Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Less than a decade ago, the use of continuous mammalian cell lines for the production of cloned proteins was considered strictly a research tool. At that time, few thought it possible to allay the many safety concerns associated with transformed cells. It soon became clear that mammalian expression systems had numerous advantages over bacteria for production of therapeutic proteins, initiating a multidisciplinary effort to address these concerns in a thorough and reliable manner. The success of these efforts is exemplified by the emergence of product molecules into the market. Today, there are seven recombinant human therapeutics that have received FDA approval. Almost half of them (OKT3, t-PA, and EPO) are produced in mammalian cells, with the remainder produced in bacteria (insulin, growth hormone, and alpha-interferon) or yeast (hepatitis vaccine). At least a dozen more recombinant cell culture products are in advanced human clinical trials. With the accumulation of data and experience, continuous mammalian cell lines will no doubt be the preferred hosts for many future products of biotechnology.
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PMID:Downstream processing of proteins from mammalian cells. 136 66

A general concern in the lyophilization of protein pharmaceuticals is how dry a product should be in order to maintain its stability during storage. This paper presents our exploratory studies on determining if there is an optimal residual moisture content for lyophilized recombinant protein products. The proteins used in this study were methionyl human growth hormone (met-hGH) and tissue type plasminogen activator (tPA). The amount of water adsorbed on each protein can be determined and approximated as a monolayer by the Brunauer-Emmett-Teller method. The result was in good agreement with the theoretical value calculated from the total number of strong polar groups in the molecule without regard to the conformation of the protein. This approach suggests that each protein may have a minimum moisture content that is necessary to shield the polar groups, and that over-drying will lead to exposure of these groups. The effect of residual moisture content on the stability of tPA in lyophilized excipient-free powder was studied. Samples that were dried to a water content below the calculated monolayer exhibited opalescence upon reconstitution, while those that were dried to either monolayer or multilayer water content tended to show a greater loss in biological stability upon storage under temperature stress conditions. The results of our studies reveal that the generally accepted concept "the drier the better" may not be appropriate for tPA. An optimum residual moisture content is required to balance the physical stability and the biological stability. These observations may apply to other protein products as well.
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PMID:Determining the optimum residual moisture in lyophilized protein pharmaceuticals. 159 75

The clearance and volume of distribution of five human proteins (recombinant CD4, CD4 immunoglobulin G, growth hormone, tissue-plasminogen activator, and relaxin) in humans and laboratory animals were analyzed as a function of body weight using allometric scaling techniques. These proteins cover a 16-fold range of molecular weight (6 to 98 kD), are produced by recombinant or synthetic methods, and may be cleared by different mechanisms. The analyses revealed that the clearance and volume data for each protein were satisfactorily described by an allometric equation (Y = a Wb). The allometric exponent (b) for clearance (ml/min) ranged from 0.65 to 0.84, the allometric exponent for the initial volume of distribution (ml) ranged from 0.83 to 1.05, and the allometric exponent for the volume of distribution at steady state (ml) ranged from 0.84 to 1.02. Exponent values from 0.6 to 0.8 for clearance and 0.8 to 1.0 for volumes are frequently cited for small molecules and are expected based on empirical interspecies relationships. When the preclinical data were analyzed separately, the preclinical allometric relationships were usually predictive of the human results. These findings indicate that the clearance and volume of distribution of select biomacromolecules follow well-defined, size-related physiologic relationships, and preclinical pharmacokinetic studies provide reasonable estimates of human disposition. Employing this methodology during the early phases of drug development may provide a more rational basis for dose selection in the clinical environment.
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PMID:Interspecies scaling of clearance and volume of distribution data for five therapeutic proteins. 179 69

Over the last few years several groups have used retroviral vectors to achieve stable gene transfer into endothelial cells. In vitro experiments include transduction of cultured cells with genes of potential therapeutic interest, such as growth hormone and tissue plasminogen activator (t-PA). Animal studies have demonstrated the feasibility of in vivo recombinant gene expression from transduced endothelial cells, but have thus far been accomplished only with the lacZ marker gene. All studies to date have been oriented primarily toward the use of transduced endothelial cells to provide gene therapy. Numerous issues remain to be addressed with experimental data prior to the initiation of a clinical protocol using transduced endothelial cells. These issues include the introduction of larger numbers of transduced cells into the vasculature and the achievement of appropriate regulation of transgene expression. The use of retroviral vectors to study basic endothelial cell biology has been relatively ignored. The tool of retroviral vector-mediated gene transfer is available for use in answering both therapeutic and pathophysiological questions in endothelial cell biology.
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PMID:Retroviral vector-mediated gene transfer into endothelial cells. 180 67

It has been suggested that growth hormone (GH) plays a role in the regulation of Factor VIII-von Willebrand factor complex and other parameters associated with haemostasis and vascular integrity. However, limited information is available on these features in GH-deficient patients. We therefore examined, in a double-blind, placebo-controlled crossover design, the effects of 4 months' replacement therapy with biosynthetic human GH in 22 GH-deficient adults on circulating haemostatic parameters and capillary fragility. A non-significant increase in the plasma levels of von Willebrand factor antigen (p = 0.09), Factor VIII antigen (p = 0.6), fibrinogen (p = 0.4) and fibronectin (p = 0.2) was observed at the end of the GH treatment period along with a non-significant decrease in tissue-type plasminogen activator (p = 0.2). Capillary fragility tended to decrease during GH therapy (p = 0.2). All variables remained within the reference range following both the placebo and the GH treatment period. It is concluded that GH-deficient patients display normal levels of the haemostasis parameters recorded, and that 4 months of GH therapy in a conventional replacement dose does not significantly affect these values.
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PMID:Growth hormone (GH) therapy in GH-deficient patients, the plasma factor VIII-von Willebrand factor complex, and capillary fragility. A double-blind, placebo-controlled crossover study. 211 72

Excess production of growth hormone (GH) in poorly controlled diabetes is believed to be a causal factor in the development of diabetic angiopathy, the mechanism(s) of which is unknown. The present study was undertaken to determine whether exogenous growth hormone would specifically change some quantities and functional parameters known to often be abnormal in long-standing diabetes and thought to result from the development of vascular lesions in general. The authors studied capillary resistance, factor VIII coagulant antigen (F VIII:Ag), von Willebrand factor (vWf:Ag), fibronectin, fibrinogen, and tissue-type plasminogen activator (t-PA) before, during, and after 1 week's subcutaneous GH administration (6 IU per day divided into two doses). Capillary resistance decreased insignificantly, but returned to higher levels (p less than 0.05) 1 week after withdrawal. F VIII:Ag, vWf:Ag, fibronectin, and fibrinogen all increased significantly during GH treatment. Except for F VIII:Ag, these quantities returned to pre-medication levels 7 days after termination of GH administration. The present results may contribute to the clarification of the role of GH hypersecretion in diabetic microangiopathy and macroangiopathy.
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PMID:Diabetes-like alterations in hemostatic parameters after growth hormone administration for one week in normal man. 252 35

Cells from gliomas induced by N-ethyl-N-nitrosourea have a high basal level of plasminogen activator activity compared with cells from normal tissue. Plasminogen activator activity is known to be affected by many substances but whether inhibition or stimulation occurs depends on the cell and agent involved. It is not clear whether tumour and control cells from the same type of tissue respond similarly. A comparison has been made of the effect of several factors on both cell associated and secreted enzyme activity of cloned lines from a glioma and normal tissue. The effect of two cAMP elevating compounds was stimulatory while that of the steroid, dexamethasone, was generally inhibitory for both cells. However, the polypeptide hormone, epidermal growth factor, had a differential effect. It caused an increase in secreted enzyme activity in the tumour line but had no such effect on the control clone. The precise mechanism by which this occurs is unknown. Co-operative effects of the enzyme and growth hormone could result in more aggressive behaviour of the tumour cells.
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PMID:A comparison of the effect of several factors on the plasminogen activator activity of cloned lines from an ethylnitrosourea-induced glioma and from normal tissue. 262 4

Rat adrenal glands were stained immunocytochemically using antibodies against plasminogen activators of the tissue-type (t-PA) and urokinase-type (u-PA). A subpopulation of the cells in the adrenal medulla showed intense cytoplasmic t-PA immunoreactivity, while no u-PA immunoreactivity was detected in any adrenal cells. Fluorescence microscopy of adjacent sections demonstrated that the cells stained for t-PA contained noradrenaline. Analysis with a histochemical fibrin slide technique demonstrated a plasminogen-dependent fibrinolysis in the adrenal medulla. SDS-PAGE of adrenal gland extracts followed by zymography established the molecular weight of this plasminogen activator to be similar to that of rat t-PA. In addition SDS-PAGE followed by immunoblotting with anti-t-PA IgG of adrenal gland extracts revealed one band with an electrophoretic mobility indistinguishable from that found in the zymography. When tissue-sections and immunoblots were incubated with antibodies absorbed with highly purified t-PA no staining was found. In view of the previous finding of t-PA in growth hormone-containing cells of the pituitary gland, these findings substantiate that t-PA can be found in the intact normal organism outside endothelial cells, and further point to t-PA having a function in endocrine cells.
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PMID:Tissue-type plasminogen activator in rat adrenal medulla. 309 16

In cross-sectional studies elevations in growth hormone (GH), factor VIII related antigen (VIIIR:Ag), and plasminogen activator activity (PAA) have been connected with diabetic retinopathy. To evaluate the importance of these factors for the development of retinopathy, we have carried out a prospective study. In a primary study GH, VIIIR:Ag, and PAA were evaluated during a 25 min exercise test in 22 insulin dependent diabetes mellitus (IDDM) patients. After 5-7 years, the patients were re-evaluated and the presence of retinopathy in the follow-up study was correlated to the findings in the primary study. Patients with retinopathy in the primary or the second study (n = 14) showed a significant increase in GH (p less than 0.05) during the first 5 min of exercise compared with patients without retinopathy. Moreover, the 14 retinopathy patients showed further significant elevations in GH (p less than 0.001), VIIIR:Ag (p less than 0.01) and PAA (p less than 0.001) during the remaining 20 min of exercise. In contrast, patients without retinopathy (n = 8) in the follow-up study, did not show significant elevations in GH, VIIIR:Ag, and PAA during exercise. A lack of rise in GH, VIIIR:Ag, and PAA during exercise seems to indicate a resistance to retinopathy in IDDM patients.
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PMID:Absent elevations in growth hormone, factor VIII related antigen, and plasminogen activator activity during exercise in diabetic patients resistant to retinopathy. 313 76

We immunocytochemically stained rat pituitary glands using antibodies against plasminogen activators of the tissue type (t-PA) and the urokinase type (u-PA). A large population of endocrine cells in the anterior lobe of the gland displayed intense cytoplasmic immunoreactivity with anti-t-PA. In some areas of the intermediate lobe we found a weak staining, and we observed weakly staining granular structures in the posterior lobe. Controls included absorption of the antibodies with highly purified t-PA. In addition, SDS PAGE followed by immunoblotting of pituitary gland extracts revealed only one band with an electrophoretic mobility similar to that of t-PA when stained with anti-t-PA IgG. No u-PA immunoreactivity was detected in the rat pituitary gland. Sequential staining experiments using antibodies against growth hormone and t-PA demonstrated that the t-PA-immunoreactive cells constitute a large subpopulation of the growth hormone-containing cells. These findings represent the first direct evidence for the presence of t-PA in cell types other than endothelial cells in the intact normal organism. In this article we discuss the implications of the results for a possible role of t-PA in the posttranslational processing of prohormones.
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PMID:Immunocytochemical demonstration of tissue-type plasminogen activator in endocrine cells of the rat pituitary gland. 389 62


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