Modulation of one of three murine bone marrow stromal cell lines to adipose cells by serum and insulin

Adipose cells have been recognized as an integral component of the bone marrow hematopoietic microenvironment in vivo and as an essential cell type required for in vitro maintenance of stem cells. Four stromal cell lines obtained from the adherent cell population of murine bone marrow cultures have been enriched and purified by multiple trypsinizations. We noted that these cell lines exhibited an accumulation of vacuoles of lipid, the extent of which varied be-tween cell lines in response to a change from medium containing 10% fetal calf serum to medium containing 20% horse serum. The lipid was lost when the cell lines were transferred back into the medium supplemented with fetal calf serum. In light of the reported lipogenic and antilipolytic effects of insulin on fibroblasts and adipocytes, we investigated the ability of insulin to induce adipocyte transformation of these bone marrow stromal cell populations. Three cell lines were exposed to bovine insulin at concentrations ranging from 10^?9 to 10^?6 M. All three cell lines responded to the insulin by accumulating lipid, but the extent of accumulation and the insulin concentration at which maximum lipid content was attained were population specific. One cell line (MC₁) responded fully at physiological levels of insulin (10^?9 M), whereas the other two showed lipid accumulation only at pharmacological concentrations. The initial growth of MC₁ was inhibited in the presence of 10^?9 M insulin which is compatible with the observed differentiation to adipocytes. The growth of MC₃ was unaltered in the presence of physiological concentrations of insulin, whereas that of MC₄ was accelerated. Grafts of organ cultures of the cell lines under the kidney capsule of syngeneic mice developed specific characteristics rep-resentative of the different cell lines. In particular, the majority of the grafts of MC₁ consisted primarily of fat cells which were not observed in the grafts of MC₃ and MC₄. These data strongly suggest that these cell lines comprise cells with different potentialities and that the MC₁ line represents a preadipocyte stromal cell of bone marrow.     

Stimulation of immune suppressive CD34+ cells from normal bone marrow by Lewis lung carcinoma tumors

 Progressive growth of metastatic Lewis lung carcinoma (LLC-LN7) tumors is associated with increased levels of bone-marrow-derived CD34⁺ cells having natural suppressor (NS) activity toward T cells. The present studies determined whether tumor-derived products are responsible for this induction of NS activity. Culturing normal bone marrow cells with LLC-LN7-conditioned medium (LLC-CM) or with recombinant granulocyte/macrophage-colony-stimulating factor (GM-CSF) resulted in the appearance of NS activity. The development of NS activity coincided with a prominent increase in the levels of CD34⁺ cells. That the CD34⁺ cells were responsible for the NS activity of the bone marrow cultures containing LLC-CM was shown by the loss of NS activity when CD34⁺ cells were depleted. The stimulation of CD34⁺ NS cells by LLC-CM was attributed to tumor production of GM-CSF, since neutralization of GM-CSF within the LLC-CM reduced its capacity to increase CD34⁺ cell levels. Studies also showed that the induction of CD34⁺ NS cells by LLC-CM and GM-CSF could be overcome by including in the cultures an inducer of myeloid differentiation, 1α,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃]. These results demonstrate that the mechanism by which the LLC-LN7 tumors stimulate increased levels of CD34⁺ NS cells from normal bone marrow is by their production of GM-CSF and that this can be blocked with the myeloid differentiation inducer 1,25(OH)₂D₃. Received: 8 December 1997 / Accepted: 27 February 1998     

Variations in the Microcystin Production of Planktothrix rubescens (Cyanobacteria) Assessed from a Four-Year Survey of Lac du Bourget (France) and from Laboratory Experiments

