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PubMed1994

Fibrin-targeted recombinant hirudin inhibits fibrin deposition on experimental clots more efficiently than recombinant hirudin.

BACKGROUND: Although the indirect thrombin inhibitor heparin and the more potent direct inhibitor hirudin are useful in preventing thrombosis, a substantial opportunity remains for improving the thrombus selectivity of thrombin inhibitors. METHODS AND RESULTS: To explore the effect of targeting an antithrombin to the surface of a clot, we covalently linked recombinant hirudin to the Fab' (or IgG) of a monoclonal antibody (59D8) that selectively binds to an epitope on fibrin that becomes exposed only after thrombin cleaves fibrinopeptide B. Antibody-coupled hirudin bound to an immobilized peptide of the fibrin beta-chain amino-terminal sequence and inhibited the peptidolytic activity of thrombin more efficiently than free hirudin. Thrombin inhibition dependent on binding to immobilized fibrin monomer was enhanced 1100-fold (P < .0001). Hirudin-59D8 Fab' was 10 times more effective than hirudin in inhibiting fibrin deposition on experimental clot surfaces in fibrinogen solution (P < .0001) and human plasma (P < .0001). The more effective inhibition of thrombin by the conjugate was supported by significantly diminished concentrations of fibrinopeptide A in the plasma supernatant of the clot (P = .0001). Inhibition of clotting by an uncoupled mixture of hirudin and 59D8 Fab' was indistinguishable from that by hirudin alone, indicating that the conjugate's greater inhibitory activity was due to the covalent linkage between antibody and hirudin. CONCLUSIONS: Fibrin-targeted hirudin (in comparison with unmodified hirudin) significantly reduces fibrin deposition on the surface of experimental clots.

Antibodies, Monoclonal↗
PubMed1993

Recombinant human inhibin A and recombinant human activin A regulate pituitary and ovarian function in the adult female rat.

The roles of recombinant human inhibin A (rh-inhibin A) and rh-activin A in regulating the pituitary and ovary of the adult female rat were examined. Serum and pituitary FSH and LH and serum estradiol and progesterone concentrations were evaluated at 1, 2, and 6-12 h after sc hormone administration on metestrus and on proestrus. A second study examined the effect of the hormones 24 h after injection at 1000 h on each day of the cycle. Rh-inhibin A inhibited FSH secretion 60 min after injection on proestrus but did not alter serum FSH concentration on metestrus. FSH remained low for the 12 h examined during the evening of proestrus and on the morning of estrus. Serum LH concentration, pituitary FSH content, and pituitary LH content were not significantly changed under any experimental condition. Rh-inhibin A did not regulate estradiol concentration on metestrus or on proestrus; however, it did cause a rise in serum estradiol in animals treated on metestrus and diestrus and examined 24 h later. This suggests that inhibin may participate in regulating follicular maturation in a subset of developing follicles. Last, after rh-inhibin A treatment, the duration of the proestrus progesterone surge was shortened. Serum FSH concentration rose by 6 h after rh-activin A administration on proestrus and both FSH and LH rose by 6 h after hormone administration on metestrus. Rh-activin A significantly increased serum estradiol through 6 h of treatment on proestrus. Progesterone levels were significantly greater in animals treated on metestrus and killed 24 h later. The increased length of the midcycle progesterone surge may be the result of increased LH on metestrus. These studies suggest that rh-inhibin A and rh-activin A may regulate ovarian and pituitary function in a cycle dependent manner. Specifically, rh-inhibin A can acutely regulate FSH and progesterone on proestrus and estradiol during follicular development. Rh-activin A acutely regulates FSH on both proestrus and metestrus and LH on metestrus. Whether circulating endogenous inhibin or activin participate physiologically in these functions is under investigation.

Activins↗
PubMed1993

In situ ligand binding of recombinant human [125I] activin-A and recombinant human [125I]inhibin-A to the adult rat ovary.

Inhibin and activin are hormones produced by ovarian follicles. Specific ovarian cells that bind iodinated recombinant human (rh)-activin-A and rh-inhibin-A were identified by in situ ligand binding. Iodinated rh-molecules were incubated with tissue sections from ovaries, uterus, and oviduct, collected on the mornings of metestrus, diestrus, proestrus, and estrus and the evening of proestrus. Additionally, inhibin/activin subunit mRNA and follistatin mRNA accumulation was examined by in situ hybridization of radiolabeled antisense riboprobes. The cellular site of activin/inhibin binding could thus be colocalized to the cellular site of ligand mRNA and binding protein mRNA production. The association of both [125I]rh-activin-A and [125I] rh-inhibin-A with specific cell types varied across the rat estrous cycle. Nonspecific binding was evaluated by competition with a 1000-fold excess of homologous ligand, and low affinity association of the heterologous ligand was evaluated by competition with a 1000-fold excess of heterologous ligand. [125I]rh-activin-A binding was more widespread than was [125I]rh-inhibin-A binding under our experimental conditions. [125I]rh-Activin-A bound to the granulosa cells of all stages of follicles: unrecruited, growing, and Graafian follicles. Thecal cell binding was found in developing follicles (350-500 microns). The granulosa cells of stimulated follicles (evening of proesterus) bound less [125I]rh-activin-A than those of unstimulated follicles. [125I]rh-Activin-A binding was also associated with antral fluid of follicles in each size class. Although early atretic follicles retained some [125I]rh-activin-A binding, late atretic follicles did not bind [125I]rh-activin-A. Corpus luteum present on metestrus and diestrus bound [125I]rh-activin-A; however, corpus lutea present on proestrus and estrus bound little or no [125I]rh-activin-A. [125I]rh-Activin-A-binding sites were also present in the uterus and oviduct in a cycle-dependent manner. The highest levels of binding were found in the muscle wall of the uterus and the epithelial lining of the thick-walled portion of the uterus on metestrus and diestrus. In addition, [125I]rh-activin-A bound to the cumulus-oocyte complex present in the oviduct on metestrus, but did not bind to the oocytes present in developing follicles. Binding of [125I]rh-inhibin-A was restricted to the antral granulosa cells of 450- to 500-microns follicles. No other ovarian, uterine, or oviduct cells bound [125I]rh-inhibin-A. [125I]rh-Activin-A and [125I]rh-inhibin-A ligand binding was associated primarily with follicles coexpressing inhibin/activin subunit and follistatin mRNA.(ABSTRACT TRUNCATED AT 400 WORDS)

Activins↗
PubMed1996

Recombinant human insulin-like growth factor I, recombinant human growth hormone, and sex steroids: effects on markers of bone turnover in humans.

Sex steroids, GH, and insulin-like growth factor I (IGF-I) have all been shown to be highly anabolic in bone. Using available markers of bone formation, we measured the changes in serum concentrations of carboxy-terminal propeptide of type I collagen (PICP) and osteocalcin in five groups of subjects given different bone anabolic hormones: group I (five males and three females; mean +/- SE age, 25 +/- 2 yr) received recombinant human IGF-I (rhIGF-I) as a constant 28-h infusion i.v. (5-10 micrograms/kg.h); group II (three males and two females; 25 +/- 2 yr) received rhIGF-I (100 micrograms/kg, sc, twice daily) for 5-7 days; group III (five males; 28 +/- 2 yr) received rhGH (0.025 mg/kg.day, sc, for 7 days, alone (group IIIa) or followed by a 28-h sc infusion of rhIGF-I (10 micrograms/kg.h) in addition to rhGH (group IIIb); group IV (six prepubertal boys; 13 +/- 0.6 yr) received testosterone enanthate (100 mg, im) twice over 4 weeks; and group V (five hypogonadal girls with Turner's syndrome) received different forms of estrogen for 4 weeks. Most groups (except for III) had deoxypyridinoline concentrations (a marker of bone resorption) measured in urine as well. Each subject served as his/her own control. rhIGF-I treated subjects in group I showed a marked decrease in circulating PICP concentrations after 4 h of infusion (from 116.8 +/- 19.2 micrograms/L to 89.6 +/- 16.3; P < 0.01), followed by a marked increase at 28 h (137.6 +/- 19.7; P < 0.01) and a sustained increase 5-7 days after sc therapy (group II). This decrease followed by an increase in PICP concentrations after rhIGF-I may be secondary to the marked suppression of circulating insulin observed at 4 h followed by the establishment of an insulin-like effect of the peptide. Subjects receiving rhGH alone (group IIIa) also had comparable increases in circulating PICP (from 107.6 +/- 8.7 to 125.0 +/- 10.9; P < 0.01) and a further additive increase when rhIGF-I was coadministered (140.9 +/- 10.3; P < 0.01). These changes were accompanied by comparable increases in IGF-I concentrations in all groups (I, II, and III). Hypogonadal children had higher levels of circulating PICP than adults and showed the most significant increases after therapy [group IV, 212.2 +/- 13.8 to 429.9 +/- 52.4 micrograms/L (P < 0.001); group V, 312.8 +/- 49.0 to 355.5 +/- 44.3 (P < 0.04)]. The latter was observed despite either a modest (group IV) or no increase (group V) in circulating IGF-I concentrations. None of the groups studied showed any change in serum osteocalcin concentrations after treatment. Urinary deoxypridinoline concentrations also increased after rhIGF-I and testosterone administration. We conclude that rhIGF-I, rhGH, and sex steroid hormones all markedly increase measures of bone turnover, and that rhIGF-I and rhGH can synergize on this effect on bone. These data collectively suggest that IGF-I and sex steroid hormones (testosterone and estrogen) can impact bone formation independently, and that the actions of IGF-I, GH, sex steroid hormones (and perhaps insulin) may synergize to maximally stimulate attainment of peak bone mass in humans. PICP measurement appears to be a sensitive marker of short term anabolic hormone actions in bone.

Adult↗
PubMed2001

Recombinant human growth hormone and recombinant human insulin-like growth factor I diminish the catabolic effects of hypogonadism in man: metabolic and molecular effects.

Severe gonadal androgen deficiency can have profound catabolic effects in man. Hypogonadal men develop a loss of lean body mass, increased adiposity, and decreased muscle strength despite normal GH and insulin-like growth factor I (IGF-I) concentrations. We designed these studies to investigate whether GH or IGF-I administration to male subjects with profound hypogonadism can diminish or abolish the catabolic effects of testosterone deficiency. Moreover, we also examined the nature of the interactions among GH, IGF-I, and androgens in specific genes of the im system. A group of 13 healthy subjects (mean age, 22 +/- 1 yr) was studied at baseline (D1) and 10 weeks after being made hypogonadal using a GnRH analog (GnRHa; D2). At 6 weeks from baseline they were started on either recombinant human (rh) IGF-I (60 microg/kg, sc, twice daily) or rhGH (12.5 microg/kg, sc, daily) for 4 weeks. On each study day subjects had infusions of L-[(13)C]leucine; indirect calorimetry; isokinetic dynamometry of the knee extensors; determination of body composition (dual energy x-ray absortiometry) and hormone and growth factor concentrations, as well as percutaneous muscle biopsies. Their data were compared with those of previously studied male subjects who received only GNRHA: Administration of rhIGF-I and rhGH to the hypogonadal men had similar effects on whole body metabolism, with maintenance of protein synthesis rates, fat oxidation rates, and fat-free mass compared with the eugonadal state, preventing the decline observed with hypogonadism alone. This was further amplified by the molecular assessment of important genes in muscle function. During rhIGF-I treatment, im expression of IGF-I declined, and IGF-binding protein-4 increased, similar to the changes during GnRHa alone. However, rhGH administration was associated with a marked increase in IGF-I and androgen receptor messenger ribonucleic acid concentrations in skeletal muscle with a reciprocal decline in IGF-binding protein-4 expression in the hypogonadal men. The gene expression for myostatin did not change. These effects were accompanied by a much greater increase in plasma IGF-I concentrations after rhIGF-I (225 +/- 32 vs. 768 +/- 117 microg/L) compared with the concentrations achieved during rhGH (217 +/- 20 vs. 450 +/- 19 microg/L). We conclude that 1) rhGH and rhIGF-I both may be beneficial in preserving lean body mass and sustaining rates of protein synthesis during states of severe androgen deficiency in man; 2) GH may affect the im IGF system via an a paracrine, local production of IGF-I; 3) androgens may be necessary for the full anabolic effect of GH/IGF-I in man. These hormones, particularly GH, may play a role in the treatment of hypogonadal men rendered hypogonadal pharmacologically or those unable to take full testosterone replacement. The latter requires further study.

Adult↗
PubMed1992

Purification and refolding of recombinant human IGF II from silkworms infected with recombinant Bombyx mori nuclear polyhedrosis virus.

We have reported that insulin-like growth factor II (IGF II) was produced as a fusion protein in Bombyx mori (silkworm) larval bodies infected with recombinant B. mori nuclear polyhedrosis virus [J. Gen. Virol., 68, 2599-2606 (1987)]. In this study, the purification of IGF II from the infected silkworms is reported. The fusion protein was extracted with 6.0 M guanidine-HCl from the infected larval bodies homogenized in water. The use of organic solvents to remove the impurities, such as lipid derived from the larval bodies, was a very effective method of purification. IGF II was released from the partially purified fusion protein by treatment with CNBr, purified by HPLC, and refolded by air-oxidization. Refolded IGF II had an identical primary structure including disulfide bonds and showed identical thymidine uptake stimulation activity with human IGF II. Furthermore, protein disulfide-isomerase was shown to be able to refold scrambled IGF II rapidly.

Amino Acid Sequence↗
PubMed2001

Characterizations of recombinant human tartrate-resistant acid phosphatase from osteosarcoma: comparison study between recombinant and placental proteins.

We cloned the human tartrate-resistant acid phosphatase (TRAP) gene from human osteosarcoma cells (Saos-2), and produced recombinant human TRAP (rhTRAP) using a baculovirus vector expression system. RhTRAP from Sf9 culture medium was purified by cation exchange chromatography, gel filtration and affinity chromatography. The molecular mass and amino acid composition of the rhTRAP were consistent with the deduced amino acid composition from the TRAP gene. The N-terminal amino acid sequence of rhTRAP was identical to that of TRAP purified from osteoclastoma and hairy cell leukemia spleen. The monoclonal antibodies generated against rhTRAP also reacted to human placental TRAP (pTRAP). The optimum pH of rhTRAP and pTRAP were pH 5.0-5.5 and pH 6.0-6.5, respectively. The enzymatic activities of rhTRAP and pTRAP were activated by reducing agents such as 2-mercaptoethanol, dithiothreitol and ascorbic acid. The activities of rhTRAP and pTRAP were enhanced by Fe2+ ions, but were inhibited by Fe3+ ions. The present results indicate that rhTRAP has similar properties to the native human TRAP, and suggest that the enhancement of TRAP activity by reducing agents might be expressed via the reduction of Fe ions at the metal center.

Acid Phosphatase↗
PubMed1992

The International Standard for Recombinant DNA-derived Erythropoietin: collaborative study of four recombinant DNA-derived erythropoietins and two highly purified human urinary erythropoietins.

The International Standard (IS) for Recombinant DNA-Derived (rDNA) Erythropoietin (EPO) (in ampoules coded 87/684) and three other rDNA EPO preparations in ampoules coded 87/690, 87/696 and 88/574 respectively, were compared with two preparations of highly purified human urinary (HU) EPO and the 2nd International Reference Preparation of Human Urinary Erythropoietin for Bioassay (2nd IRP) by 26 laboratories in 11 countries using a wide range of in-vivo and in-vitro bioassays and immunoassays. These EPO preparations were also compared by electrophoresis and isoelectric focusing. Estimates of EPO content in terms of the 2nd IRP by all in-vivo bioassay methods gave combined unweighted geometric means (with 95% fiducial limits) of: 86 (75-99) IU/ampoule for the IS, 81 (70-94) IU/ampoule for 87/690, 58 (48-71) IU/ampoule for 87/696 and 120 (100-143) IU/ampoule for 88/574. Mean estimates of EPO content in terms of the 2nd IRP by in-vitro bioassays (except receptor assays) were larger than, and those by immunoassays were similar to, the mean estimates by in-vivo bioassays. The use of purified rDNA or HU EPO as standards in place of the 2nd IRP reduced the inter-laboratory variability of estimates of purified EPO preparations by in-vivo and in-vitro bioassays and by immunoassays, and reduced the variability of overall mean estimates for each of these preparations between the three types of method. The inter-laboratory variability of immunoassay estimates of human serum EPO was similar whether the 2nd IRP or one of the purified EPOs was used as standard. Significant differences in in-vivo and in-vitro biological, immunological and physicochemical properties were found between these four rDNA EPO preparations and between them and the HU EPO in the two purified preparations and in the 2nd IRP. There were also differences between the immunoreactivities of the two serum EPO samples included in the study, and between them and the immunoreactivities of the purified EPOs. The differences between rDNA EPOs appeared to be related to differences between the cells used for their biosynthesis, but may also be the result of differences in purification methods and of inter-batch variations. Significant differences in assay specificity were observed within each of the three general types of method. The specificity of the in-vivo bioassays was influenced by the route of hormone administration. The specificities of the mouse spleen cell in-vitro bioassays differed from that of the mouse spleen receptor-binding assay.(ABSTRACT TRUNCATED AT 400 WORDS)

Biological Assay↗
PubMed1997

A phase I/II clinical trial to evaluate a combination of recombinant human platelet-derived growth factor-BB and recombinant human insulin-like growth factor-I in patients with periodontal disease.

The primary objective of this study was to assess the safety of recombinant human (rh) platelet-derived growth factor-BB (PDGF-BB) and (rh) insulin-like growth factor-I (IGF-I) when applied to periodontal osseous defects in humans; a secondary objective was to begin to accrue data on the therapeutic dose of these growth factors (GFs) required to stimulate periodontal regeneration. Thirty-eight human subjects possessing bilateral osseous periodontal lesions were assigned to one of two treatment groups in a split-mouth design. Following full-thickness flap reflection, test sites received local application of the therapeutic drug delivered in coded syringes by a "masked" investigator. Two dose levels were tested, 50 micrograms/ml each of rhPDGF-BB and rhIGF-I in a gel vehicle (LD-PDGF/IGF-I) and 150 micrograms/ml each of rhPDGF-BB and rhIGF-I plus vehicle (HD-PDGF/IGF-I). Control treatment consisted of either conventional periodontal flap surgery or surgery plus vehicle. Safety analyses included physical examination, hematology, serum chemistry, urinalysis, antibody titers, and radiographic evaluation of bony changes. The primary therapeutic assessment was bone fill measured at re-entry 6 to 9 months after treatment. No local or systemic safety issues were found as a result of GF administration. No patients developed antibodies to the rhGF proteins. In subjects treated with LD-PDGF/IGF-I, there were no enhancements in periodontal regeneration compared to controls. However, in patients treated with HD-PDGF/IGF-I, statistically significant increases in alveolar bone formation were noted as measured by surgical re-entry 9 months following drug delivery (P < 0.05). This corresponded to an increase of 2.08 mm of new vertical bone height and 42.3% osseous defect fill in the HD-PDGF/IGF-I subjects versus only 0.75 mm and 18.5% gains in new bone height and osseous fill, respectively, in the controls. Furcation lesions, although limited in number, responded most favorably to treatment, with 2.8 mm horizontal osseous fill. The results from this study suggest that the local application of rhPDGF-BB and rhIGF-I to periodontal lesions is safe at the dose levels studied. LD-PDGF/IGF-I did not elicit increased defect fill compared to the control; however, HD-PDGF/IGF-I resulted in a significant promotion in bone regeneration. Additional studies are warranted to more fully characterize the effects of PDGF/IGF-I on periodontal regeneration in humans.

