摘要:

AbstractCloned, large vessel endothelial cells derived from fetal bovine and bovine calf aortas formed three‐dimensional structures in vitro without tumor‐conditioned medium or special substrata. Transmission electron microscopy showed the structures to be hollow tubes composed of typical endothelial cells with overlapping and interdigitating cytoplasmic processes typical of those seen in in vivo capillaries. The putative lumen of these tubes generally contained abundant electron‐dense fibrous material, which by ruthenium red and indirect immunofluorescent staining appeared to be extracellular matrix. This suggests that the endothelial cell orientation in the tubes is the reverse of that normally found in in vivo ve

ISSN:0021-9541    

DOI:10.1002/jcp.1041160102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractLong‐term cultures established from spleen cells were compared to those established from bone marrow cells for their ability to maintain hemopoiesis as measured by the presence of hemopoietic progenitor cells (in vitro CFU) and multipotent stem cells (CFU‐S). The frequency of both in vitro CFU and CFU‐S increased dramatically during the first 2 weeks in the spleen cultures. Following this early peak of activity, the number of progenitors and stem cells declined to undetectable levels by week 6 of culture. During this short phase of hemopoiesis, large amounts of GM‐CSF could be detected in the supernatant of the spleen cultures. In contrast, bone marrow cultures did not share this early peak of hemopoiesis; however, they maintained activity for much longer periods of time than did the spleen cultures. When spleen stem cells were seeded onto functional bone marrow adherent cells, spleen‐derived in vitro CFU were maintained well beyond week 6 of culture. Spleen cultures established from athymic nu/nu mice showed a greatly reduced ability to support hemopoiesis while those from S1/S1dmice maintained GM‐CFU as well as cultures from

ISSN:0021-9541    

DOI:10.1002/jcp.1041160103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractAdult susceptible mice (DBA/2J) infected with MPSV (myeloproliferative sarcoma virus), a defective RNA tumour virus, develop splenomegaly and progressive disruption of the haematologic system culminating in death. The present study was specifically directed toward determining the effects of the virus on erythroid differentiation. Early and late precursor cells (erythroid burst‐forming units; BFU‐E and colony‐forming units; CFU‐E, respectively) were evaluated by the ability of bone marrow and spleen cells to form colonies of fully differentiated erythroid cells in vitro. MPSV caused substantial modification of both the BFU‐E and CFU‐E populations in the bone marrow and spleen of infected animals. Changes were detected in the CFU‐E population preceding any significant increase in spleen weight. In the bone marrow, the proportion of CFU‐E cells increased almost twofold by days 5–10 after virus infection but decreased by day 15. In the spleen, CFU‐E frequency rose 40‐fold by days 10–15 and then declined steadily prior to death. At the peak of CFU‐E expansion, a small proportion of the population appeared to be erythropoietin (Ep) independent, although there was no evidence of a complete switch to Ep‐independence which occurs in Friend virus‐induced erythroleukemia. Dose‐response curves showed that none of these data could be explained in terms of a changing responsiveness to Ep. However, evidence is presented that indicates that BFU‐E from MPSV‐infected animals lose or have a reduced requirement for burst‐promoting activity (BPA) relative to normal cells although their progeny still need Ep f

ISSN:0021-9541    

DOI:10.1002/jcp.1041160104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractSaccharomyces cerevisiaemannan inhibits the pinocytosis of horseradish peroxidase (HRP) by resident, thioglycollate‐, proteose peptone‐, andCo‐rynebacterium parvum‐elicited macrophages from 30 to 70% when 1 mg/ml HRP is used, and 65 to 87% when 250 μg/ml HRP is used. In contrast, HRP uptake by J774 cells, a macrophage cell line reported to have little mannose receptor activity, is inhibited only about 25% by mannan. HRP uptake by resident and thioglycollate‐elicited (thio) macrophages is also inhibited 34 and 66% by addition of EGTA to the medium and 55 and 79% by trypsin treatment of the macrophages, respectively. The inhibitory effect of EGTA can be reversed by 1 mM excess Ca2+. High extracellular concentrations of Ca2+, in the range of 10–20 mM, however, inhibit pinocytosis in resident macrophages by about 50%. Sucrose uptake by resident macrophages is not appreciably affected by mannan. These results support the hypothesis that HRP uptake is mediated by the macrophage mannose/N‐acetylgluco‐samine receptor. PMA stimulates fluid‐phase pinocytosis of HRP by thio‐macrophages but does not affect receptor‐mediated uptake of HRP, while the combination of adenosine, homocysteine, anderythro‐9‐(2‐hydroxy‐3‐nonyl) adenine (EHNA) selectively inhibits bulk

ISSN:0021-9541    

DOI:10.1002/jcp.1041160105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractDose‐response curves for the inhibition of heterogeneous nuclear RNA (hnRNA) synthesis in HeLa cells by 5,6‐dichloro‐1‐β‐D‐ribofuranosylbenzimidazole (DRB; 5–100 μM; 30 min) are biphasic and indicate the existence of two subpopulations of hnRNA molecules, one highly sensitive and the other completely resistant, as previously reported for molecules>1,000 nucleoides long (Tamm et al., 1976; Sehgal et al., 1976a). In the short‐term experiments, the drug‐sensitive synthesis of hnRNA was inhibited 50% at a DRB concentration of ∼7 μM, and 70% at 20 μM, whereas drug‐resistant synthesis, which comprises ∼20% of total, continued at DRB concentrations as high as 100 μM. After 24 hr of DRB treatment in medium containing 5% fetal calf serum, the increase in cell number in the exponentially growing population was inhibited by only 42% at 20 μM DRB, and the formation of colonies of ≥ ten cells was not decreased. DRB at 40 μM concentration decreased population growth by 76% and colony formation by 63%. Treatment with 60 μM DRB was sufficient to prevent a net increase in cell number and to reduce colony formation by 78%. After termination of treatment, the time required for the surviving population to begin rapid proliferation was directly related to the concentration of DRB used to treat cells and to the duration of treatment. After 24‐hr treatment with 40 μM DRB, cultures recovered within 1 day, whereas after 60 μM DRB, 3–4 days were required. After 40‐hr treatment with 60 μM DRB, 5–6 days were required for recovery, and after 80 μM DRB, 9–11 days. During the “dormant” period the cell number ranged from 15 to 60% of the initial number and was fairly stable for given conditions. After the “dormant” period, recovery was rapid. The population growth rate in cultures undergoing treatment with DRB is directly related to serum concentration; however, the recovery rate during the po

ISSN:0021-9541    

DOI:10.1002/jcp.1041160106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractReticulocytes, isolated by centrifugal elutriation from massively bled sheep and identified by cytometric techniques, were analyzed with respect to their cation transport properties. In sheep with genetically high K+(HK) or low K+(LK) red cells, two reticulocyte types were distinguished by conventional or fluorescence‐staining techniques 5–6 days after hemorrhage: Large reticulocytes as part of a newly formed macrocytic (M) erythrocyte population, and small reticulocytes present among the adult red cell population (volume population III of normal sheep blood, Valet et al., 1978). Although cellular reticulin disappeared within a few days, the M‐cell population persisted throughout weeks in the peripheral circulation permitting a transport study of in vivo maturation. At all times, M cells of LK sheep had lower K+and higher Na+contents than M cells of HK sheep. Regardless of the sheep genotypes, M cells apparently reduced their volume during their first days in circulation; however, throughout the observation period, they did not attain that characteristic for adult red cells. Both ouabain‐sensitive K+pump and ouabain‐insensitive K+leak fluxes were elevated in M cells of both HK and LK sheep. The increased K+pump flux was mainly due to higher K+pump turnover rather than to the modestly increased number of pumps as measured by [3H]ouabain binding. In contrast, small reticulocytes enriched from separated volume population III cells by a Percoll‐density gradient exhibited transport parameters close to their prospective mature HK or LK red cells. The data support the concept that the M cells derived from emergency reticulocytes while the small reticulocytes represented precursors of normal red cell maturation. The Na+and K+composition found in M cells of HK and LK sheep, respectively, suggest development of the LK steady state at or prior to the reticulocyte state, a finding consistent with that of Lee and Kirk (1982) on low K+do

