John Alexander Bartlett, MD

• Professor of Medicine
• Director of the AIDS Research and Treatment Center
• Research Professor of Global Health
• Professor in the School of Nursing
• Affiliate of the Duke Initiative for Science & Society
• Member of the Duke Cancer Institute

https://medicine.duke.edu/faculty/john-alexander-bartlett-md

Incidence rates are relatively constant throughout the world symptoms dust mites generic lincocin 500 mg without a prescription, with an average of about 2 per 100 000 and a prevalence of about 16 20 24 28 (b) 4 32 8 36 12 40 16 44 20 48 24 28 32 36 40 44 48 14 medicine of the wolf lincocin 500 mg buy mastercard. Decreases in flumazenil binding involve both motor and extramotor areas 4 medications at walmart order 500 mg lincocin otc, particularly the prefrontal cortex medicine youth lyrics buy lincocin 500 mg with amex. As expected symptoms during pregnancy order generic lincocin on-line, the decrease in binding appears more widespread at a lower level of statistical significance (b). Pathogenic mutations in these multiple genes arise at low frequency in apparently sporadic cases. The influence of environmental factors remains relevant in sporadic disease but is poorly characterized. The mutations cause disease through a toxic gain-of-function mechanism often associated with evidence of abnormal protein folding and altered dimer interactions. The autosomal recessive D90A mutation, most commonly encountered in Scandinavia,11 is typically associated with a slowly progressive ascending spastic paraparesis with later lower motor neuron and bulbar involvement. Virtually all these models rely on significant genetic overexpression and their relevance to mechanisms in human disease is disputed. An intermediate range from 4 to 27 repeats is encountered and is of less certain pathogenetic significance. Excitotoxic neuronal damage involves the excessive action of excitatory amino acids or excitotoxins on receptors expressed by susceptible neurons. Glutamate has been shown to increase neurofilament phosphorylation and slow axonal transport. Experimental studies suggest that the balance between neurofilament subunits and peripherin is important in motor neuron survival, and factors such as excitotoxicity and inflammatory responses also influence cytoskeletal function and may contribute to cell death. A change in a trophic factor expression or availability might render motor neurons more susceptible to programmed cell death and apoptosis. However, modern clinical management of significant bulbar weakness includes percutaneous endoscopic gastrostomy nutrition. Such patients are likely to have a normal body weight or weight reduction commensurate with loss of muscle bulk through atrophy. Tracheostomy to protect the airway in cases with severe bulbar dysfunction has been replaced by non-invasive ventilation. The previous frequent association with changes of bronchopneumonia (often aspiration pneumonia) is less commonly encountered in the era of more intensive nutritional and respiratory care. Symmetrical involvement of the intrinsic hand muscles is a useful indication of this at autopsy. Post-mortem blood samples may be used to look for the presence of autoantibodies in appropriate cases. Pathological Changes in the Brain and Spinal Cord Macroscopically, the brain is generally unremarkable. In some cases, visible atrophy of the precentral gyrus is seen, best detected by removing the leptomeninges after fixation. There may be some atrophy of the medullary pyramids most obvious in horizontal slices through the medulla rather than externally. Marked reduction in the number of large myelinated fibres is seen in ventral nerve roots, whereas peripheral nerves show axonal degeneration and (a) (b) 14. Motor Neuron Disease (Amyotrophic Lateral Sclerosis) 825 reduced numbers of large myelinated fibres. A variety of inclusion bodies may be seen on haematoxylin and eosin (H&E) staining in surviving motor neurons and are discussed later. Despite ultrastructural characterization showing that they are likely to be of lysosomal derivation,254 their origin and significance remain uncertain. Such neuronal swelling appears to be non-specific and do not represent true central chromatolysis. Similar appearances are seen in (b) in relation to skein-like inclusion body material. Motor Neuron Disease (Amyotrophic Lateral Sclerosis) 829 neuronal cytoplasmic inclusions have been observed in these nuclei, indicating subclinical involvement. Neuronal cytoplasmic inclusions may be seen but are infrequent compared with the spinal cord. Myelin loss from corticospinal tracts, using conventional myelin staining, may be subtle in patients with early or mild upper motor neuron disease and it is possible that an axonopathy is the predominant feature of corticospinal tract degeneration in some patients. Thus, myelin loss is most evident in lower cord segments, supporting the hypothesis of a dying back degeneration of axons. These irregular masses of neurofilaments occupy much of the soma of lower motor neurons, but they are also present in many non-motor neurons across the brain and spinal cord. They are immunoreactive against both phosphorylated (a) and non-phosphorylated (b) neurofilament epitopes. Note the absence of generalized somatic staining for the non-phosphorylated epitope, suggesting sequestration of neurofilaments within the lesion. Loss of myelin from the spinocerebellar tracts and posterior columns may also be seen in up to 50 per cent of sporadic cases and in familial cases. However, there is undoubtedly a preponderance of pathology in the motor system associated with the prominent early clinical manifestations of motor system disease. Ubiquitylated cytoplasmic inclusions are usually absent or very few in number in most but not all cases. This is the most sensitive method of demonstrating white matter degeneration in amyotrophic lateral sclerosis and other neurodegenerative disorders associated with relatively rapid clinical progression. It is particularly evident in long-term survivors with assisted ventilation, and anti-p62 immunostaining is recommended to detect inclusions. There may also be degeneration of non-motor tracts in the spinal cord and loss of myelinated fibres with segmental demyelination in the sensory nerves correlating with electrophysiological abnormalities. In some patients, this change may be seen in the absence of clinical motor neuron disease, presenting as a primary dementia of frontal type. The morphology and immunocytochemistry of lower motor neuron pathology in motor system disorders are summarised in Table 14. There may be an associated mild sensory neuronopathy, indicating that the nervous system pathology is not confined entirely to the motor system. In addition, features such as gynaecomastia reflect androgen insensitivity whereas abnormalities of serum biochemistry suggest that there is also visceral pathology (Table 14. Inflammation, in the form of perivascular, parenchymal and meningeal lymphocytic infiltrates of mainly T-cell type, persists for many years after the acute infection. The size of the repeat expansion correlates with disease severity and inversely with age of onset of the disease but, in contrast to some other trinucleotide repeat disorders, the expansions appear to be relatively stable so that kindreds do not show anticipation as a feature. The inclusions sequester transcription factors and chaperone proteins, which may result in transcriptional dysregulation. A point mutation in dynactin has itself been associated with a form of (non-X-linked) spinal and bulbar muscular atrophy with laryngeal involvement. Loss of small neurons from the intermediate zone of spinal cord grey matter has also been demonstrated by quantitative studies. Proteins are also ubiquitinated, so they may be demonstrated by ubiquitin immunohistochemistry. They may also be detected by immunohistochemistry with antibodies that recognize the expanded polyglutamine tract. This latter method appears to be the more sensitive and is of diagnostic use in autopsy material. Whilst intercostal muscles are affected, there is relative early sparing of diaphragmatic function. Despite the name, there may also be involvement of bulbar neurons and, in certain rare forms (see later), this is the predominant feature. Atrophic, shrunken neurons may be seen and occasional neurons may show neuronophagia. Ubiquitin immunostaining reveals an abnormal pattern of diffuse reactivity, distinct from the inclusions seen in motor neuron disease. These are mostly seen in the anterior horn white matter, in the ventral outflow region. Morphological and immunohistochemical features suggest that they are undifferentiated and their numbers decline exponentially with the age of the subject at death. Infant aged 3 months: (a) cervical, (b) thoracic (note preserved cells in dorsal nuclei) and (c) sacral (note relative atrophy of anterior roots) spinal cord. A more recent, genetically confirmed, case demonstrated peripheral perikaryal staining for neurofilament but no ubiquitinated inclusions in anterior horn motor neurons. Families with variability in age at onset are described and cases have been described with onset in infancy. Motor neuron loss and anterior horn gliosis with depletion of axons from motor roots have been observed in the spinal cord. There appears to be genetic heterogeneity, with autosomal recessive forms with two patterns and a very rare autosomal dominant form. Neuropathological studies demonstrate severe cell loss from the hypoglossal, motor vagal and facial nuclei with occasional chromatolytic neurons. Anterior horn cell loss from the spinal cord, trigeminal motor and oculomotor nuclei is less marked. Neuronal loss has also been seen in the thalamus, striatum, dentate nucleus and cerebellar cortex. Progressive bulbar paralysis with a phenotype similar to Fazio­Londe disease has also be described in association with a mitochondrial respiratory chain defect,239 as has a clinical phenocopy of primary muscular atrophy. A number of candidate cellular mechanisms are emerging for the corticospinal tract degeneration from the study of the function of these genes. These include defects in membrane trafficking and axonal transport, mitochondrial dysfunction and developmental abnormalities. The comparatively long length of corticospinal tract axons may render them particularly susceptible to mechanisms impairing axonal physiology. It is involved in membrane fusion and has a role in the structure and maintenance of the endoplasmic reticulum. These and other gene mutations implicate impairment of axonal transport, membrane dynamics and maintenance of organelle form as common mechanisms leading to corticospinal tract degeneration. This disorder is allelic with a form of distal hereditary motor neuropathy so that the term seipinopathies has been coined for this group of disorders. The spinocerebellar tracts and dorsal columns, particularly fasciculus gracilis at cervical levels, may also be involved. Quantitative studies have confirmed relative distal loss of axons, supporting this hypothesis. Loss of Betz cells from the motor cortex has been described in some, but not all, studies. Their significance is currently unclear, but altered staining patterns for cytoskeletal proteins and mitochondria in these cases provide evidence that the lower motor neuron may be involved in some cases. In paraplegin-mutation related cases, skeletal muscle has shown changes of mitochondrial pathology, with ragged red fibres, cytochrome oxidase negative (a) fibres, peripheral accumulation of mitochondria and elevated succinate dehydrogenase activity. A loss of cortical neurons and immunohistochemical evidence of a decrease in calbindin D28K+ cells and parvalbumin reactive dendrites have been described. Spastic paraparesis may be a component of a number of diseases, including B12 disorders, adrenomyeloneuropathy, metachromatic leukodystrophy, globoid leukodystrophy, Lesch­Nyhan syndrome or Sjögren­Larson syndrome. In certain other neurodegenerative diseases, dementia may be associated with, and be preceded by, spastic paraparesis. The posterior columns are more affected at the higher level and the pyramidal tracts at the lower one. We thank Dr Graham Lennox, Professor James Lowe and Professor Nigel Leigh for their contributions to this chapter in the 6th and 7th editions. Pathogenesis and molecular targeted therapy of spinal and bulbar muscular atrophy. Deletions of the heavy neurofilament subunit tail in amyotrophic lateral sclerosis. Autosomal recessive adult-onset amyotrophic lateral sclerosis associated with homozygosity for Asp90Ala CuZnsuperoxide dismutase mutation. How frequently does classic amyotrophic lateral sclerosis develop in survivors of poliomyelitis Mutant androgen receptor accumulation in spinal and bulbar muscular atrophy scrotal skin: a pathogenic marker. Molecular aspects of poliovirus biology with a special focus on the interactions with nerve cells. Superoxide dismutase 1 with mutations linked to familial amyotrophic lateral sclerosis possesses significant activity. Mitochondrial enzyme activity in amyotrophic lateral sclerosis: implications for the role of mitochondria in neuronal cell death. Effects of non-invasive ventilation on survival and quality of life in patients with amyotrophic lateral sclerosis: a randomized controlled trial. Superoxide dismutase activity, oxidative damage and mitochondrial energy metabolism in familial and sporadic amyotrophic lateral sclerosis. Age-related cognitive decline in hereditary spastic paraparesis linked to chromosome 2P. Rate of familial amyotrophic lateral sclerosis: a systematic review and meta-analysis. Transgenic mice for interleukin 3 develop motor neuron degeneration associated with 2. Aberrant glycosylation/ phosphorylation in chromatolytic motorneurons of Werdnig­Hoffman disease. Cytochrome c oxidase subunit I microdeletion in a patient with motor neuron disease. Peripherin and neurofilament protein coexist in spinal spheroids of motor neuron disease. Biomagnification of cyanobacterial neurotoxins and neurodegenerative disease among the Chamorro people of Guam. Epidemiology of mutations in superoxide dismutase in amyotrophic lateral sclerosis.

Later still medications mexico purchase 500mg lincocin visa, the reduced supply of single carbon groups to brain metabolism might result in myelin abnormalities medications causing pancreatitis discount generic lincocin uk. Clinical Features Most patients present with a severe neonatal-onset form medications affected by grapefruit generic 500mg lincocin amex, although milder cases present later in infancy or even in childhood medications post mi generic lincocin 500 mg line. In the neonatal-onset form medication 3 checks cheap lincocin 500mg without a prescription, most develop symptoms in the first 2 days of life, becoming profoundly hypotonic (with preserved or brisk tendon reflexes) and lethargic, with abnormalities of eye movement. The encephalopathy progresses to coma, with the development of segmental myoclonic jerks, hiccups and apnoea. In addition, there are areas of neuronal loss with abnormal vasculature and perivascular calcification, which may affect basal ganglia, cerebral cortex or thalamus. These changes correlate with those in the radiological literature (reviewed in Longo205). In one case, there was abnormal neuronal orientation with abnormalities of dendrites and dendritic spines349 and in another, prominent white matter neurons. Survivors regain respiration at around 3 weeks of age; intractable epilepsy develops after about 3 months and infants and children have profound impairment, with no adaptive or social behaviour. The normal physiological hyperglycinuria of the newborn renders urinary glycine difficult to interpret. Branched chain amino acids Odd-chain fatty acids 5 Methionine Propionyl-CoA Propionyl-CoA decarboxylase S-adenosylmethionine Methionine synthase S-adenosylhomocysteine B12 Methylmalonyl-CoA Methylmalonyl-CoA mutase Succinyl-CoA Pathology Abnormalities of myelination are the most frequently reported pathological feature. The cerebellar white matter, corticospinal and optic tracts were particularly affected. Ultrastructurally, the vacuoles were lined by myelin and appeared to form by intraperiod splitting. Methionine is converted to homocysteine in a series of reactions that donate a methyl group to an acceptor molecule. The homocysteine can then either be converted to cystathionine by cystathionine -synthase or be remethylated to regenerate methionine in a vitamin B12-dependent reaction. In cystathionine -synthase deficiency, plasma methionine is raised, whereas in the remethylation defects, it is reduced. Homocysteine can then be recycled to methionine in a vitamin B12-dependent reaction (catalyzed by methionine synthase) or converted to cysteine through a pathway that includes the enzyme cystathionine -synthase. Mutations in methionine synthase or a range of enzymes involved in vitamin B12 metabolism can also cause homocystinuria. On the right, the pathway shows that propionyl-CoA is generated from odd-chain fatty acids or branched chain amino acids. It is converted to methylmalonyl CoA by propionyl-CoA decarboxylase, mutations in which cause propionic acidaemia. Methylmalonic CoA mutase is vitamin B12-dependent and mutations affecting this enzyme or vitamin B12 metabolism can cause methylmalonic acidaemia. The skeletal abnormalities become more obvious around puberty, with arachnodactyly, dolichostenomelia and enlargement of both metaphyses and epiphyses. Thromboembolism in childhood is commonly precipitated by an intercurrent illness that causes dehydration. Approximately half of the patients with cystathionine -synthase deficiency respond to pharmacological doses of pyridoxine (the coenzyme for cystathionine -synthase) and subsequently do well. The other patients are more difficult to treat and often require dietary methionine restriction and an alternative methyl group donor, such as betaine; their outcome is less favourable. Patients diagnosed at birth and treated prospectively do not develop complications. The ocular, skeletal and vascular complications of cystathionine -synthase deficiency appear to be secondary to the accumulation of homocysteine. The pathogenesis of the neural complications is less clear, but involves metabolic mechanisms as well as cerebrovascular disease. In contrast to the remethylation defects (see later), cystathionine -synthase deficiency is not usually associated with white matter disease, although this has occasionally been described. Several of these cobalamin (cbl) disorders have been classified according to their complementation in cell culture. Each group has similar clinical features that vary according to age of onset (and, presumably, defect severity). Infants with inborn errors of cobalamin metabolism can also present with a micro-angiopathy with widespread organ involvement. In the early infantile-onset remethylation defects, the child often suffers an acute neurological deterioration, which may be fatal. In late infantile/early childhood-onset, there is usually a neurological presentation with slowing of brain growth and development, followed by progressive neurological disorder. During the progressive phase, the child dements, may develop an ataxic­spastic or extrapyramidal movement disorder and often has signs of a peripheral neuropathy. However, there may be asymptomatic siblings, stroke, unexplained psychosis and symptoms of subacute combined degeneration. A high index of suspicion and a raised plasma total homocysteine with a reduced (or low normal) plasma methionine concentration are the initial clues to a remethylation defect. Pathology Cystathionine -Synthase Deficiency In classic homocystinuria, the principal lesions are ischaemic: thromboembolic occlusive vascular disease in arteries, veins and dural sinuses leads to cerebral, cerebellar, thalamic and midbrain infarcts. Remethylation Defects Appearances suggestive of subacute combined degeneration have been reported in a patient with an inborn error of cobalamin metabolism,85 although the spinal cord was not examined. The disease was complicated by haemolytic uraemic syndrome, which undoubtedly influenced the neuropathological findings. There was diffuse white matter involvement with spongiosis and necrosis, and severe astrocytosis. Both patients showed perivascular demyelination of the cerebrum and one had features of subacute combined degeneration of the spinal cord. Propionic acid is produced from metabolism of branched chain amino acids (valine, methionine, isoleucine, threonine) and from odd chain fatty acids. Investigation reveals neutropenia and thrombocytopenia with acidosis, ketosis, hyperammonaemia, mild or moderate hyperglycinaemia, reduced free carnitine and raised propionylcarnitine, and the excretion of propionylglycine and methylcitrate in the urine (especially during an acute episode). An isolated functional defect in methylmalonyl-CoA mutase can be caused by inborn errors of cobalamin metabolism affecting its coenzyme adenosylcobalamin. Clinical Features As might be anticipated by the biochemistry, the clinical presentation of methylmalonic acidaemia is very similar to that of propionic acidaemia, with the exception that large amounts of methylmalonic acid are excreted in the urine. The neurological outcome is determined by the age at onset and cobalamin responsiveness. Long-term treatment depends on dietary modifications with some patients coming to liver transplantation. Sarnat and Flores-Sarnat308 have described a case showing immature cortical organization with prominent microcolumns. Pathology Neuropathological observations from fatalities in early infancy include widespread white matter sponginess with loss of oligodendroglia, astrocytosis and reduced myelination,76 but usually no evidence of myelin destruction. Lipid patterns in the white matter at this early stage are normal,216 but in untreated older patients, cerebrosides and proteolipid protein are markedly reduced compared with treated patients. The enzyme catalyzes the conversion of glutaryl-CoA to crotonyl-CoA and is involved in the breakdown of lysine, hydroxylysine and tryptophan. At this stage, neuroimaging shows characteristic frontotemporal atrophy often in the presence of a large head (microencephalic macrocephaly). Symptoms develop towards the end of the first year with approximately two-thirds of patients developing an encephalitic crisis (often mistaken for encephalitis), subsequently recovering with a complex movement disorder consisting of dystonia and chorea. The remaining onethird develop an insidiously progressive dystonia without an encephalitic crisis. Neuroimaging at this stage shows basal ganglia lesions (striatal necrosis) in addition to frontotemporal atrophy. Thereafter, there may be further encephalitic crises resulting in an increasingly severe movement disorder, spasticity, mental retardation and epilepsy, or these may develop insidiously. Rarely, infants present with acute subdural and retinal haemorrhage, which may be misdiagnosed as non-accidental head injury. Published treatment guidelines principally consist of low lysine diet and carnitine supplementation. One possible contributory mechanism is the prominent cerebral atrophy in the context of an enlarged head, causing an enlarged space to be traversed by the emissary veins,124 which become vulnerable to rupturing. This raises the possibility of in utero effects on the fetus, despite heterozygous compensation from the mother. In lateronset forms, there is often a preceding history of protein avoidance, vomiting, failure to thrive and mental retardation. Children with arginosuccinic aciduria develop brittle hair with trichorrhexis nodosa. Although children with arginase deficiency can have episodes of acute hyperammonaemic encephalopathy, most present with a progressive diplegia and dementia. The key investigations are plasma ammonia and amino acids, and urinary orotic acid. These determine the severity of hyperammonaemia (and, therefore, the acute management) and point towards the site of the defect. Depending upon the disease, the diagnosis is confirmed enzymatically or by mutation analysis. The principles of the latter are the restriction of dietary protein intake, promoting nitrogen excretion Miscellaneous Metabolic Disorders 429 diverse, but neurological complications (developmental delay, ataxia and visual disorders), dysmorphic facial features, failure to thrive and coagulopathies are frequent. Some but not all of these showed a severe pattern of olivopontocerebellar atrophy. In childhood, retinitis pigmentosa, stroke-like episodes and epilepsy may occur, but dementia is not evident. Mild facial dysmorphism, abnormal subcutaneous fat distribution on the buttocks and inverted nipples may be apparent early. There is great variability in the involvement of other organs, even between siblings. The diagnosis is suspected from abnormalities of serum transferrin isoelectric focusing and confirmed on leukocyte phosphomannomutase activity. There was marked cerebellar atrophy, particularly affecting the anterior lobe and sparing the flocculonodular lobe. Loss of Purkinje cells accompanied occasional axonal torpedoes and some dendritic swellings. The autopsy showed multisystem disease with hepatosplenomegaly and hypertrophic cardiomyopathy. Muscle samples showed mild myopathic changes with focal myofibrillary disarray on electron microscopy. Protein glycosylation may be N-linked or O-linked and disorders affect one or both. Given the rapidly expanding list of complex glycosylation disorders, a new classification was proposed in 2009. Among the disorders of O-linked glycosylation are the dystroglycanopathies presenting with muscular dystrophy, type 2 lissencephaly and ocular anomalies. Disorders of N-linked glycosylation have similarly expanded (see Theodore and Morava351) with disorders being due to either sugar chain assembly (type 1) or processing (type 2). The child was born preterm and presented in the neonatal period with oedema, hypotonia, seizures and coagulopathy. At post-mortem evaluation, there was mild cerebellar atrophy but no cortical malformations. The child had optic atrophy, severe hypotonia, dysmorphism, hypoglycaemia and skeletal abnormalities. The post-mortem brain showed Dandy­Walker malformation with vermal agenesis and agenesis of the corpus callosum. Miscellaneous paediatric disorders There has been a large and on-going expansion in the number of genetic and metabolic disorders in children, many with relatively limited neuropathological descriptions. Phenylalanine assembly into toxic fibrils suggests amyloid etiology in phenylketonuria. Congenital disorder of glycosylation-X: clinicopathologic study of an autopsy case with distinct neuropathologic features. A progressive familial encephalopathy in infancy with calcifications of the basal ganglia and chronic cerebrospinal fluid lymphocytosis. Progressive fibrinoid degeneration of fibrillary astrocytes associated with mental retardation in a hydrocephalic infant. A comparative morphologic analysis of adult onset leukodystrophy with neuroaxonal spheroids and pigmented glia ­ a role for oxidative damage. Spongy degeneration in the white matter of the central nervous system in the newborn: pathological findings in three infants, one with hyperglycinaemia. Genetic, clinical, and imaging characterization of one patient with late-onset, slowly progressive, pantothenate kinase-associated neurodegeneration. Cerebellar atrophy: an important feature of carbohydrate deficient glycoprotein syndrome type 1. Decreased dendritic branching in frontal, motor and limbic cortex in Rett syndrome compared with trisomy 21. Congenital disorder of glycosylation type Ia: a clinicopathological report of a newborn infant with cerebellar pathology. Are astrocytes the missing link between lack of brain aspartoacylase activity and the spongiform leukodystrophy in Canavan disease Morphologic and histoanatomic observations of the brain in untreated human phenylketonuria. Consanguineous 3-methylcrotonyl-CoA carboxylase deficiency: early-onset necrotizing encephalopathy with lethal outcome. Disturbed myelination in patients with treated hyperphenylalaninaemia: evaluation with magnetic resonance imaging. White matter abnormalities in patients with treated hyperphenylalaninaemia: magnetic resonance relaxometry and proton spectroscopy findings. Glutaric aciduria type 1 presenting as bilateral subdural hematomas mimicking nonaccidental trauma. A volumetric study of basal ganglia structures in individuals with early-treated phenylketonuria.

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Image courtesy of Professor Pawel Liberski medicine to prevent cold order on line lincocin, Medical University of Lodz treatment sciatica generic lincocin 500mg buy line, Lodz symptoms quivering lips lincocin 500mg for sale, Poland treatment diabetes type 2 discount lincocin online visa. Spongiform change is usually accompanied by neuronal loss treatment 2014 purchase 500 mg lincocin fast delivery, the degree of which is not necessarily consistent with the degree of vacuolation. Reactive astrocytes and microglial cells are also evident within and around amyloid plaques in prion diseases. Neuritic dystrophy around PrP plaques has been identified ultrastructurally and by immunohistochemistry for ubiquitin on paraffin sections. It is perhaps not surprising that a rare condition can coexist with a far more common condition. The differential diagnosis of individual prion diseases is discussed under the relevant headings (later). It may also be performed on peripheral tissues in cases where this is likely to be informative and it is well suited to the analysis of biopsy specimens of brain and tonsil when such tests are required. In variations of this method,67,143,274 small quantities of frozen tissue (around 100 mg) are homogenized in the presence of non-denaturing detergents, cleared of debris and then digested with proteases, usually proteinase K at 50­100 g/mL, before being denatured with sodium dodecyl sulphate and separated by polyacrylamide gel electrophoresis. The separated proteins are then transferred on to nitrocellulose or nylon membranes, and protease-resistant PrP (PrPres) is detected, commonly using mAb 3F4, which binds to an epitope in the proteaseresistant core. Although PrPres is usually detectable in almost all grey matter regions of the brain at end-stage disease, in rare cases, multiple sampling or centrifugal concentration of PrPres in the sample may be necessary. N-terminal sequencing of these species shows that the 21-kDa type 1 fragment has a major N-terminus at glycine 82, whereas the 19-kDa type 2 fragment has a major N-terminus at serine 97. Some of the familial or genetic forms of human prion diseases are characterized by type 1 or type 2 PrPres with a glycoform ratio in which mono- and diglycosylated predominate at the expense of non-glycosylated form. Studies of the geographical distribution of cases within individual countries suggest that the condition is distributed randomly in time and space; clusters of cases have been described only rarely and may reflect the chance aggregation of cases. The full length (23­231) abnormal prion protein consists of a protease-resistant C-terminal core (boxed) and a protease-sensitive N-terminus (dots), between which lies a region of variable protease resistance (dashes). The amino acid sequence of the region of variable protease resistance (71­118) is shown in single-letter amino acid code. Arrows denote the N-termini of protease-treated type 1 (grey arrows) and type 2 (black arrows) PrPres, as determined by N-terminal sequencing. The relative mobility of type 1 and type 2 protease-resistant core fragments seen on western blot analysis relates to the difference in the extent of their N-terminal truncation. The distribution of cases by sex is equal, with no overall female or male preponderance. The most frequent presenting feature is cognitive impairment or ataxia but, typically, there is a rapid decline, with the accumulation of neurological deficits and the development of myoclonic involuntary movements of the limbs and trunk (Table 18. Occasional patients may also exhibit a range of other clinical features during the course of the illness, including those of a peripheral neuropathy. Death is usually caused by intercurrent infection such as bronchopneumonia and the mean survival is only about 4 months from symptom onset. This may be because of the development of 85 ­ 89 90 + Sporadic Creutzfeldt­Jakob Disease 1043 Table 18. The 14-3-3 protein is a marker for neuronal damage and can be elevated in a range of neurological disorders, including stroke and viral encephalitis. There may be a variable degree of diffuse cerebral cortical atrophy or cerebellar cortical atrophy, the latter particularly involving the vermis. In some cases the occipital cortex is affected most severely, whereas in other cases the cerebellar cortex bears the brunt of the neuronal loss, with extensive granular cell loss, usually with relative preservation of Purkinje cells. Surviving Purkinje cells do not all appear normal, and both dendritic hypertrophy and axonal torpedoes may be present. Severe neuronal loss and gliosis in the cerebral cortex result in status spongiosis, a non-specific finding characterized by collapse of the cortical cytoarchitecture and coarse vacuolation in the surviving neuropil (Box 18. A fuller description of typical features in each group follows (see Gambetti et al. An onset with dementia is followed by rapidly progressive multifocal neurological signs, including myoclonus, ataxia and visual abnormalities. The clinical presentation is cerebellar ataxia, with subsequent cognitive impairment and visual abnormalities, but myoclonus is infrequent. The basal ganglia, thalamus and hypothalamus are involved less severely, and the brain stem and hippocampus are relatively spared, although spongiform change is usually severe in the entorhinal cortex. Spongiform change occurs in a patchy distribution in the cerebellar molecular layer, and no amyloid plaques are present. Confluent spongiform change may also occur in the cerebral cortex, particularly in the occipital cortex, with accompanying neuronal loss and gliosis. Immunohistochemistry for PrP shows a predominantly synaptic-like or punctate (a) Neuropathology Spongiform change in the cerebral cortex is usually microvacuolar in type and occurs in a laminar distribution, usually in layers 4­6, particularly in the frontal and temporal cortex. Spongiform change is usually more severe in the basal ganglia, thalamus and hippocampus, with patchy involvement of the dorsal midbrain regions. Some synaptic positivity is also present in a more widespread distribution in the cortex. In the cerebral cortex, there are numerous plaque-like deposits of PrP, usually in layers 2 and 3. Perineuronal and plaque-like deposits are also evident in the basal ganglia and thalamus, but in the cerebellum the plaque-like deposits can be widespread, involving the molecular and granular layers as well as the white matter and the dentate nucleus. Brain stem involvement can be severe in some cases, with widespread plaque-like deposits and spongiform changes in the pontine nuclei and midbrain. In some cases, these lesions are present in the subcortical grey matter nuclei, but they are relatively uncommon in the cerebral cortex. However, the clinical duration of illness is significantly longer, being around 10­15 months on average. Sporadic Creutzfeldt­Jakob Disease 1047 significantly longer duration of illness of 17 months. The onset is usually characterized by cognitive impairment, followed by myoclonus and pyramidal signs, although ataxia is uncommon. Patients usually have dementia at disease onset, with subsequent myoclonus and pyramidal signs. Amyloid plaques are not present, but the confluent spongiform change is accompanied by widespread neuronal loss and severe astrocytosis. The spongiform change is less pronounced in the basal ganglia and thalamus, and, although the hippocampus is spared, the entorhinal cortex is usually severely involved. The cerebellum may show only patchy spongiform change, whereas the brain stem shows only minimal pathology. The gliosis is best demonstrated by immunohistochemistry for glial fibrillary acidic protein. The mean age at onset is around 50 years, with ataxia, followed by visual signs, dementia and eventually insomnia, with a range of motor abnormalities. Spongiform change is usually absent in the thalamus but may be identified in the cerebral cortex, entorhinal cortex and, occasionally, cerebellum. Amyloid plaques are not present, and neuronal loss and gliosis are uncommon outside the thalamus. Immunohistochemistry for PrP appears negative in many regions (including the thalamus), but faint synaptic-like positivity can be identified in the cerebral cortex and entorhinal cortex. Interestingly, type 1 PrPres was found to predominate in areas with diffuse PrP immunoreactivity, whereas type 2 PrPres was found to predominate in areas with perivacuolar and plaque-like deposits. It is implicit in this revised classification that cases exist in which a minority type is absent. Western blot analysis detects PrPres in the brain, spinal cord, pituitary body, trigeminal ganglion, optic nerve, retina and central olfactory pathway. The regions of cerebral cortex shown are frontal cortex (A), subfrontal cortex (B), parietal cortex (C), subparietal cortex (D), temporal cortex (E), subtemporal cortex (F), occipital cortex (G) and suboccipital cortex (H). Type 2 PrPres is seen in all brain regions except subfrontal cortex (B) in which type 1 PrPres is seen. Neuronal loss and gliosis are variable, but the presence of amyloid microplaques is an important diagnostic feature. The pattern of PrP immunoreactivity in these aggregates may vary according to the antibodies used and the degree of proteolytic predigestion on the tissue sections. Current clinical and genetic diagnostic criteria for familial prion diseases are summarized in Box 18. Definite prion disease + definite or probable prion disease in first-degree relative B. Progressive neuropsychiatric disorder + definite or probable prion disease in first-degree relative B. The most common signs at onset include cognitive impairment, psychiatric changes (80­83 per cent), cerebellar signs (43­45 per cent), visual signs (19 per cent) and myoclonus (12 per cent). Immunohistochemistry shows PrP deposits with a synapticlike pattern and sometimes a coarse or perivacuolar pattern of immunoreactivity. The mean age at onset of disease is 39 years (range 26­47 years) in 129V homozygous patients and 49 years (range 45­56 years) in heterozygous patients. The duration of disease is shorter ­ 14 months (range 9­18 months) ­ for valine homozygotes compared with 27 months (range 7­51 months) for heterozygotes. The typical presentation is with cognitive impairment, depression and abnormal behaviour. Neuropathology the neuropathological changes seen in patients with the D178N-129V haplotype include spongiform degeneration, gliosis and neuronal loss. The lesions have a distinctive distribution, with the frontal and temporal cortices generally more affected than the occipital cortex. Among the subcortical structures, the putamen and the caudate nucleus show severe spongiosis, whereas the thalamus is affected minimally or moderately. PrP Familial or Genetic Prion Diseases 1053 immunostaining demonstrates synaptic-like deposits most prominent in areas with severe spongiform lesions, whereas the cerebellum shows minimal immunostaining for PrP. The onset of disease among the reported cases is at age 46­80 years, and the duration of disease is 2­24 months. Memory loss and gait disturbance are predominant presenting signs, followed by dementia and myoclonus. The age at onset for patients with the V180I-129M haplotype varies between 66 and 81 years. Studies on two patients showed cognitive impairment, followed by akinetic mutism, pyramidal and extrapyramidal signs and myoclonus. All show spongiform degeneration and gliosis in the grey matter, which is most prominent in the cerebral cortex and the molecular layer of the cerebellum. Kuru-type plaques were observed in two patients who were heterozygous at codon 129 and in one patient homozygous for methionine at codon 129. All the patients developed the disease at a young age (range 18­40 years), and the duration of the disease was lengthy (range 1­4 years). Neuropathology the main histological lesions seen in these patients are spongiform degeneration in the cerebral cortex and basal ganglia. PrP-immunoreactivity was reported to be widespread and punctate, particularly in the cerebral cortex, with a plaque-like pattern in the putamen. Presenting signs included memory and gait disturbances, followed by myoclonus and mutism. Neuropathology the few patients with the M232R-129M haplotype who were studied neuropathologically showed spongiform degeneration, astrogliosis and neuronal loss in variable degrees. All three lesions were observed in the cerebral cortex, basal ganglia and brain stem. No spongiform Neuropathology Neuropathological examination revealed spongiform degeneration, mostly in the cortex and basal ganglia, 1054 Chapter 18 Prion Diseases degeneration was reported in the cerebellum. Studies of a large kindred with this mutation have revealed a wide phenotypic spectrum, including variable age of onset. Sleep disturbances are often associated with autonomic alterations, including mild blood pressure elevation, mild pyrexia and increased heart rate. However, phenotypic variability is also present within genetic subgroups, even among members of the same family, indicating that epigenetic factors may also play a role. The age of the patients was uncharacteristically young, but no autopsy investigation was performed. Post-mortem examination of the left parietal region showed spongiform degeneration and diffuse PrP immunoreactivity. The third case displayed distinct neuropathological features characterized by tau pathology in the hippocampus and entorhinal cortex and ballooned neurons in the cortex, hippocampus and subcortical grey matter. More recently a fourth case has been described presenting as progressive supranuclear palsy. Other thalamic nuclei are affected less severely and more inconsistently (see Kong et al. In cases with longer disease duration, progressive spongiform degeneration and variable degrees of astrocytosis and neuronal loss are seen in the cerebral cortex. The cerebellar cortex, periaqueductal grey matter, raphe nucleus and reticular formation in the brain stem may also show mild neuronal loss and astrocytosis. Studies on paraffin sections have reported the absence of PrP immunoreactivity in most brain regions analyzed, but PrP accumulation has been reported in the molecular layer of the (a) cerebellum and in the subiculum and entorhinal cortex, particularly in cases with a long clinical duration of illness. Behavioural and cognitive dysfunctions are seen in most cases, which evolve into dementia or akinetic mutism. Clinical symptoms start in the fourth to sixth decade of life, with a disease duration of a few months to 6 years. The severe gliosis is best demonstrated on immunohistochemistry for the fibrillary acidic protein. Neuronal loss appears to be more severe in cases with spongiform degeneration than in cases with PrP plaques only. In addition, this mutation is associated with a clinical course that may last up to 12 years, significantly longer than in the P102L-129M haplotype. Spastic gait, hyperreflexia and the Babinski sign are prominent in the initial stages. Extrapyramidal signs such as fine finger tremor and rigidity of limbs may be observed.

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