Between 1999 and 2002, a routine survey of water quality in the Lac du Bourget was performed to study the dynamics and microcystin (MC) production of Planktothrix rubescens. Using liquid chromatography coupled to diode array detection and mass spectrometry, we found that two main variants ([d-Asp³] and [d-Asp³, Dhb⁷] microcystin-RR) were produced. The proportion of these two variants was not influenced by the depth or season of sampling. Expressed in microcystin-LR equivalents, high microcystin concentrations were recorded from August to December each year, reaching values of up to 6.7 μg L⁻¹. A significant correlation was found between the microcystin cell content and the cell densities of P. rubescens. Cellular quotas of microcystins ranged from 0.1 to 0.3 pg cell⁻¹. Simultaneously, laboratory experiments were performed on a strain of P. rubescens isolated from the lake to assess the potential impact of various P–PO₄³⁻ concentrations on intra- and extracellular microcystin production. Unlike natural populations, this strain only produced [d-Asp³] MC-RR. The intracellular microcystin content was similarly correlated to the cell density, but the cellular quota was slightly higher (0.3–0.7 pg cell⁻¹) than in the natural population. Again, as in the natural population, a linear relationship was found between growth rate and microcystin production rate. These findings support the hypothesis that environmental factors, such as phosphate concentrations, have no direct impact on microcystin production by P. rubescens, but act indirectly by affecting growth rate.     

Effects of cortisol, 17beta-estradiol and thyroliberin on prolactin and growth hormone production, cell growth and cell cycle distribution in cultured rat pituitary tumour cells.

Prolactin and growth hormone production were measured in a rat pituitary tumour cell strain (GH₃) after treatment with cortisol (5 × 10^?6 M), thyroliberin (2.5 × 10^?6 M) and 17β-estradiol (10^?6 M). The changes in hormone production were related to alterations in cell growth rate and cell cycle distribution. Cortisol inhibited prolactin production, stimulated growth hormone production and reduced the cellular growth rate measured two days after start of treatment (maximum about 40% inhibition). Flow-micro fluorometric analysis of DNA distributions showed that cortisol treatment reduced the relative number of cells in S phase (maximum effect about 50%) with a compensatory increase of the proportion of cells in G₁ phase. The lack of inhibition of prolactin production after three days of cortisol treatment may partly be related to the increased number of cells in G₁ phase. Thyroliberin and 17β-estradiol did not significantly affect cell growth after six days of treatment, although the fraction of cells in S phase was reduced by approximately 40% with a corresponding increase of cells in G₁ phase. For thyroliberin and 17β-estradiol, the stimulatory effect on prolactin production and the inhibitory effect on growth hormone production witin a period of treatment of six days cannot be explained by a shift in cell cycle distributions. None of the three hormones influenced the growth fraction which was equal to unity. In conclusion, thyroliberin and 17β-etradiol are able to change prolactin and growth hormone production without altering the cell cycle distribution. However, the effects of cortisol on prolactin and growth hormone production may partly be due to an alteration in cell cycle traverse resulting in an increased number of cells in the G₁ phase.     

Carbon dioxide biofixation by Chlorella vulgaris at different CO2 concentrations and light intensities

In order to develop an effective CO₂ mitigation process using microalgae for potential industrial application, the growth and physiological activity of Chlorella vulgaris in photobioreactor cultures were studied. C. vulgaris was grown at two CO₂ concentrations (2 and 13% of CO₂ v/v) and at three incident light intensities (50, 120 and 180 μmol m^?2 s^?1) for 9 days. The measured specific growth rate was similar under all conditions tested but an increase in light intensity and CO₂ concentration affected the biomass and cell concentrations. Although carbon limitation was observed at 2% CO₂, similar cellular composition was measured in both conditions. Light limitation induced a net change in the growth behavior of C. vulgaris. Nitrogen limitation seemed to decrease the nitrogen quota of the cells and rise the intracellular carbon:nitrogen ratio. Exopolysaccharide production per cell appeared to be affected by light intensity. In order to avoid underestimation of the CO₂ biofixation rate of the microalgae, exopolysaccharide production was taken into account. The maximum CO₂ removal rate (0.98 g CO₂ L^?1 d^?1) and the highest biomass concentration (4.14 g DW L^?1) were determined at 13% (v/v) CO₂ and 180 μmol m^?2 s^?1. Our results show that C. vulgaris has a real potential for industrial CO₂ remediation.     

