Synteettisten biohajoavien polymeerien lääketieteellinen laatuluokitus

Lääketieteessä käytetään paljon synteettisiä biohajoavia polymeerejä. Niitä on muun muas-sa implanteissa, kudosteknologian tukimateriaaleissa sekä lääkkeiden annostelujärjestelmissä. Vaikka lääketieteessä käytetään monia eri materiaaleja, niiden laadulle ei ole yhdenmukaista määritelmää. Lääkinnällisten laitteiden lopulliseen laatuun ja bioyhteensopivuuteen vaikuttavat monet asiat, mutta tässä työssä keskitytään niiden raaka-aineisiin ja vaikutuksiin. Työssä selvi-tetään, mitä lääketieteellinen laatu tarkoittaa ja mitä käytetyiltä materiaaleilta vaaditaan. Lisäksi tarkastellaan markkinoilla olevien synteettisten biohajoavien polymeerien saatavuutta ja niiden vastaamista laatuvaatimuksiin. Kirjallisuuskatsaus jakautuu kolmeen osaan: Ensimmäisessä osassa esitellään synteettisiä biohajoavia polymeerejä, joita käytetään lääketieteellisissä tarkoituksissa, ja analysoidaan nii-den bioyhteensopivuutta sekä siihen vaikuttavia asioita. Toisessa osassa esitellään lääketieteel-lisiin materiaaleihin kohdistuvia säädöksiä. Viimeisessä osassa käydään läpi markkinoilla olevia ja lääketieteellisiin tarkoituksiin myytäviä synteettisiä biohajoavia polymeerejä. Osiossa tutkitaan materiaalien saatavuutta ja sitä, miten materiaalien lääketieteellinen laatu markkinoilla osoite-taan. Työ osoittaa, että tärkeydestään huolimatta lääketieteellisten materiaalien koostumusta sekä markkinointia valvotaan suhteellisen vähän. Joitakin säädöksiä tulee kuitenkin vastaan, kun lää-ketieteellisen materiaalin haluaa saada markkinoille. Esimerkiksi lopullinen käyttötarkoitus ja valmistuksessa käytetyt aineet vaikuttavat materiaalivaatimuksiin. Materiaalien säädökset jää-vät silti vain osaksi lääkinnällisten laitteiden säätelyä, eivätkä ne määrittele raaka-aineiden laa-tua. Tutkimuksessa käy myös ilmi, että lääketieteellisten materiaalien laadun määrittelemättö-myys heijastuu biohajoavien polymeerien markkinoille. Yritysten myymien materiaalien laadun osoittaminen vaihtelee ja useimmiten se todistetaan osana yrityksen noudattamaa laatujärjes-telmää. Varsinaisen materiaalin laadun osoittaminen ostajalle voi kuitenkin jäädä todella vä-häiseksi. Synteettisten biohajoavien polymeerien saatavuus perustuu materiaalin käyttöhistori-aan ja pätevään dataan sen turvallisesta käytöstä. Tästä syystä uusia materiaaleja on lääketie-teessä työläämpää ottaa käyttöön, koska ne vaativat tarkemman testauksen.Synthetic biodegradable polymers are a widely used material group in the medical field. They are used for example in implants, as scaffolds in tissue engineering and in drug delivery systems. Even though many different materials are used in the medical field, there is no unified definition for medical grade materials. There are a lot of factors that affect the quality and biocompatibility of a medical device, but this paper concentrates on the raw material and its effects. This work aims to find out what medical quality in a material means and what is required of a material so that it can be called medical grade. In addition, the paper examines commercial synthetic biodegradable medical grade polymers’ availability and how they meet the requirements. Literary survey is divided into three parts: The first section presents synthetic biodegradable polymers and their uses in the medical field. In addition, material’s biocompatibility and things that influence it are viewed in this section. The second part presents different regulations and standards that focus on biomedical materials. The last part reviews availability of synthetic biodegradable medical grade polymers in the current market and examines how companies prove the medical quality of their materials. This research conducted that even though medical materials are important, the supervision of their composition and marketing is relatively low. However, some requirements are mandatory when medical grade material is put into the market. For example, things like the material’s final use and the substances used in the polymerization affect the material requirements. Regulations and standards are still mainly directed at medical devices and materials are just a part of that entity. Regulations do not define the medical grade classification of materials. In addition, this work shows that the obscurity of the medical quality is reflected in the biodegradable polymer market. The way that material companies prove their material’s quality varies, but mainly they associate the quality of their products to the company complying with quality standards. Still, from the customer’s perspective the actual proof of the material’s medical quality may remain minimal. The availability of synthetic biodegradable polymers is related to the material’s long use in medicine and reliable data on it. Therefore, new materials are more complex to utilize in the medical field due to their more demanding testing

An immunocapture-LC-MS-based assay for serum SPINK1 allows simultaneous quantification and detection of SPINK1 variants

Pancreatic secretory trypsin inhibitor Kazal type 1 (SPINK1) is a 6420 Da peptide produced by the pancreas, but also by several other tissues and many tumors. Some mutations of the SPINK1 gene, like the one causing amino acid change N34S, have been shown to confer susceptibility to recurrent or chronic pancreatitis. Detection of such variants are therefore of clinical utility. So far SPINK1 variants have been determined by DNA techniques. We have developed and validated an immunocapture-liquid chromatography-mass spectrometric (IC-LC-MS) assay for the detection and quantification of serum SPINK1, N34S-SPINK1, and P55S-SPINK1. We compared this method with a time-resolved immunofluorometric assay (TR-IFMA) for serum samples and primer extension analysis of DNA samples. We used serum and DNA samples from patients with acute pancreatitis, renal cell carcinoma, or benign urological conditions. With the help of a zygosity score calculated from the respective peak areas using the formula wild-type (wt) SPINK1/(variant SPINK1 + wt SPINK1), we were able to correctly characterize the heterozygotes and homozygotes from the samples with DNA information. The score was then used to characterize the apparent zygosity of the samples with no DNA characterization. The IC-LC-MS method for SPINK1 was linear over the concentration range 0.5-1000 mu g/L. The limit of quantitation (LOQ) was 0.5 mu g/L. The IC-LC-MS and the TR-IFMA assays showed good correlation. The median zygosity score was 1.00 (95% CI 0.98-1.01, n = 11), 0.55 (95% CI 0.43-0.61, n = 14), and 0.05 (range 0.04-0.07, n = 3) for individuals found to be wt, heterozygous, and homozygous, respectively, for the N34S-SPINK1 variant by DNA analysis. When DNA samples are not available, this assay facilitates identification of the N34S- and P55S-SPINK1 variants also in archival serum samples.Peer reviewe

Inhibition of β2Integrin–Mediated Leukocyte Cell Adhesion by Leucine–Leucine–Glycine Motif–Containing Peptides

Many integrins mediate cell attachment to the extracellular matrix by recognizing short tripeptide sequences such as arginine–glycine–aspartic acid and leucine–aspartate–valine. Using phage display, we have now found that the leukocyte-specific β2 integrins bind sequences containing a leucine–leucine–glycine (LLG) tripeptide motif. An LLG motif is present on intercellular adhesion molecule (ICAM)-1, the major β2 integrin ligand, but also on several matrix proteins, including von Willebrand factor. We developed a novel β2 integrin antagonist peptide CPCFLLGCC (called LLG-C4), the structure of which was determined by nuclear magnetic resonance. The LLG-C4 peptide inhibited leukocyte adhesion to ICAM-1, and, interestingly, also to von Willebrand factor. When immobilized on plastic, the LLG-C4 sequence supported the β2 integrin–mediated leukocyte adhesion, but not β1 or β3 integrin–mediated cell adhesion. These results suggest that LLG sequences exposed on ICAM-1 and on von Willebrand factor at sites of vascular injury play a role in the binding of leukocytes, and LLG-C4 and peptidomimetics derived from it could provide a therapeutic approach to inflammatory reactions

Comparative Metaproteomics and Diversity Analysis of Human Intestinal Microbiota Testifies for Its Temporal Stability and Expression of Core Functions

Peer reviewe

The molecular relationship between antigenic domains and epitopes on hCG

Antigenic domains are defined to contain a limited number of neighboring epitopes recognized by antibodies (Abs) but their molecular relationship remains rather elusive. We thoroughly analyzed the antigenic surface of the important pregnancy and tumor marker human chorionic gonadotropin (hCG), a cystine knot (ck) growth factor, and set antigenic domains and epitopes in molecular relationships to each other. Antigenic domains on hCG, its free hCGα and hCGβ subunits are dependent on appropriate inherent molecular features such as molecular accessibility and protrusion indices that determine bulging structures accessible to Abs. The banana-shaped intact hCG comprises ∼7500 Å2 of antigenic surface with minimally five antigenic domains that encompass a continuum of overlapping non-linear composite epitopes, not taking into account the C-terminal peptide extension of hCGβ (hCGβCTP). Epitopes within an antigenic domain are defined by specific Abs, that bury nearly 1000 Å2 of surface accessible area on the antigen and recognize a few up to 15 amino acid (aa) residues, whereby between 2 and 5 of these provide the essential binding energy. Variability in Ab binding modes to the contact aa residues are responsible for the variation in affinity and intra- and inter-species specificity, e.g. cross-reactions with luteinizing hormone (LH). Each genetically distinct fragment antigen binding (Fab) defines its own epitope. Consequently, recognition of the same epitope by different Abs is only possible in cases of genetically identical sequences of its binding sites. Due to combinatorial V(D)J gene segment variability of heavy and light chains, Abs defining numerous epitopes within an antigenic domain can be generated by different individuals and species. Far more than hundred Abs against the immuno-dominant antigenic domains of either subunit at both ends of the hCG-molecule, the tips of peptide loops one and three (Ł1 + 3) protruding from the central ck, encompassing hCGβŁ1 + 3 (aa 20–25 + 64 + 68–81) and hCGαŁ1 (aa 13–22; Pro16, Phe17, Phe18) plus hCGαŁ3 (Met71, Phe74), respectively, have been identified in the two “ISOBM Tissue Differentiation-7 Workshops on hCG and Related Molecules” and in other studies. These Abs recognize distinct but overlapping epitopes with slightly different specificity profiles and affinities. Heterodimeric-specific epitopes involve neighboring αŁ1 plus βŁ2 (hCGβ44/45 and 47/48). Diagnostically important Abs recognize the middle of the molecule, the ck (aa Arg10, Arg60 and possibly Gln89) and the linear hCGβCTP “tail” (aa 135–145; Asp139, Pro144, Gln145), respectively. Identification of antigenic domains and of specific epitopes is essential for harmonization of Abs in methods that are used for reliable and robust hCG measurements for the management of pregnancy, pregnancy-related disease and tumors