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PubMed2001

Fenvalerate treatment affects development of olfactory glomeruli in Manduca sexta.

Low doses of fenvalerate, a widely used type-II pyrethroid insecticide, have been shown previously to produce abnormal olfactory centers in the brain and abnormal olfactory-mediated behavior in beetles (Wegerhoff et al. [1998] Neuroreport 9:3241-3245). Here, we use the experimental advantages of the moth Manduca sexta to explore the cellular changes that lead to these abnormalities. Our results indicate that treatment with fenvalerate may affect multiple aspects of the development of the primary olfactory centers, the antennal lobes, in Manduca, including ingrowth of olfactory receptor axons, axon fasciculation, and targeting within the antennal lobe, and intercellular signaling between the receptor axons and the glial cells that ordinarily surround and stabilize the developing olfactory glomeruli.

Animals↗
PubMed1977

Morphogenesis of pancreatoblastoma, infantile carcinoma of the pancreas: report of two cases.

Two cases of infantile carcinoma of the pancreas were diagnosed as pancreatoblastoma based on the morphogenesis of the tumors. These encapsulated tumors adhered to the head of the pancreas and to the descending portion of the duodenum. Histologic examination revealed an organoid structure made up of cords or nodules of squamoid cells with elongated nuclei arranged in a parallel fasciculating pattern (squamoid corpuscles), surrounding tubular structures of columnar epithelial cells and intermediate light cell masses with little differentiation. Electron microscopy revealed zymogen-like granules and well developed granular endoplasmic reticulum in the cytoplasm. There were no detectable islet cells in tumor tissue. Both of these tumors could be derived from the ventral pancreas and be isolated by the lack of communication with the duct of Wirsung. As the duct of Santorini was patent, extirpation of these organoid tumors would not influence secretion of pancreatic juice. Considering the favorable prognosis after extirpation of these tumors, they should be differentiated from the usual adenocarcinoma of the pancreas occurring in adults.

Adolescent↗
PubMed2001

Embryonic development of the central projection of auditory afferents (Schistocerca gregaria, Orthoptera, Insecta).

The auditory system of Schistocerca gregaria is a well investigated sensory network in the adult grasshopper. Here we present a first study on the embryonic development of this neuronal network. Focussing on the auditory receptor cells we show that they differentiate axonal processes at around 45% of embryonic development. These axons fasciculate with the intersegmental nerve and enter the central nervous system by 45-50% of development. First collaterals sprout into the major arborization area, the frontal auditory projection area of the metathoracic ganglion by 60%. This projection increases in density until an adult-like morphology is established by 90% of development. Furthermore, by the end of embryogenesis all three types of receptor fiber projections can be distinguished. This development is independent of a hearing ability, which develops much later during postembryonic life. The auditory projection co-develops with the fusion of neuromeres to the metathoracic ganglion, the formation of the target neuropile areas and the expression of the synapse associated molecule synapsin. Fasciclin I and Lachesin, both potential axon-guidance molecules, are expressed strongly on both, peripheral and central auditory pathways and, although much weaker, within the synaptic target area.

Animals↗
PubMed2000

Neuregulin, a factor with many functions in the life of a schwann cell.

The signalling system comprising the ligand Neuregulin-1, and its receptors, ErbB2 and ErbB3, plays multiple and important roles in glial development. These include functions in early development of neural crest cells, in expansion of the Schwann cell precursor pool and in myelination. Neuregulin is one of the crucial axon-derived signals that influence development of Schwann cells. These are specialized cells that ensheath peripheral axons and provide electrical insulation. Schwann cells have also long been implicated in providing more than a simple ensheathing function. Compelling evidence for this has emerged from the analysis of mice lacking these cells, resulting from a non-functional or compromised Neuregulin signalling system. They serve as a model to study glia-nerve interactions in vivo and indicate that Schwann cells provide important neurotrophic signals, and also cues that regulate perineurium development and nerve fasciculation.

Animals↗
PubMed2000

Pallido-Luysio-Nigral atrophy revealed by rapidly progressive hemidystonia: a clinical, radiologic, functional, and neuropathologic study.

Pallido-luysio-nigral atrophy (PLNA) is a rare neurodegenerative disease in which the clinical and radiologic correlates have not yet been clearly established. A 62-year-old man insidiously developed dystonic postures, choreoathetoid movements, slowness, and stiffness, which initially affected the right hand and foot and progressively spread to the entire right side. T2-weighted magnetic resonance imaging showed increased signal intensity in both left and right medial pallida and in the left substantia nigra. Tests using HMPAO-SPECT and FDG-PET demonstrated left cortical hyperperfusion and hypermetabolism, whereas the left lenticular nucleus was slightly hypometabolic. At age 65, abnormal movements and postures involved all four limbs and the axis causing major gait disturbances, and facial and bulbar muscles atrophied resulting in dysarthria, dysphagia, and impaired breathing. Diffuse amyotrophy and fasciculations also appeared. Death occurred at age 66, 4 years after onset. At autopsy, severe bilateral neuronal loss and gliosis restricted to the pallidum, the subthalamic nucleus, the substantia nigra, and the hypoglossal nucleus were noted, accounting for the diagnosis of PLNA with lower motor neuron involvement. Progressive hemidystonia with adult onset represents an unusual clinical presentation for this disorder. Moreover, this observation indicates that a diagnosis of PLNA should be considered for specific magnetic resonance imaging, SPECT, and/or PET data, and suggests that in PLNA, pallidal dysfunction might play a key role in the dystonic presentation.

Age of Onset↗
PubMed1994

Developmental relations between sixth nerve motor neurons and their targets in the chick embryo.

The developmental relations between abducens (VI) nerves and their targets, the lateral rectus, quadratus, and pyramidalis muscles, have been examined in the chick embryo from early neural tube stages through 10 days of incubation. Sites of myoblast origins were determined by microinjection of replication-incompetent retroviruses containing the LacZ reporter into paraxial mesoderm corresponding to somitomeres 3-5. Motor neurons and axons were identified by Bodian staining, immunocytochemistry, and application of DiI and DiO to dissected peripheral nerves. Anlage of the dorsal oblique originate in somitomere 3, close to the ventrolateral margin of the mid-to-caudal mesencephalon. Precursors of the lateral rectus arise deep within somitomere 4, beside the future metencephalon (rhombomere "A"). Quadratus and pyramidalis precursors are located between and partially segregated from these other two anlage. VIth nerve axons exit rhombomeres 5 and 6 via multiple median roots, fasciculate, and by stage 17 have elongated rostrally beneath the hindbrain. Immediately caudal to a mesenchymal pre-muscle condensation located deep to rhombomere 2, the VIth nerve separates into two branches. One branch enters the rostral portion of the condensation, from which quadratus and pyramidalis muscles will segregate. This branch projects exclusively from rhombomere 5 and is the accessory abducens nerve. The other branch enters the caudal, presumptive lateral rectus, region of the condensation. This is the abducens nerve, and it projects from cells located in both rhombomeres 5 and 6. These findings indicate that specific matching of motor nerves with their presumptive targets begins prior to the differentiation and segregation of myogenic populations, and that spatial organization of developing eye muscles is initiated well before they interact with connective tissue precursors derived from the neural crest.

Abducens Nerve↗
PubMed1981

Autosomal dominant late adult spinal muscular atrophy, type Finkel.

We describe clinical and genetic data from the study of two families with 80 members affected with the autosomal dominant, slowly progressive spinal muscular atrophy of late onset (average 48.8 years), first described by Finkel in 1962. Electromyography and muscle biopsy of a number of patients confirmed the neurogenic nature of the conditions. Unusual findings in this disorder were cramps, spontaneous fits of suffocation, and symptomatic myotonia. Other manifestations are slow loss of muscle strength and progressive proximal atrophy, which starts in the lower limbs and progresses to the upper limbs; hypoactive or absent tendinous reflexes; and generalized fasciculations. Sensory and cranial nerve function is unimpaired. Probabilities for genetic counseling are evaluated by means of a method adequate to the late-onset nature of the condition.

Diagnosis, Differential↗
PubMed2001

Intermediate CAG repeat lengths (53,54) for MJD/SCA3 are associated with an abnormal phenotype.

We report on a Dutch family in which 4 members in 2 generations have intermediate repeat lengths (53 and 54) for Machado-Joseph Disease/Spinocerebellar Ataxia (MJD/SCA3). All but the youngest have a restless legs syndrome with fasciculations and a sensorimotor axonal polyneuropathy. Central neurological abnormalities are only present in 2. This family shows that intermediate repeat lengths can be pathogenic and may predispose for restless legs and peripheral nerve disorder.

Aged↗
PubMed1979

Hyperexcitability of motor and sensory neurons in neuromyotonia.

Two members of a family with a neuropathy resembling Charcot-Marie-Tooth disease were unable to relax their muscles after voluntary contraction. Muscle spasm often outlasted voluntary contraction by 30 seconds or more before subsiding into myokymia and fasciculations. The posture of the hand during muscle spasm resembled that of tetany, and Trousseau's and Chvostek's signs were present although no abnormality of calcium or magnesium metabolism could be demonstrated. Muscle spasms ceased during medication with carbamazepine, 600 mg daily. Nerve stimulation, electromyography, and regional neuromuscular blockade with curare indicated that the condition originated in peripheral nerve, while microneurographic recordings showed that sensory as well as motor fibers were hyperexcitable. Sural nerve biopsy revealed axonal degeneration involving myelinated and unmyelinated fibers. It was concluded that the neural hyperexcitability is caused by a membrane defect resulting in a low threshold for excitation throughout the length of the axon.

Adult↗
PubMed1982

Juvenile spinal muscular atrophy: a new hexosaminidase deficiency phenotype.

A 24-year-old Ashkenazi Jewish man was evaluated for a nine-year history of progressive leg weakness with fasciculations. Electromyography, nerve conduction velocities, muscle biopsy, and serum creatine kinase were consistent with anterior horn cell disease. On rectal biopsy, ganglion cells were filled with membranous cytoplasmic bodies and an unusual submucosal layer of periodic acid-Schiff positive histiocytes filled with granules was seen. Hexosaminidase A in serum and leukocytes was severely decreased in the patient and partially decreased in parents and a brother. A paternal relative had classic infantile Tay-Sachs disease. Juvenile spinal muscular atrophy in this patient, closely resembling the Kugelberg-Welander phenotype, resulted from an alpha-locus hexosaminidase deficiency disorder, possibly a genetic compound of HEX alpha 2 and a milder hexosaminidase alpha-locus allele. Other cases of hexosaminidase deficiency have included anterior horn cell disease as part of a more complex disorder, but this is the first case, to our knowledge, of a hexosaminidase deficiency disorder presenting as spinal muscular atrophy.

Adult↗
PubMed1982

Macroglobulinemia with peripheral neuropathy simulating motor neuron disease.

A 48-year-old man with an IgM plasma cell dyscrasia died after 14 months of symptoms and signs typical of motor neuron disease, including widespread fasciculation and normal sensation. Two laboratory results were atypical: cerebrospinal fluid protein content of 132 mg/dl and slow motor nerve conduction. At autopsy, no loss or atrophy of anterior horn neurons was found; instead, degeneration of ventral and dorsal roots and retrograde changes of chromatolysis in motor neurons implied peripheral neuropathy. Most reported cases of neuropathy associated with plasma cell dyscrasias have been sensorimotor or purely sensory, but there have been 14 previous cases of motor disorders.

Adult↗
PubMed1986

N-acetyl-beta-hexosaminidase beta locus defect and juvenile motor neuron disease: a case study.

A patient with partial deficiency of N-acetyl-beta-hexosaminidase (Hex) developed a progressive motor neuron syndrome beginning at age 7, characterized by dysarthria, muscle wasting, fasciculations, and pyramidal tract dysfunction. Minor clinical features have included tremor and late distal sensory abnormalities. Rectal biopsy at age 24 demonstrated membranous cytoplasmic bodies in submucosal ganglion cells. Biochemical evaluation revealed nearly absent Hex B activity in serum, leukocytes, and fibroblasts, with partial Hex A activity in serum and leukocytes, and low normal Hex A activity in fibroblasts. Motor neuron disease can be a presentation of a Hex beta locus defect, in addition to the previously recognized Hex alpha locus defects.

Adult↗
PubMed1988

Hexosaminidase A deficiency manifesting as spinal muscular atrophy of late onset.

Proximal lower limb weakness and fasciculations were the only clinical manifestations of hexosaminidase A (Hex A) deficiency in a 39-year-old woman. Hex A activity in serum and leukocytes was 0 to 4% by standard heat inactivation fluorogenic substrate methods, and 5% when Hex A isoenzymes were fractionated by diethylaminoethanol cellulose chromatography. Computed tomography of the brain showed cerebellar atrophy. We suggest that Hex A activity studies be done in patients with typical as well as atypical spinal muscular atrophy.

Adult↗
PubMed1996

Unstable triplet repeat and phenotypic variability of spinocerebellar ataxia type 1.

A Siberian kindred with spinocerebellar ataxia genetically linked to the SCA1 locus on chromosome 6p has been screened for the CAG triplet expansion within the coding region of the SCA1 gene. The kindred includes 1,484 individuals, 225 affected and 656 at risk, making this collection the largest spinocerebellar ataxia type 1 (SCA1) pedigree known. Each of the studied 78 SCA1 patients carried an expanded allele containing a stretch of 39 to 72 uninterrupted CAG repeats. Normal alleles had 25 to 37 trinucleotide repeats. Expanded alleles containing 40 to 55 repeats were found in 26 at-risk relatives. The number of CAG repeats in the mutated allele was inversely correlated with age at disease onset. Cerebellar deficiency was present in each patient and its severity was moderately affected by the number of CAG repeats. In contrast, the associated signs, dysphagia, diffuse skeletal muscle atrophy with fasciculations, and tongue atrophy were absent or mild in patients with low CAG repeat numbers, but severely complicated the course of illness in patients with a larger number of repeat units. One female mutation carrier was asymptomatic at age 66, more than 2 standard deviations beyond the average age of risk, suggesting incomplete penetrance. In 2 symptomatic individuals who had an expanded number of CAG repeats on both chromosomes, age at onset, rate of progression, and clinical manifestation corresponded to the size of the larger allele.

Adolescent↗
PubMed1997

Machado-Joseph disease: clinical, molecular, and metabolic characterization in Chinese kindreds.

Machado-Joseph disease, an autosomal dominant multisystem motor degeneration, has been described mainly in people of Portuguese descent. Our report documents the presence of Machado-Joseph disease in the Chinese population, based on the specific molecular marker of a CAG repeat array in the 3' end of the MJD gene. We screened 21 Chinese families with dominant spinocerebellar ataxia. The results showed that Machado-Joseph disease with CAG expansion accounted for 52% of families with autosomal dominant cerebellar ataxia in this series. The clinical characteristics, besides the well-documented cerebellar ataxia, dysarthria, nystagmus, corticospinal dysfunctions, a variable degree of facial muscle fasciculation, and proprioceptive loss, included loss of optokinetic nystagmus and autonomic nervous system dysfunction. The CAG repeat number in the MJD gene ranged from 14 to 39 among normal alleles, and from 63 to 81 among MJD alleles. There was a strong inverse correlation (gamma = -0.77) between number of CAG repeats and age at symptom onset, accounting for 60% of the variance of age at onset. A strong clinical anticipation of age at onset existed in successive generations. Mild instabilities of expanded CAG repeat numbers during meiotic transmission occurred, with no significant difference according to the gender of the transmitting parent. Finally, brain metabolism in Machado-Joseph disease, studied with positron emission tomography, was characterized by significant progressive regional hypometabolism in the occipital cortex, as well as the cerebellar hemispheres, vermis, and brainstem.

Adult↗
PubMed1997

A new type of hereditary motor and sensory neuropathy linked to chromosome 3.

