Specific metal-catalysed protein oxidation reactions in chronic degenerative disorders of ageing: focus on Alzheimer's disease and age-related cataracts

Artemisia scoparia and Metabolic Health: Untapped Potential of an Ancient Remedy for Modern Use

Botanicals have a long history of medicinal use for a multitude of ailments, and many modern pharmaceuticals were originally isolated from plants or derived from phytochemicals. Among these, artemisinin, first isolated from Artemisia annua, is the foundation for standard anti-malarial therapies. Plants of the genus Artemisia are among the most common herbal remedies across Asia and Central Europe. The species Artemisia scoparia (SCOPA) is widely used in traditional folk medicine for various liver diseases and inflammatory conditions, as well as for infections, fever, pain, cancer, and diabetes. Modern in vivo and in vitro studies have now investigated SCOPA's effects on these pathologies and its ability to mitigate hepatotoxicity, oxidative stress, obesity, diabetes, and other disease states. This review focuses on the effects of SCOPA that are particularly relevant to metabolic health. Indeed, in recent years, an ethanolic extract of SCOPA has been shown to enhance differentiation of cultured adipocytes and to share some properties of thiazolidinediones (TZDs), a class of insulin-sensitizing agonists of the adipogenic transcription factor PPARγ. In a mouse model of diet-induced obesity, SCOPA diet supplementation lowered fasting insulin and glucose levels, while inducing metabolically favorable changes in adipose tissue and liver. These observations are consistent with many lines of evidence from various tissues and cell types known to contribute to metabolic homeostasis, including immune cells, hepatocytes, and pancreatic beta-cells. Compounds belonging to several classes of phytochemicals have been implicated in these effects, and we provide an overview of these bioactives. The ongoing global epidemics of obesity and metabolic disease clearly require novel therapeutic approaches. While the mechanisms involved in SCOPA's effects on metabolic, anti-inflammatory, and oxidative stress pathways are not fully characterized, current data support further investigation of this plant and its bioactives as potential therapeutic agents in obesity-related metabolic dysfunction and many other conditions.

Topical nutraceutical Optixcare EH ameliorates experimental ocular oxidative stress in rats

PURPOSE

Based on the hypothesis that oral nutraceuticals do not adequately reach all ocular tissues in the anterior segment, we evaluated the ability of a 3% concentration of the ingredients in a topical nutraceutical antioxidant formulation called Optixcare Eye Health (Optixcare EH) to ameliorate oxidative stress in rat models of age-related ocular diseases.

METHODS

Diabetes was induced by tail-vein injection of streptozotocin, and the development of cataracts was monitored by slit lamp. Young rats were exposed to ultraviolet (UV) light, and the reduction in lens glutathione (GSH) levels and increase in 4-hydroxynonenol (4-HNE) were measured. Oxidative stress in the neural retina was generated by exposure of dark-adapted rats to 1,000 lx of light, and oxidative stress markers were measured. Dry eye was induced in rats by twice daily (b.i.d.) subcutaneous scopolamine injections. Topical Optixcare EH was administered b.i.d. and compared in select experiments to the multifunctional antioxidant JHX-4, the topical aldose reductase inhibitor (ARI) Kinostat™, oral Ocu-GLO™, and the topical ocular comfort agents Optixcare Eye Lube, Optixcare Eye Lube + Hyaluron, and Idrop Vet Plus hyaluronic acid.

RESULTS

In diabetic rats, topical ARI treatment prevented cataract formation while the nutraceuticals delayed their development with Optixcare EH>Ocu-GLO. In UV-exposed rats, the reduction of GSH and increase in 4-HNE in the lens were normalized in order JHX-4>Optixcare EH>Ocu-GLO. In the retina, oxidative stress markers were reduced better by oral JHX-4 compared with topical Optixcare EH. In the scopolamine-induced dry-eye rats, tear flow was maintained by Optixcare EH treatment, while none of the comfort agents examined altered tear flow.