Effects of H2O2 on the growth, secretion, and metabolism of hybridoma cells in culture

Summary The effect of low concentrations of hydrogen peroxide (H₂O₂) (5 × 10⁻⁷−9.5 × 10⁻⁷ M) on cell growth and antibody production was investigated with murine hybridoma cells (Mark 3 and anti-hPL) in culture. Cell growth, measured by flow cytometry with morphological parameters, was significantly stimulated by H₂O₂ (8 × 10⁻⁷ M) but H₂O₂ concentration of 7 × 10⁻⁶ M and above increased cell death. H₂O₂ stimulation of antibody production was nonsignificant. The metabolism of cells treated with 8 × 10⁻⁷ or 1 × 10⁻⁵ M H₂O₂ was similar to that of the control in terms of glucose and glutamine consumption, lactate and ammonia production, and amino acid concentrations in the medium. The concentrations of lactate dehydrogenase, a marker of cell death, in test and control cells were similar. However, concentrations of intracellular free radicals measured by flow cytometry with dihydrorhodamine 123 (DHR 123) and dichlorofluorescein diacetate (DCFH-DA) as fluorochromes were different. The reactive oxygen species content of cells in 8 × 10⁻⁷ M H₂O₂ was similar to that of the controls, but there was a sudden, marked production of superoxide anions (detected with DHR 123) and H₂O₂ or peroxides (detected with DCFH-DA) by cells incubated with 1 × 10⁻⁵ M H₂O₂ which increased with increasing H₂O₂ until cell death.     

Expansion of CD34+ cells from human umbilical cord blood by FL and/or TPO gene transfected human marrow stromal cell lines

To elucidate the effect of gene transfected marrow stromal cell on expansion of human cord blood CD34⁺ cells, a culture system was established in which FL and TPO genes were transfected into human stromal cell line HFCL. To establish gene transfected stromal cells co-culture system, cord blood CD34⁺ cells were purified by using a magnetic beads sorting system. The number of all cells and the number of CD34⁺ cells and CFC (CFU-GM and BFU-E) were counted in different culture systems. The results showed that in all 8 culture systems, SCF+IL-3+HFT manifested the most potent combination, with the number of total nucleated cells increasing by (893.3 ±52.1)-fold, total progenitor cells (CFC) by (74.5 ±5.2)-fold and CD34⁺ cells by 15.7-fold. Maximal expansions of CFC and CD34⁺ cells were observed at the end of the second week of culture. Within 14 days of culture, (78.1 ± 5.5)-fold and (57.0 ± 19.7)-fold increases in CFU-GM and BFU-E were obtained. Moreover, generation of LTC-IC from amplified CD34⁺ cells within 28 days was found only in two combinations, i.e. SCF+IL-3+FL+TPO and SCF+IL-3+HFT, and there was no significant difference between these two groups statistically. These results suggest that human umbilical cord blood CD34⁺ cells can be extensively expandedex vivo by using gene transfected stromal cells along with cytokines.     

The influence of CO2 enrichment, phosphorus deficiency and water stress on the growth, conductance and water use of Pinus radiata D. Don

Abstract. Seedlings of Pinus radiata D. Don were grown in growth chambers for 22 weeks with two levels of phosphorus, under either well-watered or water-stressed conditions at CO₂ concentrations of either 330 or 660mm³ dm^?3. Plant growth, water use efficiency and conductance were measured and the relationship between these and needle photosynthetic capacity, water use efficiency and conductance was determined by gas exchange at week 22. Phosphorus deficiency decreased growth and foliar surface area at both CO₂concentrations; however, it only reduced the maximum photosynthetic rates of the needles at 660 mm³ CO₂ dm^?3 (plants grown and measured at the same CO₂ concentration). Water stress reduced growth and foliar surface area at both CO₂ concentrations. Increases in needle photosynthetic rates appeared to be partly responsible for the increased growth at high CO₂ where phosphorus was adequate. This effect was amplified by accompanying increases in needle production. Phosphorus deficiency inhibited these responses because it severely impaired needle photosynthetic function. The relative increase in growth in response to high CO₂ was higher in the periodically water-stressed plants. This was not due to the maintenance of cell volume during drought. Plant water use efficiency was increased by CO₂ enrichment due to an increase in dry weight rather than a decrease in shoot conductance and, therefore, transpirational water loss. Changes in needle conductance and water use efficiency in response to high CO₂ were generally in the same direction as those at the whole plant level. If the atmospheric CO₂ level reaches the predicted concentration of 660 mm³ dm^?3 by the end of next Century, then the growth of P. radiata will only be increased in areas where phosphorus nutrition is adequate. Growth will be increased in drought-affected regions but total water use is unlikely to be reduced.     

