An ultrastructural study on the cerebellum of the brindled mouse

Molecular basis of neurodegeneration and neurodevelopmental defects in Menkes disease

ATP7A mutations impair copper metabolism resulting in three distinct genetic disorders in humans. These diseases are characterized by neurological phenotypes ranging from intellectual disability to neurodegeneration. Severe ATP7A loss-of-function alleles trigger Menkes disease, a copper deficiency condition where systemic and neurodegenerative phenotypes dominate clinical outcomes. The pathogenesis of these manifestations has been attributed to the hypoactivity of a limited number of copper-dependent enzymes, a hypothesis that we refer as the oligoenzymatic pathogenic hypothesis. This hypothesis, which has dominated the field for 25 years, only explains some systemic Menkes phenotypes. However, we argue that this hypothesis does not fully account for the Menkes neurodegeneration or neurodevelopmental phenotypes. Here, we propose revisions of the oligoenzymatic hypothesis that could illuminate the pathogenesis of Menkes neurodegeneration and neurodevelopmental defects through unsuspected overlap with other neurological conditions including Parkinson's, intellectual disability, and schizophrenia.

C1q, the classical complement pathway protein binds Hirano bodies in Pick's disease

Haematoxylin/Eosin staining was performed to screen for Hirano bodies from the temporal lobe including the hippocampus in 10 Pick's disease cases containing Pick bodies. Although the inclusions were confirmed in 9 out of 10 cases, only 4 out of 10 were particularly enriched with the eosinophilic bodies. These were subjected to immunostaining with anticomplement antibodies and astrocyte marker antiglial fibrillary acidic protein antibody and the HLA class II CR3/43 antibody to visualize microglia. An intraneuronal Hirano body was observed in one case that otherwise contained mainly the extracellular inclusions. In all cases, the extracellular Hirano bodies were seen lying adjacent to soma of neurons within CA1 region of the hippocampus. The extracellular Hirano bodies stained intensely with C1q, the first component of the classical pathway of activation but remained unreactive against antibodies to C4 and the C3 activation products (C3b and iC3b) and the alternative complement pathway component factor B. Hirano bodies also remained negative with the antiglial fibrillary acidic protein for astrocytes and HLA class II antibody CR3/43 for microglia. The results demonstrate that Hirano bodies have strong immunoreactivity to C1q; however, whether other complement components are associated with these inclusions remains to be further investigated.

Perinatal copper deficiency alters rat cerebellar purkinje cell size and distribution

Copper is required for activity of several key enzymes and for optimal mammalian development, especially within the central nervous system. Copper-deficient (CuD) animals are visibly ataxic, and previous studies in rats have demonstrated impaired motor function through behavioral experiments consistent with altered cerebellar development. Perinatal copper deficiency was produced in Holtzman rat dams by restricting dietary copper during the last two thirds of gestation and lactation. Male offspring were evaluated at postnatal day 25. Compared to cerebella from copper-adequate pups, the CuD pups had larger Purkinje cell (PC) size and irregularities in the Purkinje cell monolayer. These results suggest that the ataxic behavioral phenotype of CuD rats may result from disrupted inhibitory pathways in the cerebellum. A similar PC phenotype is seen in Menkes disease and in mottled mouse mutants with genetic copper deficiency, suggesting that copper deficiency and not just specific loss of ATP7A function is responsible.

A cell culture model for investigation of Hirano bodies

Hirano bodies are paracrystalline F-actin-rich aggregations associated with a variety of conditions including aging, and neurodegenerative diseases. The composition and structure of these inclusions have been described by immunohistochemistry and ultrastructure, respectively. However, studies of the physiological function and dynamics of Hirano bodies have been hindered due to lack of a facile in vitro experimental system. We have developed a model for formation of Hirano bodies in mammalian cell cultures by expression of the carboxy-terminal fragment (CT) of a 34-kDa actin-bundling protein. Expression of the CT protein induces F-actin rearrangement in HEK 293, HeLa, Cos7 cells, neuroblastoma and astrocytic cells, and in primary neurons. We have termed these structures model Hirano bodies, since their composition and ultrastructure is quite similar to that reported in vivo. Model Hirano bodies in cell cultures sometimes appeared to be formed of a number of smaller domains, suggesting that small aggregates are intermediates in the formation of Hirano bodies. Stable lines expressing CT and bearing model Hirano bodies exhibit normal growth, morphology, and motility. This model provides a valuable system for the study of the dynamics of Hirano bodies, and their role in disease processes.

Cytoskeletal abnormalities in long-term embryonic CNS transplants isolated within peripheral nerve

Cells from the fetal central nervous system (CNS) of rat embryos survive and differentiate when transplanted into the peripheral nervous system (PNS) of adult rats. The experiments described here were aimed at investigating selected molecular and ultrastructural features of dissociated CNS cells from the telencephalon of 12-day-old embryos isolated for long periods of time within PNS segments. Neurons and glia of grafts examined 6-12 months after transplantation into the PNS developed several cytoskeletal abnormalities. In neurons, these changes included Hirano bodies within dendrites and a marked perikaryal immunoreactivity to RT97, a monoclonal antibody that normally recognizes in neuronal processes the phosphorylated 200 kDa protein subunit of neurofilaments. Rosenthal fibres were seen within the glial cells. Similar-looking abnormalities have been described in certain human and animal neurodegenerative diseases and in ageing. Although a relationship between the changes in these long-term neural transplants and such diseases is unknown, these observations provide an opportunity for studying their pathogenesis within laboratory conditions.

Patterned Purkinje cell death in the cerebellum

The object of this review is to assemble much of the literature concerning Purkinje cell death in cerebellar pathology and to relate this to what is now known about the complex topography of the cerebellar cortex. A brief introduction to Purkinje cells, and their regionalization is provided, and then the data on Purkinje cell death in mouse models and, where appropriate, their human counterparts, have been arranged according to several broad categories--naturally-occurring and targeted mutations leading to Purkinje cell death, Purkinje cell death due to toxins, Purkinje cell death in ischemia, Purkinje cell death in infection and in inherited disorders, etc. The data reveal that cerebellar Purkinje cell death is much more topographically complex than is usually appreciated.

Formation of Hirano bodies induced by expression of an actin cross-linking protein with a gain-of-function mutation

Hirano bodies are paracrystalline actin filament-containing structures reported to be associated with a variety of neurodegenerative diseases. However, the biological function of Hirano bodies remains poorly understood, since nearly all prior studies of these structures were done with postmortem samples of tissue. In the present study, we generated a full-length form of a Dictyostelium 34-kDa actin cross-linking protein with point mutations in the first putative EF hand, termed 34-kDa DeltaEF1. The 34-kDa DeltaEF1 protein binds calcium normally but has activated actin binding that is unregulated by calcium. The expression of the 34-kDa DeltaEF1 protein in Dictyostelium induces the formation of Hirano bodies, as assessed by both fluorescence microscopy and transmission electron microscopy. Dictyostelium cells bearing Hirano bodies grow normally, indicating that Hirano bodies are not associated with cell death and are not deleterious to cell growth. Moreover, the expression of the 34-kDa DeltaEF1 protein rescues the phenotypes of cells lacking the 34-kDa protein and cells lacking both the 34-kDa protein and alpha-actinin. Finally, the expression of the 34-kDa DeltaEF1 protein also initiates the formation of Hirano bodies in cultured mouse fibroblasts. These results show that the failure to regulate the activity and/or affinity of an actin cross-linking protein can provide a signal for the formation of Hirano bodies. More generally, the formation of Hirano bodies is a cellular response to or a consequence of aberrant function of the actin cytoskeleton.

Formation of Hirano bodies in Dictyostelium and mammalian cells induced by expression of a modified form of an actin-crosslinking protein

We report the serendipitous development of the first cultured cell models of Hirano bodies. Myc-epitope-tagged forms of the 34 kDa actin bundling protein (amino acids 1-295) and the CT fragment (amino acids 124-295) of the 34 kDa protein that exhibits activated actin binding and calcium-insensitive actin filament crosslinking activity were expressed in Dictyosteliumand mammalian cells to assess the behavior of these modified forms in vivo. Dictyostelium cells expressing the CT-myc fragment: (1) form ellipsoidal regions that contain ordered assemblies of F-actin, CT-myc, myosin II, cofilin and α-actinin; (2) grow and develop more slowly than wildtype, but produce normal morphogenetic structures; (3) perform pinocytosis and phagocytosis normally; and (4) produce a level of total actin equivalent to wildtype, but a higher level of F-actin. The paracrystalline inclusions bear a striking resemblance to Hirano bodies, which are associated with a number of pathological conditions. Furthermore, expression of the CT fragment in murine L cells results in F-actin rearrangements characterized by loss of stress fibers, accumulation of numerous punctate foci, and large perinuclear aggregates, the Hirano bodies. Thus, failure to regulate the activity and/or affinity of an actin crosslinking protein can provide a signal for formation of Hirano bodies. More generally, formation of Hirano bodies is a cellular response to or a consequence of aberrant function of the actin cytoskeleton. The results reveal that formation of Hirano bodies is not necessarily related to cell death. These cultured cell models should facilitate studies of the biochemistry, genetics and physiological effects of Hirano bodies.

Age-related appearance of dystrophic axon terminals in cerebellar and vestibular nuclei of Mongolian gerbils

In the brains of 360-day-old Mongolian gerbils, numerous swellings immunoreactive to anti-neurofilament antibody were observed in cerebellar and vestibular nuclei. The number of these swellings was the same in two gerbil strains with different susceptibility to spontaneous motor seizures by various stimuli, but much more numerous in gerbils as compared with the 360-day-old Slc:Wistar rats. Such swellings were only occasionally found before 60 days of age in gerbils, but they increased in number about fivefold from 60 to 180 days of age and about quadruple from 180 to 360 days of age. Electron microscopic observation showed that these swellings were dystrophic axon terminals (DATs) whose cytoplasms were occupied with large bundles of neurofilaments, numerous vesicular structures containing membranous and/or granular materials, and many rod-shaped mitochondria. Additionally, other types of DATs displaying degenerative changes of cytoplasmic organelles were observed. ACPase cytochemistry showed that the vesicular structures in the DATs contained ACPase and released it into the cytoplasm.

Electron microscopic study of retinas of macular mice

BACKGROUND

Menkes' disease may be due to a lack or deficiency of copper in various organs. The macular mouse is known as a model for Menkes' disease. We examined melanin granules in the retinal pigment epithelium and the activity of cytochrome oxidase, a copper-containing enzyme, in the retinas of macular mice by electron microscopy.

METHODS

In the retinas of hemizygote macular mice we demonstrated cytochemically (oxidative polymerization of diaminobenzidine to an osmophilic reaction product) the activity of cytochrome oxidase. The distribution of melanin granules in the retinal pigment epithelium related to the activity of another copper-containing enzyme, tyrosinase was also studied. Stereological methods were applied to obtain quantitative data.

RESULTS

In the retinal photoreceptor inner segments of the macular mouse, the mitochondria were more numerous than in normal litermates and they appeared swollen. There were fewer melanin granules in the retinal pigment epithelium of macular mice than in that of normal littermates. The cytochrome oxidase activity was significantly lower in the macular mice than in the controls.

CONCLUSION

Macular mice have lower activity of cytochrome oxidase and fewer melanin granules than do normal mice. Both changes may be related to copper deficiency. These results correspond to the retinal changes seen in patients with Menkes' disease.

Hirano bodies and related neuronal inclusions

Hirano bodies are bright eosinophilic intracytoplasmic inclusions which have a highly characteristic crystalloid fine structure. They occur preferentially in the neuronal processes of the CA1 area in Ammon's horn in a wide variety of conditions, especially amyotrophic lateral sclerosis and parkinsonism-dementia complex on Guam, Alzheimer's disease, Pick's disease and 'normal' elderly individuals. Hirano bodies contain epitopes of actin, actin-associated proteins, tau, middle molecular weight neurofilaments subunit and a C-terminal fragment of beta-amyloid precursor protein. In addition to the CA1 area of Ammon's horn, they have also been identified in many other areas of the nervous system in humans and various experimental animals. Although usually observed in neurons, Hirano bodies may also be present in other cell types. It is the consensus that Hirano bodies in the pyramidal layer of CA1 originate largely from an age-related alteration of the microfilamentous system.

Biochemical study on the critical period for treatment of the mottled brindled mouse

Hemizygous mottled brindled mice (Mobr/y mice) were treated by subcutaneous injection of copper and were decapitated on postnatal day 14. Cytochrome c oxidase (COX) activity of the brain mitochondria in the mice given 10 micrograms of copper/g on day 4 or 7 showed significant increases compared with that of untreated Mobr/y animals, and these mice had no neurological symptoms. Mice given 10 micrograms of copper/g on day 12 showed neither increases in COX activity nor clinical improvement. The brain levels of copper, noradrenaline, and dopamine in the mice treated on day 12 were the same as those in animals treated on day 4 or 7. The in vitro activities of dopamine-beta-hydroxylase of the brain were also the same among the treated mice, irrespective of the date of treatment. The results indicate that delays in copper treatment produce irreversible changes in COX activity of the brain and lead to clinical unresponsiveness to treatment.

Chronological observations of histological changes, cytochrome oxidase activity and copper level in the brain of the postnatal brindled mouse

Neuropathological and enzyme-histochemical studies were performed on brindled mouse hemizygotes (BMs) and normal littermates at the age of 2 days, 7 days, 11 days and 14 days, together with an investigation of their tissue copper levels. A greatly increased copper concentration was confirmed in the kidney and intestine and a greatly reduced concentration in the liver and brain of BMs. The copper concentration in the brain increased gradually with age in the normal littermates, whereas this did not occur in BMs. There was no significant difference in the tissue copper concentration between the cerebrum and the cerebellum-brainstem in BMs or in normal littermates. Light and electron microscopy of the BM brain revealed progressive neuronal degeneration in association with increased mitochondrial changes (ballooning and crista disintegration). Enzyme histochemical examinations demonstrated a progressive comparative decrease (i.e., an increased difference from normal) of cytochrome oxidase activity in the BM brain. These data suggest that progressive degeneration of the brain in Menkes' disease is attributable to mitochondrial degeneration caused by a comparative decrease of both copper concentration and cytochrome oxidase activity in the brain.

Abnormal movements in brindled mutant mouse heterozygotes: as related to the development of their offspring--biochemical and morphological studies

As a possible preventive measure for brain dysfunction in Menkes disease, prenatal treatment by maternal administration of zinc, vitamin E and copper was examined in brindled mutant mice. During pregnancy and lactation, female heterozygous mice received 20 ppm zinc or 0.004% alpha-tocopherol acetate (vitamin E) throughout and 6 ppm copper from gestational day 13 in the drinking fluid, ad libitum. The maternal administration of zinc and vitamin E, as antioxidants, or copper resulted in decreased fetal and neonatal death of offspring, especially those of hemizygous males, as compared with the administration of water only. When offspring did not grow, maternal abnormal movements, which comprised rotatory movements of high speed with tremor and ataxia, were frequently observed. In the heterozygotes with abnormal movements, the level of lipid peroxidation in cerebrum and the concentration of copper in kidney were much higher than those in the heterozygotes with normal movement. Morphologically, in cerebellum of the heterozygotes with abnormal movements, the loss of Purkinje cells, abundance of lipofuscin granules and abnormal mitochondria or degenerative bodies of high electron density were frequently observed, as compared with heterozygotes with normal movement. These findings suggest that the development of hemizygous male mice may be influenced by both copper and oxygen radical metabolism.

Decreased activity of cytochrome c oxidase in the macular mottled mouse: an immuno-electron microscopic study

The macular mottled mouse is a murine model of the kinky hair syndrome, characterized by a deficiency in copper transport. Cytochrome c oxidase (CCO), a respiratory enzyme, is located in the inner mitochondrial membrane and consists of seven subunits, along with copper and iron. Biochemical and histochemical findings indicated that CCO activity was decreased in the cerebellum of the macular mottled mice but not in that of the controls. Immunocytochemical analysis, using anti-CCO and anti-complex III rabbit sera, revealed that CCO in the macular mottled mice was stained more weakly than that in the controls. Immuno-electron microscopic examination of CCO and complex III, using a method of gold labeling, was also performed. In the control mice, a high concentration of gold particles present over CCO and complex III could be seen in the inner mitochondrial membrane. The number of CCO-labeled gold particles was remarkably less, however, in the macular mottled mice, while no significant difference was found in the labeling of complex III between the two groups. It may be concluded that the very low CCO enzyme content in the macular mottled mouse results not only from a copper transport disorder but also from a CCO protein synthesis disorder which impairs the localization of CCO protein in the cerebellum.

Rapid increases in glial fibrillary acidic protein mRNA and protein levels in the copper-deficient, brindled mouse

The brindled mouse (MObr/y) carries an X-linked mutation that produces severe copper deficiency. Affected males suffer profound deficits in oxidative metabolism. We have examined astrocyte pathology in MObr/y during development and have found marked changes in the metabolism of glial fibrillary acidic protein (GFAP). Immunocytochemistry with anti-GFAP antisera revealed a marked increase in staining at postnatal day 12 (P12), compared to heterozygous female and unaffected male littermates, particularly in neocortex and thalamus. Septum, hypothalamus, and striatum showed little change. Western blot analysis revealed increased levels of GFAP in MObr/y forebrain and cerebellum. Levels of GFAP mRNA were determined by Northern blotting with a mouse GFAP cDNA probe. At P10, mRNA levels were normal, but increased to 8-10 times normal by P12. Levels at P15 remained similarly elevated. Thus, immunostaining and protein determinations correlate with mRNA elevations. Astrocytes can alter GFAP mRNA and protein levels over a relatively short time. Counts of neocortical cells did not reveal differences in cell numbers between MObr/y and controls, indicating that the observed changes reflect increased cellular levels and not a large increase in the numbers of astrocytes.

X-linked genetic homologies between mouse and man

X-linked genes are conserved among all mammalian species, but the organization of genes on the X chromosome varies from one species to another. This review summarizes the evidence for established gene homologies between mice and human beings. It also describes genes that are possible homologies because of their locations in the human and murine X chromosomes and similarities in the phenotypes they produce. Based on current knowledge of homologous gene location, the human and murine X chromosomes appear to contain four highly conserved segments and differ in organization by only three to four simple chromosomal rearrangements.

Hirano bodies and other cytoskeletal abnormalities develop in fetal rat CNS grafts isolated for long periods in peripheral nerve

Dissociated cells from the telencephalic region of 12-day-old rat embryos were cultured in vitro for 3-5 days and transplanted into segments of the sciatic nerve of adult inbred rats. Transplanted progenitor cells survived, differentiated, and expressed various morphological and molecular features characteristic of neurons and glia. Six to twelve months after grafting, many neurons underwent changes compatible with an alteration of their cytoskeleton. These included: (1) a strong perikaryal immunoreactivity to the monoclonal antibody RT97, directed against the 200-kDa phosphorylated neurofilament subunit and (2) the formation of Hirano bodies within dendrites. Similar cytoskeletal abnormalities are seen as part of the spectrum of changes that occur in some human neurodegenerative diseases and in aging. The approach we have used may provide new possibilities for the study of the pathogenesis of these lesions under controlled laboratory conditions.

Clinico-pathological study on macular mutant mouse

The macular mutant mouse was clinically and pathologically examined. The hemizygotes began to show white fur color and curly whiskers around postnatal day 3, then seizures and ataxia around day 8, while the normal littermates did not. The hemizygotes also increased weight gradually from birth to day 9, but then showed weight loss and died around day 15 with severe emaciation. These clinical features resembled those in Menkes kinky hair disease. There were no pathological changes in the cerebral cortex in the hemizygotes on day 7. On day 10, two to three clear vacuoles began to appear in a few neurons in the cerebrum. These neurons with vacuoles increased gradually in number and degenerative neurons were also observed by day 14. Ultrastructurally, they corresponded to giant abnormal mitochondria with an electron-lucent matrix and short peripherally located cristae. Other abnormal mitochondria, which were characterized by an electron-dense matrix with tubular or vesicular cristae, were also observed in the cerebral cortical neurons.

Light and electron microscopic study on cerebellar cortex of macular mutant mouse as a model of Menkes kinky hair disease

The macular mouse is a mutant mouse, the hemizygotes of which show clinical and biochemical abnormalities similar to those in Menkes kinky hair disease (MKHD) in humans. The cerebellar cortex of this mutant suckling mouse was examined by light and electron microscopy. In hemizygotes, the Purkinje cells showed a delay in the maturation of dendrites and somatic spines. Somal sprouts, abnormal mitochondria, and filamentous cytoplasmic inclusions were observed on these cells on day 13. Axonal swellings, containing abnormal mitochondrias were also seen in the inner granular layer. These findings correspond with those of MKHD in humans and those of the brindled mouse, another model mouse of MKHD.

