RESUMEN
Angiogenesis is critical for the growth and proliferation of tumors as well as for normal development. We now describe a novel role for histidine-rich glycoprotein (HRGP) in the modulation of angiogenesis. HRGP is a plasma protein that circulates in relatively high concentrations (1.5 microM), but has no known function in vivo. We have shown previously that HRGP binds with high affinity to thrombospondin-1 (TSP-1), a homotrimeric glycoprotein that is a potent inhibitor of angiogenesis. The antiangiogenic activity of TSP-1 is mediated by the binding of properdin-like type I repeats to the receptor CD36. We found that binding of HRGP to TSP-1 was similarly mediated by TSP type I repeats. HRGP colocalized with TSP-1 in the stroma of human breast cancer specimens, and this interaction masked the antiangiogenic epitope of TSP-1. In assays performed in vitro of endothelial cell migration and tube formation, and in vivo corneal angiogenesis assays, HRGP inhibited the antiangiogenic effect of TSP-1. These studies suggest that HRGP can modulate the antiangiogenic activity of TSP-1, and identify a potential mechanism of resistance to the antiangiogenic effect of TSP-1.
Asunto(s)
Glicoproteínas/farmacología , Neovascularización Fisiológica/efectos de los fármacos , Proteínas/farmacología , Trombospondina 1/antagonistas & inhibidores , Trombospondina 1/farmacología , Secuencia de Aminoácidos , Sitios de Unión/genética , Neoplasias de la Mama/irrigación sanguínea , Neoplasias de la Mama/etiología , Neoplasias de la Mama/metabolismo , Movimiento Celular/efectos de los fármacos , Células Cultivadas , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Femenino , Glicoproteínas/genética , Glicoproteínas/metabolismo , Humanos , Técnicas In Vitro , Modelos Biológicos , Datos de Secuencia Molecular , Neovascularización Patológica , Proteínas/genética , Proteínas/metabolismo , Secuencias Repetitivas de Aminoácido , Homología de Secuencia de Aminoácido , Trombospondina 1/genética , Trombospondina 1/metabolismoRESUMEN
OBJECTIVE: To identify how some general practices have low growth in prescribing costs relative to other practices. DESIGN: Observational study. SETTING: Trent region of England. PARTICIPANTS: 162 general practices: 54 with low growth in prescribing costs, 54 with average increases in costs, and 54 with large increases in costs. MAIN OUTCOME MEASURES: Changes in prescribing costs in therapeutic categories in which it has been suggested that savings can be made. RESULTS: There were significant differences between the three groups of practices in terms of their changes in prescribing costs for almost all the variables studied. For the group of practices with lowest growth in costs the most important factors were reducing numbers of prescription items and costs per item; relatively low growth in the costs of "new and expensive" drugs; increasing generic prescribing; and reducing costs for modified release products. This group of practices did not increase costs as much as the others for lipid lowering drugs (P=0.012) and hormone replacement therapy (P=0. 007). The practices with the greatest increases in costs had particularly large increases for proton pump inhibitors, selective serotonin reuptake inhibitors, and modified release products. Compared with the other groups these practices had larger increases in costs for "expensive hospital initiated drugs" (P=0.009). CONCLUSION: General practices vary in their growth in prescribing costs in many ways, with growth in costs for "new and expensive" drugs being particularly important.
Asunto(s)
Costos de los Medicamentos/tendencias , Utilización de Medicamentos/tendencias , Administración de la Práctica Médica/economía , Pautas de la Práctica en Medicina/tendencias , Utilización de Medicamentos/estadística & datos numéricos , Inglaterra , HumanosRESUMEN
The members of the transforming growth factor-beta (TGF-beta) superfamily are secreted proteins that interact with cell-surface receptors to elicit signals that regulate a variety of biological processes during vertebrate embryogenesis. Alk2, also known as ActRIA, Tsk7L, and SKR1, encodes a type I TGF-beta family receptor for activins and BMP-7. Initially, Alk2 transcripts are detected in the visceral endoderm of gastrula stage mouse embryos, suggesting a signaling role in extraembryonic tissues during development. To study the role of Alk2 during mammalian development, Alk2 mutant mice were generated. After embryonic day 9.5 (E9.5), no homozygous mutants were recovered from heterozygote matings. Homozygous mutants with morphological defects were first detected at E7.0 and were smaller than controls. Morphological and molecular examination demonstrated that Alk2 mutant embryos formed a primitive streak, although abnormally thickened, and were arrested in their development around the late streak stage. These gastrulation defects were rescued in chimeric embryos generated by injection of Alk2 mutant embryonic stem (ES) cells into wild-type blastocysts. This rescue of gastrulation defects was also observed in chimeric embryos generated by aggregation of Alk2 homozygous mutant ES cells with tetraploid wild-type embryos. However, at E9.5, these embryos that were completely ES-derived also had defects. In contrast, chimeric embryos generated by injection of wild-type ES cells into Alk2 mutant blastocysts did not show rescue of the gastrulation defects. These results suggest that signaling through this type I receptor is essential in extraembryonic tissues at the time of gastrulation for normal mesoderm formation and also suggest that subsequent Alk2 signaling is essential for normal development after gastrulation.