High-level productivity of <Emphasis Type="Italic">α,ω</Emphasis>-dodecanedioic acid with a newly isolated <Emphasis Type="Italic">Candida viswanathii</Emphasis> strain

α,ω-Dicarboxylic acids (DC) are versatile chemical intermediates with different chain lengths, which are well-known as polymer building block. In this work, a new strain with high productivity of DC was isolated from oil-contaminated soil. Based on the morphology and phylogenetic analyses of the internal transcribed spacer sequences, it was characterized as Candida viswanathii. It was found that the contribution of carbon flux to the cell growth and DC production from n-dodecane could be regulated by the sucrose and yeast extract concentrations in the medium, and besides the broth pH, a suitable proportioning of sucrose and yeast extract was the key to achieve the optimal transition from cell growth phase to DC production phase. By optimizing culture conditions in a 7.5-L bioreactor, a higher DC productivity of 1.59 g·L^?1 h^?1 with a corresponding concentration of 181.6 g/L was obtained. After the purification of DC from the culture, the results from gas chromatography–mass spectrometry, infrared spectroscopy and ¹H-NMR showed that α,ω-dodecanedioic acid (DC₁₂) was the major product of C. viswanathii ipe-1 using pure n-dodecane as substrate. For the first time, we reported that a high productivity of DC₁₂ could be produced by C. viswanathii.     

Influence of electron acceptor,carbon, nitrogen,and phosphorus on polyhydroxyalkanoate (PHA) production by <Emphasis Type="Italic">Brachymonas</Emphasis> sp. P12

Polyhydroxyalkanoates (PHAs), intracellular carbon and energy reserve compounds in many bacteria, have been used extensively in biodegradable plastics. PHA formation is influenced by nutrient limitations and growth conditions. To characterize the PHA accumulation in a new denitrifying phosphorus-removing bacterium Brachymonas sp. P12, batch experiments were conducted in which the electron acceptor (oxygen or nitrate) was varied and different concentrations of carbon (acetate), nitrogen (NH₄Cl), and phosphorus (KH₂PO₄) were used. Polyhydroxybutyrate (PHB) was the dominant product during PHA formation when acetate was the sole carbon source. The PHB content of aerobically growing cells increased from 431 to 636 mg PHB g⁻¹ biomass, but the PHB concentration of an anoxic culture decreased (−218 mg PHB g⁻¹ biomass), when PHB was utilized simultaneously with acetate as an electron donor for anoxic denitrification. The specific PHB production rate of the carbon-limited batch, 158.2 mg PHB g⁻¹ biomass h⁻¹, was much greater than that of batches with normal or excess carbon. The effects of phosphorus and nitrogen concentrations on PHB accumulation were clearly less than the effect of carbon concentration. According to the correlation between the specific PHB production rate and the specific cell growth rate, PHB accumulation by Brachymonas sp. P12 is enhanced by nutrient limitation, is growth-associated, and provides additional energy for the biosynthesis of non-PHB cell constituents to increase the cell growth rate beyond the usual level.     

Factors affecting biohydrogen production by unicellular halotolerant cyanobacterium Aphanothece halophytica

The effects of several physiological parameters on H₂ production rate in the unicellular halotolerant cyanobacterium Aphanothece halophytica were investigated. Under nitrogen deprivation, the growth of cells was inhibited, but H₂ production rate was enhanced approximately fourfold. Interestingly, cells grown under sulfur deprivation exhibited a decrease in cell growth, H₂ production rate, and bidirectional hydrogenase activity. Glucose was the preferred sugar source for H₂ production by A. halophytica, but H₂ production decreased at high glucose concentrations. H₂ production rate was optimum when cells were grown in the presence of 0.75 M?NaCl, or 0.4 μM?Fe³⁺, or 1 μM?Ni²⁺. The optimum light intensity and temperature for H₂ production were 30 μmol photons m^?2?s^?1 and 35 °C, respectively. A two-stage culture of A. halophytica was performed in order to overcome the reduction of cell growth in N-free medium. In the first stage, cells were grown in normal medium to accumulate biomass, and in the second stage, H₂ production by the obtained biomass was induced by growing cells in N-free medium supplemented with various chemicals for 24 h. A. halophytica grown in N-free medium containing various MgSO₄ concentrations had a high H₂ production rate between 11.432 and 12.767 μmol H₂ mg?chlorophyll a (chl a)^?1?h^?1, a 30-fold increase compared to cells grown in normal medium. The highest rate of 13.804 μmol H₂ mg?chl a ^?1?h^?1 was obtained when the N-free growth medium contained 0.4 μM Fe³⁺. These results suggested the possibility of using A. halophytica and some other halotolerant cyanobacteria thriving under extreme environmental conditions in the sea as potential sources for H₂ production in the future.     

High Physiological Concentrations of Progesterone Reverse Estradiol-Mediated Changes in Differentiation and Functions of Bone Marrow Derived Dendritic Cells

Female sex steroids, estradiol (E2) and progesterone (P4), play a key role in regulating immune responses in women, including dendritic cell (DC) development, and functions. Although the two hormones co-occur in the body of women throughout the reproductive years, no studies have explored their complex combinatorial effects on DCs, given their ability to regulate each other’s actions. We examined murine bone marrow derived dendritic cells (BMDC) differentiation and functions, in the presence of a wide range of physiological concentrations of each hormone, as well as the combination of the two hormones. E2 (10⁻¹² to 10^-8M) enhanced the differentiation of CD11b⁺CD11c⁺ DCs from BM precursor cells, and promoted the expression of CD40 and MHC Class-II, in a dose-dependent manner. In contrast, P4 (10⁻⁹ to 10^-5M) inhibited DC differentiation, but only at the highest concentrations. These effects on BMDCs were observed both in the presence or absence of LPS. When both hormones were combined, higher concentrations of P4, at levels seen in pregnancy (10^-6M) reversed the E2 effects, regardless of the concentration of E2, especially in the absence of LPS. Functionally, antigen uptake was decreased and pro-inflammatory cytokines, IL-12, IL-1 and IL-6 production by CD11b⁺CD11c⁺ DCs, was increased in the presence of E2 and these effects were reversed by high concentrations of P4. Our results demonstrate the distinct effects of E2 and P4 on differentiation and functions of bone marrow myeloid DCs. The dominating effect of higher physiological concentrations of P4 provides insight into how DC functions could be modulated during pregnancy.     

FETAL HEMOPOIESIS IN DIFFUSION CHAMBER CULTURES

The growth pattern of fetal liver (FL), normal adult bone marrow (NABM) and regenerating (post Velban treatment) adult bone marrow (RABM) colony forming units (CFU) cultured in diffusion chambers (DC) was studied. When twenty CFU were implanted into DC the recovery of CFU after 4 days with FL, NABM or RABM was 133 ± 7, 19 + 2 and 34 ± 2 CFU, respectively. The transplantation fraction of CFU from NABM decreased from 10-4% on day 0 to 6–9 % on day 4; that of FL did not change from the initial 6-2%. The growth rate of CFU derived from FL was substantially greater than that from NABM. The relative growth of FL and RABM CFU was clearly inhibited when the concentration of cells cultured was increased. Spleen colonies from FL cells before culture were larger (P < 0–005) than colonies from NABM but after 7 days of culture there was no difference between the two groups. Histological examination of spleen colonies showed that after DC culture FL and NABM CFU were differentiating along the three normal pathways. These data suggest that intrinsic differences exist between fetal and adult stem cells in the in vivo diffusion chamber culture system.     

Effect of mixed carbon substrate on exopolysaccharide production of cyanobacterium Nostoc flagelliforme in mixotrophic cultures

The effects of organic carbon sources on cell growth and exopolysaccharide (EPS) production of dissociated Nostoc flagelliforme cells under mixotrophic batch culture were investigated. After 7?days of cultivation, glycerol, acetate, sucrose, and glucose increased the final cell density and final EPS concentrations, and mixotrophic growth achieved higher biomass concentrations. The increase in cell growth was particularly high when glucose was added as the sole carbon source. On the other hand, EPS production per dry cell weight was significantly enhanced by adding acetate. For more effective EPS production, the effects of the mixture of glucose and acetate were investigated. Increasing the ratio of glucose to acetate resulted in higher growth rate with BG-11 medium and higher EPS productivity with BG-11₀ medium (without NaNO₃). When the medium was supplemented with a mixture of glucose (4.0?g?L^?1) and acetate (2.0?g?L^?1), 1.79?g?L^?1 biomass with BG-11 medium and 879.6?mg?L^?1 of EPS production with BG-11₀ medium were achieved. Adopting this optimal ratio of glucose to acetate established in flask culture, the culture was also conducted in a 20-L photobioreactor with BG-11 medium for 7?days. A maximum biomass of 2.32?g?L^?1 was achieved, and the EPS production was 634.6?mg?L^?1.     

Genetic factors influencing murine hematopoietic productivity in culture

In order to study a previously described genetic difference manifested in stem cell kinetics of specific mouse strains, effects of this putative gene, stk, were measured on growth and expansion of stem and progenitor cell populations ex vivo. Bone marrow cells from each of two inbred mouse strains, C57BL/6J and DBA/2J, were placed into separate bioreactor cultures perfused continuously with growth medium containing erythropoietin (Epo), interleukin-3 (IL-3), granulocyte-macrphage colony stimulating factor (GM-CSF), and Kit ligand as well as 5% CO₂. Expansion of cell numbers reached 20-fold for DBA/2J and 10-fold for C57BL/6J marrow within about 1 week of culture. Significant production was also seen of colonyforming unit (CFU)-GM (up nine-fold from input levels) just prior to the cell production peak, and, importantly, moderate expansion of day 12 colony-forming unit-spleen (CFU-S; two- to threefold) occurred as well, although CFU-S production peaked at a relatively short 4 days. CFU-S and CFU-GM levels declined rapidly in culture, either because of unfavorable growth conditions or terminal differentiation. Attempts to remove toxic metabolites by increasing the media perfusion rate resulted in a boost in cell expansion capability by DBA/2J marrow. In bioreactors in which stromal cells were established before marrow inoculation, there was greater expansion of CFU-S (especially by DBA/2J) and CFU-GM, although total cell yield appeared to be unaffected, perhaps because the maximum cell density had already been reached. The relative high potential for CFU-S expansion measured in DBA/2J marrow over that of C57BL/6J will be useful in following genetic contributions to bone marrow production capacity. © 1995 Wiley-Liss, Inc.     

Growth Arrest Specific 2 Is Up-Regulated in Chronic Myeloid Leukemia Cells and Required for Their Growth

Although the generation of BCR-ABL is the molecular hallmark of chronic myeloid leukemia (CML), the comprehensive molecular mechanisms of the disease remain unclear yet. Growth arrest specific 2 (GAS2) regulates multiple cellular functions including cell cycle, apoptosis and calpain activities. In the present study, we found GAS2 was up-regulated in CML cells including CD34⁺ progenitor cells compared to their normal counterparts. We utilized RNAi and the expression of dominant negative form of GAS2 (GAS2DN) to target GAS2, which resulted in calpain activity enhancement and growth inhibition of both K562 and MEG-01 cells. Targeting GAS2 also sensitized K562 cells to Imatinib mesylate (IM). GAS2DN suppressed the tumorigenic ability of MEG-01 cells and impaired the tumour growth as well. Moreover, the CD34⁺ cells from CML patients and healthy donors were transduced with control and GAS2DN lentiviral vectors, and the CD34⁺ transduced (YFP⁺) progeny cells (CD34⁺YFP⁺) were plated for colony-forming cell (CFC) assay. The results showed that GAS2DN inhibited the CFC production of CML cells by 57±3% (n = 3), while affected those of normal hematopoietic cells by 31±1% (n = 2). Next, we found the inhibition of CML cells by GAS2DN was dependent on calpain activity but not the degradation of beta-catenin. Lastly, we generated microarray data to identify the differentially expressed genes upon GAS2DN and validated that the expression of HNRPDL, PTK7 and UCHL5 was suppressed by GAS2DN. These 3 genes were up-regulated in CML cells compared to normal control cells and the growth of K562 cells was inhibited upon HNRPDL silence. Taken together, we have demonstrated that GAS2 is up-regulated in CML cells and the inhibition of GAS2 impairs the growth of CML cells, which indicates GAS2 is a novel regulator of CML cells and a potential therapeutic target of this disease.     

