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PubMed1999

Increased bioactive luteinizing hormone levels and bio/immuno ratio in women with hyperthecosis of the ovaries: possible role of hyperinsulinemia.

Unlike women with polycystic ovarian disease, women with hyperthecosis have normal or low immunoactive LH levels. They have severe insulin resistance with marked hyperinsulinemia. Bioactive LH levels have not been studied in these women. The purpose of this study was to investigate 1) whether there is an increase in bioactive LH levels in women with hyperthecosis of the ovaries and 2) whether hyperinsulinemia has an effect on LH secretion. Six women with hyperthecosis of the ovaries confirmed by histological examination were included in the study. Six normal women in the midproliferative phase of the cycle served as controls. All women were admitted to the Clinical Research Center at 0800 h, and blood samples were obtained every 15 min for 6 h. All samples were assayed for LH by RIA and bioassay. The PC Pulsar Program was used for pulse analysis of LH secretion. Patients with hyperthecosis had significantly higher (P < 0.002) bioactive LH levels (66.9 +/- 13 mIU/mL) than controls (29.3 +/- 6 mIU/mL). Immunoactive LH levels in hyperthecosis were not significantly different from those in control women. Significantly higher bio/immuno LH ratios (P < 0.001) were observed in women with hyperthecosis (6.2 +/- 0.9) than in normal control women (2.4 +/- 0.5). There was a significant positive correlation between insulin levels and the bio/immuno ratio of LH. Pulse amplitude and interpulse intervals for immunoactive LH in hyperthecosis patients were similar to those in control women. The pulse amplitude of bioactive LH was significantly higher (P < 0.01) in women with hyperthecosis compared to that in normal controls. Hyperinsulinemia induced during LH sampling resulted in increased bioactive LH levels with no change in immunoactive LH. These results indicate that 1) women with hyperthecosis of the ovaries have increased secretion of biologically active LH, and 2) hyperinsulinemia may enhance the secretion of the biologically active form of LH.

Adult↗

PubMed2002

A new recombinant cell bioassay for ultrasensitive determination of serum estrogenic bioactivity in children.

The evaluation of estrogenic status is necessary for many physiological and pathological conditions in pediatric as well as adult endocrinology. Because current immunoassays exclusively measure E2--and with a sensitivity that is insufficient for prepubertal children--we developed a new recombinant cell bioassay for ultrasensitive determination of serum estrogenic bioactivity. This assay is based on human uterine cervix carcinoma cells, HeLa cells, that do not naturally express E2 receptor. These cells were transfected with plasmids encoding the human ERalpha or beta, along with an estrogen-responsive promoter fused to the luciferase gene, and called HELNalpha and HELNbeta for HeLa estrogen-responsive element luciferase neomycin alpha and beta. HELNalpha and HELNbeta are able to respond to estrogens and various compounds having estrogenic activity but, because of the importance of ERalpha in the reproductive function, we chose to work with the HELNalpha cell line. The luciferase activity we obtained was compared with an E2 standard curve specific for each serum sample and established with stripped serum. The estrogenic bioactivity was expressed in picograms of E2 equivalents, and the detection limit was < 1 pg x ml(-1) E2 equivalents. The intra and interassay error was lower than 10% and 20%, respectively. We measured estrogenic bioactivity in 18 normal prepubertal boys (age = 9.7 +/- 2.4 yr), 18 normal prepubertal girls (age = 9.2 +/- 1.7 yr) and 18 normal pubertal girls (age = 13.6 +/- 1.8 yr). The estrogenic bioactivity in the prepubertal girls was significantly higher than in the boys, i.e. 3.53 +/- 2.23 pg x ml(-1) vs. 1.44 +/- 0.87 pg x ml(-1) (P < 0.01). A significant difference was found between the pre- and pubertal girls, i.e. 3.53 +/- 2.23 pg x ml(-1) vs. 26.77 +/- 18.32 pg x ml(-1) (P < 0.01). This ultrasensitive bioassay measures total estrogenic bioactivity of serum with very high sensitivity. It has numerous potential applications in pediatric and adult endocrinology. In addition, this assay may help to evaluate excess estrogenic activity related to aromatase overexpression or contamination by environmental chemicals.

Biological Assay↗

PubMed1989

Serum prolactin in uraemia: correlations between bioactivity and activity in two immunoassays.

The clinical significance of hyperprolactinaemia in uraemic patients is uncertain and discrepancies between immunoactivity and biological activity of serum hPRL have been reported. We have modified the Nb2 cell bioassay to improve specificity for hPRL and used this assay to measure hPRL bioactivity in sera from 26 uraemic patients and 40 control subjects. Seventeen patients were receiving regular haemodialysis and 9 continuous ambulatory peritoneal dialysis. Levels of hPRL bioactivity were compared with hPRL immunoactivity measured by RIA (PRL-RIA) and by immunoradiometric assay (PRL-IRMA). Serum hPRL levels measured by all three assays were significantly elevated in uraemic patients compared with control subjects (P less than 0.001). The immunoradiometric method gave significantly lower results than RIA in control subjects but not in uraemic patients (P less than 0.05). There was no significant difference in mean ratio of hPRL bioactivity to PRL-RIA between patients and control subjects (1.18 +/- 0.05 vs 1.11 +/- 0.03, mean +/- SEM). The ratio of hPRL bioactivity to PRL-IRMA was slightly decreased in uraemic patients compared with controls (P = 0.05). Serum hPRL bioactivity was closely correlated with immunoactivity in both immunoassays (r greater than or equal to 0.96) in patients and controls. These results confirm that elevated serum hPRL levels in uraemic patients represent biologically active hormone which may contribute to hypogonadism.

Adult↗

PubMed2005

Bioactive glass efficacy in the periodontal healing of intrabony defects in monkeys.

The purpose of this study was the histomorphologic analysis of the efficacy of bioactive glass particles with a narrow size range (Biogran) in the periodontal healing of 2-wall intrabony defects in monkeys. The 2-wall defects were made in the mesial area of the left and right second premolars of four monkeys, filled with gutta-percha and, after 15 days, they were debrided and either naturally filled with coagulum (control) or implanted with bioactive glass (test). In the control sites, the junctional epithelium migrated up to the base of the defect. The presence of newly formed cementum was more significant in the test defects. Both control and test sites showed newly formed bone at the base of the defect. The test defects presented foci of newly formed bone around and within the glass particles localized in the middle third, distant from the defect walls. Histologic analysis showed that the 300- to 355-microm bioactive glass particles aided new periodontal insertion. In conclusion, the tested bioactive glass had better healing potential than debridement only. The graft material showed a promising inhibition of apical migration of the junctional epithelium and greater cementum deposition on the radicular surface of the intrabony defects. The replacement of bioactive glass particles by new bone occurred due not only to an osteoconductive property, but also to an osteostimulatory capacity. Future investigations should evaluate this potential comparatively or together with other grafting materials, regenerative techniques and biological modifiers, as well as assess the longitudinal stability of the new attachment.

Alveolar Bone Loss↗

PubMed2005

Bioactive glass three decades on.

Bioglasses were first introduced in the early 1970s and since have found wide use in dentistry. The original 45S5 bioglass, as described by Hench, is a silica-based melt-derived glass characterized by a Si02 content of less than 60%, a high Na2O and CaO content, and a high CaO:P2O5 ratio. Bioactivity has been defined as the ability of an implant to form a bond with living tissue. These glasses exhibit bone bonding, a phenomenon also observed with other bioactive ceramics. This process is a result of the surface reactive silica, calcium, and phosphate groups that are characteristic of these materials. Silica is believed to play a critical role in bioactivity. Bioactive glass is a very biocompatible material. There is a good deal of experimental data supporting its use in a variety of clinical applications, including ridge preservation, sinus augmentation, and the repair of periodontal bone defects. There are limitations inherent in the bioglass products that are currently available. They are granular in nature and cannot be depended upon to serve reliably as space-making devices. Although they are quite biocompatible and exhibit bone bonding, bioglasses are not osteoinductive and are not capable of forming bone in ectopic sites (although they can be used to deliver osteopromotive growth factors). The range of applications for these products could be extended if the material could be made in various space-making forms. Incorporation or coating with osteogenic agents such as growth factors might be worthwhile. The full potential of bioactive glasses has yet to be fully realized.

