Neurodegenerative diseases and risk factors: a literature review

Exploring the Therapeutic Potential of Phytoconstituents for Addressing Neurodegenerative Disorders

Neurodegenerative disorder is a serious condition that is caused by abnormal or no neurological function. Neurodegenerative disease is a major growing cause of mortality and morbidity worldwide, especially in the elderly. After World War Ⅱ, eugenics term was exterminated from medicines. Neurodegenerative disease is a genetically inherited disease. Lifestyle changes, environmental factors, and genetic modification, together or alone, are involved in the occurrence of this disorder. The major examples of neurodegenerative disorders are Alzheimer's and Parkinson's disease, in which apoptosis and necrosis are the two major death pathways for neurons. It has been determined from various studies that the etiology of the neurodegenerative disease involves the role of oxidative stress and anti-oxidant defence system, which are prime factors associated with the activation of signal transduction pathway that is responsible for the formation of synuclein in the brain and manifestation of toxic reactions in the form of functional abnormality, which ultimately leads to the dysfunction of neuronal pathway or cell. There has not been much success in the discovery of effective therapy to treat neurodegenerative diseases because the main cause of abnormal functioning or death of neurons is not well known. However, the use of natural products that are derived from plants has effective therapeutic potential against neurodegenerative disease. The natural compounds with medicinal properties to prevent neurological dysfunction are curcumin, wolfberry, ginseng, and Withania somnifera. The selection and use of natural compounds are based on their strong anti-inflammatory and anti-oxidant properties against neurodegenerative disease. Herbal products have active constituents that play an important role in the prevention of communication errors between neurons and neurotransmitters and their respective receptors in the brain, which influence their function. Considering this, natural products have great potential against neurodegenerative diseases. This article reviews the natural compounds used to treat neurodegenerative diseases and their mechanisms of action.

Ensemble Model for Diagnostic Classification of Alzheimer's Disease Based on Brain Anatomical Magnetic Resonance Imaging

Alzheimer's is one of the fast-growing diseases among people worldwide leading to brain atrophy. Neuroimaging reveals extensive information about the brain's anatomy and enables the identification of diagnostic features. Artificial intelligence (AI) in neuroimaging has the potential to significantly enhance the treatment process for Alzheimer's disease (AD). The objective of this study is two-fold: (1) to compare existing Machine Learning (ML) algorithms for the classification of AD. (2) To propose an effective ensemble-based model for the same and to perform its comparative analysis. In this study, data from the Alzheimer's Diseases Neuroimaging Initiative (ADNI), an online repository, is utilized for experimentation consisting of 2125 neuroimages of Alzheimer's disease (n = 975), mild cognitive impairment (n = 538) and cognitive normal (n = 612). For classification, the framework incorporates a Decision Tree (DT), Random Forest (RF), Naïve Bayes (NB), and K-Nearest Neighbor (K-NN) followed by some variations of Support Vector Machine (SVM), such as SVM (RBF kernel), SVM (Polynomial Kernel), and SVM (Sigmoid kernel), as well as Gradient Boost (GB), Extreme Gradient Boosting (XGB) and Multi-layer Perceptron Neural Network (MLP-NN). Afterwards, an Ensemble Based Generic Kernel is presented where Master-Slave architecture is combined to attain better performance. The proposed model is an ensemble of Extreme Gradient Boosting, Decision Tree and SVM_Polynomial kernel (XGB + DT + SVM). At last, the proposed method is evaluated using cross-validation using statistical techniques along with other ML models. The presented ensemble model (XGB + DT + SVM) outperformed existing state-of-the-art algorithms with an accuracy of 89.77%. The efficiency of all the models was optimized using Grid-based tuning, and the results obtained after such process showed significant improvement. XGB + DT + SVM with optimized parameters outperformed all other models with an efficiency of 95.75%. The implication of the proposed ensemble-based learning approach clearly shows the best results compared to other ML models. This experimental comparative analysis improved understanding of the above-defined methods and enhanced their scope and significance in the early detection of Alzheimer's disease.

