Developmental change in ganglioside expression in primary culture of rat neurons

Developmental changes in ganglioside levels and patterns were investigated in neuronal cells dissociated from 17-day-old fetal rat hemispheres for up to 7 days of culture. Increases in ganglioside contents and the onset of GM3 synthesis, which is associated with proliferation of glial cells, were observed as the neuronal network was established in cell cultures. The distribution of gangliosides in developing neurons was monitored by the indirect immunofluorescent technique using three anti-ganglioside antibodies. Anti-GM1 antibody showed immunofluorescence only on the cell soma 1 and 3 days after plating and additional binding between cell aggregates by 7 days in culture. GD3 ganglioside, the predominant species in embryonic neurons, was not detected on the neuronal cell surface, whereas the number of positively stained non-neuronal cells was increased at 7 days. Monoclonal A2B5 antibody suggested that polysialogangliosides play a role in neuronal network formation. In 1-day-old culture, however, all antibodies bound poorly to cell surface antigens and strongly to cells, the membranes of which were permeabilized with acetone. These results suggest that a substantial amount of gangliosides are retained, transformed within the cell to more complex gangliosides, and translocated to the cell surface following neurite outgrowth and morphological changes.     

Synapse formation and synaptic activity in mammalian nerve-muscle co-culture are not inhibited by antibodies to neural cell adhesion molecule L1

Co-cultures of rat myotubes and spinal cord explants from mouse embryos were maintained in the presence of Fab fragments of polyclonal antibodies to neuronal cell surface antigen L1. Microscopic observation showed that neurite outgrowth was not blocked by anti-L1. By intracellular recording, no effect was observed on the number of myotubes that showed endplate potentials, nor on the efficiency of synaptic contacts. As was demonstrated by indirect immunofluorescence, added Fab fragments remained bound to the neurite surface and were present in the medium for at least two days in culture, after which time antibodies were replaced during the medium change. Taken together, these observations show that L1 antigen is not involved in synapse formation between nerve and muscle.     

Functional elongation of CA1 hippocampal neurons with aging in Fischer 344 rats

Dendritic function of CA1 pyramidal cells was measured during intracellular recording in vitro and correlated with in vivo behavior in Fischer 344 rats. The aged rats (greater than 26 months) were significantly impaired on a water maze test of hippocampal behavioral function. CA1 neurons from these aged rats demonstrated an elevated action potential threshold compared to the young rats. Electrotonic length (L, in lambda), calculated independently from physiological transients and electrotonic cell reconstructions, was significantly longer in neurons from aged rats (L = 0.73 +/- 0.02 lambda; mean +/- SEM) than in neurons from young rats (L = 0.66 +/- 0.02 lambda). Analysis of proximal and distal synaptic potentials pointed to a more distal electrotonic siting of all dendritic synapses in the aged neurons. Thus, electrical lengthening of dendrites, alterations in synaptic location and decreased excitability in neurons from aged rats with behavioral impairment may represent an endpoint of neuronal reactive mechanisms in response to the aging process.     

A new monoclonal antibody against the GABA-protein conjugate shows immunoreactivity in sensory neurons of the rat.

A monoclonal antibody, 115AD5, was raised against GABA coupled to bovine serum albumin. The monoclonal antibody 115AD5 also reacted with other GABA-protein conjugates. The specificity of the monoclonal antibody was corroborated by enzyme-linked immunoassay, dot-immunobinding experiments and immunostaining of rat cerebellum sections. The monoclonal antibody 115AD5 could successfully be applied on Vibratome and cryostat sections using either indirect immunofluorescence or peroxidase techniques. In rat cerebellar cortex the monoclonal antibody 115AD5 gave an intense immunoreaction in stellate cells, in Golgi neurons, and in basket cells and their processes around Purkinje cell bodies. Purkinje cell dendrites showed GABA immunoreactivity while the cell bodies were non-reactive or only weakly reactive. There was labelling in some nuclei of Purkinje cells. GABA immunoreactivity was also found in dot-like structures in the granular layer. A large population of sensory neurons in rat thoracic and lumbar spinal dorsal root ganglia presented an intense immunoreactivity for the monoclonal antibody 115AD5. Nerve bundles immunoreactive for GABA were also seen in these ganglia. In the trigeminal ganglion, a major population of sensory neurons and some of their processes presented immunoreactivity for GABA. In the sensory nodose ganglion of the vagus nerve, many neuronal cell bodies and some fibres were immunoreactive for GABA. Ligation of the vagus nerve caudal to the ganglion resulted in an increased GABA immunoreactivity in neuronal somata of the ganglion, as well as in nerve fibres on the ganglionic side of the ligature. The present results suggest that in the rat, a population of sensory neurons in thoracic and lumbar spinal dorsal root ganglia, as well as in the trigeminal and nodose ganglia contain GABA. The presence of GABA immunoreactivity in these neurons raises the possibility of a neurotransmitter or modulator role.     

Long-term optical recording of patterns of electrical activity in ensembles of cultured Aplysia neurons

1. Left upper quadrant (LUQ) cells isolated from the abdominal ganglion of Aplysia were maintained in culture to study how the cellular and synaptic properties of individual neurons contribute to the generation of patterns of electrical activity by neuronal ensembles. 2. Conventional microelectrodes were used to examine the spiking characteristics of individually cultured LUQ cells in vitro and to characterize their synaptic interactions. 3. In vitro, in contrast to in situ, LUQ neurons innervate other LUQ neurons. Intracellular recordings from pairs of LUQ cells showed that the prevalent type of postsynaptic potential was purely inhibitory. The other type of response was a dual-action postsynaptic potential, with inhibition followed by a delayed, slow excitation. 4. We established a set of criteria for the use of multiple-site optical recording techniques, in combination with impermeant probes of membrane potential, to observe the patterns of electrical activity generated by ensembles of co-cultured LUQ cells. 5. The spiking activity of individual cells within the neuronal ensembles was detected by means of the change in optical absorption of cells that were vitally stained with the dye RH155. The change in absorption was typically delta A congruent to 4 X 10(-4) per spike. We achieved a signal-to-noise (peak-to-peak) ratio of approximately 10 for a 50 X 50-microns photodetector field and an incident intensity of approximately 10 mW/cm2, close to the theoretical limit. 6. These conditions permitted, for the first time, continuous optical recording from cultured neurons for periods of up to 3 h with no discernible photodynamic damage or photobleaching. This long-term optical recording permitted examination of the different patterns of electrical activity generated by individual neuronal ensembles under several different experimental conditions. 7. An elaborate tracery of regenerated neurites present in these cultures resulted in individual photodetectors recording simultaneously the activity of multiple neurons. We reconstructed the temporal firing patterns for individual neurons within ensembles even with all the neurons active simultaneously and determined the functional connections in the ensemble by analyzing the temporal relationships between firing patterns of individual neurons. Excitatory as well as inhibitory functional interactions could be observed within the neuronal ensemble, the latter after the tonic activity of the neurons was increased by reducing the extracellular [Mg2+]. 8. Examination of the optical data from ensembles constructed from identified cells having characteristic physiological responses allowed us to address the question of how cellular and synaptic properties affect the patterns of electrical activity generated by neuronal ensembles.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ultrastructural localization of TRH-like immunoreactivity

Summary With the peroxidase-antiperoxidase (PAP) method TRH-like immunoreactivity (TRH-LI) was observed in certain neurons of the central nervous system. Their distribution agreed well with findings previously obtained with the indirect immunofluorescence technique. At the ultrastructural level electron-dense precipitates representing TRH-LI were observed in so-called large dense core vesicles, which were localized both in the cytoplasm of some hypothalamic neuronal cell bodies, as well as in boutons in the hypothalamus and spinal cord. The boutons often seemed to form axo-somatic or axodendritic synapses.     

L-citrulline immunostaining identifies nitric oxide production sites within neurons

The cellular and subcellular localization of L-citrulline was analyzed in the adult rat brain and compared with that of traditional markers for the presence of nitric oxide synthase. Light, transmission electron, and confocal laser scanning microscopy were used to study tissue sections processed for immunocytochemistry employing a monoclonal antibody against L-citrulline or polyclonal anti-neuronal nitric oxide synthase sera, and double immunofluorescence to detect neuronal nitric oxide synthase and L-citrulline co-localization. The results demonstrate that the same CNS regions and cell types are labeled by neuronal nitric oxide synthase polyclonal antisera and L-citrulline monoclonal antibodies, using both immunocytochemistry and immunofluorescence. Short-term pretreatment with a nitric oxide synthase inhibitor reduces L-citrulline immunostaining, but does not affect neuronal nitric oxide synthase immunoreactivity. In the vestibular brainstem, double immunofluorescence studies show that many, but not all, neuronal nitric oxide synthase-positive cells co-express L-citrulline, and that local intracellular patches of intense L-citrulline accumulation are present in some neurons. Conversely, all L-citrulline-labeled neurons co-express neuronal nitric oxide synthase. Cells expressing neuronal nitric oxide synthase alone are interpreted as neurons with the potential to produce nitric oxide under other stimulus conditions, and the subcellular foci of enhanced L-citrulline staining are viewed as intracellular sites of nitric oxide production. This interpretation is supported by ultrastructural observations of subcellular foci with enhanced L-citrulline and/or neuronal nitric oxide synthase staining that are located primarily at postsynaptic densities and portions of the endoplasmic reticulum. We conclude that nitric oxide is produced and released at focal sites within neurons that are identifiable using L-citrulline as a marker.     

Substance P-containing primary sensory neurons projecting to the inferior mesenteric ganglion: evidence from combined retrograde tracing and immunohistochemistry

The origin of substance P-containing fibres in the inferior mesenteric ganglion of the guinea-pig was studied by combining retrograde tracing and indirect immunofluorescence techniques. 'True Blue' or propidium iodide was injected into the inferior mesenteric ganglion. Four days later the animals were perfused with formalin and the dorsal root ganglia L2 and L3 were dissected out. Sections of the spinal ganglia were cut on a cryostat and analysed in a fluorescence microscope with appropriate filter combinations and subsequently processed for indirect immunofluorescence using antiserum to substance P. Several ganglion cells containing both dye (True Blue or propidium iodide) and substance P-like immunoreactivity were observed, strongly supporting the view that at least some of the substance P fibres in the inferior mesenteric ganglion are of sensory nature. Taken together with physiological results from other workers, the present findings suggest that substance P can be released from peripheral, sensory nerve endings, inducing changes in the membrane potential of sympathetic neurons.     

Immunohistochemical and western analyses of protein arginine N-methyltransferase 3 in the mouse brain

The distribution of protein arginine N-methyltransferase 3 (PRMT3) was investigated in the mouse brain using indirect immunofluorescence. PRMT3 was observed to be localized in the cell bodies and dendrites of neurons but not in the axons and glial cells, indicating that PRMT3 is involved in neuronal function. The distribution of the immunoreactive neurons in the brain was uneven, indicating that PRMT3 plays a role in specific neuronal systems such as the motor and limbic systems, as well as functions related to the cerebellum. The present ontogenetic analysis of PRMT1 and PRMT3 using Western blot methodology clearly revealed that PRMT3 develops during the perinatal stage and its expression is maintained even in adulthood. PRMT1, on the other hand, is expressed transiently during the early embryonic stage. These findings indicate that PRMT3 is related with neuronal function in both young and adult brains, while PRMT1 has roles in the immature brain, such as the formation of neural circuits.     

Capsaicin receptor immunoreactivity in the human trigeminal ganglion

The cloned capsaicin receptor, also known as vanilloid receptor subtype 1 (VR1) receptor, has been demonstrated to be an integral membrane protein with homology to a family of putative store-operated calcium channels. The VR1 receptor is activated not only by capsaicin but also by noxious heat and protons, and therefore it is suggested as a molecular integrator of chemical and physical stimuli that elicit pain. In the present study, indirect immunofluorescence detected a small number of neurons that are VR1 receptor immunoreactive (ir) (171 versus 1038 or 16% of all neuronal cell bodies) in the human trigeminal ganglion (TG). In addition, RT-PCR confirmed the presence of VR1 mRNA in the human TG. It has been hypothesized that TG neuronal cell bodies are the source of capsaicin-stimulated release of calcitonin gene-related peptide (CGRP), and hence co-localization experiments were performed. Around 10% of the VR1 receptor-ir is expressed on neurons that contain CGRP-ir (ten among 74) in the human TG, indicating that capsaicin may act through the VR1 receptor to modulate the release of CGRP and in turn to modulate pain. We observed that 8% of the VR1 receptor-ir neuronal cell bodies contain substance P-ir and 5% nitric oxide synthase. Capsaicin can release nitric oxide, CGRP and substance P from sensory nerves and contribute to central sensitization.     