In vitro acetylcholine synthesis and oxidative metabolism during development of normal and brindled mouse brain

During early development normal and brindled mouse brain use 3-hydroxy-butyrate preferentially to glucose as a source for biosynthetic carbon units. On postnatal days 5-60, CO2 and acetylcholine production from 3-hydroxybutyrate decrease while that from glucose increases. Glucose metabolism exceeds that of 3-hydroxybutyrate after weaning (day 21). These findings indicate that the immature brain uses 3-hydroxybutyrate to support effectively oxidative metabolism and acetylcholine synthesis. Deficits in oxidative and acetylcholine metabolism occur in the developing brindled mouse, a genetic mutant with a defect in copper homeostasis. In the brindled mouse forebrain and cerebellum, the incorporation of either substrate into CO2 and acetylcholine was decreased 15%, 50% and 80% at days 5, 10 and 15 postnatal, respectively, when compared to the normal littermates. The brindled mouse demonstrates deficits in both oxidative metabolism and acetylcholine synthesis before the appearance of neuropathology.

Abnormalities of dendritic actin organization in the brindled mouse

The brindled mouse is an X-linked mutant with alterations in copper homeostasis. Ultrastructural analysis of the cerebellum and neocortex reveals several dendritic abnormalities, including the formation of Hirano bodies and other cytoskeletal alterations. Immunocytochemical evidence demonstrates that actin is a component of these microfilament lattices.

Cytoskeletal protein abnormalities in neurodegenerative diseases

The nervous system is a rich source of filamentous proteins that assume critical roles in determining and maintaining neuronal form and function. Neurons contain three major classes of these cytoskeletal organelles: microtubules, intermediate filaments, and microfilaments. They also contain a variety of proteins that organize them and serve to connect them with each other. Such major neurodegenerative diseases as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as a variety of toxic neuropathies, are characterized pathologically by intraneuronal filamentous inclusions. Recent studies using biochemical and immunocytochemical techniques have established that these abnormalities represent disorganized states of the neuronal cytoskeleton and have determined some of the specific molecular constituents of these inclusions. This knowledge has led to new ways of thinking about their origins.

Hirano body in an inflammatory cell of leptomeningeal vessel infected by fungus Paecilomyces

An intracytoplasmic microfilamentous lattice, ultrastructurally identical to Hirano body, was found in an inflammatory cell within a leptomeningeal vessel wall infected by fungus Paecilomyces javanicus. The structure was well preserved and not associated with phagosomes. This is the first report of Hirano body found in an inflammatory cell at the site of fungal infection. The present finding suggests that the formation of Hirano body is non-specific and not restricted to the cell of the neuro-muscular system.

Cerebellar changes of the female mice heterozygous for brindled gene

The brindled mutation is an X-linked neurological mutation in mice. Male mice hemizygous for the brindled gene have metabolic defects homologous with kinky hair disease in humans. Neuropathologically, the mutation is characterized by extensive neuronal degeneration associated with pronounced mitochondrial changes in cerebral cortex and abnormal arborization of Purkinje cell dendrites, which are most pronounced in the rostral vermis or anterior lobules. In the cerebellum of female mice heterozygous for brindled gene, Purkinje cells with abnormal dendritic arborization and with unusually enlarged mitochondria were also observed. Morphological changes in affected Purkinje cells in young heterozygotes were similar to those of young hemizygotes. However, in older heterozygotes, the changes were far less conspicuous, indicating the presence of some extrinsic factor(s) to compensate expression of the mutant gene in heterozygous brains.

