Cytochrome-c oxidase isolated from the brain of swayback-diseased sheep displays unusual structure and uncharacteristic kinetics

Spinal Cord and Peripheral Nerve Abnormalities of the Ruminant

In food animals, spinal cord damage is most commonly associated with infection or trauma. Antemortem diagnosis is based on clinical signs, history, cerebrospinal fluid analysis, and imaging. As clinical signs are often severe, and prognosis is grave, necropsy may provide a postmortem diagnosis. Peripheral nerve abnormalities are most often the result of trauma. Calving paralysis or paresis is the most common condition affecting the sciatic or obturator nerve and often concurrently involves the peroneal branch of the sciatic. Damage to peripheral nerves is often transient and resolves within a few days as long as the nerve is not severed.

Copper deficiency myelopathy (human swayback)

The hematologic manifestations of copper deficiency are well known and include anemia and neutropenia. In the past few years, the neurological manifestations of acquired copper deficiency in humans has been recognized, the most common being a myelopathy presenting with a spastic gait and prominent sensory ataxia. The known causes of acquired copper deficiency include prior gastric surgery, excessive zinc ingestion, and malabsorption; however, often the cause is unclear. Hyperzincemia may be present even in the absence of exogenous zinc ingestion. The clinical features and neuroimaging findings are similar to the subacute combined degeneration seen in patients with vitamin B12 deficiency. Copper and vitamin B12 deficiency may coexist. The neurological syndrome may be present without the hematologic manifestations. Copper supplementation resolves the anemia and neutropenia promptly and completely and may prevent the neurological deterioration. Improvement, when it occurs, is often subjective and preferentially involves sensory symptoms. This article describes patients with copper deficiency myelopathy seen at the Mayo Clinic in Rochester, Minn, and reviews the literature on neurological manifestations of acquired copper deficiency in humans.

The role of Thr5 in human neuron growth inhibitory factor

GIF, a member of the metallothionein (MT) family (assigned as MT3), is a neuron growth inhibitory factor that inhibits neuron outgrowth in Alzheimer's disease. The conserved Thr5 is one of the main differences between GIF and other members in the MT family. However, natural sheep GIF has an unusual Ala5, casting doubt on the role of common Thr5. We constructed a series of human GIF mutants at site 5, and characterized their biochemical properties by UV spectroscopy, circular dichroism spectroscopy, EDTA reaction, 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) reaction, and pH titration. Their inhibitory activity toward neuron survival and neurite extension was also examined. Interestingly, the T5A mutant exhibited distinct metal thiolate activity in the EDTA and DTNB reactions, and also lost its bioactivity. Meanwhile, the T5S mutant had similar biochemical properties and biological activity as wild-type human GIF, indicating the hydroxyl group on the Thr5 was critical to the bioactivity of human GIF. We suggest the hydroxyl group in human GIF may help stabilize the biologically active conformation. On the other hand, lack of the hydroxyl group in sheep GIF may be partially compensated by its abnormal structure.

Epilepsy in Menkes Disease: Analysis of Clinical Stages

PURPOSE

Epilepsy is one of the main features of Menkes disease (MD), although it is not described in depth. To determine the spectrum of epilepsy, we studied its main characteristics.

METHODS

Based on clinical charts, we retrospectively analyzed the evolution of electroclinical features of 12 patients with confirmed MD.

RESULTS

Epilepsy could be divided into three periods: (a) an early stage (median age, 3 months), characterized by focal clonic status epilepticus, usually triggered by fever (10 patients). Ictal EEG showed runs of slow spike-waves and slow waves in the posterior regions, and interictal EEG multifocal and polymorphic slow waves (three cases), or mixed slow spike-waves and slow waves (seven cases). Partial seizure control was obtained in nine patients during 5.9 months; (b) an intermediate stage (median age, 10 months) with intractable infantile spasms (11 patients) in which interictal EEG demonstrated modified hypsarrhythmia (seven cases), diffuse irregular slow waves and spike-waves (four cases). Six patients died at the median age of 15 months; and (c) a late stage in the six remaining patients (median age, 25 months), with multifocal seizures, tonic spasms, and myoclonus in four patients, whereas two patients became seizure free. Interictal EEG showed multifocal high-amplitude activity, mixed with irregular slow waves in all six cases. These patients died at the median age of 3.6 years.

CONCLUSIONS

Based on a relatively large series of MD patients with a quite prolonged survival, we individualized three successive periods in the course of epilepsy: early focal status, then infantile spasms, and then myoclonic and multifocal epilepsy after age 2 years.

Imaging features of copper deficiency myelopathy: a study of 25 cases

Acquired copper deficiency presents with a spastic gait and sensory ataxia. Spinal cord magnetic resonance imaging (MRI) in patients with copper deficiency myelopathy may show increased T2 signal, most commonly in the dorsal midline cervical and thoracic cord. These imaging findings may be reversible with normalization of serum copper. The clinical and imaging picture is very similar to the subacute combined degeneration seen in patients with vitamin B12 deficiency. Neuroradiologists should consider this possibility when a long segment of symmetric dorsal spinal cord T2-hyperintensity is identified.

Sheep have an unusual variant of the brain-specific metallothionein, metallothionein-III

Sheep metallothionein-III (MT-III) cDNA was isolated from a brain cDNA library and characterized. In contrast with MT-III from other species, sheep MT-III cDNA is predicted to encode a protein with significantly different metal-binding properties, owing to the loss of three of its cysteine residues. RT-PCR from other sheep confirmed that this aberrant structure is ubiquitous in this species. MT-III was successfully isolated from sheep brain, demonstrating that the cDNA does give rise to a protein product of the predicted structure. Sheep MT-III is similar to other mammalian MT-IIIs in that it retains the Cys-Pro-Cys-Pro motif which is thought to encode growth-inhibitory activity, and we show that it is likewise able to inhibit neuron survival in vitro. This is the first naturally occurring variant of MT-III (or any other major mammalian MT gene) which gives rise to a protein product. These findings are discussed in light of proposed roles of MT in the mammalian brain.