A monoclonal antibody equivalent to anti-rat neural antigen-1 as a marker for Schwann cells

The monoclonal antibody 217c, raised by Peng et al. [(1982) Science, Wash. 215, 1102-1104] in mice against the rat glioma cell line C6, can be used as a marker for normal Schwann cells. In mixed cultures of Schwann cells and fibroblasts from neonatal rat sciatic nerve, this monoclonal antibody, detected by indirect immunofluorescence, bound to the surface of cells with the same elongated morphology as those that express a previously described surface antigen, rat neural antigen-1 (Ran-1), defined by polyclonal mouse antisera. In these experiments Ran-1 and the antigenic determinant recognized by monoclonal 217c were both found on normal rat Schwann cells and on the rat glial tumor cell lines C6, 33B and 21A and the pheochromocytoma PC12. Neither anti-Ran-1 nor the monoclonal antibody bound to neurons, fibroblasts or glial cells in newborn rat cerebellum cultures, the rat muscle cell line L6, the transformed rat fibroblast cell line Rat 1, the rat brain tumor cell line B28 or the mouse Schwannoma cell line TR6B. Thus the monoclonal 217c behaved as if it were detecting Ran-1 by binding to normal rat Schwann cells and to those tumor cells that have this antigen. Our data show that this monoclonal antibody is a reliable and convenient marker for rat Schwann cells in culture.     

抗人PD-L1 单克隆抗体的制备及其应用

目的:获得能应用于临床诊断以及阻断PD-L1 与PD-1 结合的抗人PD-L1 单克隆抗体。方法:采用重组表达的人PD-L1 蛋白免疫BALB/ c 小鼠,通过杂交瘤细胞融合技术获得稳定分泌抗人PD-L1 单抗的阳性细胞株,ELISA 方法鉴定抗体的特异性、亲和力、亚型等方面特性;免疫印迹、间接免疫荧光方法对肿瘤细胞进行检测;肿瘤杀伤实验验证抗体阻断活性。结果:共获得2 株抗人PD-L1 单抗,抗体效价分别为1 2.56 106 和1 3 105 ,亲和力分别为1.5 109 L/ mol 和2.5 108 L/ mol,均与PD-L2 蛋白无交叉反应。免疫印迹、间接免疫荧光证实抗体有诊断作用。杀伤实验显示抗体有阻断作用。结论:共获得两株稳定分泌高效价、高特异性的抗人PD-L1 单抗的杂交瘤细胞株,能作为诊断抗体应用于肿瘤表型检测和预后有效性的评估。抗体的阻断功能可应用于联合CIK 细胞免疫治疗。     

Origins of 1/f2 scaling in the power spectrum of intracortical local field potential

It has been noted that the power spectrum of intracortical local field potential (LFP) often scales as 1/f(-2). It is thought that LFP mostly represents the spiking-related neuronal activity such as synaptic currents and spikes in the vicinity of the recording electrode, but no 1/f(2) scaling is detected in the spike power. Although tissue filtering or modulation of spiking activity by UP and DOWN states could account for the observed LFP scaling, there is no consensus as to how it arises. We addressed this question by recording simultaneously LFP and single neurons ("single units") from multiple sites in somatosensory cortex of anesthetized rats. Single-unit data revealed the presence of periods of high activity, presumably corresponding to the "UP" states when the neuronal membrane potential is depolarized, and periods of no activity, the putative "DOWN" states when the membrane potential is close to resting. As expected, the LFP power scaled as 1/f(2) but no such scaling was found in the power spectrum of spiking activity. Our analysis showed that 1/f(2) scaling in the LFP power spectrum was largely generated by the steplike transitions between UP and DOWN states. The shape of the LFP signal during these transitions, but not the transition timing, was crucial to obtain the observed scaling. These transitions were probably induced by synchronous changes in the membrane potential across neurons. We conclude that a 1/f(2) scaling in the LFP power indicates the presence of steplike transitions in the LFP trace and says little about the statistical properties of the associated neuronal firing.     

Detection by immunofluorescent anti-idiotypic antibodies of yeast killer toxin cell wall receptors of Candida albicans

Yeast killer toxin cell wall receptors of Candida albicans were observed by indirect immunofluorescence using an affinity purified rabbit anti-idiotypic antiserum. The antiserum had been raised against a monoclonal antibody neutralizing the in vitro activity of a killer toxin produced by a selected strain of Hansenula anomala UCSC 25F. This simple procedure permitted the location of killer toxin cell wall receptors in various morphological phases of the yeast cells. The use of the indirect immunofluorescence technique with anti-idiotypic antibodies may have potential value in determining the occurrence of killer toxin receptors in other microbial systems.     

Preliminary research of induction of the multiple HPV antibody by HPV L1 type conserved sequence aimed at human papillomavirus major protein

To investigate whether a conserved sequence of the human papillomavirus(HPV) L1 protein consisted of 12 amino acid residue can induce the antibody aimed at multiple HPV types, we screened a conserved sequence of the HPV L1 protein by forecasting B cell epitope and comparing multiple sequences. The peptide was synthesized, mixed with Freund adjuvant, and used to immunize rabbits, and those in the control group were only immunized with Freund adjuvant. Then the antibody titer was identified by indirect enzyme-linked immunosorbent assay (ELISA). And immunocytochemistry, immunofluorescence, western blot and immunohistochemistry were used to detect whether the antibody could react with cervical cancer cell lines and cervical tissue that had been identified with HPV infections. We found that the antibody titer was greater than 1:25600. Moreover, we confirmed that the antibody could react with cervical cancer cell lines and cervical tissue with HPV infections. The results showed that the peptide could induce antibody aimed at multiple HPV types. Our findings have great significance in further research of the broad spectrum HPV, HPV L1 diagnosis kits.     

Characterization of an antibody directed against a surface component of normal and pleomorphic cells of Streptococcus sanguis.

Whole cells of Streptococcus sanguis were utilized as an immunoadsorbent to purify large quantities of an antibody (S1) directed against a cell surface component. The S-1 antibody was isolated from antisera to normal (N) and pleomorphic (O) cells by a similar adsorption-elution procedure. The S-1 antibody isolated from antisera to N cells reacted in gel diffusion in identify with the S-1 antibody to O cells, indicating that the antigen which binds S-1 antibody (Ag-1) may not be radically altered when cells become pleomorphic. The S-1 antibodies directed against both N and O cells had restricted heterogeneity, indicating that for both types of cell Ag-1 may have a simple repeating structure. However, N cells were agglutinated to a greater extent by S-1 antibody than O cells. In addition the distribution of the bound S-1 antibody became altered as the cells became pleomorphic. Utilizing the technique of indirect immunofluorescence we observed that the S-1 antibody was distributed evenly on the surface of N cells. As the cells became pleomorphic, the antibody appeared to bind preferentially at the cell poles (capping). Later, as the cells became more grossly deformed, additional bands of immunofluorescence appeared to bisect the cells. Electron microscopic analysis indicated that the bound antibody was not associated with septal notches. The results suggest that the arrangement rather than the immunological properties of Ag-1 became altered as cells became pleomorphic.     

Antinuclear matrix antibody. Hidden antinuclear antibody in patients with connective tissue diseases

A total of 435 serum samples from patients with different rheumatic diseases were screened for the presence of autoantibody to nuclear matrix components by indirect immunofluorescence on 0.1 mol/L HCl extracted HEp-2 cell and WiL2 cell substrates. A total of 28 specimens were positive in this assay. Eighteen of them were from patients with systemic lupus erythematosus (18 of 250), 2 from patients with rheumatoid arthritis (2 of 115), and 8 from patients with mixed connective tissue disease (8 of 10). Antigenic material for this antibody is resistant to DNase, partially sensitive to RNase, and sensitive to trypsin. This indicates that the antigen is composed of protein and possibly RNA. In immunoblot analysis, sera positive for this antibody in indirect immunofluorescence assay recognized different peptides. This suggests that protein peptides are the major antigenic material.     

Neuronal and glial activity during spreading depression in cerebral cortex of cat.

1. Extra- and intracellular potentials were recorded from neurons and glia during spreading depression (SD) in cerebral cortex of cats. The glial membrane depolarized during SD and the time course of depolarization was concurrent with the surface DC change of SD. The glial depolarization evoked by 20-Hz repetitive cortical stimulation disappeared during the negative DC shift of SD. Simultaneous recording of the extra- and intracellular potentials from a single glial cell with a coaxial microelectrode showed that the extracellular DC potential change was of opposite polarity to the glial intracellular potential, which suggests that the slow glial depolarization concurrent with SD is not the field potential. In contrast to glial cells, the neuronal burst discharges as well as the neuronal membrane depolarization associated with SD did not show a close relationship to SD: the neuronal membrane depolarization and discharge were frequently delayed by 10-3- s from the onset of the SD slow wave. Sometimes SD was observed without accompanying neuronal depolarization. The degree of neuronal depolarization was not always correlated with the amplitude of the negative wave of SD. 2. The effect of tetrodotoxin (TTX) on the negative DC potential of SD was examined. Simultaneous recording of glial membrane potential and the neuronal unit activity as well as extracellular DC potential and surface DC potential during SD was performed and the TTX-treated cortex was compared with the normal state. TTX did not change the DC level of the cerebral cortex. SD could be evoked by KCl when neuronal discharge was completely abolished by TTX application...     