Degeneration of thalamic neurons in "Purkinje cell degeneration" mutant mice. I. Distribution of neuron loss

The Purkinje cell degeneration (pcd) mutation of the mouse is an autosomal recessive allele which previous studies have shown to be the cause of rapid degeneration of nearly all cerebellar Purkinje cells between 18 and 30 postnatal days of age (P18-P30), and slowly developing, progressive losses of retinal photoreceptor cells and mitral cells of the olfactory bulb. Through examination of serial frozen sections alternately stained for Nissl substance and for degenerating neuronal processes, we have found that discrete populations of thalamic neurons degenerate rapidly between P50 and P60. Severely affected nuclei, in which a majority of neurons degenerate, include the central division of the mediodorsal nucleus, the ventral medial geniculate, posterior, posterior ventromedial, and submedial nuclei, and those portions of the ventrolateral and posteromedial nuclei which immediately surround the medial division of the ventrobasal complex. More subtle cell losses occur during the same time period in restricted portions of the lateral ventrobasal, dorsal lateral geniculate, and lateral posterior nuclei, but even at P180 these nuclei are not markedly atrophic. No common denominator among target cell populations has been established. The pcd allele affects a diverse assortment of specific relay nuclei; degeneration has not been recognized in thalamic nuclei characterized primarily or exclusively by subcortical projections or by cortical projections directed relatively selectively to superficial or deep cortical laminae. The neuronal degenerations in the thalamus are not precipitated by prior or concurrent degeneration of cortical targets or afferent sources, though striking transneuronal changes, including cell death, do develop following thalamic neuronal degeneration in this mutant. No previously described murine mutant phenotype includes the rapid degeneration of highly restricted neuronal populations beginning at these relatively advanced ages.

Neuropathologic study in the heterozygotes of X-linked brindled mutant mouse

The clinical and morphological features were studied in female heterozygotes of the sex-linked brindled mutant mice, which are an appropriate animal model for human Menkes' kinky hair disease (MKHD). Clinically, female heterozygotes presented phenotypical variety. In these heterozygotes, we distinguished the unique group of mice, which showed mottled white and dark brown fur and curly whiskers. We designated this unique group "heterozygote, variant type", in contrast to the remaining group--"heterozygote, usual type"--, of which the fur was mottled dark and light brown, and the whiskers were straight. Ultrastructurally, various degrees of mitochondrial changes, from an almost normal appearance of the mitochondria to similar to those of the hemizygotes, were observed. Furthermore we noticed that, in the heterozygotes, there were positive correlations between this morphological spectrum and those phenotypical varieties. These findings were interpreted as a possible subclinical copper deficiency in the heterozygotes, and the morphological alterations in heterozygotes were probably due to X-chromosome inactivation according to Lyon's hypothesis. The presence, however, of clinical and morphological varieties in the heterozygotes leads us to the hypothesis that the inactivation rate is not necessarily the same for all carriers. Moreover, it can be speculated that pathologic changes similar to those in heterozygotes may be present in the female carriers of human MKHD.

Hirano bodies in the perikaryon of the Purkinje cell in a case of Alzheimer's disease

Cylindrical forms of Hirano bodies were observed in the perikaryon of a Purkinje cell in a case of Alzheimer's disease. Scattered, typical senile plaques were also seen in the cerebellar cortex.

Alterations in the postnatal development of the cerebellar cortex due to zinc deficiency. II. Impaired maturation of Purkinje cells

Zinc deficiency during the first 3 postnatal weeks retarded the maturation of Purkinje cells. The dendrites of the Purkinje cells of 21-day-old zinc-deficient (ZD) rats were reduced in size and had fewer branches. Somatic processes were found in 24% of the Purkinje cells of ZD animals. Only 3% of the Purkinje cells of normal animals had somatic processes. A basal polysomal mass in the Purkinje cells of 21-day-old ZD rats indicated that zinc deficiency impaired the cytoplasmic maturation of Purkinje cells. The development of the glial envestment of the dendrites and the maturation of climbing fibers also were retarded. Pair-fed controls were studied to control for the effects of inanition in the ZD dams. In the pups of pair-fed dams, undernutrition slightly impaired the growth of the dendrites but produced few qualitative changes in the maturation of the soma and climbing fibers. Somatic processes were found on 10% of the Purkinje cells of pair-fed animals. Thus, the findings in the ZD animals were not only caused by the decreased maternal food consumption but by zinc deficiency. The retarded maturation of Purkinje cells was related to the altered metabolism of Purkinje cells and to effects secondary to decreased numbers of parallel fibers.

