Urinary Hydroxy-Proline Estimation Is Cheap Biochemical Marker of Bone Turnover in Post Menopausal Women

Sabiullah, Mohammed; Suleman, Dawood; Rehmatunissa, Rehmatunissa; Ather,; Nasreen, Nasreen

doi:10.22270/jddt.v5i4.1155

Cited by 2 publications

(1 citation statement)

References 4 publications

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“…Considering that different types of real samples contain different percentages of d -amino acids, the d -amino acid content within an isotopically labeled internal standard should meet these requirements. Nonribosomal lipopeptides, for instance, contain not only an unexpectedly large number of proteinogenic d -amino acids, which may even exceed the racemic 50% level, but also many uncommon amino acids, such as aThr, homoserine (Hse), aIle, and hydroxylproline (Hyp), just to name a few. On the other hand, physiological fluids may contain trace amounts of d -amino acids and require isotopically labeled IS with below 1% to 10% d -amino acids. , …”

Section: Resultsmentioning

confidence: 99%

Derivatize, Racemize, and Analyze—an Easy and Simple Procedure for Chiral Amino Acid Standard Preparation for Enantioselective Metabolomics

Horak

Lämmerhofer

2019

Anal. Chem.

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A simple, controllable, and reproducible stereoisomerization (racemization and epimerization) protocol for the preparation of scalemic α-amino acid mixtures from stereoisomerically pure standards was developed. Simply derivatize your amino acids with a racemization tag that incorporates a urea bond on the N-terminus of the target amino acid and incubate at elevated temperatures up to 95 °C for defined time periods until the targeted d-amino acid levels are obtained. The racemization tags investigated were 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC), aminophenyl-N-hydroxysuccinimidyl carbamate (AC), and 3-aminopyridyl-N-hydroxysuccinimidyl carbamate (APC). Employing this method, it was possible to create a ready-to-use, tailor-made chiral uniformly 13C and 15N labeled [U- 13C15N]-amino acid standard with the desired d-amino acid percentage within minutes or hours without sample cleanup. A racemization time of 30 min at 95 °C will lead to a d-amino acid level of 1–5%, while 6 h at 95 °C provides 15–30% d-amino acids. Racemization occurs due to imine formation at the chiral carbon atom bound to the urea-linking group without decomposition of labile amino acids such as Asn, Gln, Trp, Cit, and theanine. For amino acids possessing two chiral centers such as dl-Ile or dl-Thr, only the epimerization of isomers with different stereochemistry at the second chiral center will produce all four possible isobaric enantiomers. All measurements were performed on the zwitterionic Chiralpak ZWIX(+) column using a dual hydro-organic flow gradient combined with HPLC-ESI-QTOF-MS analysis. This new racemization method solves the problem of (enantioselective) matrix effects and inaccurate results in LC-MS based enantioselective metabolomics and warrants full MS-compatibility.

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Section: Resultsmentioning

confidence: 99%

Derivatize, Racemize, and Analyze—an Easy and Simple Procedure for Chiral Amino Acid Standard Preparation for Enantioselective Metabolomics

Horak

Lämmerhofer

2019

Anal. Chem.

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The mechanics and biomechanics of OASIS POP and incontinence—is active management of labour protective?

2020

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The mechanics of labour traditionally concern the 3Ps, powers, passages and passengers. Studies on OASIS prevention seem concentrated on minimizing trauma to the passages. A recent study examined the powers (uterine contraction strength). It concluded that passive management of labour was more likely to cause weaker contractions, head deflexion and a larger presenting part, which was more likely to tear the anal sphincter. Comparing third and fourth degree tears (8.17%) from 100,000 primiparous women against an independent control group with the O'Driscoll active management regime (2.5% tear rate), the authors concluded that a deflexed foetal head (11.2 cm diameter) was more likely to overstretch the vagina, ligaments and external anal sphincter muscles than a flexed head (9.4 cm).The study [1] raised further questions: why do only some women undergoing passive management primiparous deliveries suffer OASIS, while most, even with a deflexed head, do not? Do the same mechanics of OASIS carry over to pelvic organ prolapse (POP) and symptom causation?To answer these questions, we examined the biomechanics of labour/delivery from a dynamic tissue injury perspective. It is evident that a foetal head at full dilatation (10 cm) will put considerable stress on the cardinal/uterosacral ligaments. What prevents these ligaments from rupturing in the vast majority of cases is that the change in collagen and glycosaminaoglycans effectively "plasticizes" the ligaments so they stretch rather than rupture. This is necessary, as the inlet and outlet diameters through which the head must pass are no more than 12-13 cm. Collagen fibrils depolymerize to lose up to 93% of their strength [2]. Pregnancy-associated softening of the uterine cervix occurs 48 h before labour. The biomechanical changes are extremely complex and not well understood. They can be explained at least partly by qualitative changes in the collagen and proteoglycans, for example an increase in dermatan sulphate. These reactions seem to be mediated by sex steroids by eicosanoids such as prostaglandin E2 and F2a and perhaps by relaxin, leukotrines and cytokines [3]. Fibroblasts, inflammatory cells such as polymorphonuclear leukocytes, eosinophils and macrophages are also of great importance, as is collagenase [3].However, not all connective tissue is protected from rupture by softening. At the pelvic inlet, dilatation of the cervix to 10 cm may overstretch the anterior attachments of the cardinal ligaments and pubocervical vaginal fascia to the cervical ring to actually tear them, causing a transverse defect (high cystocele). Approaching the outlet, damage to the pubourethral ligaments may cause stress urinary incontinence; the ATFP may become overstretched to dislocate from the pubic bone or, more likely, its attachment to the ischial spine; collagenous attachments of levators to the symphysis may cause overstretching. As the head descends to pass the pelvic outlet, the perineum must expand for the head to emerge.Why does the anal sphincter rupture? Whereas ligament...

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Urinary Hydroxy-Proline Estimation Is Cheap Biochemical Marker of Bone Turnover in Post Menopausal Women

Cited by 2 publications

References 4 publications

Derivatize, Racemize, and Analyze—an Easy and Simple Procedure for Chiral Amino Acid Standard Preparation for Enantioselective Metabolomics

Derivatize, Racemize, and Analyze—an Easy and Simple Procedure for Chiral Amino Acid Standard Preparation for Enantioselective Metabolomics

The mechanics and biomechanics of OASIS POP and incontinence—is active management of labour protective?

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