Effect of ginsenoside Rg3 on mouse neural stem cell differentiation In vitro北大核心

BACKGROUND: Application of neural stem cells (NSCs) is of great current interest in neuroscience, but NSCs origin is very limited. And they always differentiate into a large percentage of glial cells and small percentage of neurons in natural differentiation process, so researchers should take effective measures to promote NSCs differentiation into certain offsprings. Previous studies have shown that ginseng saponin ingredients, such as Rb1 and Rg1, have certain influence on NSCs differentiation, but it is unclear whether Rg3 plays a role on NSCs differentiation. OBJECTIVE: To preliminarily investigate the effect of ginsenoside Rg3 on mouse NSCs differentiation into neurons and astrocytes in vitro. METHODS: The fetal cortices of embryonic 14 days (E14) C57BL/6 mice were isolated for culturing primary NSCs. Then passaged NSCs were identified by their purity with NSCs specific antibodies, Nestin and Sox2, by immunofluorescence staining. NSCs were induced for 3 days in the differentiation medium containing ginsenoside Rg3 of different concentrations (blank control, 50 and 250 nmol/L). After that, immunofluorescence staining was used to identify differentiated neurons with neuronal specific antibody, Tuj1, and differentiated astrocytes with astrocyte specific antibody, GFAP. Then, we calculated and statistically analyzed Tuj1+/DAPI and GFAP+/DAPI percentages in the three different groups. Besides, real-time PCR assay was used to test Tuj1 and GFAP mRNA expression in the three groups after 3 days of differentiation. RESULTS AND CONCLUSION: Primary and passaged NSCs were successfully cultured and almost of cells were positive for both Nestin and Sox2, so these high-purity NSCs could be used in the following experiments. Immunofluorescence staining and statistical analysis results showed that compared with the blank control and 250 nmol/L groups, 50 nmol/L group had an obviously increased neuronal percentage after 3 days differentiation (P < 0.01), while the blank control and 250 nmol/L groups had no significant difference (P > 0.05); compared with the blank control group, 50 and 250 nmol/L groups had significantly increased astrocyte percentages (P < 0.05), whereas there was no obvious difference between 50 and 250 nmol/L groups (P > 0.05). The results of real-time PCR assay were similar with the above immunofluorescence results. In conclusion, 50 nmol/L ginsenoside Rg3 can enhance mouse NSCs differentiation into neurons and astrocytes, while 250 nmol/L ginsenoside Rg3 can only promote mouse NSCs differentiation into astrocytes. © 2018, Journal of Clinical Rehabilitative Tissue Engineering Research. All rights reserved.     

Ultrastructural and virological aspects of Langat virus-induced SSPE in suckling hamsters.

The morphology of subacute sclerosing panencephalitis (SSPE) lesions in hamsters following i.p. inoculation of Langat virus was studied by light microscopy and electron microscopy. The lesions' temporal relationship to virus presence and antibody production was studied by immunofluorescence, virus isolation from brains and brain cell cultures, and by antibody assay of serum and spinal fluid. All 10-day-old hamsters infected with Langat virus developed SSPE lesions, most prominently in the cerebellum, without any overt signs. The lesions appeared 10 days after infection, progressed in severity until Day 21 and persisted unaltered at least 3 months. They consisted of neuronal degeneration, calcification, and intracellular lipid accumulation. Virus was isolated from Days 3 to 15 and disappeared on Day 21. Demonstration by cerebellar immunofluorescence of viral antigen was observed 10 days after inoculation. Antibody appeared in the serum on Day 6, rose to very high titres by Day 21, and thereafter declined. Cell-associated virus was not demonstrable in negative brain-cell cultures. These findings suggest that SSPE in hamsters, associated with Langat virus infection, is biologically different from measles SSPE. Purkinje-cell lipid accumulation and mineralization sparing mitochondria were manifestations of the response of neurons to cell injury at the threshold of irreversibility.