Asunto(s)
Desarrollo Embrionario y Fetal , Receptores de Factores de Crecimiento/fisiología , Transducción de Señal/fisiología , Factor de Crecimiento Transformador beta/fisiología , Receptores de Activinas Tipo I , Animales , Gástrula/fisiología , Ratones , MutaciónRESUMEN
Tumour formation relies on a complex combination of genetic and environmental factors. In particular, the contributions from inherited predisposition genes as well as carcinogens, for example from cigarettes or in the diet, are amongst the major contributors to tumorigenesis. Since the study of such processes in particularly difficult in human cancers, the availability of a well-defined model system is of obvious benefit. The mouse skin model of multistage carcinogenesis offers an excellent tool for the study of the target cells, the target genes and the biological events associated with neoplasia. In this system, tumorigenesis occurs in a series of defined stages, each of which is characterized by specific and reproducible alterations in genes such as H-ras, cyclin D1, p53 and p16INK4A. Additional changes occur in the production of, or response to, factors such as transforming growth factor beta (TGF beta). These genetic and biological alterations are mirrored in human tumours of epithelial origin. Hence, research into the general principles of tumour initiation, promotion and progression in the context of the mouse skin model is likely to prove valuable in the continual search for new methods for the diagnosis, prevention, and therapeutic treatment of human cancers.
Asunto(s)
Transformación Celular Neoplásica , Células Epiteliales/patología , Neoplasias/genética , Animales , Ciclo Celular , Ciclina D1/genética , Daño del ADN , Células Epiteliales/citología , Genes p16 , Genes p53 , Genes ras , Humanos , Ratones , Modelos Biológicos , Neoplasias/patología , Neoplasias/fisiopatología , Neoplasias Experimentales/genética , Neoplasias Experimentales/patología , Neoplasias Experimentales/fisiopatologíaRESUMEN
LIMPII (lysosomal integral membrane protein II) is one of a family of proteins structurally related to the cell surface glycoprotein CD36. We recently defined a single structural domain on CD36 that mediates binding to adhesive glycoprotein thrombospondin-1 (TSP1). The CD36-TSP1 interaction is known to play a role in platelet-tumor and platelet-monocyte adhesion, angiogenesis, and in monocyte uptake of apoptotic cells. To test whether LIMPII also binds TSP1, a LIMPII peptide corresponding to the TSP1 binding domain of CD36 was expressed as a recombinant glutathione S-transferase (GST) fusion protein. In solid phase binding assays, purified 125I-TSP1 bound to immobilized GST/LIMPII in a time-dependent and saturable manner. Inhibition by excess unlabeled TSP1 or EDTA demonstrated specificity. LIMPII.TSP1 complex formation was specifically blocked by soluble LIMPII fusion protein, by monospecific rabbit IgG directed against the LIMPII peptide and by CD36 fusion proteins containing the TSP1 binding domain. Transfection of Bowes melanoma cells with a chimeric LIMPII cDNA that targets expression to the plasma membrane conferred the ability to bind 125I-TSP1 and to adhere to TSP1-coated surfaces. This study defines a TSP1 binding site conserved between LIMPII and CD36 and suggests that cell surface LIMPII may function in some circumstances as an adhesion receptor for TSP1. Computer-assisted homology searches suggest that the TSP1 recognition motif identified from study of CD36 family members may be widely expressed in nature.
Asunto(s)
Antígenos CD36/metabolismo , Lisosomas , Glicoproteínas de Membrana , Trombospondina 1/metabolismo , Secuencia de Aminoácidos , Animales , Sitios de Unión , Unión Competitiva , Plaquetas/metabolismo , Antígenos CD36/genética , Compartimento Celular , Secuencia Conservada , Evolución Molecular , Proteínas de Membrana de los Lisosomas , Melanoma Experimental , Datos de Secuencia Molecular , Unión Proteica , Ratas , Ratas Sprague-Dawley , Proteínas Recombinantes de Fusión , Homología de Secuencia de Aminoácido , Transfección , Células Tumorales CultivadasRESUMEN
Human and non-human primate salivas retard the infectivity of HIV-1 in vitro and in vivo. Because thrombospondin 1 (TSP1), a high molecular weight trimeric glycoprotein, is concentrated in saliva and can inhibit the infectivity of diverse pathogens in vitro, we sought to determine the role of TSP1 in suppression of HIV infectivity. Sequence analysis revealed a TSP1 recognition motif, previously defined for the CD36 gene family of cell adhesion receptors, in conserved regions flanking the disulfide-linked cysteine residues of the V3 loop of HIV envelope glycoprotein gp120, important for HIV binding to its high affinity cellular receptor CD4. Using solid-phase in vitro binding assays, we demonstrate direct binding of radiolabeled TSP1 to immobilized recombinant gp120. Based on peptide blocking experiments, the TSP1-gp120 interaction involves CSVTCG sequences in the type 1 properdin-like repeats of TSP1, the known binding site for CD36. TSP1 and fusion proteins derived from CD36-related TSP1-binding domains were able to compete with radiolabeled soluble CD4 binding to immobilized gp120. In parallel, purified TSP1 inhibited HIV-1 infection of peripheral blood mononuclear cells and transformed T and promonocytic cell lines. Levels of TSP1 required for both viral aggregation and direct blockade of HIV-1 infection were physiologic, and affinity depletion of salivary TSP1 abrogated >70% of the inhibitory effect of whole saliva on HIV infectivity. Characterization of TSP1-gp120 binding specificity suggests a mechanism for direct blockade of HIV infectivity that might be exploited to retard HIV transmission that occurs via mucosal routes.
Asunto(s)
Antígenos CD36/metabolismo , Proteína gp120 de Envoltorio del VIH/química , Proteína gp120 de Envoltorio del VIH/metabolismo , VIH-1/metabolismo , Saliva/metabolismo , Saliva/virología , Trombospondina 1/metabolismo , Secuencia de Aminoácidos , Animales , Sitios de Unión/genética , Antígenos CD36/genética , Antígenos CD4/metabolismo , Genes env , Proteína gp120 de Envoltorio del VIH/genética , Infecciones por VIH/prevención & control , Infecciones por VIH/transmisión , Infecciones por VIH/virología , VIH-1/genética , VIH-1/aislamiento & purificación , Humanos , Técnicas In Vitro , Datos de Secuencia Molecular , Mapeo Peptídico , Homología de Secuencia de AminoácidoRESUMEN
Pearlizing agents have been used for many years in cosmetic formulations to add a pearlescent effect. Cold pearl surfactant-based blends are mixtures of glycol stearates and surfactants which can be blended in the cold into a wide range of personal-care formulations to create a pearlescent lustre effect. Under controlled manufacturing conditions constant viscosities and crystalline characteristics can be obtained. The development of these blends has been driven by efforts to improve the economics of adding solid pearlizing agents directly into a hot mix formulation. This paper summarizes the history of pearlizers, describes their advantages and physical chemistry of the manufacturing process. Finally some suggestions for applications are given. Les agents nacrants sont utilises depuis de nombreuses annees dans les formulations cosmetiques pour ajouter un effet nacre. Les melanges a froid a base de tensioactif nacre sont des melanges de stearates de glycol et de tensioactifs qui peuvent etre melanges a froid dans une large gamme de formulations d'hygiene personnelle pour creer un effet de lustre nacre. On peut obtenir des viscosites et des proprietes cristallines constantes avec des conditions de fabrication maitrisees. Le developpement de ces melanges a ete porte par les efforts pour ameliorer les couts de l'ajout d'agents nacrants solides directement dans une formulation melangee de l'ajout d'agents nacrants solides directement dans une formulation melangee a chaud. Cet article resume l'histoire des agents nacrants, decrit leurs avantages et al physico-chimie du procede de fabrication. On emet a la fin cetaines suggestions d'applications.
RESUMEN
The ultimate stage of carcinogenesis in both human and mouse epithelial cells is the ability to invade surrounding tissues and metastasize to distant sites. In mouse skin tumours, the development of the invasive, spindle cell phenotype is associated with an imbalance of alleles on mouse chromosome 7, including the H-ras gene. In previous work, we have described clonally related squamous and spindle cell lines from the same primary tumour which differed substantially in morphology and behaviour, but showed the same series of mutations in H-ras and p53 genes. One of the events which takes place during this transition is disruption of cell-cell contacts, possibly due to the induced expression of metalloproteinases such as stromelysin-1 and disappearance of the cell adhesion molecule E-cadherin. Parallel studies using somatic cell hybrids have shown that the spindle cell phenotype is recessive in hybrids between squamous and spindle cells. We propose that an important epidermal differentiation-controlling gene is lost during the spindle cell transition.
Asunto(s)
Neoplasias Cutáneas/patología , Neoplasias Cutáneas/secundario , Animales , Carcinoma/genética , Carcinoma/patología , Carcinoma/secundario , Progresión de la Enfermedad , Ratones , Invasividad Neoplásica , Fenotipo , Neoplasias Cutáneas/genética , Células Tumorales CultivadasRESUMEN
Genes encoding the chi and psi accessory proteins of the DNA polymerase III holoenzyme replicase of Escherichia coli have been identified, sequenced, and used to express and purify both chi and psi in quantity. The holC gene encoding chi is located between the xerB and valS genes at 96.5 min on the chromosome; it encodes a 147-amino acid protein of 16.6 kDa. holD encoding psi lies upstream of rimI at 99.3 min and encodes a 137-amino acid protein of 15.2 kDa. The genes have been cloned into expression vectors, and both chi and psi have been purified in quantity. The accompanying report characterizes the function and physical interactions of chi and psi with other holenzyme subunits (Xiao, H., Dong, Z., and O'Donnell, M. (1993) J. Biol. Chem. 268, 11779-11784).
Asunto(s)
ADN Polimerasa III/genética , Escherichia coli/enzimología , Escherichia coli/genética , Genes Bacterianos , Secuencia de Aminoácidos , Secuencia de Bases , Cromatografía , Cromatografía de Afinidad , Cromatografía por Intercambio Iónico , ADN Polimerasa III/aislamiento & purificación , ADN Polimerasa III/metabolismo , Replicación del ADN , ADN Bacteriano/genética , ADN Bacteriano/metabolismo , Durapatita , Hidroxiapatitas , Cinética , Sustancias Macromoleculares , Datos de Secuencia Molecular , Oligodesoxirribonucleótidos , Plásmidos , Mapeo RestrictivoRESUMEN
Extended hyperimmunization of rabbits with Sindbis (SIN) or Semliki Forest (SF) viruses causes the production of antisera that are cross-reactive with virus-infected cells in antibody-dependent, complement-mediated cytotoxicity assays but that do not cross-neutralize viruses in vitro. C3H/HeJ mice given gamma globulin fractionated from the extended hyperimmune antiserum against SIN, but not control sera, were protected from challenge by 100 LD50 of SF, a virus which is in a different subgroup than SIN. All mice survived if the gamma globulin was given 24 hr before challenge virus and partial protection occurred if the globulin was given 24 hr after the virus. Cobra venom factor treatment of normal C3H mice challenged with SF did not reduce the protection, suggesting that complement was not involved. Methyl palmitate (40 mg/mouse) given before gamma globulin and virus challenge suppressed macrophage activity and reduced the level of protection 23% in females and 70% in males. Silica treatment (3 mg/mouse) reduced the protection equally in both males and females by 92%. In vitro experiments were done to test if it were possible that cross-antibody-dependent cellular cytotoxicity (ADCC) could account for the passive cross-protection observed in this system. Cross-ADCC could be demonstrated in vitro at high dilutions of antiserum (1:25,600). On the basis of the in vitro and in vivo results presented, we suggest that cross-ADCC against SF-infected target cells is one of the likely mechanisms to explain the passive cross-protection observed.