Animals↗

PubMed1988

The stability in vitro of bioactive and immunoreactive LH in human blood and plasma.

The degree of stability in vitro of bioactive and immunoreactive LH in human blood, plasma and serum was examined. Bioactivity and immunoreactivity of LH were assayed by the dispersed mouse Leydig cell assay and by standard radioimmunoassay respectively, using the same reference preparation (first international reference preparation for human pituitary LH 68/40 for immunoassay). Bioactive and immunoreactive LH were stable in blood and plasma at 22 degrees C for up to 4 and 24 h respectively, and in blood at 4 degrees C for up to 24 h. There was no loss of biological or immunological LH activity in plasma which had been either snap-frozen and stored at -70 degrees C, allowed to freeze at -20 degrees C and stored at that temperature or kept at 4 degrees C for 24 h and then stored at -70 degrees C. Likewise, the levels of LH in plasma and serum which had been stored at either -20 or -70 degrees C and then thawed and refrozen up to four times remained unchanged. In addition, the biological and immunological activity of LH was not affected after vortexing samples of plasma or serum for up to 60 s. Bioactive LH was also stable in plasma samples after prolonged storage (up to 9 months) at either -70 or -20 degrees C. We conclude that LH bioactivity and immunoreactivity are stable in blood and plasma following a variety of treatments commonly experienced during normal handling of a blood sample after venepuncture.

Biological Assay↗

PubMed1991

Discordant levels of serum bioactive LH in man as measured in different in-vitro bioassay systems using rat and mouse interstitial cells and human granulosa-luteal cells.

Serum samples from healthy men (n = 6), perimenopausal women (n = 9) and patients with polycystic ovarian disease (n = 4) were analysed for LH bioactivity by the two widely used in-vitro bioassay systems: the mouse and rat interstitial cell testosterone-formation assays. The results were compared with an assay employing LH-stimulated cyclic AMP production by cultured human granulosa-luteal cells. Average bioactive LH levels in the mouse cell assay were 1.6-fold higher than those measured using the rat assay. A good correlation (r = 0.89, P less than 0.01) was observed between the bioactive LH levels measured by these two assays. No significant difference was found between the sensitivities of the two assays: 0.009 +/- 0.003 IU/l (mean +/- S.E.M., n = 10) with rat cells and 0.011 +/- 0.003 IU/l (n = 10) with mouse cells. The LH level resulting in half-maximal stimulation of testosterone production in the mouse model was twofold higher than that in the rat model (0.185 +/- 0.020 vs 0.083 +/- 0.022 IU/l, P less than 0.01). The bioactive LH levels measured by the human granulosa-luteal cell assay averaged 12% higher than those obtained with the rat assay (r = 0.84, P less than 0.01), but 58% lower than levels measured with the mouse assay (r = 0.86, P less than 0.01). The data indicate that the target cell model used in the in-vitro bioassay of LH contributes to the documented discrepancies in reports on serum levels of bioactive LH.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1997

Ontogeny of inhibin secretion in the rat testis: secretion of inhibin-related proteins from fetal Leydig cells and of bioactive inhibin from Sertoli cells.

The ontogeny of inhibin secretion in the testis of rats was investigated. Testicular localization, content of immunoactive and bioactive inhibin and its molecular size in fetal and neonatal rats (from 16 days of gestation to 5 days of age) were determined. Strong immunostaining with an antiserum against a polypeptide of porcine inhibin alpha-subunit was noted in testicular interstitial cells from 16 days of gestation. Co-localization of inhibin alpha-subunit and 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) was observed in the interstitial cells until 2 days of age. Immunoreactive inhibin alpha-subunit in the interstitial tissue had disappeared by 5 days of age, although 3 beta HSD-positive cells were still detected. Weak immunostaining for the inhibin alpha-subunit was detected in the seminiferous tubules, probably in the cytoplasm of Sertoli cells, from 20 days of gestation onward. No inhibin alpha-subunit immunostaining was observed in germ cells throughout the experimental period. Testicular inhibin was detected at 16 days of gestation (49.5 +/- 6.7 pg per testis) by RIA. Testicular immunoreactive inhibin showed a tendency to increase during fetal life and levels were maintained at a similar value after birth (697.0 +/- 46.9 pg per testis at 5 days of age). Inhibin bioactivity and its molecular size in testicular homogenate was examined at 17 days of gestation and 0 and 5 days of age. Although no bioactivity was detected at 17 days of gestation, bioactivity was noted at 0 and 5 days of age (177.7 and 1303.9 pg per testis respectively). Immunoblot analysis with antiserum against inhibin alpha-subunit revealed only approximately 40 kDa molecular masses in the testis at 17 days of gestation, probably inhibin-related proteins, but not inhibin. At 0 and 5 days of age, a protein of 30 kDa molecular mass, possibly inhibin, was detected as well as material of approximately 40 kDa molecular mass. FSH in the plasma was first detected at 19 days of gestation (1197.0 ng/l), increased towards birth, and thereafter decreased (4588.5 +/- 572.3 ng/l at 21 days of gestation and 2400.0 +/- 179.6 ng/l at 5 days of age). These results indicate that Leydig cells in fetal and neonatal rats produce inhibin-related substances with no inhibin bioactivity, whereas Sertoli cells begin to produce inhibin during the perinatal period as a possible regulator of FSH secretion.

3-Hydroxysteroid Dehydrogenases↗

PubMedDate not supplied

Bioactivity of androgens within the testes and serum of normal men.

Little is known about how human spermatogenesis is regulated, so it is not surprising that there have been few breakthroughs in the treatment of male infertility resulting from abnormalities of spermatogenesis. Testosterone is the predominant intratesticular steroid in both the rat and man. Previous studies have shown that the testosterone concentration within the rat testis that is required for the quantitative maintenance of spermatogenesis is far higher than the total testosterone concentration in rat blood, indicating that much of the testosterone within the testis might be biologically inactive. In contrast to the rat, little is known about the androgen requirements for human spermatogenesis, in part because, until recently, a minimally invasive method suitable for obtaining intratesticular fluids from the human testis has not been available. Percutaneous aspiration now makes it feasible to do so. A major objective of the present study was to assay the bioactive androgen concentration within the testes of normal, fertile men. Percutaneous aspiration was used to obtain intratesticular fluid from such men, and we adapted a highly sensitive recombinant protein mammalian cell-based bioassay to measure androgen bioactivity. Total intratesticular testosterone concentration, which we define as immunoreactive testosterone as measured by radioimmunoassay, was well in excess of that in serum (1236 +/- 86 nM vs 11.7 +/- 0.7 nM). The concentration of bioactive androgens within the normal human testis was found to be about two thirds that of the total testosterone concentration. Interestingly, the concentration of the major, known binding proteins for testosterone within the testis, serum hormone-binding globulin (SHBG)/ABP (52.4 +/- 9.7 nM), was insufficient to account for the difference between total testosterone and bioactive androgens. This indicates that, in addition to its binding to SHBG/ABP, androgens may also be bound by unknown molecules, and that this contributes to reducing androgen bioactivity. These observations could have relevance for understanding the relationship between spermatogenesis and intratesticular androgens in normal men and in men diagnosed with infertility.

Adult↗

PubMed2005

The concept of functional peptidomics for the discovery of bioactive peptides in cell culture models.

Detection and purification of novel bioactive peptides from biological sources is a scientific task that led to a substantial number of important discoveries. One major laborious approach used is the repetitive stepwise separation of the test sample into several fractions followed by the determination of their bioactivity, until purity allows for sequence identification. We tested whether functional peptidomics, a combination of biological read-outs with differential peptide display (DPD) is a suitable strategy to isolate bioactive peptides at lower workload and with improved success. Additionally, we evaluated the use of DPD to monitor the processing status of proinsulin by inhibition of the insulin processing pathway. The rat insulinoma cell line INS-1 stimulated either with 2 mmol/l or 10 mmol/l glucose was used as model to generate differential peptide displays. In parallel, the bioactivity of the supernatants from the INS-1 cells was measured by glucose uptake and lipolysis assays using the adipocyte cell line 3T3-L1. We were able to quickly and elegantly trace the known activity of insulin to increase glucose uptake and inhibit lipolysis. Following re-chromatography of selected fractions, relevant peptides were identified by DPD and bioassays: the rat insulin-1 precursor and two different insulin peptides. We demonstrated in a semi-quantitative fashion that inhibition of proinsulin processing leads to accumulation of the insulin precursor, and reduced secretion of insulin-1. Thus, we conclude that DPD is an attractive support technology in peptide purification strategies aiming to identify bioactive compounds, and is superior to ELISA in discriminating between the processing status of insulin and its precursor.

Adult↗

PubMed2002

On the diversity of oxidative bioactivation reactions on nitrogen-containing xenobiotics.

The unexpected occurrence of idiosyncratic drug reactions during late clinical trials or after a drug has been released can lead to a severe restriction in its use or failure to release/withdrawal. This leads to considerable uncertainty in drug development and has led to attempts to try to predict a drug's potential to cause such reactions. The biotransformation of relatively inert drugs to highly reactive metabolites, commonly referred to as "bioactivation", is now recognized to be an obligatory step in several kinds of drug-induced adverse reactions. Reactive metabolites can be formed by most, if not all, of the enzymes that are involved in drug metabolism. A major theme explored in this review includes the diversity of oxidative bioactivation reactions on nitrogen-containing xenobiotics including drugs. A variety of Phase I enzymes including P450, MAO, and peroxidases bioactivate nitrogen-containing xenobiotics via direct oxidations on the nitrogen atom leading to reactive intermediates or by oxidation at an alternate site in the molecule; for the metabolite to be reactive via the latter sequence nitrogen participation in required. Examples of direct oxidations on nitrogen include the N-oxidation of aromatic amines (e.g. procainamide), single electron N-oxidation of imides (e.g. phenytoin), or alpha-carbon oxidations of arylalkyl- or alkylamines (e.g. mianserin), to reactive nitroso, nitrogen free radical and iminium species, respectively. Examples of indirect bioactivation are highlighted with aromatic amines (e.g. diclofenac) that undergo p-hydroxylation resulting in the formation of p-aminophenols, two-electron oxidation of which results in the formation of reactive quinoneimines. Potential strategies that could be utilized in the screening of novel bioactivation pathways are also discussed.

Biotransformation↗

PubMed1996

Bioactive glass granules and plates in the reconstruction of defects of the facial bones.

Non-vascularised bone grafts that are used for reconstruction of skeletal deformities of the face after trauma or tumour surgery are prone to resorption. The outcome may, therefore, not be what was expected. Bone was reconstructed with bioactive glass S53P4 granules and plates at 36 sites in 13 patients. The behaviour of the material was compared with that of bone grafts at 16 sites in the same patients. Bioactive glass granules were used in facial bone defects in subperiosteal pockets and to obliterate frontal sinuses, whereas bioactive glass plates were used mostly in orbital wall reconstruction. Clinical examination, middle face radiographs, and computed tomograms (CT) showed that the material was well tolerated. A third of the glass granules and a quarter of the membranous bone grafts that were fixed with miniplates retained their original size. The glass plates did not change in size. Bone contact to the host bone was found more often with the bioactive glass plates than with the bioactive glass granules or the bone grafts. Both the glass plates and the bone grafts retained their density, but there was a reduction in density of the glass granules. The clinical outcome showed no relapses after one year's follow up. No further operations were needed because of the material used.

Adolescent↗

PubMed1999

Bioactivity of peptide analogs of the neutrophil chemoattractant, N-acetyl-proline-glycine-proline.

PURPOSE: The release of N-acetyl-proline-glycine-proline (PGP), a chemoattractant resulting from direct alkaline hydrolysis of corneal proteins, is believed to be the initial trigger for neutrophil invasion into the alkali-injured cornea. The purpose of this study is twofold: (1) to compare the activity of N-acetyl-PGP with the bioactivities of other similar synthetic peptides in an effort to uncover information about this chemoattractant molecule, and (2) to test these peptide analogs as potential antagonists of N-acetyl-PGP. METHODS: The polarization assay was used to measure the potential chemotactic response of human neutrophils to peptides. Bioactivity was expressed as the peptide concentration required to produce 50% neutrophil polarization (EC50). Antagonist activity was expressed as the peptide concentration required to produce 50% inhibition (ID50) of polarization activated by N-acetyl-PGP. RESULTS: Peptide bioactivities (EC50) were ranked as follows: APGPR (0.34 mM) > N-acetyl-PGP (0.5 mM) > N-(PGP)4-PGLG (3 mM) = t-Boc-PGP (3 mM) > N-acetyl-PG (3.4 mM) > N-methyl-PGP (15 mM) = PGP (15 mM) > peptides without detectable activity (t-Boc-PGP-OMe, N-acetyl-P, PG, PGG, GP, GG and gly-pro-hyp). Peptides with no detectable bioactivity were tested as potential antagonists of neutrophil polarization induced by N-acetyl-PGP. Gly-Pro-Hyp inhibited N-acetyl-PGP activation of polarization at 20 mM (ID50). No other synthetic peptide demonstrated a capacity for inhibition. CONCLUSIONS: The minimum requirement to elicit bioactivity was the presence of PGP alone or derivatives of PG in which the N-terminal proline is blocked. Using this approach, active and inactive mimetic peptides of N-acetyl-PGP were produced. The most active peptide, APGPR, was equal to or slightly greater than N-acetyl-PGP, suggesting that more potent analogs might be designed. Gly-pro-hyp was the only inactive peptide analog to inhibit the chemoattractant.

Chemotactic Factors↗

PubMedDate not supplied

Bioactive peptides encrypted in milk proteins: proteolytic activation and thropho-functional properties.

The bioactivities of peptides encrypted in major milk proteins are latent until released and activated by enzymatic proteolysis, e.g. during gastrointestinal digestion or food processing. The proteolytic system of lactic acid bacteria can contribute to the liberation of bioactive peptides. In vitro, the purified cell wall proteinase of Lactococcus lactis was shown to liberate oligopeptides from beta- and alpha-caseins which contain amino acid sequences present in casomorphins, casokinines, and immunopeptides. The further degradation of these peptides by endopeptidases and exopeptidases of lactic acid bacteria could lead to the liberation of bioactive peptides in fermented milk products. However, the sequences of practically all known biologically active peptides can also be cleaved by peptidases from lactic acid bacteria. Activated peptides are potential modulators of various regulatory processes in the body: Opioid peptides are opioid receptor ligands which can modulate absorption processes in the intestinal tract, angiotensin-I-converting enzyme (ACE)-inhibitory peptides are hemodynamic regulators and exert an antihypertensive effect, immunomodulating casein peptides stimulate the activities of cells of the immune system, antimicrobial peptides kill sensitive microorganisms, antithrombotic peptides inhibit aggregation of platelets and caseinophosphopeptides may function as carriers for different minerals, especially calcium. Bioactive peptides can interact with target sites at the luminal side of the intestinal tract. Furthermore, they can be absorbed and then reach peripheral organs. Food-derived bioactive peptides are claimed to be health enhancing components which can be used for functional food and pharmaceutical preparations.

Amino Acid Sequence↗

PubMed1992

Requirement of hydrophilic amino-terminal residues for granulocyte-macrophage colony-stimulating factor bioactivity and receptor binding.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a glycoprotein required for the proliferation and differentiation of granulocyte and macrophage precursors. Previous investigations have identified regions in human and murine GM-CSF that are required for bioactivity. In the present study, alanine substitution mutagenesis was undertaken to define more precisely specific amino-terminal residues in murine GM-CSF that are involved in bioactivity and receptor binding. Five double alanine mutants were identified that showed at least 10-fold reductions in bioactivity (K14AK20A, K14AE21A, H15AK20A, H15AE21A, K20AE21A). Each of these mutants maintained a normal N-linked glycosylation pattern when expressed in COS-1 cells, suggesting that native polypeptide backbone conformation was preserved. The purified prokaryotic expression products of two mutants (K14AE21A and H15AE21A) had a 100-fold decrease in bioactivity and a decrease in receptor binding, indicating that the side chains of K14, H15, and E21 are required for optimal receptor binding and maximal bioactivity.

Alanine↗

PubMed2003

[Research and development of A-W bioactive glass ceramic].

Studies on bioactive glass and glass-ceramic are important research high-lights in the field of biomedical materials. Due to their bioactivity, these materials can form a tight chemical bond with the living bone, when implanted. As a preeminent kind of these materials, A-W(Apatite/Wollastonite) bioactive glass ceramic has not only the excellent bioactivity and biocompatibility, but also the eminent mechanical properties, so it has been largely applied and developed in clinical practice. The development, preparation, properties, applications and the mechanism of its bond with bone are introduced in this paper. We will also put forward the prospect of the research and development of A-W bioactive glass ceramic.

Apatites↗

PubMedDate not supplied

Bioactive peptides derived from food.

As interest in the ability of functional foods to impact on human health has grown over the past decade, so has the volume of knowledge detailing the beneficial roles of food-derived bioactive peptides. Bioactive peptides from both plant and animal proteins have been discovered, with to date, by far the most being isolated from milk-based products. A wide range of activities has been described, including antimicrobial and antifungal properties, blood pressure-lowering effects, cholesterol-lowering ability, antithrombotic effects, enhancement of mineral absorption, immunomodulatory effects, and localized effects on the gut. Although there is still considerable research to be performed in the area of food-derived bioactive peptides, it is clear that the generation of bioactive peptides from dietary proteins during the normal digestive process is of importance. Therefore, it will become necessary when determining dietary protein quality to consider the potential effects of latent bioactive peptides that are released during digestion of the protein.

Absorption↗

PubMed2005

Infrainguinal ePTFE vascular graft with bioactive surface heparin bonding. First clinical results.

AIM: The ultimate aim of improved expanded polytetrafluoroethylene (ePTFE) vascular graft design is to achieve patency rates in femoropopliteal bypass grafting comparable with autologous saphenous vein grafts. Enhanced thromboresistance of the ePTFE material by bioactive surface heparin bonding is one conceivable path toward this goal. This retrospective study was performed to collect the first clinical data for a new ePTFE graft with bioactive surface heparin immobilization. METHODS: Between March 2003 and February 2004, 43 femoropopliteal or femorocrural ePTFE vascular prostheses with bioactive end-point immobilized heparin (Gore-Tex Propaten Vascular Graft), using the Car-meda BioActive Surface technology, were implanted in 40 patients. Twelve prostheses were implanted in above-knee and 31 in below-knee position. The indication for bypass grafting was limb-threatening ischemia in 88% of the patients. The mean follow-up was 16.6 months. RESULTS: The primary 1-year patency was 91% for above-knee bypass grafts and 92% for below-knee bypass grafts. The 2-year primary patency rate for above-knee bypass grafts was 68% and 81% for below-knee bypass grafts. Limb salvage was achieved in 98%. The perioperative mortality was 0%, but during follow-up 22% of the patients died with patent bypass grafts. CONCLUSIONS: While conventional ePTFE grafts, particularly in the below-knee position, have shown poor results even in the short-term, the bioactive heparinized ePTFE graft evaluated in this study provides patency rates comparable with autologous vein grafts. Because the influence of luminal heparin bonding is not only limited to thromboresistance but has impact on, amongst other elements, protein adsorption (thereby improving hemocompatibility), a continuous effect for long-term patency could also be expected.

Aged↗