Menkes' disease and swayback. A comparative study of two copper deficiency syndromes

The neuropathological findings in two siblings with Menkes' disease were compared with representative material obtained from lambs suffering from swayback (enzootic ataxia). The aim of the study was to demonstrate the similarity of lesions in a genetic and a nutritional form of copper deficiency in support of the view that all lesions in Menkes' disease could be ascribed to simple hypocupraemia. All lesions of Menkes' disease were shown to have their counterpart in swayback, with exception of the abnormal arborisations of the Purkinje cell dendrites. These have often been interpreted as malformations and cited in evidence of the prenatal origin of the cerebral lesions. They are, however, non-specific and similar lesions have been reported in conditions arising in later life. While there is abundant collateral evidence of disturbed copper metabolism in utero, the problem of the prenatal versus postnatal origin of cerebral damage remains unresolved.

Mitochondrial abnormalities in Menkes' kinky hair disease (MKHD). Electron-microscopic study of the brain from an autopsy case

The brain of an autopsy case of Menkes' kinky hair disease (MKHD), after routine histological examination, was studied extensively by electron microscopy, particularly the mitochondrial alteration. There were widespread mitochondrial abnormalities, including enlargement with tubulo-vesiculated cristae, swelling, and dense body formation and occasional accumulation of glycogen within mitochondria, in addition to increased numbers of mitochondria in some neurons. These abnormalities of mitochondria were present in decreasing severity in the following: Purkinje cells, neurons of the molecular and granule cell layers of the cerebellum, and neurons of the cerebral cortex, globus pallidus, lateral nuclei of the thalamus, caudate nucleus, and the myelinated axons in the white matter. This distribution and the degree of mitochondrial abnormalities in the various structures of the brain were compared with those of degenerative lesions in the respective structures. The comparison disclosed that there was a positive correlation between the two. The mitochondrial enlargement and swelling as in the present study had been well documented in the brain of the brindled mouse; mitochondrial dense bodies had also been reported in previous case reports of MKHD by other authors. The present study strongly suggests that the mitochondrial disease is an essential abnormality and may be responsible for the progressive degeneration of the CNS in MKHD.

The effect of copper supplementation on the concentration of copper in the brain of the brindled mouse

The brindled mutant mouse is a useful model to study Menkes kinky-hair syndrome. The metabolic dysfunctions in both human and rodent are related to insufficient levels of bioavailable copper. Recently, copper supplementation therapy has been able both to prevent the appearance of various neuropathological changes and to prolong the life of these mutant mice. The optimum conditions for supplementation have been shown to be two intraperitoneal injections on postnatal days 7 and 10. The present study reports on the brain copper concentrations before, during and after the intraperitoneal copper therapy. The results demonstrate that postnatal days 7 and 10 correspond to two important epochs in copper homoeostasis. The supplementation therapy seems to provide sufficient bioavailable copper to respond to the needs of the animal at these crucial time points. The results are discussed in terms of their importance to the human copper disorder.

'Dystrophic' Purkinje cell dendrites in an infant

A 6 1/2 month old male infant presented a week after his birth with secretory diarrhea of unknown etiology. He was sustained by central hyperalimentation for the rest of his life, and treated for presumed sepsis with a wide variety of antibiotics. The brain showed vacuolation in the diencephalic nuclei and white matter of the brain stem. There were also many clusters of enlarged Purkinje cell dendrites in the molecular layer. In Golgi preparations the primary and secondary dendrites showed segmental swellings and absent tertiary branchlets. The swellings were due to remarkable accumulations of mitochondria. The pathogenesis of the dendritic changes is discussed, and 'dying back' phenomenon is proposed to explain the changes.

High molecular weight microtubule-associated proteins bind to actin lattices (Hirano bodies)

Hirano bodies are filamentous, paracrystalline inclusions that are found in dendrites and cell bodies of neurons in Alzheimer's and other neurodegenerative diseases. Actin appears to be a major component of these structures. We present evidence that tropomyosin and high molecular weight microtubule-associated proteins (MAPs) are also components of Hirano bodies. Although an association between actin and MAPs has been noted in vitro, interactions in vivo have not heretofore been demonstrated. Since microtubules are not present in Hirano bodies, and anti-tubulin and anti-neurofilament antibodies do not bind to Hirano bodies, the association between MAPs and these inclusions is likely a result of interactions between MAPs and actin, and not MAPs and microtubules or neurofilaments.