speed of nonshunted children were significantly higher than for those who required shunt placement (P=.02 and P=.01, respectively). Mean VIQ and PIQ tended to be higher in nonshunted fMMC children (P=.05).

CONCLUSION

The majority of fMMC children in this highly selective population had average preschool neurodevelopmental scores. fMMC children who did not require shunt placement were more likely to have better scores.

Axon guidance and neuronal migration research in China

Proper migration of neuronal somas and axonal growth cones to designated locations in the developing brain is essential for the assembly of functional neuronal circuits. Rapid progress in research of axon guidance and neuronal migration has been made in the last twenty years. Chinese researchers began their exploration in this field ten years ago and have made significant contributions in clarifying the signal transduction of axon guidance and neuronal migration. Several unique experimental approaches, including the migration assay of single isolated neurons in response to locally delivered guidance cues, have been developed by Chinese neuroscientists to investigate the molecular machinery underlying these guidance events.

Combinational treatment of gap junctional activator and tamoxifen in breast cancer cells

Tamoxifen is a drug of choice for endocrine-responsive breast tumor patients. However, tamoxifen resistance has become a major concern for the treatment of breast cancer. Combinational therapies of tamoxifen and different drugs are being frequently studied. In this study, we tested the efficacy of substituted quinolines (code name=PQ1; a gap junctional activator) in combination with tamoxifen in T47D cells. Colony growth assay was performed using soft agar to measure the colony growth, whereas cell proliferation was measured by the MTT assay in T47D cells. The level of Ki67, survivin, and BAX was measured using confocal microscopy along with western blot analysis. Apoptosis-bromodeoxyuridine triphosphate labeling was also examined in the induced treatment of T47D cells. We observed a 55% decrease in the colony growth in the presence of combination of PQ1 and tamoxifen, whereas tamoxifen alone had little effect. A combination of 10 micromol/l tamoxifen and 200 or 500 nmol/l PQ1 resulted in only 16% cell viability compared with controls at 48 h in T47D cells by the MTT assay. We found a significant increase in BAX protein at 1 h in the presence of 500 nmol/l PQ1 alone, 10 micromol/l tamoxifen alone, and the combination of PQ1 and tamoxifen. A two-fold increase was observed in active caspase 3 in the presence of combinational treatment of 10 micromol/l tamoxifen and 200 or 500 nmol/l PQ1. In addition, flow cytometric analysis showed a 50% increase in the number of apoptotic cells in the presence of the combination of tamoxifen and PQ1 compared with the control. Furthermore, the results show that combinational treatment of tamoxifen and PQ1 significantly reduces the expression of survivin in T47D cells. Gap junction inhibitor studies with carbenexolone were also performed confirming the role of gap junctions in cell proliferation and cell death. The combinational treatment of PQ1 and tamoxifen has a significant increase in BAX expression, caspase 3 activation, and DNA fragmentation. Tamoxifen alone and in combination with PQ1 showed a decrease in the expression of survivin, whereas PQ1 alone was shown to be independent of the survivin-mediated pathway. This suggests that an increase in gap junction activity can potentiate the effect of tamoxifen. The combinational treatment of tamoxifen and PQ1 also showed a significant decrease in cell viability compared with tamoxifen treatment alone. The gap junction inhibitor carbenexolone was shown to increase cell proliferation by increased cyclin D1 expression, MTT assay, and Ki67 expression. It further decreased cell death. This study shows for the first time that combinational treatment of tamoxifen and PQ1 (a gap junctional activator) can be used to potentiate apoptosis of T47D human breast cancer cells. Thus, a gap junctional activator, PQ1, could potentially alter either the length or dose of tamoxifen clinically used for breast cancer patients.