Administration, Topical↗
PubMed2006

Comparison of the biological activity of recombinant human thyroid-stimulating hormone with bovine thyroid-stimulating hormone and evaluation of recombinant human thyroid-stimulating hormone in healthy dogs of different breeds.

OBJECTIVE: To evaluate whether use of recombinant human (rh) thyroid-stimulating hormone (TSH) induces equivalent stimulation, compared with bovine TSH (bTSH), and to evaluate activity of rhTSH in dogs of various large breeds. ANIMALS: 18 healthy research Beagles and 20 healthy client-owned dogs of various breeds with body weight > 20 kg. PROCEDURES: The 18 Beagles were randomly assigned to 3 groups, and each dog received either 75 microg of rhTSH, IM or IV, or 1 unit of bTSH, IM, respectively, in a crossover design. The 20 client-owned dogs received 75 microg of rhTSH, IV. Blood samples were taken before and 6 hours after TSH administration for determination of total serum thyroxine (T(4)) concentration. Additional blood samples were taken after 2 and 4 hours in Beagles that received rhTSH, IM. RESULTS: There was a significant increase in T(4) concentration in all dogs, but there were no differences between values obtained after administration of bTSH versus rhTSH or IV versus IM administration of rhTSH. Although there was a significant difference in age and body weight between Beagles and non-Beagles, there was no difference in post-TSH simulation T(4) concentration between the 2 groups. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated an equivalent biological activity of rhTSH, compared with bTSH. Use of 75 microg of rhTSH, IV, did not induce a different magnitude of stimulation in large-breed dogs, compared with Beagles. Euthyroidism was confirmed if post-TSH simulation T(4) concentration was > or = 2.5 microg/dL and at least 1.5 times basal T(4) concentration.

Animals↗
PubMed2000

Analyses of TCRB rearrangements substantiate a profound deficit in recombination signal sequence joining in SCID foals: implications for the role of DNA-dependent protein kinase in V(D)J recombination.

We reported previously that the genetic SCID disease observed in Arabian foals is explained by a defect in V(D)J recombination that profoundly affects both coding and signal end joining. As in C.B-17 SCID mice, the molecular defect in SCID foals is in the catalytic subunit of the DNA-dependent protein kinase (DNA-PKCS); however, in SCID mice, signal end resolution remains relatively intact. Moreover, recent reports indicate that mice that completely lack DNA-PKCS also generate signal joints at levels that are indistinguishable from those observed in C.B-17 SCID mice, eliminating the possibility that a partially active version of DNA-PKCS facilitates signal end resolution in SCID mice. We have analyzed TCRB rearrangements and find that signal joints are reduced by approximately 4 logs in equine SCID thymocytes as compared with normal horse thymocytes. A potential explanation for the differences between SCID mice and foals is that the mutant DNA-PKCS allele in SCID foals inhibits signal end resolution. We tested this hypothesis using DNA-PKCS expression vectors; in sum, we find no evidence of a dominant-negative effect by the mutant protein. These and other recent data are consistent with an emerging consensus: that in normal cells, DNA-PKCS participates in both coding and signal end resolution, but in the absence of DNA-PKCS an undefined end joining pathway (which is variably expressed in different species and cell types) can facilitate imperfect signal and coding end joining.

Alleles↗
PubMed1999

Pharmacological effects of a novel recombinant hirudin, CX-397, in vivo and in vitro: comparison with recombinant hirudin variant-1, heparin, and argatroban.

The novel recombinant hirudin analog CX-397 was investigated with respect to its pharmacological activity and antithrombin profiles in vivo and in vitro. In three different types of thrombosis models in rats, including stasis and thrombin-induced venous, glass surface-activated arterio-venous shunt, and ferric chloride-induced arterial thrombosis models, CX-397 and rHV-1 elicited potent antithrombotic effects, where the minimum effective doses of rHV-1 tended to be higher than those of CX-397 in the arterio-venous shunt and arterial thrombosis models. The hemorrhagic risk of CX-397 in template bleeding in rats was not higher than that of rHV-1, indicating that CX-397 is superior to rHV-1 for treating the platelet-dominant type of thrombosis. However, no differences were detected between CX-397 and rHV-1 in their effects on in vitro coagulation times and thrombin-induced platelet aggregation, suggesting the possibility that some unknown mechanisms other than simple thrombin inhibition are also involved in their antithrombotic actions.

Amino Acid Sequence↗
PubMed1998

Enhanced TGFbeta1 maturation in high five cells coinfected with recombinant baculovirus encoding the convertase furin/pace: improved technology for the production of recombinant proproteins in insect cells.

One important limitation of the widely used insect baculovirus overexpression system is its inefficiency to properly process heterologous proteins which are initially biosynthesized as larger inactive precursor proteins. One example is transforming growth factor beta 1 (TGFbeta1), a 25-kDa homodimeric protein with pleiotropic functions. As many growth factors, the inactive TGFbeta1 precursor molecule needs to be proteolytically cleaved C-terminal to a basic sequence to yield the mature and active homodimer. In insect cells, a large proportion of overexpressed TGFbeta1 was found in an inactive precursor form suggesting that the levels of endogenous convertases are limiting for the production of mature and bioactive TGFbeta1 in this system. We have demonstrated that furin, a member of a novel family of mammalian prohormone convertases (PCs) can efficiently process TGFbeta1 precursor resulting in the production of the mature and active growth factor. Taking advantage of this observation, we have developed an improved overproduction system for TGFbeta1 by coexpressing prohTGFbeta1 and human furin convertase in High Five cells. Using this system, the production of mature active TGFbeta1 increased in a dose-dependent fashion reaching up to 7. 8-fold the amount obtained with the growth factor only. Thus, eliminating the rate-limiting step in recombinant TGFbeta1 production maximizes its processing efficiency and the yield of the mature active growth factor. Such simple and efficient technology could be useful for large scale production of other proproteins which undergo similar maturation processes and share furin recognition sequences at the junction between the proregion and the mature polypeptide.

Animals↗
PubMed1999

Immunization with recombinant human granulocyte-macrophage colony-stimulating factor as a vaccine adjuvant elicits both a cellular and humoral response to recombinant human granulocyte-macrophage colony-stimulating factor.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important cytokine for the generation and propagation of antigen-presenting cells and for priming a cellular immune response. We report here that use of recombinant human GM-CSF (rhGM-CSF), administered as an adjuvant in a peptide-based vaccine trial given monthly by intradermal injection, led to the development of a T-cell and antibody response to rhGM-CSF. An antibody response occurred in the majority of patients (72%). This antibody response was not found to be neutralizing. In addition, by 48-hour delayed type hypersensitivity (DTH) skin testing, 17% of patients were shown to have a cellular immune response to the adjuvant rhGM-CSF alone. Thymidine incorporation assays also showed a peripheral blood T-cell response to rhGM-CSF in at least 17% of the patients. The generation of rhGM-CSF-specific T-cell immune responses, elicited in this fashion, is an important observation because rhGM-CSF is being used as a vaccine adjuvant in various vaccine strategies. rhGM-CSF-specific immune responses may be incorrectly interpreted as antigen-specific immunity, particularly when local DTH responses to vaccination are the primary means of immunologic evaluation. We found no evidence of hematologic or infectious complications as a result of the development of rhGM-CSF-specific immune responses.

Adjuvants, Immunologic↗
PubMed2000

N-Methylprotoporphyrin is a more potent inhibitor of recombinant human than of recombinant chicken ferrochelatase.

The potency of N-methylprotoporphyrin IX (N-methylPP) as a ferrochelatase (FC) inhibitor has been previously studied using crude chick embryo liver FC preparations. However, interactions between N-methylprotoporphyrin IX (N-methylPP) and impurities in the enzyme preparation may have compromised the results. The first objective of this study was to compare the potency of N-methylPP as an inhibitor of purified chicken FC and crude chick embryo liver FC. The EC(50) values of N-methylPP previously observed in crude chick embryo liver FC was 2.9 x 10(-3) nmol/mg protein, and with purified recombinant chicken FC was 2.07 x 10(-3) nmol/mg protein. The difference in EC(50) values was not statistically significant, and we conclude that interactions between N-methylPP and impurities in crude enzyme preparations did not affect the estimation of potency of N-methylPP. The second objective of this study was to compare the potency of N-methylPP between purified human and chicken FC. The EC(50) value of N-methylPP observed in the purified human FC preparation was 1.7 x 10(-6) nmol/mg protein (chicken FC 2.07 x 10(-3) nmol/mg protein). Thus, the potency of N-methylPP was much higher with purified human FC than with purified chicken FC. Because the porphyrinogenicity of several xenobiotics involves N-alkylprotoporphyrin IX formation, results on drug-induced porphyria obtained with avian species may underestimate the potential porphyrinogenicity in humans.

Animals↗
PubMedDate not supplied

Recombinant human interleukin-1 beta: new possibilities for the prophylaxis and correction of toxic myelodepression in patients with malignant tumors. I. Phase I-II clinical trials of recombinant human interleukin-1 beta as a leukopoiesis stimulator in cancer patients receiving combination chemotherapy.

Human recombinant interleukin-1 beta (IL-1beta), administered by intravenous drop infusion, at doses of 10-20 ng/kg daily over 5 days, to a group of 67 patients suffering from malignant tumors and with grade II-IV toxic leukopenia, caused an increase in the leukocyte count to the normal value, within, on average, 8 +/- 1 days. The leukostimulatory effect of IL-1beta, administered subcutaneously at an average dose of 4.6 +/- 0.3 ng/kg (n = 16), appeared to be almost equal to that found for intravenous drop infusion at a dose of 10-20 ng/kg (n = 67). In patients receiving subcutaneous IL-1beta injections, the peripheral blood total leukocyte and granulocyte counts achieved normal values within 9 days. The side effects of IL-1beta at a dose of 0.1-20.0 ng/kg were well tolerated.

Adolescent↗
PubMedDate not supplied

Recombinant human interleukin-1 beta: new possibilities for the prophylaxis and correction of toxic myelodepression in patients with malignant tumors. II. Phase II study of the protective effect of recombinant human interleukin-1 beta on myelodepression induced by chemotherapy in cancer patients.

The clinical study of human recombinant IL-1beta as a leukopoiesis protector, administered intravenously and subcutaneously, simultaneously with the chemotherapy, confirmed the "protective" effect of this cytokine in patients with grade II leukopenia induced by previous cycles of chemotherapy. The highly protective effect of IL-1beta was proved by the normalization of absolute peripheral blood granulocyte counts over 5 days, from the start of hemostimulation in patients with leukopenia induced by previous cycles of chemotherapy, despite the continuation of cytostatic treatment. Changing the method of IL-1beta administration from the intravenous to the subcutaneous route had no statistically significant effect on the protective influence of IL-1beta. The time taken for complete restoration of leukopoiesis was almost the same for both methods, 5 +/- 1 days and 7 +/- 1 days for s.c. and i.v. methods respectively. This effect of IL-1beta, not seen in other hematopoietic growth factors such as GM-CSF and G-CSF, allows greater flexibility as regards chemotherapy and provides increased effectiveness of anticancer treatments.

Adolescent↗