CONCLUSIONS

Topical administration of a 3% concentration of the ingredients in Optixcare EH reduces experimentally induced reactive oxygen species in rats exposed to several sources of ocular oxidative stress. In addition, Optixcare EH maintains tear volume in scopolamine-induced dry eye. This suggests that in the anterior segment, the ingredients in Optixcare EH may have clinical potential against ocular oxidative stress.

Cataract: Window for systemic disorders

Cataract is the leading cause of visual handicap throughout the world, and almost all elderly individuals develop lens opacities. Epidemiological studies have shown that nuclear cataracts in young adults are associated with higher mortality. Many cataractogenic stressors induce endoplasmic reticulum (ER) stress, which in turn induces the unfolded protein response (UPR). The UPR can damage or kill a wide range of cell types and may be involved in many human diseases. We hypothesize that a cataract can be considered a window that can indicate the presence of systemic disorders. This is important because cataract is easily detected during a routine ocular examination. The slightest opacity in any region of the lenses, especially in younger patients, may be a sign of systemic disorders. Earlier detection of systemic disorders can save the lives of patients. If our hypothesis is correct, then elimination of known ER/cataractogenic stressors from individuals with cataracts should be the one of the first steps for treatments of the systemic disorders. We discuss the potential risk factors and beneficial effects of removal of such risk factors in patients with early cataracts. All patients with cataract should be referred for comprehensive medical examination.

La lunga attesa: towards a molecular approach to neuroimaging and therapeutics in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are Aβ amyloid plaques, neurofibrillary tangles (NFT), synaptic loss and reactive gliosis. Current diagnosis of AD is made by clinical, neuropsychologic, and neuroimaging assessments. Routine structural neuroimaging evaluation with computed tomography (CT) and magnetic resonance imaging (MRI) is based on non-specific features such as atrophy, a late feature in the progression of the disease, hence the crucial importance of developing new approaches for early and specific recognition at the prodromal stages of AD. Functional neuroimaging techniques such as functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET) and single photon emission computed tomography (SPECT), possibly in conjuction with other related Aβ biomarkers in plasma and CSF, could prove to be valuable in the differential diagnosis of AD, as well as in assessing prognosis. With the advent of new therapeutic strategies aimed at reducing the Aβ amyloid burden in the brain, there is increasing interest in the development of MRI contrast agents and PET and SPECT radioligands that will permit the assessment of Aβ amyloid burden in vivo. - ma dov'è / la lenta processione di stagioni / che fu un'alba infinita e senza strade, / dov'è la lunga attesa e qual è il nome / del vuoto che ci invade. - Eugenio Montale.

Imaginem oblivionis: the prospects of neuroimaging for early detection of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are A beta amyloid plaques, neurofibrillary tangles, and reactive gliosis. Current diagnosis of AD is made by clinical, neuropsychologic, and neuroimaging assessments. Routine structural neuroimaging evaluation is based on non-specific features such as atrophy, a late feature in the progression of the disease, hence the crucial importance of developing new approaches for early and specific recognition at the prodromal stages of AD. Functional neuroimaging techniques such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) could prove to be valuable in the differential diagnosis of AD, as well as in assessing prognosis. With the advent of new therapeutic strategies aimed at reducing the A beta amyloid burden in the brain, there is increasing interest in the development of PET and SPECT radioligands that will permit the assessment of A beta amyloid burden in vivo. From this, the prospect of specific preclinical diagnosis arises, possibly in conjunction with other related A beta biomarkers in plasma and CSF.

Cytosolic beta-amyloid deposition and supranuclear cataracts in lenses from people with Alzheimer's disease

BACKGROUND

Pathological hallmarks of Alzheimer's disease include cerebral beta-amyloid (Abeta) deposition, amyloid accumulation, and neuritic plaque formation. We aimed to investigate the hypothesis that molecular pathological findings associated with Alzheimer's disease overlap in the lens and brain.

METHODS

We obtained postmortem specimens of eyes and brain from nine individuals with Alzheimer's disease and eight controls without the disorder, and samples of primary aqueous humour from three people without the disorder who were undergoing cataract surgery. Dissected lenses were analysed by slit-lamp stereophotomicroscopy, western blot, tryptic-digest/mass spectrometry electrospray ionisation, and anti-Abeta surface-enhanced laser desorption ionisation (SELDI) mass spectrometry, immunohistochemistry, and immunogold electron microscopy. Aqueous humour was analysed by anti-Abeta SELDI mass spectrometry. We did binding and aggregation studies to investigate Abeta-lens protein interactions.

FINDINGS

We identified Abeta1-40 and Abeta1-42 in lenses from people with and without Alzheimer's disease at concentrations comparable with brain, and Abeta1-40 in primary aqueous humour at concentrations comparable with cerebrospinal fluid. Abeta accumulated in lenses from individuals with Alzheimer's disease as electron-dense deposits located exclusively in the cytoplasm of supranuclear/deep cortical lens fibre cells (n=4). We consistently saw equatorial supranuclear cataracts in lenses from people with Alzheimer's disease (n=9) but not in controls (n=8). These supranuclear cataracts colocalised with enhanced Abeta immunoreactivity and birefringent Congo Red staining. Synthetic Abeta bound alphaB-crystallin, an abundant cytosolic lens protein. Abeta promoted lens protein aggregation that showed protofibrils, birefringent Congo Red staining, and Abeta/alphaB-crystallin coimmunoreactivity.

INTERPRETATION

Abeta is present in the cytosol of lens fibre cells of people with Alzheimer's disease. Lens Abeta might promote regionally-specific lens protein aggregation, extracerebral amyloid formation, and supranuclear cataracts.

Lens defects and age-related fiber cell degeneration in a mouse model of increased AbetaPP gene dosage in Down syndrome

Early-onset cataract and Alzheimer's disease occur with high frequency in Down syndrome (trisomy 21), the most common chromosome duplication in human live births. Previously, we used in vivo and lens organ culture models to demonstrate Alzheimer pathophysiology in oxidative stress-related lens degeneration. Currently, well-characterized Alzheimer transgenic mouse models are used to extend these findings. Here, we report on mice carrying a complete copy of a wild-type human AbetaPP (hAbetaPP) gene from the Down syndrome critical region on chromosome 21. hAbetaPP mice produce fiber cell membrane defects similar to those described in human cataracts and increased age-related lens degeneration. hAbetaPP expression and mRNA alternative splicing in human and mouse lens and cornea favor longer, potentially more amyloidogenic forms. Endogenous mouse AbetaPP expression is increased in transgenic lenses, consistent with the cycle of oxidative stress proposed in the mechanism of Alzheimer pathophysiology. Alternative splicing previously designated as neuron-specific occurs in human lens and cornea, and is maintained by hAbetaPP expressed in mouse tissues. These present data implicate AbetaPP in fiber cell formation and in early-onset cataracts in Down syndrome. Finally, our findings provide further support for our hypothesis that Alzheimer pathophysiology contributes to the cataract formation that is increasing in the aging population.

Iron in neurodegenerative disorders

Increasing evidence implicates a role of iron in the pathogenesis of numerous neurodegenerative diseases due to its capacity to enhance production of toxic reactive radicals and to induce protein aggregation. The underlying mechanism of iron accumulation in areas of the brain specific for the respective disease, however, is still unknown. Recent molecular and biochemical studies provide new insights into the consequences of impairment of brain iron metabolism. This review summarizes our understanding of the regulation of iron in the brain and defines the current knowledge on the involvement of iron metabolism in neurodegenerative diseases with genetically determined iron accumulation in the brain.

'...and C is for Clioquinol' - the AbetaCs of Alzheimer's disease

Alzheimer's disease (AD) is a devastating age-related neurodegenerative disorder that has been intensively studied over the last several years. In vitro and in vivo studies have led to an understanding of some of the physico-chemical properties of amyloid, a well-characterized hallmark of AD. Clioquinol is a drug that acts on amyloid by perturbing amyloid's metallo-chemistry, and Clioquinol treatment has been shown to be beneficial in a mouse model of AD. This short review examines the recent studies relating to Clioquinol and AD, and anticipates the imminent results of a Phase II trial of Clioquinol in AD, due in March 2002.