Identification of vestibuloocular projection neurons in the developing chicken medial vestibular nucleus

Biocytin was injected into the oculomotor, trochlear, or abducens nucleus on one side using isolated chicken brainstem preparations or brain slices to identify the medial vestibular nucleus (MVN) neurons projecting to these targets. Oculomotor nucleus injections produced retrogradely labeled neurons in the contralateral ventrolateral MVN (MVN(VL)), with few labeled neurons in the ipsilateral MVN(VL) and rarely in the dorsomedial MVN on either side. Labeled MVN(VL) neurons were identified as stellate (95%) and elongate (5%) cells. Trochlear nucleus injections produced a similar pattern of MVN neuron labeling. Abducens nucleus injections resulted in retrogradely labeled stellate (87%) and elongate (13%) neurons in the MVN(VL), which had smaller cell bodies than those projecting to the oculomotor nucleus. Anteroposteriorly, labeled MVN(VL) neurons were coextensive with the tangential nucleus, with neurons projecting to the oculomotor nucleus distributed lateral to and intermixed with the more medially situated neurons projecting to the abducens nucleus. The fundamental pattern of vestibuloocular projecting neurons was similar at both embryonic ages studied, E16 and E13. In contrast to the case in mammals, where most vestibuloocular projection neurons reside within the MVN, most retrogradely labeled neurons in these chicken preparations were found within the ventrolateral vestibular, descending vestibular, and tangential nuclei. The morphological identification and mapping of vestibuloocular projection neurons in the chicken MVN described here represents the first step in a systematic evaluation of the relationship between avian vestibuloocular neuron structure and function.

Systemic thyroid hormone is necessary and sufficient to induce ultraviolet-sensitive cone loss in the juvenile rainbow trout retina

Rainbow trout possess ultraviolet-sensitive (UVS) cones in their retina that degenerate naturally during development. This phenomenon can be induced with exogenous thyroxine [T4, a thyroid hormone (TH)] treatment. However, the previous T4 exposure experiments employed static water immersion; a method that could introduce confounding stress effects on the fish. Because of this, it was uncertain if T4 alone was sufficient to induce retinal changes or if stress-related hormones were also necessary to initiate this process. Furthermore, it was unclear whether endogenous T4 was the factor responsible for initiating natural UVS cone loss during development. The current study examined the role of systemic T4 on the juvenile rainbow trout retina using a slow-release implant. Exogenous T4 treatment resulted in SWS1 opsin downregulation and UVS cone loss after four weeks of exposure, signifying that T4 is sufficient to induce this process. Blocking endogenous T4 production with propylthiouracil (PTU, an anti-thyroid agent) attenuated SWS1 downregulation and UVS cone loss in the retina of naturally developing rainbow trout, suggesting that endogenous T4 is necessary to initiate retinal remodelling during development. Quantitative real-time RT-PCR analysis demonstrated that several TH-regulating components are expressed in the trout retina, and that expression levels of the TH receptor isoform TRbeta and the type 2 deiodinase (D2) change with T4 treatment. This suggests that T4 may act directly on the retina to induce UVS cone loss. Taken together, these results demonstrate that systemic TH is necessary and sufficient to induce SWS1 opsin downregulation and UVS cone loss in the retina of juvenile rainbow trout.

Estrogenic activity of xanthorrhizol isolated from curcuma xanthorrhiza ROXB

Plant-derived estrogen-like compounds, or phytoestrogens, are given much attention due to their potential therapeutic use. In this study, xanthorrhizol, a natural sesquiterpenoid isolated from the rhizome of Curcuma xanthorrhiza ROXB. (Zingiberaceae), was evaluated for its estrogenic activity. It has been known that compounds acting as ligands for estrogen receptors (ERs) are considered to possess estrogenic activity. Therefore, the Gal-4/ER transactivation assay in transiently transfected African green monkey kidney (COS-7) cells was used to examine the estrogenic activity of xanthorrhizol. Both subtypes of ERs, ERalpha and ERbeta, were involved in this assay. Further transactivation assays and pS2 mRNA analysis were also conducted in estrogen receptor-positive human breast cancer (MCF-7). Our results showed that xanthorrhizol significantly increased Gal-4/ER luciferase activity in a dose-dependent manner and induced the endogenous ER-estrogen response element (ERE) interaction in MCF-7 cells. Xanthorrhizol also significantly enhanced the expression of the pS2 gene in MCF-7 cells. In contrast, treatment using ICI 182780, an ER antagonist, suppressed all activities induced by xanthorrhizol, indicating ER-dependant activities were involved. These results suggest that xanthorrhizol possesses estrogenic activity and its estrogenic effects are mediated by estrogen-induced gene expression.

Differential abilities of the mushroom ribosome-inactivating proteins hypsin and velutin to perturb normal development of cultured mouse embryos

The teratogenicity of two fungal ribosome-inactivating proteins, hypsin from Hypsizigus mamoreus and velutin from Flammulina velutipes, was examined in this investigation using microinjection and postimplantation whole-embryo culture. The results demonstrated that hypsin induced abnormal embryonic development at 2.5 microM during the organogenesis period from E8.5 to E9.5. As its dosage increased, there was an increase in the total number of abnormal embryos, a drop in the final somite number, and a rise of abnormal structures. Structural abnormalities were detected: open cranial neural tube, abnormal branchial arches, absence of forelimb buds and twisted body axis. The otic and optic placodes were, however, less affected. Histological study of the abnormal embryos revealed a correlation of increased cell death with abnormal structures, suggesting that induction of cell death by hypsin may account for its teratogenicity. In contrast, velutin did not exert any adverse influence on mouse development.

The discovery of the subpial granular layer in the human cerebral cortex

The subpial granular layer (SGL) is a transient accumulation of tangentially migrating small granular neurons in the marginal zone of the developing fetal neocortex. It has recently attracted attention as a possible additional source of future cortical interneurons, or even as a putative precursor pool for generation of Cajal-Retzius cells. The discovery of the SGL is generally attributed to Otto Ranke and it is usually claimed that the SGL is specific for human brain. The aim of this review is: (1) to demonstrate that the first to observe SGL in the human cerebral cortex was not Otto Ranke in 1910, but Franz Boll in 1874; (2) to provide an English translation of Ranke’s original description of the SGL and thus demonstrate that he described the SGL in both human and animal brain; and (3) to provide a concise review of current studies concerning the developmental fate and possible functions of the transient fetal SGL.

The cerebellar dysplasia of Chiari II malformation as revealed by eye movements

INTRODUCTION

Chiari type II malformation (CII) is a developmental deformity of the hindbrain. We have previously reported that many patients with CII have impaired smooth pursuit, while few make inaccurate saccades or have an abnormal vestibuloocular reflex. In contrast, saccadic adaptation and visual fixation are normal. In this report, we correlate results from several eye movement studies with neuroimaging in CII. We present a model for structural changes within the cerebellum in CII.

METHODS

Saccades, smooth pursuit, the vestibulo-ocular reflex, and visual fixation were recorded in 21 patients with CII, aged 8-19 years and 39 age-matched controls, using an infrared eye tracker. Qualitative and quantitative MRI data were correlated with eye movements in 19 CII patients and 28 controls.

RESULTS

Nine patients with CII had abnormal eye movements. Smooth pursuit gain was subnormal in eight, saccadic accuracy abnormal in four, and vestibulo-ocular reflex gain abnormal in three. None had fixation instability. Patients with CII had a significantly smaller cerebellar volume than controls, and those with normal eye motion had an expanded midsagittal vermis compared to controls. However, patients with abnormal eye movements had a smaller (non-expanded) midsagittal vermis area, posterior fossa area and medial cerebellar volumes than CII patients with normal eye movements.

CONCLUSIONS

The deformity of CII affects the structure and function of the cerebellum selectively and differently in those with abnormal eye movements. We propose that the vermis can expand when compressed within a small posterior fossa in some CII patients, thus sparing its ocular motor functions.

Changes in thyroid hormone reception precede SWS1 opsin downregulation in trout retina

Rainbow trout undergo natural cone degeneration and thus are interesting models for examining mechanisms of neural degeneration. They have ultraviolet-sensitive (UVS) cones that are lost over most of the retina during development; only a small functional population remains in the dorsal retina. How this spatial distribution of UVS cones is maintained is unclear. Thyroxine (T4) induces UVS cone loss, and local thyroid hormone regulation was hypothesized to control UVS cone distribution. Thyroid hormone receptor alpha (TRalpha), thyroid hormone receptor beta (TRbeta) and Type 2 deiodinase (D2) regulate thyroid hormone exposure to target cells. Regional retinal expression of these genes was investigated during exogenous T4 treatment and natural smoltification of rainbow trout. Each retina from dark-adapted parr, T4-treated parr and natural smolts was divided into four quadrants, and total RNA was isolated. Quantitative real-time RT-PCR analysis demonstrated that all retinal quadrants had increased accumulation of TRbeta transcripts 2 days post-T4 treatment, corresponding to initiation of SWS1 opsin downregulation. Smolts exhibited decreased accumulation of TRalpha and TRbeta transcripts in all quadrants, but this effect was most pronounced in the dorso-temporal (DT) retinal quadrant where UVS cones persist. By contrast, in 2 day T4-treated parr, the DT quadrant showed increased expression of TRalpha and TRbeta. Furthermore, D2 transcripts decreased in the DT quadrant of T4-treated parr but increased in the DT quadrant of smolts. These results suggest that T4 upregulates TRbeta expression to initiate SWS1 opsin downregulation, while TRalpha and TRbeta downregulation occurs to prevent natural loss of UVS cones from the DT retina.

Advances in Auditory and Vestibular Medicine

Auditory and Vestibular medicine is becoming more accepted as a specialty of its own, Medical NeurOtology. Recent advances in the field have been instrumental in the understanding of the scientific foundations, pathophysiology, clinical approach and management of patients with hearing and vestibular disorders. This paper will review these advances.

Should spikes be treated with equal weightings in the generation of spectro-temporal receptive fields?

Knowledge on the trigger features of central auditory neurons is important in the understanding of speech processing. Spectro-temporal receptive fields (STRFs) obtained using random stimuli and spike-triggered averaging allow visualization of trigger features which often appear blurry in the time-versus-frequency plot. For a clearer visualization we have previously developed a dejittering algorithm to sharpen trigger features in the STRF of FM-sensitive cells. Here we extended this algorithm to segregate spikes, based on their dejitter values, into two groups: normal and outlying, and to construct their STRF separately. We found that while the STRF of the normal jitter group resembled full trigger feature in the original STRF, those of the outlying jitter group resembled a different or partial trigger feature. This algorithm allowed the extraction of other weaker trigger features. Due to the presence of different trigger features in a given cell, we proposed that in the generation of STRF, the evoked spikes should not be treated indiscriminately with equal weightings.

Reactive oxygen species, reactive nitrogen species and antioxidants in etiopathogenesis of diabetes mellitus type-2

Diabetes mellitus type-2 (DMT-2) is a hyperglycemic syndrome with several characteristic features. It continues to rise unabatedly in all pockets of the world, parallels with affluence and can be controlled but not cured. It has a definite involvement of genetic component but environmental factors play overwhelmingly dominant role in etiopathogenesis. Insulin resistance (IR) and obesity are singular instigators of DMT-2. The various events cause critical defects in insulin signaling cascade followed by beta-cell dysfunction. Over a period of time, numerous other metabolic aberrations develop, resulting in diabetic complications which could be both vascular (cardiovascular complications, nephropathy, neuropathy, retinopathy and embryopathy) or a-vascular (cataract and glaucoma etc). It has been proposed that all these abnormal events are initiated or activated by a common mechanism of superoxide anion, which is accompanied with generation of a variety of reactive oxygen species (ROS), reactive nitrogen specie (RNS) and resultant heightened oxidative stress (OS). Provoked OS causes IR and altered gene expressions. Hyperglycemia induces OS through multiple routes: a)stimulated polyol pathway where in ≤ 30% glucose can be diverted to sorbitol and fructose, b)increased transcription of genes for proinflammatory cytokines and plasminogen activator inhibitor-1 (PAI-1) c) activation of protein kinase-C (PKC) leading to several molecular changes d)increased synthesis of Advanced Glycation End Products (AGEs) e)changes in a receptor far AGEs and f) autooxidation of glucose with formation of ketoimines and AGEs. All these processes are accompanied with alteration in redox status, ROS, RNS and OS which trigger DMT-2 and its complications. Initial hurriedly planned and executed experimental and clinical studies showed promising results of antioxidant therapies, but recent studies indicate that excess intake/supplement may have adverse outcomes including increased mortality. It is advocated that antioxidants should be given only if preexisting deficiency is present. Selection of antioxidant is another important aspect. Lastly but most importantly the impact of OS is not obligatory but facultative. As such only those diabetic patients will be benefited by antioxidant therapies that have impelling punch of prooxidants.

Engineering retina from human retinal progenitors (cell lines)

Retinal degeneration resulting in the loss of photoreceptors is the leading cause of blindness. Several therapeutic protocols are under consideration for treatment of this disease. Tissue replacement is one such strategy currently being explored. However, availability of tissues for transplant poses a major obstacle. Another strategy with great potential is the use of adult stem cells, which could be expanded in culture and then utilized to engineer retinal tissue. In this study, we have explored a spontaneously immortalized human retinal progenitor cell line for its potential in retinal engineering using rotary cultures to generate three-dimensional (3D) structures. Retinal progenitors cultured alone or cocultured with retinal pigment epithelial cells form aggregates. The aggregate size increases between days 1 and 10. The cells grown as a 3D culture rotary system, which promotes cell-cell interaction, retain a spectrum of differentiation capability. Photoreceptor differentiation in these cultures is confirmed by significant upregulation of rhodopsin and AaNat, an enzyme implicated in melatonin synthesis (immunohistochemistry and Western blot analysis). Photoreceptor induction and differentiation is further attested to by the upregulation of rod transcription factor Nrl, Nr(2)e(3), expression of interstitial retinal binding protein, and rhodopsin kinase by reverse transcription-polymerase chain reaction. Differentiation toward other cell lineages is confirmed by the expression of tyrosine hydroxylase in amacrine cells, thy 1.1 expression in ganglion cells and calbindin, and GNB3 expression in cone cells. The capability of retinal progenitors to give rise to several retinal cell types when grown as aggregated cells in rotary culture offers hope that progenitor stem cells under appropriate culture conditions will be valuable to engineer retinal constructs, which could be further tested for their transplant potential. The fidelity with which this multipotential cell line retains its capacity to differentiate into multiple cell types holds great promise for the use of tissue-specific adult stem cells for therapy.

A novel Fas ligand in mollusk abalone: molecular characterization, immune responses and biological activity of the recombinant protein

Fas ligand is a member of the TNF superfamily that plays an important role by inducing apoptosis and homeostasis of immune responses. The gene encoding Fas ligand was isolated from a disk abalone (Haliotis discus discus) cDNA library, denoted as the AbFas ligand. It contains an 1832bp transcript with a 945bp open reading frame, encoding 315 amino acids. The AbFas ligand showed characteristic transmembrane and TNF family signature domains. The deduced amino acid comparison showed that the AbFas ligand exhibits 22.0, 16.1 and 14.5% identities to human Fas ligand, TNF-alpha, and lymphotoxin (LT-alpha), respectively. Phylogenetic analysis indicates that the AbFas ligand belongs to the invertebrate TNF family and it is closely related to vertebrate Fas ligand counterparts. Quantitative real-time PCR analysis results showed that the AbFas ligand transcripts were constitutively expressed in abalone hemocytes, gills, mantle, muscle, digestive tract and digestive gland in a tissue-specific manner. By immune stimulation, AbFas ligand mRNA was significantly (p<0.05) up-regulated after infection with a mixture of bacteria (Vibrio alginolyticus, Vibrio parahemolyticus, and Listeria monocytogenes), viral haemorrhagic septicaemia virus (VHSV), and lipopolysaccharide (LPS) in abalone gills. The recombinant AbFas ligand was over-expressed in Escherichia coli (E. coli) and purified using a pMAL protein fusion system. This recombinant AbFas ligand showed its biological activity by inducing both superoxide anion (O(2-) and H(2)O(2) in human THP-1 cells in concentration-dependant manner. Correlating the AbFas ligand transcriptional up-regulation against bacteria, virus and LPS with the biological activity of its recombinant protein, we could suggest that the abalone Fas ligand may control microbial infection by inducing O(2-), H(2)O(2) and other ROS.

A patient with bilateral persistent pupillary membrane: a conservative approach

The author describes the case of a girl with bilateral persistent pupillary membranes and good visual acuity. An otherwise healthy 10-year-old girl presented with persistent pupillary membranes in both eyes since childhood. The patient had ametropic amblyopia, which was treated with spectacles and part-time occlusion therapy, with the patient responding conventionally. After therapy, her best-corrected visual acuity was 20/25 in both eyes. She had stereopsis of 50 seconds of arc, orthophoria, and normal extraocular movements. The remainder of the examination was normal. Patients with bilateral persistent pupillary membranes may not require surgery if there is adequate opening. The author suggests a trial of refractive correction and occlusion therapy before deciding on surgical and laser intervention, even if it seems an absolute requirement.

Over 900 oocyte cryopreservation babies born with no apparent increase in congenital anomalies

Over the past decade, the number of reported live births resulting from oocyte cryopreservation has rapidly increased. To appreciate the true number of children born, verified live births were tabulated and assessed. A literature search was performed; authors were then contacted to verify birth outcomes and provide updates. A database including all verified live born infants was constructed. A total of 58 reports (1986-2008) were reviewed, which included 609 live born babies (308 from slow freezing, 289 from vitrification and 12 from both methods). Additionally, 327 other live births were verified. Of the total 936 live borns, 1.3% (12) were noted to have birth anomalies: three ventricular septal defects, one choanal and one biliary atresia, one Rubinstein-Taybi syndrome, one Arnold-Chiari syndrome, one cleft palate, three clubfoot and one skin haemangioma. Compared with congenital anomalies occurring in naturally conceived infants, no difference was noted. With more live born data accumulating, this procedure may become mainstream as a fertility preservation option, particularly for women diagnosed with malignancy requiring cytotoxic therapy. A registry would help to assure the safest, most expeditious development of this technology.

Microglia derived IL-6 suppresses neurosphere generation from adult human retinal cell suspensions

Following retinal degeneration or inflammation that disrupts tissue architecture, there is limited evidence of tissue regeneration, despite evidence of cells with progenitor properties in the adult human retina at all ages. With the prospect of tissue/cell transplantation, redressing homeostasis whilst overcoming glial barrier or gliosis remains key to successful graft versus host integration and functional recovery. Activated human retinal microglia (MG) secrete cytokines, including IL-6, which may suppress neurogenesis or cellular (photoreceptor) replacement. To investigate this hypothesis, adult human retinal explants were cultured in cytokine-conditioned media (TNFalpha, TGFbeta, LPS/IFNgamma) to activate microglia in situ. Following culture of retinal explants for 4 days, supernatant conditioned by resulting migrated microglia was collected after a further 3 days and fed to retinal cell suspensions (RCS). Neurosphere (NS) generation and survival analysis was performed after 7 and 14 days in culture, with or without addition of conditioned media and with or without concomitant IL-6 neutralisation. Neurosphere phenotype was analysed by immunohistochemistry and cell morphology. Migratory MG from retinal explants were activated (iNOS-positive) and expressed CD45, CD11b, and CD11c. LPS/IFNgamma-activated MG conditioned media (MG-CM) contained significant levels of IL-6 (1265 +/- 143) pg/ml, which inhibited neurosphere generation within RCS in the presence of optimal neurosphere generating N2-FGF2 culture medium. Neutralising IL-6 activity reinstated NS generation and the differentiation capacity was maintained in the spheres that formed. Even in the presence of high levels of IL-6, those few NS that did form demonstrated a capacity to differentiate. The data supports activated MG-derived IL-6 influence retinal cell turnover.

[Significance of magnetic resonance studies in prenatal diagnosis of malformations of the fetal central nervous system]

MRI investigation, as an imaging technique, has been gaining more and more importance in prenatal diagnostics. It has become essential due to its advantages in diagnosing the malformations of the central nervous system. Similarly to ultrasonography, its reliability is greatly dependent on the knowledge of the person performing the investigation. In addition to the knowledge of the exact anatomy of central nervous system, the researcher should have a multidisciplinary approach. In the case of malformations where repeated investigations are needed to provide a diagnosis in early pregnancy (e.g. neural tube defects), ultrasonography is more effective than MRI. In case of intrauterine infections and malformations of the posterior fossa, however, the two imaging techniques are excellent supplements to each other. MRI also plays an important role in making the prognosis for fetal ventriculomegaly, as well as in the short term diagnosis of ischaemias affecting the fetal nervous system. Difficulties in evaluating ultrasonographic images (owing to maternal obesity, oligohydramnion) render MRI an important technique in making the final diagnosis. Currently, the drawbacks of MRI include reduced accessibility, poor cost-effectiveness and shortage of skilled experts in this technique.

Phenotypic diversity and expression of GABAergic inhibitory interneurons during postnatal development in lumbar spinal cord of glutamic acid decarboxylase 67-green fluorescent protein mice

The synthesis enzyme glutamic acid decarboxylase (GAD65 or GAD67) identifies neurons as GABAergic. Recent studies have characterized the physiological properties of spinal cord GABAergic interneurons using lines of GAD67-green fluorescent protein (GFP) transgenic mice. A more complete characterization of their phenotype is required to better understand the role of this population of inhibitory neurons in spinal cord function. Here, we characterize the distribution of lumbar spinal cord GAD67-GFP neurons at postnatal days (P) 0, 7, and 14, and adult based on their co-expression with GABA and determine the molecular phenotype of GAD67-GFP neurons at P14 based on the expression of various neuropeptides, calcium binding proteins, and other markers. At all ages >67% of GFP(+) neurons were also GABA(+). With increasing age; (i) GFP(+) and GABA(+) cell numbers declined, (ii) ventral horn GFP(+) and GABA(+) neurons vanished, and (iii) somatic labeling was reduced while terminal labeling increased. At P14, vasoactive intestinal peptide and bombesin were expressed in approximately 63% and approximately 35% of GFP(+) cells, respectively. Somatostatin was found in a small number of neurons, whereas calcitonin gene-related peptide never co-localized with GFP. Moderate co-expression was found for all the Ca(2+) binding proteins examined. Notably, most laminae I-II parvalbumin(+) neurons were also GFP(+). Neurogranin, a protein kinase C substrate, was found in approximately 1/2 of GFP(+) cells. Lastly, while only 7% of GFP(+) cells contain nitric oxide synthase (NOS), these cells represent a large fraction of all NOS(+) cells. We conclude that GAD67-GFP neurons represent the majority of spinal GABAergic neurons and that mouse dorsal horn GAD67-GFP(+) neurons comprise a phenotypically diverse population.

In utero eye development documented by fetal MR imaging

BACKGROUND AND PURPOSE

To date, very limited attention has been given to ocular abnormalities or growth parameters detected by fetal MR imaging. Our objective was to retrospectively determine the relationship between different parameters of eye development and estimated gestational age in the human fetus by use of fetal MR imaging.

MATERIALS AND METHODS

A retrospective study was performed to measure the transverse diameter, interocular distance, and lens diameter of the globes of 127 fetuses who had a morphologically normal central nervous system. Multiple single-shot T2 fast spin-echo images were obtained with a 1.5T magnet by use of contiguous 3-mm intervals in at least 2 orthogonal planes. Loess curves were fitted to explore the relationship between gestational age and each of the 3 measurements of interest. Different models were compared statistically to determine the model of best fit.

RESULTS

For each variable of interest, the "best" model of eye growth was a quadratic function. Specifically, lens growth seems to plateau after 36 weeks of gestation, interocular distance plateaus after 36 weeks of gestation, and globe growth plateaus after 42 weeks of gestation.

CONCLUSIONS

The lens, orbit, and interocular distance growth of the fetus can be demonstrated on fetal MR imaging. All 3 measurements suggest a quadratic model of growth, which indicates slowing of growth toward the end of gestation.

Expression patterns of 5-HT receptor subtypes 1A and 2A on GABAergic neurons within the spinal dorsal horn of GAD67-GFP knock-in mice

5-HT plays an important role in GABA transmission at the spinal cord level. The main purpose of the present article is to find out, which 5-HT receptor subtypes may be involved in the regulation of GABAergic transmission in the spinal dorsal horn, by using the combination of tissue RT-PCR, single-cell RT-PCR and double immunofluorescent staining on the GAD(67)-GFP knock-in mice. The present result showed that 5-HT(1A) receptor subtype mRNA was present on about half of GFP-positive GABAergic interneurons in the spinal dorsal horn, which suggests a role of 5-HT(1A) receptor in GABA-mediated modulation of nociception at the spinal cord level. However, it is unexpected that just a very limited sub-population of the total GABAergic interneurons express 5-HT(2A) receptor mRNA or proteins in the spinal dorsal horn, which suggests that the 5-HT(2A) receptor subtype may not be important for spinal GABAergic effects in nociceptive modulation.

Brain injury in premature infants: a complex amalgam of destructive and developmental disturbances

Brain injury in premature infants is of enormous public health importance because of the large number of such infants who survive with serious neurodevelopmental disability, including major cognitive deficits and motor disability. This type of brain injury is generally thought to consist primarily of periventricular leukomalacia (PVL), a distinctive form of cerebral white matter injury. Important new work shows that PVL is frequently accompanied by neuronal/axonal disease, affecting the cerebral white matter, thalamus, basal ganglia, cerebral cortex, brain stem, and cerebellum. This constellation of PVL and neuronal/axonal disease is sufficiently distinctive to be termed "encephalopathy of prematurity". The thesis of this Review is that the encephalopathy of prematurity is a complex amalgam of primary destructive disease and secondary maturational and trophic disturbances. This Review integrates the fascinating confluence of new insights into both brain injury and brain development during the human premature period.

Expression of transcripts for myelin related genes in postmortem brain from cocaine abusers

Chronic abuse of cocaine is known to cause neuroadaptive changes in the nucleus accumbens (NAc) and ventral tegmental area (VTA). In addition, altered expression of the myelin-related genes MBP, MOBP, PLP1 as well as of MAL2 in NAc was recently reported by gene array analysis in brains from cocaine abusers. In the present study we used in situ hybridization to quantify transcript expression of these four genes, as well as for the myelin-related transcripts encoding quaking, EDG2, claudin-11, transferrin, CNP, and MAG in caudate, putamen, internal capsule, and NAc in postmortem brain from cocaine abusers and matched comparison subjects. Most transcripts were not different between these groups in these striatal regions, and contrary to previous reports, we did not detect any changes in the NAc. However, expression of the transcript encoding PLP1 was significantly decreased in ventral and dorsal regions of the caudate, putamen, and in the internal capsule. Additionally, expression of claudin-11 and transferrin was decreased in the caudate and internal capsule, respectively. PLP1 is expressed at very high levels in oligodendrocytes and is essential in maintaining stability of myelin sheets. Based on these findings, altered expression of PLP1 in most areas of the striatum suggests that widespread changes to the myelin structure could be associated with the adaptive changes following chronic cocaine abuse.