摘要:

AbstractIt has been demonstrated that mosquito larvae crude extract has an inhibiting effect on the mitotic rate of several mouse cell populations. The sampling period was 16–24h after treatment, when mitotic peak normally occurs. The present paper reports the effect of mosquito larvae crude extract on the proliferation of hepatocytes, renocytes, Lieberkhün crypt enterocytes, and sialocytes. In this case, the sampling period covered the dark phase of the day, during the first 12h after treatment. Colchicine‐arrested metaphases were controlled at 20/04, 00/08 and 04/12 (Time of Day/Time Post Injection). The mitotic rate was significantly increased in hepatocytes and renocytes and inhibited in duodenum enterocytes. In view of the time chosen to administer the treatments and the time elapsed until sampling, we conclude a probable effect of the extract at the G2‐M point of the cell

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0028

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe microenvironment in the haematopoietic organs plays an important role in regulating and sustaining differentiation and self‐renewal of haematopoietic stem cells. Although crucial for stem cell maintenance and homing, the stromal cell—stem cell interactions are poorly understood. Here we show that an ICAM‐like molecule is responsible for stem cell adhesion to stromal cellsin vitro. The molecule was characterized by a monoclonal antibody 3E10. Immunoblotting results indicated that the molecule had an electrophoretic mobility equal to that of intercellular cell adhesion molecule‐1 (ICAM‐1). Binding inhibition assays, however, showed that inhibition of binding of enriched CD34 cells by 3E10was more prominent in comparison with that

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0029

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe epidermal keratinocytes express two major pairs of keratin polypeptides. One pair (K5/K14) expressed specifically in basal generative compartment and the other (K1/K10) expressed specifically in the differentiating suprabasal compartment. The switch in the expression of the keratins from proliferating to differentiating compartment indicates the changes that occur in the keratin filament organization which in turn influences the functional properties of the epidermis. Proper regulation of keratin gene expression and the filament organization are absolutely necessary for normal functioning of the skin. Keratin gene mutations can influence the filament integrity thereby causing several heritable blistering disorders of the skin such as epidermolysis bullosa, bullous icthyosiform erythroderma, etc. Changes in the keratin gene expression may lead to incomplete differentiation of the epidermal keratinocyte, causing hyperproliferative diseases of the skin such as psoriasis, carcinomas, etc. This review briefly describes the changes in keratin structure or gene expression that are known to result in various disorders of the skin.

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0030

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe regulation of mitosis in higher plant cells has been investigated by microinjecting protein kinase from the metaphase‐arresting (met1) mutant ofChlamydomonas. Biochemical characterization of this enzyme complex confirms the presence of a p34cdc2/cyclin B‐like kinase. The enzyme was injected into living stamen hair cells ofTradescantia virginianain which microtubules (MTs) were visualized using fluorescent analogue cytochemistry and confocal laser scanning microscopy. Microinjection of this p34cdc2/cyclin B‐like kinase caused rapid disassembly of the preprophase band of MTs but not of interphase‐cortical, spindle or phragmoplast MTs. Effects of the enzyme on the cytomorphology of live prophase cells were also monitored using video microscopy. We found that injection of this enzyme accelerated chromatin condensation and nuclear envelope breakdown. This indicates the presence and function in plants of an enzyme that can initiate nuclear division similar to the maturation or mitosis promoting factor (MPF) of animal cells. These studies provide the first direct evidence that the mitotically‐active form of plant MPF can drive disassembly of preprophase band MTs, chromosome condensation and initiation of mitosis in pl

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0031

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractColony‐forming ability was employed in evaluating the susceptibility toin vitrogamma ionizing radiation in human diploid skin fibroblasts (HDF). Twelve pairs of HDF, each composed of fibroblasts from excised keloid lesion and local normal skin tissue as its control, were studied in patients with clinically persistent keloids. Parameters of radiosensitivity, both D0and D10, and growth kinetics were examined. The radiosensitivity in three of the 12 keloids (25%) were demonstrated significantly increased than their counterpart controls, even though no difference in growth kinetics in between. Moreover, a broad range in the radiosensitivity of fibroblast cells was demonstrated and it is suggested that there is a great heterogeneity of cellular response to radiation in HD

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0032

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe rat pheochromocytoma cell line PC12 contains two distinct pathways of protein secretion. Proteins secreted via the regulated pathway are stored in secretory vesicles and exocytosed only in response to a specific signal, whereas proteins secreted via the constitutive pathway are exported continuously. Analysis of regulated secretion of a heterologous protein in this system often relies on comparison of secretion rates with those of endogenous proteins known to be secreted via the constitutive route. In order to improve these controls, we have evaluated a number of secreted enzymes, selected for the sensitivity and convenience of their assays, as transgenic markers for the constitutive pathway. We show that both human‐secreted placental alkaline phosphatase (SEAP) and bacterial β‐lactamase operate in this way in transfected PC12 cells. In contrast, transfected human tissue plasminogen activator (tPA) is shown to be sorted to the regulated pat

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0033

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0034

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY