Tissue concentrations of both homocysteine (Hcy) and cysteine (Cys) are maintained at low levels by regulated production and efficient removal of these thiols. The regulation of the metabolism of methionine and Cys is discussed from the standpoint of maintaining low levels of Hcy and Cys while, at the same time, ensuring an adequate supply of these thiols for their essential functions. S-Adenosylmethionine coordinately regulates the flux through remethylation and transsulfuration, and glycine N-methyltransferase regulates flux through transmethylation and hence the S-adenosylmethionine/S-adenosylhomocysteine ratio. Cystathionine beta-synthase activity is also regulated in response to the redox environment, and transcription of the gene is hormonally regulated in response to fuel supply (insulin, glucagon, and glucocorticoids). The H2S-producing capacity of cystathionine gamma-lyase may be regulated in response to nitric oxide. Cys is substrate for a variety of anabolic and catabolic enzymes. Its concentration is regulated primarily by hepatic Cys dioxygenase; the level of Cys dioxygenase is upregulated in a Cys-responsive manner via a decrease in the rate of polyubiquitination and, hence, degradation by the 26S proteasome.

SULFUR AMINO ACID METABOLISM: Pathways for Production and Removal of Homocysteine and Cysteine

Hallervorden-Spatz syndrome (HSS) is an autosomal recessive neurodegenerative disorder associated with iron accumulation in the brain. Clinical features include extrapyramidal dysfunction, onset in childhood, and a relentlessly progressive course. Histologic study reveals iron deposits in the basal ganglia. In this respect, HSS may serve as a model for complex neurodegenerative diseases, such as Parkinson disease, Alzheimer disease, Huntington disease and human immunodeficiency virus (HIV) encephalopathy, in which pathologic accumulation of iron in the brain is also observed. Thus, understanding the biochemical defect in HSS may provide key insights into the regulation of iron metabolism and its perturbation in this and other neurodegenerative diseases. Here we show that HSS is caused by a defect in a novel pantothenate kinase gene and propose a mechanism for oxidative stress in the pathophysiology of the disease.

A novel pantothenate kinase gene ( PANK2 ) is defective in Hallervorden-Spatz syndrome

Parkinson's disease evolves slowly, and there is current interest in exploring the earliest stages of the disorder, because of new approaches to studying pathogenesis and developing potential neuroprotective treatment. Recognizing early Parkinson's disease is not easy. The certainty of diagnosis increases as the disease advances. To address the problem of identifying Parkinson's disease in its initial phases of clinical expression, we propose the following designated levels of confidence for the diagnosis: (1) clinically possible, (2) clinically probable, and (3) clinically definite. Laboratory support for the diagnosis may be applied to each category. Criteria are provided as a framework underpinning this classification.

Criteria for diagnosing Parkinson's disease.

Background Olfactory deficits in Alzheimer's disease (AD) and idiopathic Parkinson's disease (PD) have been well established. Objective To clarify and review the literature by evaluating the evidence for olfactory deficits in 3 olfactory domains, including odor identification, recognition, and detection threshold. Data Sources A literature search of English-language studies of olfaction in AD, PD, and healthy controls was conducted via online databases (PsycInfo and MEDLINE) and reference lists from review articles. Study Selection To meet selection criteria for meta-analysis, each study required a control group and complete and usable data. This review yielded 26 publications of olfactory identification, recognition, and/or detection threshold. Because of the inclusion of more than 1 relevant study of olfaction in several of these publications (eg, both identification and threshold assessed), 43 studies were ultimately appropriate for meta-analysis. Data Extraction Effect sizes were calculated for each study by expressing differences between patient and control group means in SD units (Cohen's d ). Data Synthesis Extremely large effect sizes were shown across all tasks in both AD and PD groups. Both between-group analyses using the Mann-Whitney U test and within-group analyses using Friedman 2-way analysis of variance did not reveal any significant differences (all P >.30). Conclusions As expected, severe deficits were found for both patients with AD and PD in each of the 3 olfactory domains relative to controls. However, no discriminating olfactory deficits were seen between patient groups or among the 3 measured olfactory domains, suggesting a similar disturbance in olfactory function between patients with AD and PD.

https://jamanetwork.com/journals/jamaneurology/articlepdf/773547/noc7055.pdf

Olfaction in Neurodegenerative Disease: A Meta-analysis of Olfactory Functioning in Alzheimer's and Parkinson's Diseases

Because of the biological importance of thiols, the development of probes for thiols has been an active research area in recent years. In this review, we summarize the results of recent exciting reports regarding thiol-addition reactions and their applications in thiol recognition. The examples reported can be classified into four reaction types including 1,1, 1,2, 1,3, 1,4 addition reactions, according to their addition mechanisms, based on different Michael acceptors. In all cases, the reactions are coupled to color and/or emission changes, although some examples dealing with electrochemical recognition have also been included. The use of thiol-addition reactions is a very simple and straightforward procedure for the preparation of thiol-sensing probes.

Thiol-addition reactions and their applications in thiol recognition

Plasma cysteine and sulphate levels in patients with motor neurone, Parkinson's and Alzheimer's disease.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Fearn S

Author Tools

Chat about Author

Papers

Plasma cysteine and sulphate levels in patients with motor neurone, Parkinson's and Alzheimer's disease.