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PubMed1991

Serum bioactive follicle-stimulating hormone-like activity in human pregnancy is a methodological artifact.

Serum from pregnant women has been shown to contain both FSH-like and FSH antagonistic activities when measured by an in vitro bioassay based upon FSH-dependent aromatase activity of immature rat Sertoli cells. In the present study we further tested the hypothesis that the FSH-like bioactivity of pregnancy serum was due to an authentic aromatase stimulator. A potent inhibitor of aromatase which completely blocked the FSH action on Sertoli cells had no effect on the bioactivity of pregnancy serum. Experiments using conversion of tritiated testosterone to estradiol showed that the factor did not stimulate aromatase activity in rat Sertoli cells. After incubation with pregnancy serum, equally high amounts of estradiol were measurable in the medium in both the absence and presence of Sertoli cells. The activity was almost completely lost after charcoal treatment or ether extraction of the serum and was shown to probably be due to the release of endogenous estrogens by the carrier proteins in the incubation medium of the Sertoli cell assay. These data suggest that the FSH-like bioactivity in serum from pregnant women is an artifact due to nonspecific interference(s) in the bioassay.

Androstenedione↗

PubMed1994

Production of bioactive and immunoreactive interleukin-6 (IL-6) and expression of IL-6 messenger ribonucleic acid by human pituitary adenomas.

Preliminary studies have demonstrated that some pituitary adenomas secrete immunoreactive interleukin-6 (irIL-6) when cultured in vitro. We have extended these studies by investigating 100 pituitary adenomas of different types measuring immunoreactive and bioactive IL-6. Tumors were cultured either as explants without fetal calf serum or as dispersed cells with 10% total calf serum. Fifty-three of the 100 (53%) pituitary cultures were found to release irIL-6 and in 44 adenomas examined, 32 (72.7%) secreted bioactive IL-6. In 61 explant cultures, 30 adenomas released IL-6, indicating autonomous secretion. The amount of IL-6 released by adenomas in cell culture was generally higher, although the incidence was similar to explant cultures. IrIL-6 was released by 7 of 14 prolactinomas, 15 of 27 somatotrophinomas, 5 of 7 corticotrophinomas (including 2 Nelson's adenomas), 1 of 1 thyrotrophinomas, 2 of 2 gonadotrophinomas, and 23 of 49 clinically non-functioning adenomas. Periadenomatous tissue removed from a patient with a corticotrophinoma was found to secrete IL-6 but in much lower concentration than from the adenoma tissue. Tumor necrosis factor-alpha and -gamma-interferon were not detected in the conditioned media. Four IL-6-secreting adenomas were examined by in situ hybridization for IL-6 messenger RNA, and three of these were positive with fluorescence present throughout the tissue examined. We have provided evidence that over half of pituitary adenomas secrete IL-6 which is bioactive and that IL-6 is synthesized within the tumor by the adenoma cells.

Adenoma↗

PubMed1994

Evidence for the secretion of thyrotropin with enhanced bioactivity in syndromes of thyroid hormone resistance.

Resistance to thyroid hormone (RTH) is a rare genetic disorder associated with diverse mutations in the thyroid hormone receptor beta-gene. TSH-dependent thyroid hyperstimulation, leading to goiter and elevated thyroid hormone levels, is a characteristic feature of RTH. However, about 60% of untreated resistance patients have circulating TSH levels within the normal range, raising the possibility that the biological activity of TSH is altered. We, therefore, assayed the bioactivity of circulating TSH in 11 patients from 8 different kindreds with RTH, measuring cAMP production in Chinese hamster ovary cells transfected with the recombinant human TSH receptor as well as in FRTL-5 cells. The ratio of biologically active vs. immunoreactive TSH (B/I) was significantly higher in RTH patients than in 8 normal controls [TSH B/I, 4.2 +/- 0.9 (range, 2.2-11.9) vs. 1.3 +/- 0.2 (range, 0.6-2.1)]. TSH released in response to TRH had a bioactivity similar to that of circulating TSH under basal conditions. On the contrary, supraphysiological doses of T3 normalized the B/I ratio of circulating TSH. Concanavalin-A chromatography of TSH from RTH patients showed the presence of circulating forms with altered carbohydrate branching. Our data indicate that the bioactivity of circulating TSH in thyroid hormone resistance syndromes is enhanced and can be normalized after T3 administration. These findings may account for the occurrence of goiter and elevated thyroid hormone levels in RTH patients despite normal serum TSH concentrations.

Adult↗

PubMed1998

Mechanical properties of bioactive glasses, glass-ceramics and composites.

The application of bioactive glass and glass-ceramics has been widely documented over the past twenty years but the high modulus and low fracture toughness has made them less applicable for clinical, load bearing, applications. The development of non-resorbable polyethylene and polysulphone matrices for these materials has improved the mechanical properties. However, the primary concern of whether the bioactivity of the composites is reduced is still unresolved. The more recent development of resorbable carrier systems, dextran and collagen, for bioactive glasses does not introduce such problems, hence making this form of composite suitable for novel soft tissue applications. The development of a simple quality index has enabled some of the materials described within this paper to be ranked by their ability to replace bone, thus enabling possible new research directions to be emphasized.

Biocompatible Materials↗

PubMed2006

Selective laser sintering of hydroxyapatite reinforced polyethylene composites for bioactive implants and tissue scaffold development.

Selective laser sintering (SLS) has been investigated for the production of bioactive implants and tissue scaffolds using composites of high-density polyethylene (HDPE) reinforced with hydroxyapatite (HA) with the aim of achieving the rapid manufacturing of customized implants. Single-layer and multilayer block specimens made of HA-HDPE composites with 30 and 40 vol % HA were sintered successfully using a CO2 laser sintering system. Laser power and scanning speed had a significant effect on the sintering behaviour. The degree of particle fusion and porosity were influenced by the laser processing parameters, hence control can be attained by varying these parameters. Moreover, the SLS processing allowed exposure of HA particles on the surface of the composites and thereby should provide bioactive products. Pores existed in the SLS-fabricated composite parts and at certain processing parameters a significant fraction of the pores were within the optimal sizes for tissue regeneration. The results indicate that the SLS technique has the potential not only to fabricate HA-HDPE composite products but also to produce appropriate features for their application as bioactive implants and tissue scaffolds.

Biocompatible Materials↗

PubMed2007

Comparative study on major bioactive components in natural, artificial and in-vitro cultured Calculus Bovis.

Major bioactive components in various Calculus Bovis, including natural, artificial and in-vitro cultured Calculus Bovis, were comparatively studied. An approach of high-performance liquid chromatography coupled with ultraviolet and evaporative light scattering detections (HPLC/UV/ELSD) was established to simultaneously determinate six bioactive components thereof, including five bile acids (cholic acid, deoxycholic acid, ursodeoxycholic, chenodeoxycholic acid, hyodeoxycholic acid) and bilirubin. ELSD and UV detector were applied to detect bile acids and bilirubin respectively. The assay was performed on a C(18) column with water-acetonitrile gradient elution and the investigated constituents were authenticated by comparing retention times and mass spectra with those of reference compounds. The proposed method was applied to analyze twenty-one Calculus Bovis extraction samples, and produced data with acceptable linearity, precision, repeatability and accuracy. The result indicated the variations among Calculus Bovis samples under different developmental conditions. Artificial and in-vitro cultured Calculus Bovis, especially in-vitro cultured ones, which contain total bioactive constituents no less than natural products and have the best batch-to-batch uniformity, suffice to be used as substitutes of natural Calculus Bovis.

Chromatography, High Pressure Liquid↗

PubMed2005

Influence of progestin bioactivity on cutaneous vascular responses to passive heating.

PURPOSE: Oral contraceptives influence the regulation of cutaneous vascular tone, and both estrogen and progesterone have been shown to affect nitric oxide (NO)-mediated vasodilation. We tested the hypothesis that cutaneous vascular conductance (CVC) during passive heating would be lower in women taking oral contraceptives with higher progestational bioactivity compared with those taking oral contraceptives with lower progestational bioactivity. We further hypothesized that this difference could be attributed to the relative degree of NO-dependent vasodilation. METHODS: Fourteen women (20.3 +/- 0.3 yr) taking combined oral contraceptives (low progestin: 6 subjects, high progestin: 8 subjects) participated in a whole-body heating protocol and were tested during the end of active and placebo pill phases. Red blood cell (RBC) flux was measured by laser-Doppler flowmetry at a control microdialysis site (Ringer's solution) and an experimental site where NO-synthase (NOS) was inhibited (10 mM L-NAME). CVC was calculated as RBC flux/MAP. RESULTS: Baseline oral temperature (Tor) was significantly higher during the active pill phase for all subjects (active: 36.8 +/- 0.1 degrees C; placebo: 36.6 +/- 0.1 degrees C) (P = 0.02) but was not affected by progestational bioactivity. CVC at the control site during heating did not differ between low and high progestin users during either phase of oral contraceptive use. However, CVC in the NOS inhibited site was diminished during both phases of oral contraceptive use in the low progestin group at a given change in Tor (active: DeltaT(or) of 0.6-1.0 degrees C, placebo: DeltaT(or) of 0.8-1.0 degrees C) (P < 0.05). (DeltaT(or) 1.0 degree C: active: 30.86 vs 46.56%CVC(max); placebo: 26.29 vs 49.22% CVC(max)) (P < 0.05). CONCLUSION: Progestational activity in oral contraceptives may alter the mechanisms by which skin blood flow increases during passive heating via NO-dependent cutaneous active vasodilation.

Adult↗

PubMed2001

Modulation of cytochrome P4501-mediated bioactivation of benzo[a]pyrene by volatile allyl sulfides in human hepatoma cells.

Allyl sulfides such as diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS), typical flavor components of Allium vegetables, have been shown to inhibit benzo[a]pyrene (B[a]P)-induced carcinogenesis in animal models. As a possible mechanism of this inhibition, the effect of these volatile substances on cytochrome P450 (CYP)1 (CYP1A1, 1A2 and 1B1)-mediated bioactivation of B[a]P was investigated using a human hepatoma cell model (HepG2). DADS and DATS inhibited the B[a]P-induced ethoxyresorufin O-deethylase (EROD) activity, a marker enzyme for CYP1, by 30-90% and 70-95% at 100-1,000 microM concentration, respectively. The cell viability, an indicator of the capacity to inhibit B[a]P bioactivation, was increased by treatments of 100-1,000 microM DADS and 10-100 microM DATS. Immunoblot results indicated that the B[a]P inducible CYP1A2 protein was suppressed by 100-1,000 microM of DADS and 10-100 microM of DATS, but CYP1A1 and 1B1 were not detectable in any microsomes. Analysis of B[a]P metabolites revealed that the level of 7,8-diol formed was significantly reduced in the DADS and DATS treated microsomes as compared to the control. The level of 9,10-diol and 4,5-diol formed was also lowered by the allyl sulfide treatments. These results suggest that the protective mechanism of allyl sulfides on B[a]P-induced carcinogenesis is possibly related with the modulation of CYP1-mediated bioactivation of B[a]P.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed1984

Bioactive glass-ceramics in ear surgery: animal studies and clinical results.

In the search for better materials for middle ear reconstruction, ceramics have been suggested as an alternative. The bioactive glass-ceramic Ceravital was made available to us for animal experiments and clinical trials. To test its suitability in ear surgery, 101 ear operations were carried out in 53 rabbits including the reconstruction of 78 posterior auditory canal walls and the insertion of 174 middle ear implants. Parameters studied include the effects of bone paté in inducing new bone growth, the chronological course of bone apposition and remodeling, microscopic examination of mucous membrane growth on the implants and degree of lysis of the implant. In the past two and one half years some 250 ossicular prostheses have been implanted in man for reconstruction of the ossicular chain. A statistical analysis of 119 tympanoplasties after a follow-up of one and one half years shows no perforations of the tympanic membrane over the implants or rejection of the prosthesis from the middle ear. The audiological results achieved were more favorable with the use of ossicular prostheses made of bioactive glass-ceramic than those using allogenic ossicular grafts. On the basis of the histologic findings and observed clinical results, the bioactive material Ceravital is remarkably well suited for reconstruction of the posterior auditory canal wall and for implantation in direct contact with the tympanic membrane.

Adolescent↗

PubMed1977

Bioactivation and covalent binding of halothane to liver macromolecules.

In this manuscript we report our attempts to determine if 14C-halothane or its metabolites interact with DNA. Three bioactivation systems were used: in vitro microsomal incubations, isolated hepatocytes, and in vivo administration. Even though we used optimal conditions for bioactivation, no significant covalent binding of 14C to DNA was observed. Slight 14C activity above background (6 dpm/0.1 mg DNA) was observed in the microsomal incubations but is considered insignificant because it was not reduced when NADPH was omitted from the incubations. We are able to demonstrate covalent binding to nuclear lipids and proteins when rats were pretreated with phenobarbital and maintained in a hypoxic environment (14% O2). Similarly, these conditions markedly increased covalent binding of 14C from 14C-halothane to microsomal proteins and lipids. Isolated rat hepatocytes proved to be a viable system for studying the bioactivation of halothane. In this system it was also possible to demonstrate increased binding under N2 and/or phenobarbital pretreatment.

Animals↗

PubMed2001

3D bone tissue engineered with bioactive microspheres in simulated microgravity.

Three-dimensional (3D) osteoblast cell cultures were obtained in rotating-wall vessels (RWV), simulating microgravity. Three types of bioactive microcarriers, specifically modified bioactive glass particles, bioceramic hollow microspheres, and biodegradable bioactive glass-polymer composite microspheres, were developed and used with osteoblasts. The surfaces of composite microspheres fully transformed into bone apatite after 2-wk immersion in simulated physiological fluid, which demonstrated their bone-bonding ability. The motion of microcarriers in RWVs was photographically recorded and numerically analyzed. The trajectories of hollow microspheres showed that they migrated and eventually stayed around at the central region of the RWV. At their surfaces, shear stresses were low. In contrast, solid glass or polymer particles moved toward and finally bounced off the outer wall of the RWVs. Cell culture studies in the RWV using bone marrow stromal cells showed that the cells attached to and formed 3D aggregates with the hollow microspheres. Extracellular matrix and mineralization were observed in the aggregates. Cell culture studies also confirmed the ability of the composite microspheres to support 3D bone-like tissue formation. These data suggest that the new hollow bioceramic microspheres and degradable composite microspheres can be used as microcarriers for 3D bone tissue engineering in microgravity. They also have potential applications as drug delivery systems.

Animals↗

PubMed2005

An investigation of the long-term bioactivity of endogenous growth factor in OASIS Wound Matrix.

OBJECTIVE: To examine the retention and bioactivity of endogenous FGF-2 after prolonged storage within a complex matrix. FGF-2 is a growth factor found in OASIS Wound Matrix, a purified collagen wound-care product containing other endogenous components of the extracellular matrix. METHOD: FGF-2 content was measured by ELISA. FGF-2 activity was measured using an in vitro bioassay in rat pheochromocytoma (PC12) cells. RESULTS: FGF-2 content ranged from 15.3 ng/g to 84.3 ng/g. The bioassay showed that the FGF-2 retained in the matrix was present in a bioactive form able to cause differentiation of cells in culture. CONCLUSION: The results demonstrate that wound-care products can be developed to retain their bioactivity over time and that inherently unstable purified growth factors are preserved if stored as bound factors within their natural extracellular matrix. The results also suggest that use of acellular matrices containing active growth factors would have advantages in terms of simplicity and cost over purified recombinant growth factor therapies.

Animals↗

PubMed2006

Transformation of yeast using bioactive beads with surface-immobilized yeast artificial chromosomes.

Yeast artificial chromosomes (YACs) are useful cloning vectors with the capacity to carry large DNA inserts. The largest barrier using such large DNA molecules in transformation experiments has been their physical instability in a solution. We developed a new method for transforming yeast with chromosome-sized DNA. The method uses bioactive beads composed of calcium alginate to immobilize yeast chromosomal DNAs. Chromosomal DNA immobilized on bioactive beads is physically stable when compared with naked chromosomal DNAs. The bead-mediated transformation performed well, not only with respect to the transformation frequency, but also in successful transformation using split chromosomal DNA that exceeded 450 kb in size. In this chapter we introduce a new method for transforming yeast using bioactive beads. In conjunction with genomic YAC libraries and the yeast chromosome-splitting method, this technique will pave the way to stable and effective transfer of YACs into yeast cells.

Alginates↗

PubMed2004

Bioactive GLP-1 in gut, receptor expression in pancreas, and insulin response to GLP-1 in diabetes-prone rats.

Glucagon-like peptide-1 (GLP-1) is the most insulinogenic of the glucagon-like peptides secreted mainly by L cells in the small and large intestine in response to the ingestion of nutrients. It binds to a specific GLP-1 receptor (GLP-1R) on beta-cells and can increase islet neogenesis and beta-cell mass. It is not clear whether the transmission of information from the gut to islet beta-cells by messengers such as GLP-1 is different in individuals who develop autoimmune diabetes. In the present study the expression of bioactive GLP-1 protein in the gut and its receptor in the pancreas was examined in diabetes-prone BioBreeding (BBdp) rats in the period before overt diabetes and in age-matched control, non-diabetes-prone BB (BBc) rats. An N-terminal directed antibody specific for the bioactive forms of GLP-1 (GLP-1(7-37) and GLP-1(7-36amide)) was used to mea-sure GLP-1 by radioimmunoassay in proximal, median, and distal gut. Pancreas GLP-1R area fraction, GLP-1R gene expression, and insulin content were analyzed, as were plasma GLP-1, glucose, and insulin. The concentration of GLP-1 protein in the jejunum and ileum of BBdp rats was lower than in BBc rats. Although these animals maintained normal blood glucose, there was impaired pancreatic endocrine function, characterized by low baseline insulin concentration in plasma and pancreas. GLP-1R mRNA expression was threefold less in islets isolated from BBdp rats, and GLP-1R+ islet area fraction in pancreas sections was decreased. When injected iv with GLP-1, BBdp rats displayed lower second-phase insulin response (and insulin/glucose ratios) compared with BBc rats. Thus, young BBdp rats displayed decreased concentrations of bioactive GLP-1 in jejunum and ileum, reduced GLP-1R in islets, and lower second-phase insulin response to iv GLP-1 than controls. The decrease in insulinogenic and islet beta-cell mass-promoting signal from GLP-1 in BBdp rats may contribute to impaired glucoregulation and ineffective maintenance of normal islet mass that shifts islet homeostasis in favor of development of diabetes.

Animals↗

PubMed1988

Mechanism of inhibition of hepatic bioactivation of paracetamol by dimethyl sulfoxide.

Prior work has shown that DMSO inhibits paracetamol hepatotoxicity. In this paper we show that DMSO and its reduced metabolite dimethyl sulfide (DMS) can inhibit in vitro hepatic dimethylnitrosamine N-demethylase. We also show that DMSO can inhibit in vivo production of glutathione conjugates of paracetamol. Glutathione is known to conjugate the bioactivated form of paracetamol. Also, the isozyme of cytochrome P-450 responsible for dimethylnitrosomine N-demethylase, cytochrome P-450j, is thought responsible for paracetamol bioactivation. We therefore propose that DMSO inhibits paracetamol hepatotoxicity due to inhibition of cytochrome P-450j-dependent paracetamol bioactivation by DMSO and its metabolite DMS.

Acetaminophen↗

PubMed1989

Monitoring ovarian function and pregnancy in the giant panda (Ailuropoda melanoleuca) by evaluating urinary bioactive FSH and steroid metabolites.

Urinary excretion of oestrone conjugates, pregnanediol-3 alpha-glucuronide (PdG) and 20 alpha-hydroxypregn-4-en-3-one were measured from 8 weeks before oestrus to 2 weeks post partum and bioactive FSH was monitored during the periovulatory interval in a female giant panda. A biphasic urinary bioactive FSH excretory profile appeared to indicate a broad (approximately 10 day) follicular phase followed by a sharp preovulatory bioactive FSH surge coincident with an acute increase in urinary oestrone conjugates and behavioural oestrus. Weekly concentrations of urinary oestrone conjugates and PdG increased (P less than 0.001) by Week 9 of gestation with 20 alpha-hydroxypregn-4-en-3-one levels increasing 10-30-fold (P less than 0.001) between Weeks 11 and 14. These observations indicate that the monoestrous giant panda does not appear to require a prolonged period of endogenous FSH release or multiple FSH peaks for ovarian priming and follicle selection to proceed normally. Furthermore, the delayed rise in urinary steroid excretion during the second half of gestation in the giant panda supports the concept of delayed implantation while the estimation of steroid conjugates in urine offers a non-invasive approach for monitoring pregnancy status in this endangered species.

20-alpha-Dihydroprogesterone↗

PubMed1991

Bioactive glycosides from Chinese medicines.

Glycosides are the bioactive components of many famous Chinese medicines. Here reported are some bioactive glycosides we discovered from Chinese medicines in recent years. (1) Phenolic glycosides from Chinese medicines: Gastrodia elata, Aconitum austroyunanense and Helicia erratica, three bioactive phenolic glycosides were discovered and two of them have been developed into new drugs. (2) Terpenoidal glycosides: a) Monoterpenoid: the sweroside from Swertia moleensis has been developed into an anti-hepatitis drug; b) Diterpenoid: Phlomis betonicoides contains sweet glycosides; c) Triterpenoid: many biologically active triterpenoid glycosides were isolated from Panax plants and Siraitia grosvenorii. (3) Steroidal glycosides: a) C21-steroid: Cynanchum otophyllum and C. atratrum contain anti-epilepsy and anti-tumor glycosides; b) C27-steroid Hemostatic saponins were found in Paris polyphylla.

Animals↗

PubMed1993

Bioactive and immunoreactive variants of prolactin in milk and serum of lactating rats and their pups.

Prolactin (PRL)-like bioactivity (in Nb2 lymphoma assay) and immunoreactivity (in radioimmunoassay (RIA)) in rat milk, maternal and neonatal sera and in neonatal rat pituitary cultures were investigated. The PRL-like bioactivity in the water-soluble fraction of rat milk was high and exceeded its immunoreactivity 5.8-, 4.0- and 2.1-fold, on days 2, 12 and 22 of lactation respectively. The elevated bioactivity to immunoreactivity (B/I) ratio of PRL in milk was not due to the presence of interleukin-2 (IL-2) in milk, since the proliferation of the CTLL-2 murine T cells, which are not sensitive to PRL, was promoted by IL-2 but not by milk. Serum levels of immunoreactive PRL were low in sera of non-weaned rat pups on days 2, 12 and 22 postpartum. Similar to milk, the B/I ratio of PRL in sera of rat pups was high and decreased with time postpartum. Pituitary glands of pups obtained on days 2, 12 and 22 secreted progressively increasing amounts of PRL in vitro; the B/I ratio ranged between 1.2 and 2.1 without a significant change. The relative concentrations of size variants in milk were not proportional to those in serum of lactating rats on day 2 postpartum as assessed by Sepharcryl S-100 HR gel permeation chromatography and Nb2 bioassay or RIA. Size variants of biologically active PRL were abundant in early milk and gradually diminished as lactation progressed: a partially resolved peak representing monomeric to dimeric PRL variants (relative molecular weights ranging between 18 k and 42 k) became progressively narrower between days 2 and 22. Biologically active and immunoreactive PRLs displayed disparate elution profiles. The elution profile of PRL in sera of neonatal rats on day 2 post-partum was different from that of maternal serum or milk. The major immunological (and possibly biological) PRL-like activity eluted as two adjacent peaks at 2.2 k and 1.5 k, raising the possibility that fragments of milk-borne PRL were absorbed from the gut after partial proteolytic degradation. In contrast with PRL, GH (which is present in rat milk only in minute concentrations) did not show heterogeneity in sera of 2-day-old rat pups in gel permeation chromatography. The present results demonstrate that the concentrations of PRL-like activity in rat milk and newborn rat serum have been grossly underestimated because levels have been measured by RIA. The high B/I ratio of PRL in milk and neonatal sera is due to the presence of PRL-related compounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