We report the clinical, pathological, and genetic findings of 23 patients in 8 families with hereditary motor and sensory neuropathy (proximal dominant form) (HMSN-P) in Okinawa, Japan. The clinical features were unique with respect to autosomal dominant inheritance, Kennedy-Alter-Sung syndrome-like proximal dominant neurogenic atrophy, obvious sensory involvement, painful muscle cramp, fasciculations, areflexia, and high incidences of elevated creatine kinase levels, hyperlipidemia, and diabetes mellitus. Electrophysiological and pathological studies revealed typical motor and sensory axonal neuropathy, and decreased numbers of anterior born and dorsal ganglion cells, which suggested the presence of neuronopathy in HMSN-P. Genetic linkage studies showed a lod score of 4.04 (two-point analysis) in DNA marker D3S1284. Haplotype analysis showed that the gene locus of the disease was mapped to 3p14.1-q13 bracketed by D3S1285 and D3S1281. In this region, the patients' chromosomes showed an obvious increase in the allele frequency of five markers. One allele in D3S1591 was identical in all patients but had a low frequency in the control population. This finding suggested the presence of linkage disequilibrium and a common origin of this allele in all patients with HMSN-P. The HMSN-P described here is a new clinical entity characterized by unique clinical manifestations and a new gene locus.

Adult↗
PubMed1998

Perinatal hypoxic-ischemic thalamic injury: clinical features and neuroimaging.

A common pattern of hypoxic-ischemic cerebral injury in the term newborn involves predominantly cerebral cortex and subcortical white matter. We describe 20 term newborns with moderate or severe acute hypoxic-ischemic encephalopathy who exhibit a different pattern of abnormalities on computed tomography, with evidence of decreased tissue attenuation predominantly in thalami and basal ganglia and relative preservation of cerebral cortex and white matter. Profound, acute hypoxic-ischemic insult (eg, umbilical cord prolapse, uterine rupture, or massive placental abruption) was documented in 16 of 20 infants (80%). Characteristic clinical features during the newborn period included irritability, tonic posturing of limbs, and persistent lower cranial nerve dysfunction, often with prominent tongue fasciculations. This pattern of central injury appears to be highly predictive of poor outcome; 7 newborns (35%) died, and all survivors who had follow-up to 18 months of age (11) had major neurological sequelae (eg, spastic quadriplegia, choreoathetosis, and persistent feeding problems). This pattern of hypoxic-ischemic cerebral injury corresponds closely to experimental animal models of "acute total" perinatal asphyxia.

Apgar Score↗
PubMed1978

Supraependymal neurons overlying the periventricular region of the third ventricle of the guinea pig: a correlative scanning--transmission electron microscopic study.

The frequency of occurrence, distribution and morphology of supraependymal neurons associated with the third ventricular wall of the guinea pig were investigated by correlative scanning and transmission electron microscopy. Each of the specimens was located on the ciliated ventricular wall between the inferior border of the thalamus and the non-ciliated ependyma associated with the median eminence. Prominent clusters of neuronal perikaria in association with massive process bundles were observed in 7 of the 31 specimens examined. In those specimens lacking prominent neuronal networks a more diffuse array of independent nerve fibers was sometimes seen on the ependymal surface. Neuronal perikaria exhibited numerous surface protrusions and were covered by a rich meshwork of crisscrossing, varicosed fibers. Many of these cells were associated with multiple processes of varying diameters and lengths which either coursed independently over the ventricular surface or formed fasciculated bundles. As process bundles traversed the ependymal surface, individual processes branched off and either terminated within the ventricular lumen or penetrated the subjacent ependymal lining. Fibers also made contact with adjacent supraependymal neuronal elements. Correlative transmission electron microscopic observations indicate that both the perikaria and processes of such supraependymal networks possess ultrastructural features characteristic of neurons. The morphological characteristics of the intraventricular neuronal networks suggest that they may be engaged in functional interactions with the cerebrospinal fluid, with adjacent supraependymal neuronal elements and with the subjacent neuropil.

Animals↗