Genetically Encoded ATP Biosensors for Direct Monitoring of Cellular ATP Dynamics

Adenosine 5'-triphosphate, or ATP, is the primary molecule for storing and transferring energy in cells. ATP is mainly produced via oxidative phosphorylation in mitochondria, and to a lesser extent, via glycolysis in the cytosol. In general, cytosolic glycolysis is the primary ATP producer in proliferative cells or cells subjected to hypoxia. On the other hand, mitochondria produce over 90% of cellular ATP in differentiated cells under normoxic conditions. Under pathological conditions, ATP demand rises to meet the needs of biosynthesis for cellular repair, signaling transduction for stress responses, and biochemical processes. These changes affect how mitochondria and cytosolic glycolysis function and communicate. Mitochondria undergo remodeling to adapt to the imbalanced demand and supply of ATP. Otherwise, a severe ATP deficit will impair cellular function and eventually cause cell death. It is suggested that ATP from different cellular compartments can dynamically communicate and coordinate to adapt to the needs in each cellular compartment. Thus, a better understanding of ATP dynamics is crucial to revealing the differences in cellular metabolic processes across various cell types and conditions. This requires innovative methodologies to record real-time spatiotemporal ATP changes in subcellular regions of living cells. Over the recent decades, numerous methods have been developed and utilized to accomplish this task. However, this is not an easy feat. This review evaluates innovative genetically encoded biosensors available for visualizing ATP in living cells, their potential use in the setting of human disease, and identifies where we could improve and expand our abilities.

MIND Diet Adherence Might be Associated with a Reduced Odds of Multiple Sclerosis: Results from a Case–Control Study

Introduction

The Mediterranean Dietary Approaches to the Stop Hypertension (DASH) Intervention for Neurodegenerative Delay (MIND) diet has been shown to have beneficial neuroprotective effects. The purpose of this research was to evaluate the link between the MIND diet adherence and multiple sclerosis (MS), a degenerative neurological illness.

Methods

In a hospital-based case–control setting, 77 patients with relapsing–remitting multiple sclerosis (RRMS) and 148 healthy individuals were recruited. A validated 168-item semi-quantitative food frequency questionnaire was used to assess participants’ dietary intakes and the MIND diet score. A logistic regression model was used to evaluate the association between MIND diet adherence and MS.

Results

There was significant difference between RRMS and control groups in the median (Q1-Q3) of age (years, P value < 0.001), body mass index (BMI) (kg/m², P value < 0.001), and total intake of calories (kcal, P value = 0.032), carbohydrates (g, P value = 0.003), animal-based protein (g, P value = 0.009), and fiber (g, P value = 0.001). Adherence to the MIND diet was associated with a reduced odds of MS [adjusted odds ratio (aOR) = 0.10, 95 percent confidence interval (95% CI) = 0.01–0.88, P for trend = 0.001]. MS odds was significantly lower in the last tertile of green leafy vegetables (aOR = 0.02, 95% CI = 0.00–0.21, P value < 0.001), other vegetables (aOR = 0.17, 95% CI = 0.04–0.73, P value = 0.001), butter and stick margarine (aOR = 0.20, 95% CI = 0.06–0.65, P value = 0.008), and beans (aOR = 0.05, 95% CI = 0.01–0.28, P value < 0.001) consumption. While it was significantly higher in the last tertile of cheese (aOR = 4.45, 95% CI = 1.70–11.6, P value = 0.003), poultry (aOR = 3.95, 95% CI = 1.01–15.5, P value = 0.039), pastries and sweets (aOR = 13.9, 95% CI = 3.04–64.18, P value < 0.001), and fried/fast foods (aOR = 32.8, 95% CI = 5.39–199.3, P value < 0.001).

Conclusion

The MIND diet and its components, including green leafy vegetables, other vegetables, and beans, seem to decrease the odds of MS; besides butter and stick margarine, the MIND diet's unhealthy components seem to have the same protective effects, while pastries and sweets, cheese, poultry, and fried/fast foods have an inverse effect.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-022-00325-z.

Exosomes in Parkinson: Revisiting Their Pathologic Role and Potential Applications

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by bradykinesia, rigidity, and tremor. Considerable progress has been made to understand the exact mechanism leading to this disease. Most of what is known comes from the evidence of PD brains' autopsies showing a deposition of Lewy bodies-containing a protein called α-synuclein (α-syn)-as the pathological determinant of PD. α-syn predisposes neurons to neurotoxicity and cell death, while the other associated mechanisms are mitochondrial dysfunction and oxidative stress, which are underlying precursors to the death of dopaminergic neurons at the substantia nigra pars compacta leading to disease progression. Several mechanisms have been proposed to unravel the pathological cascade of these diseases; most of them share a particular similarity: cell-to-cell communication through exosomes (EXOs). EXOs are intracellular membrane-based vesicles with diverse compositions involved in biological and pathological processes, which their secretion is driven by the NLR family pyrin domain-containing three proteins (NLRP3) inflammasome. Toxic biological fibrils are transferred to recipient cells, and the disposal of damaged organelles through generating mitochondrial-derived vesicles are suggested mechanisms for developing PD. EXOs carry various biomarkers; thus, they are promising to diagnose different neurological disorders, including neurodegenerative diseases (NDDs). As nanovesicles, the applications of EXOs are not only restricted as diagnostics but also expanded to treat NDDs as therapeutic carriers and nano-scavengers. Herein, the aim is to highlight the potential incrimination of EXOs in the pathological cascade and progression of PD and their role as biomarkers and therapeutic carriers for diagnosing and treating this neuro-debilitating disorder.

Neurodegenerative Disorders of Alzheimer, Parkinsonism, Amyotrophic Lateral Sclerosis and Multiple Sclerosis: An Early Diagnostic Approach for Precision Treatment

Neurodegenerative diseases (NDs) are characterised by progressive dysfunction of synapses, neurons, glial cells and their networks. Neurodegenerative diseases can be classified according to primary clinical features (e.g., dementia, parkinsonism, or motor neuron disease), anatomic distribution of neurodegeneration (e.g., frontotemporal degenerations, extrapyramidal disorders, or spinocerebellar degenerations), or principal molecular abnormalities. The most common neurodegenerative disorders are amyloidosis, tauopathies, a-synucleinopathy, and TAR DNA-binding protein 43 (TDP-43) proteopathy. The protein abnormalities in these disorders have abnormal conformational properties along with altered cellular mechanisms, and they exhibit motor deficit, mitochondrial malfunction, dysfunctions in autophagic-lysosomal pathways, synaptic toxicity, and more emerging mechanisms such as the roles of stress granule pathways and liquid-phase transitions. Finally, for each ND, microglial cells have been reported to be implicated in neurodegeneration, in particular, because the microglial responses can shift from neuroprotective to a deleterious role. Growing experimental evidence suggests that abnormal protein conformers act as seed material for oligomerization, spreading from cell to cell through anatomically connected neuronal pathways, which may in part explain the specific anatomical patterns observed in brain autopsy sample. In this review, we mention the human pathology of select neurodegenerative disorders, focusing on how neurodegenerative disorders (i.e., Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis) represent a great healthcare problem worldwide and are becoming prevalent because of the increasing aged population. Despite many studies have focused on their etiopathology, the exact cause of these diseases is still largely unknown and until now with the only available option of symptomatic treatments. In this review, we aim to report the systematic and clinically correlated potential biomarker candidates. Although future studies are necessary for their use in early detection and progression in humans affected by NDs, the promising results obtained by several groups leads us to this idea that biomarkers could be used to design a potential therapeutic approach and preclinical clinical trials for the treatments of NDs.

Investigating Associations Between Inflammatory Biomarkers, Gray Matter, Neurofilament Light and Cognitive Performance in Healthy Older Adults

Background: Exploring biological variables that may serve as indicators of the development and progression of cognitive decline is currently a high-priority research area. Recent studies have demonstrated that during normal aging, individuals experience increased inflammation throughout the brain and body, which may be linked to cognitive impairment and reduced gray matter volume in the brain. Neurofilament light polypeptide (NfL), which is released into the circulation following neuronal damage, has been proposed as a biomarker for neurodegenerative diseases, and may also have utility in the context of normal aging. The present study tested associations between age, peripheral levels of the pro-inflammatory cytokine IL-6, peripheral NfL, brain volume, and cognitive performance in a sample of healthy adults over 60 years old.

Methods: Of the 273 individuals who participated in this study, 173 had useable neuroimaging data, a subset of whom had useable blood data (used for quantifying IL-6 and NfL) and completed a cognitive task. Gray matter (GM) thickness values were extracted from brain areas of interest using Freesurfer. Regression models were used to test relationships between IL-6, NfL, GM, and cognitive performance. To test putative functional relationships between these variables, exploratory path analytic models were estimated, in which the relationship between age, IL-6, and working memory performance were linked via four different operationalizations of brain health: (1) a latent GM variable composed of several regions linked to cognitive impairment, (2) NfL alone, (3) NfL combined with the GM latent variable, and (4) the hippocampus alone.

Results: Regression models showed that IL-6 and NfL were significantly negatively associated with GM volume and that GM was positively associated with cognitive performance. The path analytic models indicated that age and cognitive performance are linked by GM in the hippocampus as well as several other regions previously associated with cognitive impairment, but not by NfL alone. Peripheral IL-6 was not associated with age in any of the path models.

Conclusions: Results suggest that among healthy older adults, there are several GM regions that link age and cognitive performance. Notably, NfL alone is not a sufficient marker of brain changes associated with aging, inflammation, and cognitive performance.

Human Gait Analysis in Neurodegenerative Diseases: a Review

This paper reviews the recent literature on technologies and methodologies for quantitative human gait analysis in the context of neurodegnerative diseases. The use of technological instruments can be of great support in both clinical diagnosis and severity assessment of these pathologies. In this paper, sensors, features and processing methodologies have been reviewed in order to provide a highly consistent work that explores the issues related to gait analysis. First, the phases of the human gait cycle are briefly explained, along with some non-normal gait patterns (gait abnormalities) typical of some neurodegenerative diseases. The work continues with a survey on the publicly available datasets principally used for comparing results. Then the paper reports the most common processing techniques for both feature selection and extraction and for classification and clustering. Finally, a conclusive discussion on current open problems and future directions is outlined.

Neurite outgrowth stimulatory effects of myco synthesized AuNPs from Hericium erinaceus (Bull.: Fr.) Pers. on pheochromocytoma (PC-12) cells

Background

Hericium erinaceus has been reported to have a wide range of medicinal properties such as stimulation of neurite outgrowth, promotion of functional recovery of axonotmetic peroneal nerve injury, antioxidant, antihypertensive, and antidiabetic properties. In recent years, the green synthesis of gold nanoparticles (AuNPs) has attracted intense interest due to the potential use in biomedical applications. The aim of this study was to investigate the effects of AuNPs from aqueous extract of H. erinaceus on neurite outgrowth of rat pheochromocytoma (PC-12) cells.

Methods

The formation of AuNPs was characterized by UV–visible spectrum, energy dispersive X-ray (EDX), field-emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), particle size distribution, and Fourier transform-infrared spectroscopy (FTIR). Furthermore, the neurite extension study of synthesized AuNPs was evaluated by in vitro assay.

Results

The AuNPs exhibited maximum absorbance between 510 and 600 nm in UV–visible spectrum. FESEM and TEM images showed the existence of nanoparticles with sizes of 20–40 nm. FTIR measurements were carried out to identify the possible biomolecules responsible for capping and efficient stabilization of the nanoparticles. The purity and the crystalline properties were confirmed by EDX diffraction analysis, which showed strong signals with energy peaks in the range of 2–2.4 keV, indicating the existence of gold atoms. The synthesized AuNPs showed significant neurite extension on PC-12 cells. Nerve growth factor 50 ng/mL was used as a positive control. Treatment with different concentrations (nanograms) of AuNPs resulted in neuronal differentiation and neuronal elongation. AuNPs induced maximum neurite outgrowth of 13% at 600 ng/mL concentration.

Conclusion

In this study, the AuNPs synthesis was achieved by a simple, low-cost, and rapid bioreduction approach. AuNPs were shown to have potential neuronal differentiation and stimulated neurite outgrowth. The water-soluble bioconstituents could be responsible for the neuroactivity. This is the first report for the biosynthesis of AuNPs using the hot aqueous extract of H. erinaceus.

Combination Effects of Curcumin and Aqueous Extract of Lignosus rhinocerotis Mycelium on Neurite Outgrowth Stimulation Activity in PC-12 Cells

Neurotrophic factors are necessary for neuronal navigation to form viable neuronal networks. These factors are high molecular weight polypeptides that cannot cross the blood brain-barrier. Therefore, small molecules from mushrooms and plants are utilized to maintain neuronal function or up-regulate neurotrophic factors. The present study investigated whether a combination of Lignosus rhinocerotis mycelium aqueous extract and curcumin was more effective than L. rhinocerotis mycelium or curcumin alone in the stimulation of neurite outgrowth of PC-12 cells. The maximum neurite extension for L. rhinocerotis and curcumin was at 21.1% at 20 μg/mL and 29.5% at 10 μg/mL, respectively. Combining 20 μg/mL of L. rhinocerotis with one μg/mL curcumin gave 27.2% neurite extension. This combination was preferred because high concentrations of curcumin were toxic to cells. In the combination, 20 μg/mL of L. rhinocerotis enhanced neurite outgrowth activity at a lower dosage of curcumin at one μg/mL, and produced a comparable percentage of neurite outgrowth stimulation activity to L. rhinocerotis and curcumin alone in PC-12 cells.

Statistical Analysis of Metal Chelating Activity of Centella asiatica and Erythroxylum cuneatum Using Response Surface Methodology

The purpose of the study is to evaluate the relationship between the extraction parameters and the metal chelating activity of Centella asiatica (CA) and Erythroxylum cuneatum (EC). The response surface methodology was used to optimize the extraction parameters of methanolic extract of CA and EC with respect to the metal chelating activity. For CA, Run 17 gave optimum chelating activity with IC₅₀ = 0.93 mg/mL at an extraction temperature of 25°C, speed of agitation at 200 rpm, ratio of plant material to solvent at 1 g : 45 mL and extraction time at 1.5 hour. As for EC, Run 13 with 60°C, 200 rpm, 1 g : 35 mL and 1 hour had metal chelating activity at IC₅₀ = 0.3817 mg/mL. Both optimized extracts were further partitioned using a solvent system to evaluate the fraction responsible for the chelating activity of the plants. The hexane fraction of CA showed potential activity with chelating activity at IC₅₀ = 0.090 and the ethyl acetate fraction of EC had IC₅₀ = 0.120 mg/mL. The study showed that the response surface methodology helped to reduce the extraction time, temperature and agitation and subsequently improve the chelating activity of the plants in comparison to the conventional method.

Neuroprotective herbs and foods from different traditional medicines and diets

Plant secondary metabolites include an array of bioactive constituents form both medicinal and food plants able to improve human health. The exposure to these phytochemicals, including phenylpropanoids, isoprenoids and alkaloids, through correct dietary habits, may promote health benefits, protecting against the chronic degenerative disorders mainly seen in Western industrialized countries, such as cancer, cardiovascular and neurodegenerative diseases. In this review, we briefly deal with some plant foods and herbs of traditional medicines and diets, focusing on their neuroprotective active components. Because oxidative stress and neuroinflammation resulting from neuroglial activation, at the level of neurons, microglial cells and astrocytes, are key factors in the etiopathogenesis of both neurodegenerative and neurological diseases, emphasis will be placed on the antioxidant and anti-inflammatory activity exerted by specific molecules present in food plants or in remedies prescribed by herbal medicines.

Elemental profile of cerebrospinal fluid in patients with Parkinson's disease

To ascertain the potential role of chemical elements (namely, Al, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Ni, Pb, Sb, Si, Sn, Sr, Tl, V, W, Zn and Zr) as markers in the Parkinson's disease (PD), the elemental concentration of cerebrospinal fluid (CSF) of 42 patients with PD and 20 age-matched controls was assessed. Analyses were performed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) and Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS). Significantly lower levels of Co, Cr, Fe, Pb, Si and Sn were observed in the CSF of PD patients compared with those in controls, with a percentage of depletion up to 50% for Cr and Pb. No such variations were detected for all the other elements. Results suggested that Pb, Cr, Fe were the most suitable elements to distinguish between normality and PD. Different cut-off concentrations for these elements could be tentatively proposed as a predictive tool for the PD condition.

Epidemiological features of degenerative brain diseases as they occurred in Yaounde referral hospitals over a 9-year period

OBJECTIVE AND METHODS

It was the aim of this study to determine the relative prevalence and characteristics of degenerative disorders of the main central nervous system in Cameroon. Medical files of neurological consultations of the two main teaching hospitals of Yaounde were considered for a 9-year period ranging from 1993 to 2001. Clinical and epidemiological data were recorded for each patient.

RESULTS

Degenerative brain disorders accounted for 3.9% of consultations during the study period. Of the 84 patients received for degenerative disorders, 62 (73.8%) were men. Their age ranged from 9 to 84 years, with a mean of 54.16 years. The main degenerative diseases recorded were the following: Parkinson disease (48.8%), chorea (20.2%), dementia (19%) and amyotrophic lateral sclerosis (12%).

CONCLUSION

Degenerative brain disorders are not rare in our setting. The appropriate diagnosis and management in this environment may be compromised by the prohibitive cost of diagnostic facilities and the lack of qualified personnel.

A case-control study of the association between socio-demographic, lifestyle and medical history factors and multiple sclerosis

OBJECTIVE

The etiology of multiple sclerosis (MS) remains poorly understood. Socio-demographic characteristics may play important roles in its development.

METHODS

In a case-control study of MS, a total of 200 newly diagnosed MS patients and 202 frequency age- and sex-matched controls were studied.

RESULTS

A direct and significant association was observed between cigarette smoking and the risk of MS. Higher education seemed to reduce the risk of MS. Contact with cats was inversely associated with MS, particularly in males, whereas contact with caged birds increased the risk significantly, especially in females. A strong family aggregation of MS was observed among cases. A past history of trauma and eye problems appeared to pose a high risk of MS. Cases had a significant family history of eye problems, mumps, measles, rubella, cancer and auto-immune diseases.

CONCLUSION

If smoking and history of certain infectious diseases increase the risk of MS significantly, they could be modified and avoided, thereby reducing the likelihood of being afflicted by MS.

Genetic and environmental risk factors in Parkinson's disease

Parkinson's disease (PD) is a multifactorial disorder, caused by a combination of age, genetics and environmental factors. Nigral cells are susceptible to multiple causes of derangement of normal cell function, all of which may contribute to the same Parkinson phenotype. Autosomal dominant alpha-synuclein-gene PD represents one of the pure genetic forms, whereas cases of sporadic PD probably depend more on age and environmental factors, MPTP-Parkinsonism being the purest example of an environmentally caused Parkinson phenotype. This review suggests that pesticides-herbicides, smoking and head trauma probably represent the most eligible candidates for environmental factors involved in provoking PD or influencing its natural course.

Epidemiology of mutations in superoxide dismutase in amyotrophic lateral sclerosis

We registered 366 families in a study of dominantly inherited amyotrophic lateral sclerosis. Two hundred ninety families were screened for mutations in the gene encoding copper-zinc cytosolic superoxide dismutase (SOD1). Mutations were detected in 68 families. The most common SOD1 mutation is an alanine for valine substitution in codon 4 (50%). We present clinical and genetic data concerning 112 families with 395 affected individuals. The clinical characteristics of patients with familial amyotrophic lateral sclerosis arising from SOD1 mutations are similar to those lacking SOD1 defects. Mean age at onset was earlier (Wilcoxon test, p = 0.004) in the SOD1 group (46.9 years [standard deviation, 12.5] vs 50.5 years [11.5] in the non-SOD1 group). Bulbar onset was associated with a later onset age. The presence of either of two mutations, G37R and L38V, predicted an earlier age at onset. Kaplan-Meier plots demonstrated shorter survival in the SOD1 group compared with the non-SOD1 group at early survival times (Wilcoxon test, p = 0.0007). The presence of one mutation, A4V, correlated with shorter survival. G37R, G41D, and G93C mutations predicted longer survival. This information suggests it will be productive to investigate other genetic determinants in amyotrophic lateral sclerosis and to use epidemiological characteristics of the disease to help discern molecular mechanisms of motor neuron cell death.

Isolation, characterization, and chromosomal mapping of a novel cDNA clone encoding human selenium binding protein

We have isolated the full-length human 56 kDa selenium binding protein (hSP56) cDNA clone, which is the human homolog of mouse 56 kDa selenium binding protein. The cDNA is 1,668 bp long and has an open reading frame encoding 472 amino acids. The calculated molecular weight is 52.25 kDa and the estimated isoelectric point is 6.13. Using Northern blot hybridization, we found that this 56 kDa selenium binding protein is expressed in mouse heart with an intermediate level between those found in liver/lung/kidney and intestine. We have also successfully expressed hSP56 in Escherichia coli using the expression vector-pAED4. The hSP56 gene is located at human chromosome 1q21-22).

Clinical epidemiology of amyotrophic lateral sclerosis

The introduction of palliative therapies in amyotrophic lateral sclerosis (ALS) will alter the epidemiology of ALS as it is known now. Although incidence rates will remain unchanged in the near future, prevalence rates will likely increase dramatically. Better understanding of the age-specific presentation of motor neuron diseases worldwide will shed light on the vexing questions concerning the variable incidence rates in some countries and apparent incidence gradients in North America and Europe.