摘要:

AbstractRecombinant baculoviruses were constructed to express cDNAs encoding two distinct subtypes of human cAMP‐specific phosphodiesterase (hPDE4A and hPDE4B). Infection of Spodoptera frugiperda insect cells with the appropriate recombinant baculoviruses resulted in high level production of biologically‐active protein as measured by enzymatic activity and immunoblotting using subtype‐specific anti‐hPDE4 antisera. Both recombinant proteins showed catalytic activity with a low Km(∼ 3 μM) for cAMP (with no cGMP hydrolyzing activity) and were inhibited by R‐rolipram with apparent Kis of 0.38 and 0.25 μM, respectively. The recombinant enzymes also contained saturable, stereoselective and high‐affinity rolipram‐binding sites (Kd∼ 2 nM). Thus, insect cell‐derived hPDE4s possess kinetic properties analogous to native enzymes as well as to recombinant enzy

ISSN:1065-6995    

DOI:10.1006/cbir.1995.1091

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractWe studied the influence of substrata topography on the behaviour of murine P388D1 macrophage cell line. Cells were plated on plain fused silica substrata or substrata with microfabricated grooves of varying depth and width. Cell spread area, elongation, orientation and F‐actin content were measured on plain substratum and 6 sets of gratings. The speed and persistence of cell movement were also studied.We found that patterned substrata substantially activated cell spreading and elongation and significantly increased the persistence and speed of cell movement, shallow grooves being more effective than deep ones. The contact of cells with micropatterned substrata significantly increased the F‐actin content in cells. The sensitivity of LPS (lipopolisaccharide) stimulated and unstimulated macrophages to topographical cues was also compa

ISSN:1065-6995    

DOI:10.1006/cbir.1995.1092

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effects of cisplatin and transplatin on the conformation and association of F‐actin were studied by ESR, turbidimetry and CD measurement. The results indicate that the major component affecting F‐actin secondary conformation is derived from their effect on the tertiary or quaternary conformation and association states of F‐actin. The effect of platinum is seen by the fact that binding of cisplatin causes first an increase in molecular size followed by a later decrease. The induction time for the association depended on the concentration of cisplatin. Transplatin was able to reach the target site more readily, resulting in the dissociation of F‐actin even at a very low concen

ISSN:1065-6995    

DOI:10.1006/cbir.1995.1093

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractLithium is being used for the treatment of mental diseases and for the attenuation of muelosuppression during chemotherapy. As during long term lithium treatment kidney damage has been reported, we studied morphological alterations in cells of kidney origin after exposure to lithium chloride. Above the level of 4 mmol, lithium has fatal effects in CV1 cells while HeLa cells that are not originating from kidneys, tolerate higher lithium concentrations. Cellular morphology alters during treatment duration. At early stages, cells become flatter on their substrate and upon longer than 4 days treatment begin to detach from their substrate and eventually cell death comes in a concentration dependent manner. The only morphological alteration observed in a lymphoblastoid cell line was a statistically significant cellular swelling.

ISSN:1065-6995    

DOI:10.1006/cbir.1995.1094

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA human T cell line chronically infected with Human Immunodeficiency Virus (HIV) has been adapted to grow in a chemically defined, protein‐free medium. Virus particles are produced at rates comparable to those of serum‐supplemented cultures; virus preparations free of undesirable proteins can be produced in preparative amounts by simple ultrafiltration procedures and cell culture supernatants can be used as such for the preparation of ELISA solid phases. This material has been used very conveniently for studies concerning characterization of antibodies against HlV‐specific proteins, interaction of HIV with complement components and inclusion of human cell‐derived proteins into virions; we propose its use as a powerful tool for the structural as well as functional analysis of the virus particle

ISSN:1065-6995    

DOI:10.1006/cbir.1995.1095

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractRegulation of fibronectin (FN) by Platelet‐derived Growth Factor‐BB (PDGF‐BB) and Insulin‐like Growth Factor‐I (IGF‐I) in cultured rat thoracic aortic adventitial fibroblasts were examined. PDGF‐BB enhances FN mRNA levels in a time and concentration‐dependent fashion. The effect of IGF‐I on PDGF‐BB‐induced FN levels was also examined. There was a larger increase in FN mRNA levels (4‐fold) in the cells treated with both IGF‐I and PDGF‐BB than with either IGF‐I (2‐fold) or PDGF‐BB (2‐fold) alone. The effects of PDGF‐BB and IGF‐I on FN levels were examined. There was a larger increase in FN levels (135%) in the cells treated with both PDGF‐BB and IGF‐I than with either PDGF‐BB (43%) or IGF‐I (45%) alone. Regulation of adventitial fibroblast FN may le

ISSN:1065-6995    

DOI:10.1006/cbir.1995.1096

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractFluid‐phase and receptor‐mediated endocytosis were studied in Freund's adjuvant elicited macrophages. These cells were found to bind and internalize significantly larger amounts of peroxidase‐antiperoxidase (PAP) immune complex than resident macrophages. Similarly the rate of the fluid‐phase uptake was higher in elicited cells. When studying the early steps of endocytotic processes, omega‐shaped plasma membrane pits (d∼90 nm) were found at the macrophage cell surface. Although occurring occasionally in resident cells, their number was highly increased after elicitation in 30% of the macrophage cell population. The different morphology of these cells coincided with a lower endocytotic activity and a very strong ecto Ca2+‐ATPase reaction. The present findings indicate that the elicited macrophage population is heterogenous and consists of differe

ISSN:1065-6995    

DOI:10.1006/cbir.1995.1097

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractHuman breast epithelial cells dissociated from reduction mammoplasty specimens were embedded in two commonly used extracellular matrices, type I collagen gel or Matrigel, and subsequently transplanted subcutaneously into athymic nude mice. Histological sections from both types of recovered gels showed epithelial structures arranged as short tubules with some branching as well as preservation of epithelial cell polarity. Proliferation was studied in vivo by 5‐bromo‐2′‐deoxy‐uridine labeling followed by immunostaining of sections from recovered gels. Human breast epithelia embedded in collagen gel or Matrigel had similar proliferative activity. Cholera toxin, 17β‐estradiol, and epidermal growth factor, when tested singly, were growth promoting, and in combination 17,β‐estradiol and cholera toxin had an additive effect but 17,β‐estradiol and epidermal growth factor were not additive. Our model system provides a means to study the endocrine control of normal human

ISSN:1065-6995    

DOI:10.1006/cbir.1995.1098

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1995.1099

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1995.1100

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY