Publications by authors named "Manuel Heinzelmann"
Article Synopsis
- * In studies using Sprague-Dawley rats, KTZ exposure showed a dose-dependent increase in corticosterone levels, whereas DES did not affect circulating steroid hormone levels across different ages.
- * The findings indicate that circulating steroid hormone profiles may not be adequate for detecting EDC-induced toxicity, suggesting a need for further research to enhance existing steroidogenesis assays for better regulatory use.
Article Synopsis
- - This study investigates the effects of different sizes and concentrations of polystyrene micro- and nanoplastics (PS-MNPs) on hormone receptor activity and steroid production in lab cell cultures, despite the lack of prior research on their endocrine-disrupting properties.
- - Experimentation revealed that while PS-MNPs were taken up by various cell types, they did not significantly impact estrogen or androgen receptor activity; however, they did alter hormone levels, particularly decreasing estriol and increasing oxidative stress markers in certain cells.
- - The findings suggest that PS-MNPs have limited endocrine-disrupting effects overall, but the notable changes in estriol levels provoke further investigation into the potential risks of MNPs during pregnancy. *
Study Question: What is the effect of the chemical activation (cIVA) protocol compared with fragmentation only (Frag, also known as mechanical IVA) on gene expression, follicle activation and growth in human ovarian tissue ?
Summary Answer: Although histological assessment shows that cIVA significantly increases follicle survival and growth compared to Frag, both protocols stimulate extensive and nearly identical transcriptomic changes in cultured tissue compared to freshly collected ovarian tissue, including marked changes in energy metabolism and inflammatory responses.
What Is Known Already: Treatments based on cIVA of the phosphatase and tensin homolog (PTEN)-phosphatidylinositol 3-kinase (PI3K) pathway in ovarian tissue followed by auto-transplantation have been administered to patients with refractory premature ovarian insufficiency (POI) and resulted in live births. However, comparable effects with mere tissue fragmentation have been shown, questioning the added value of chemical stimulation that could potentially activate oncogenic responses.
Article Synopsis
- There is a lack of comprehensive data on steroid hormones in rat models, especially during early development and in unconventional matrices like the liver.
- The researchers developed a new method using enzymatic solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to measure 23 steroid hormones in liver and plasma from both adult and neonatal rats.
- Their optimized protocol, featuring a recombinant enzyme mix, allows for efficient sample processing and sensitivity in detecting steroid hormones, providing new reference intervals and enhancing understanding of hormone dynamics in early developmental stages.
Background: Immobilization of enzymes onto different carriers increases enzyme's stability and reusability within biotechnological and pharmaceutical applications. However, some immobilization techniques are associated with loss of enzymatic specificity and/or activity. Possible reasons for this loss are mass transport limitations or structural changes.
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