ISSN:0021-9541    

DOI:10.1002/jcp.1041160107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractProstaglandin production, angiotensin‐converting enzyme, and 5′‐nucleotidase were measured in porcine aortic endothelial cells in situ (with a multiwell template on an opened aorta), in primary culture and in subcultures. Changes during culture were monitored and the effects of culture conditions were investigated by growing cells on a biological matrix or on plastic, by adding different sera to the growth medium, and by harvesting cells enzymically or mechanically. Prostacyclin production by endothelium in primary culture is highest immediately after cell isolation and subsequently declines; this pattern is repeated each time the cells are subcultured. The level at which production stabilises is ∼ 200 pgċ106cells−1ċh−1. Detaching cells by physical means stimulates production much more than enzymic dispersion; the type of serum or the presence of a biological matrix does not alter prostaglandin production. The relative amount of prostaglandin E produced increases with time, from ∼20% of the prostacyclin production shortly after isolation to>100% in subcultured cells. None of the culture conditions that we tested altered this trend. Angiotensin‐converting enzyme activity decreases during primary culture, but activity can be sustained by including homologous serum (from whole blood or from platelet‐free plasma) in the culture medium. The method of harvesting cells, or the presence of a matrix, did not affect enzyme activity. 5′‐Nucleotidase also declines during culture, with a progressive decrease in both Kmand Vmaxfrom template to primary culture to subcultures. None of the variations in culture conditions prevented this change. Ectoadenosine‐deaminase activity, not detectable in cultured cells, can be measured in the template. Part of this activity was released by the vascular wall and could be due to plasma diffusing fr

ISSN:0021-9541    

DOI:10.1002/jcp.1041160108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe phorbol ester tumor promoter 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) and the calcium ionophore, A23187, have similar effects on many different cells. For example, both show mitogenic and comitogenic activities for lymphocytes. It had been suggested that some of TPA's effects are due to its ability to act as a calcium ionophore. In order to test this idea, we compared the ability of TPA and ionophore to synergize with concanavalin A (Con A) in a two‐phase system of lymphocyte mitogenesis. We found that ionophore was most comitogenic with Con A when present in the early phase of stimulation. TPA was only comitogenic when present in the late phase, lonophore and TPA could not replace one another in the system. However, both ionophore and TPA together could replace Con A and stimulate DNA synthesis when they were presented to the cells in the sequential order of ionophore followed by TPA. Both compounds required the presence of external calcium to be

ISSN:0021-9541    

DOI:10.1002/jcp.1041160109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractBased on morphological evidence, mitochondrial inner membrane growth has been reported to be discontinuous in heat shock‐synchronizedTetrahymena pyriformis. As a biochemical measure of membrane growth under these conditions, we have examined phospholipid accumulation in the cell. No marked modulation of the accumulation of any of the major phospholipids could be detected through the cell cycle. At least 89% of the cardiolipin in the cells is restricted to the mitochondria, and we have used it as a marker for the growth of the mitochondrial inner membrane. During the heat shock synchrony, cardiolipin accumulates uniformly in parallel with the exponential rate of increase of total cellular phospholipids. These results suggest that at least the phospholipid component of all membrane systems in the cell grow continuously and uniformly. Additionally, we have shown that the total phospholipid content ofTetrahymenaincreases by a factor of 2.4 per generation following a series of heat shocks. No such net overaccumulation is observed for protein conten

ISSN:0021-9541    

DOI:10.1002/jcp.1041160110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractCSF‐1 is a hemopoietic growth factor that specifically regulates the survival, proliferation, and differentiation of mononuclear phagocytic cells. A homogeneous population of mononuclear phagocytes, bone marrow derived macrophages (BMM), were used to study the regulation of protein turnover by CSF‐1. Removal of CSF‐1 (∼0.4 nM) from exponentially growing BMM cultured in 15% fetal calf serum containing medium decreases the rate of DNA synthesis by more than 100‐fold. Addition of CSF‐1 to these cells causes them to resume DNA synthesis within 12 h. More immediate effects of CSF‐1 were observed on BMM protein metabolism. BMM cultured for 24 h in the absence of CSF‐1 reduce their protein synthetic rate by 50–60%. The protein synthetic rate commences to decrease at 2–3 h after CSF‐1 removal. Readdition of CSF‐1 to BMM previously incubated in its absence causes a return to the protein synthetic rate of exponentially growing cells within 2 h. In the presence of CSF‐1, BMM synthesize protein at a rate of ∼8.7%/h and degrade it at a rate of ∼0.9%/h. Removal of CSF‐1 results in a decrease in the protein synthetic rate to ∼3.4%/h and an increase in the rate of protein degradation to ∼3.4%/h. The rate of protein synthesis by BMM increases linearly with CSF‐1 concentration over the range of concentrations stimulating both survival and proliferation, while the rate of protein degradation decreases exponentially over the range of concentrations stimulating survival without proliferation. Therefore, it appears that the stimulation of the rate of protein synthesis and inhibition of the rate of protein degradation are two distinct effects of CSF‐1, both part of the pleiotropic response to this growth factor. The inhibition of the rate of protein degradation by CSF‐1 may be most sig

ISSN:0021-9541    

DOI:10.1002/jcp.1041160111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY