Compact and almost compact breathers: a bridge between an anharmonic lattice and its continuum limit.

We demonstrate that certain strictly anharmonic one-dimensional FPU lattices with a suitable quartic site potential appended support almost-compact discrete breathers over a macroscopic localized domain that is essentially fixed independently of the sparseness of the lattice. Beyond that domain the discrete breather tails decay at a double-exponential rate in the lattice-cell index, becoming truly compact in the continuum limit. Furthermore, the discrete breather is stable for amplitudes below a sharp threshold that depends on the sparseness of the lattice.

Almost compact breathers in anharmonic lattices near the continuum limit.

Certain strictly anharmonic one-dimensional lattices support discrete breathers over a macroscopic localized domain that in the continuum limit becomes exactly compact. The discrete breather tails decay at a double-exponential rate, so such systems can store energy locally, especially since discrete breathers appear to be stable for amplitudes below a sharp stability threshold. The effective width of other solutions broadens over time, but, under appropriate conditions, only after a positive waiting time.

Critical illness myopathy associated with hyperthyroidism.

A 51-year-old woman was admitted to the intensive care unit for exacerbation of chronic obstructive pulmonary disease. She received antibiotics, neuromuscular blocking agents, and steroids. After 8 days in the intensive care unit, she was noted to be severely weak, her serum creatine kinase had risen to 1,692 U/L (normal, 20-220 U/L), and a muscle biopsy was consistent with critical illness myopathy.

Congenital myopathies/dystrophies.

The congenital myopathies and congenital muscular dystrophies are a group of relatively infrequent neuromuscular disorders. Ultimate understanding of these disorders, however, will undoubtedly shed considerable light on skeletal muscle development and function. Three classical congenital myopathies are central core disease, nemaline myopathy, and centronuclear myopathy.

Intracranial extramedullary hematopoiesis associated with pilocytic astrocytoma: a case report.

Intracranial EMH is only occasionally found in primary brain tumors (mostly hemangioblastomas) and, to our knowledge, this is the first case of EMH associated with an astrocytoma. Intracranial extramedullary hematopoiesis (EMH) is described in a 29-year-old man with a recurrent pilocytic astrocytoma in the tectal region. Special stains confirmed the identities of erythroid, myeloid and megakaryocytic cells.

Bilateral optic nerve sheath enhancement from giant cell arteritis.

An 83-year-old man presented with acute bilateral visual loss to no light perception (NLP) OD and 20/50 OS. His fundus examination showed moderate bilateral pallid disc edema. A sedimentation rate was 60 mm/h.

Intradural convexity chondroma: a case report and review of diagnostic features.

Intradural convexity chondromas are slow-growing tumors of young adults and children. Their symptoms are due to their size and degree of mass effect. They are extra-axial, avascular masses without peritumoral edema.

The outer neomembrane of chronic subdural hematoma.

Thomas Willis recognized the entity of the chronic subdural hematoma (CSH) more than 300 years ago. Modern observations of the ultrastructure of normal meninges and the CSH outer neomembrane, combined with techniques of radioactive red blood cell labeling and chemical analysis of CSH fluid, have provided insight into the pathophysiology of this entity. The outer membrane evolves as a reaction to cleavage of the dural border cell layer of the meninges.

Fulminant CNS perivascular lymphocytic proliferation: association with sargramostim, a hematopoietic growth factor.

Sargramostim (GM-CSF) therapy was instituted in a 49-year-old woman with hepatitis C on chronic interferon alpha-2b therapy. Within two weeks, she developed progressive confusion, lethargy, and gait disturbance. At autopsy 4 months later, diffuse perivascular nonmonoclonal lymphoid infiltrates were demonstrated throughout the central nervous system (CNS).

Delayed diffuse upper motor neuron syndrome after compressive thoracic myelopathy.

A 54-year-old man developed progressive spastic paraparesis beginning 2 weeks after a back injury caused by a subacute compressive thoracic myelopathy attributable to a post-traumatic arachnoid cyst. Three to 18 months after surgical decompression of the thoracic arachnoid cyst, the patient developed a diffuse predominantly upper motor neuron syndrome characterized by spastic quadriparesis, pseudobulbar paresis, and pseudobulbar affect. Retrograde corticospinal tract degeneration and upper motor neuron death after spinal cord injury is recognized.

Exertional myalgia syndrome associated with diminished serum ammonia elevation in ischemic exercise testing.

A 36-year-old man with chronic severe exertional myalgias had a normal serum lactate elevation and diminished serum ammonia elevation on an ischemic forearm exercise test (IFET). The IFET is commonly performed in the evaluation of patients with complaints of exertional myalgias, cramps, and rhabdomyolysis. The finding of a normal serum lactate elevation and a diminished serum ammonia elevation after ischemic exercise is usually considered indicative of myoadenylate deaminase deficiency.

Myotonia associated with sarcoidosis: marked exacerbation with pravastatin.

A 37-year-old man with sarcoidosis developed severe electrical and clinical myotonia while taking pravastatin for hypercholesterolemia. Myotonia associated with sarcoidosis is rare. Pravastatin is associated with myotonia in animals.

Alexander's disease: unique presentation.

Subacute necrotizing encephalomyelopathy (Leigh syndrome) refers to a nebulous disease entity characterized by lactic acidosis, a wide variety a clinical manifestations, and a consistent conglomeration of pathologic findings. Several abnormalities in metabolism have been delineated in association with Leigh syndrome, but many cases have no identified metabolic abnormality. We report a case that clinically, metabolically, and neuroradiologically appeared to be Leigh syndrome.

Progress in neuropathology of the neuronal ceroid lipofuscinoses.

Since the last, 6th, International Congress on Neuronal Ceroid-Lipofuscinoses, neuropathological advances in neuronal ceroid lipofuscinoses (NCL) have been made in several areas: (1) In adult NCL (ANCL) lipopigments have now been repeatedly confirmed to contain subunit c of mitochondrial ATP synthase and even sphingolipid activators (saposins). ANCL lipopigments have also been confirmed in extracerebral tissues including skin, skeletal muscle, and spleen, but not yet lymphocytes (2). Among circulating blood cells not only B cells and subclasses of T lymphocytes, i.

Focal rhabdomyolysis and brachial plexopathy: an association with heroin and chronic ethanol use.

A 22-year-old man presented with acute swelling of the left neck and associated weakness of the left arm upon awakening after having snorted heroin. He had consumed large amounts of ethanol regularly for 7 years. Serum creatine kinase was greater than 19,000 units/l.

Entirely intracanalicular meningioma: contrast-enhanced MR findings in a rare entity.

We report an unusual case of an entirely intracanalicular meningioma in a 51-year-old woman. Contrast-enhanced MR images showed an enhancing lesion filling the lateral portion of the left internal auditory canal. Our findings suggest that meningiomas should be considered in the differential diagnosis of entirely intracanalicular masses.

Ultrastructure of the retina in adult neuronal ceroid lipofuscinosis.

A 33-year-old woman died of biopsy-proven adult neuronal ceroid lipofuscinosis (NCL) or Kufs' disease marked by fingerprint and curvilinear lipopigments in neural and nonneural cell types. She had never experienced visual impairment or shown electroretinographic abnormalities. At autopsy, her retina appeared intact without degeneration at the light-microscopic level, but nerve cells in different layers were loaded with lipopigments of the granular type.

Ethanol level differential between postmortem blood and subdural hematoma.

Alcohol use is a major risk factor for accidental injury and death. However, when death occurs several hours after injury, ethanol in the blood may be absent or low. Ethanol in sequestered hematomas has been used to retrospectively implicate alcohol as a contributing factor at the time of injury.

Giant intracranial and extracranial cavernous malformation. Case report.

Massive enlargement of an extracerebral cavernous malformation and extension across tissue planes is very uncommon. The authors present the case of a 49-year-old woman with a giant cavernous malformation in the left frontotemporal area. It progressively enlarged during several decades, extended through the calvaria to the extradural space, and was surgically treated.

Neuropathology of aging.

The brain undergoes many gross and histopathologic changes with advancing age. Some of the changes seen with aging are also found in demented individuals, especially patients with Alzheimer's disease. The extent to which Alzheimer's disease and aging are truly different processes remains to be determined.

Myoclonus epilepsy with ragged red fibers and multiple mtDNA deletions.

In a patient with clinical features of myoclonus epilepsy with ragged red fibers (MERRF), molecular genetic analysis of mitochondrial DNA did not show either of the two point mutations typically associated with MERRF but did show multiple deletions by Southern blot. This case further illustrates the heterogeneity observed with mtDNA mutations.