The effects of epidermal growth factor on cell proliferation and prolactin production by GH3 rat pituitary cells

The effects of epidermal growth factor (EGF) were studied in rat pituitary tumor cells, GH₃, grown in serum-supplemented and serum-free chemically defined media. EGF (1 nM) increased the cell number to 132% of the control cultured in the defined medium during a 6-day incubation period, while it decreased the cell number to 60% of the control in the serum-supplemented medium. EGF altered the morphology of the cells grown in the defined medium more markedly to an elongated conformation than that of cells grown in the serum-supplemented medium. EGF also stimulated prolactin (PRL) production by culture in the presence or absence of serum. The effects of the cell density of GH₃ on the action of EGF were shown to appear in two ways. The mitogenic influence of EGF was more effective on, and more responsive to, high-density cells, whereas the stimulatory action on PRL production was less effective on high-density cells. However, the inhibitory effects on cellular growth appeared independently of cell densities. The results obtained with ¹²⁵I-EGF binding experiments indicated that the number of binding sites, affinity, and internalization of EGF receptors were similar in either serum-supplemented or serum-free culture. At low cell density, the number of available ¹²⁵I-EGF binding sites per cell was larger than at high cell density. These results suggested that there was no apparent correlation between EGF binding and its differing effects on the growth of GH₃ cultured in the serum-supplemented and the defined medium.     

Studies of effects of cyclic adenosine 3′,5′-monophosphate in regulation of human hemopoiesis in vitro

Summary Prostaglandin E₁ (PGE₁), high concentrations of dibutyryl cyclic AMP (dbcAMP), and theophylline were strikingly inhibitory both to tritiated thymidine ([³H]TdR) incorporation into bone marrow deoxyribonucleic acid (DNA) in vitro and to granulocytic colony growth. Autoradiography revealed that lower concentrations of dbcAMP were stimulatory to red blood cell precursors. This study was supported in part by United States Public Health Service Grant AM15163, by Health Research Council of the City of New York Career Scientist Award I-683, and by a Veterans Administration Medical Investigatorship to V. H.     

Effects of a dietary crude fibre concentrate on growth in weaned piglets

Many fibre sources can help the adaptation of piglets at weaning, improving the growth. In this study, the effects of a dietary crude fibre concentrate (CFC) on piglet’s growth was investigated. From 31 to 51 days of age, 108 weaned piglets (D×(Lw×L)), had access to two isofibrous, isoenergetic and isonitrogenous diets, supplemented with 1% of CFC (CFC group) or not (control (CON) group). From days 52 to 64 all piglets received the same starter diet. During the dietary treatment period the CFC group showed higher average daily gain, average daily feed intake and feed efficiency (P<0.001) than CON group. At 64 days of age, BW was higher in CFC group compared with CON group (P<0.001). Blood samples were collected at days 31, 38, 45 and 52 of age. From days 31 to 52 significant differences in the somatotropic axis between groups were observed. In particular, growth hormone levels were higher only at the end of the 1^st week of dietary treatment (P<0.05) in CFC group animals compared with CON group animals. The IGF-I trend was similar between groups even if the IGF-I levels were higher in the CFC group than CON group 1 week after starting treatment (P<0.01). The IGF-binding protein 3 (IGFBP-3) levels were higher in the first 2 weeks of dietary treatment and lower in the 3^rd week in CON group compared with CFC group (P<0.01). Specifically, the IGFBP-3 profile was consistent with that of IGF-I in CFC group but not in CON group. At the same time, an increase of leptin in CFC compared with CON group was observed (P<0.05). Piglets fed the CFC diet showed a lower diarrhoea incidence (P<0.05) and a lower number of antibiotic interventions (P<0.05) than CON diet from 31 to 51 days of age. Pig-major acute-phase protein plasma level (P<0.01) and interleukin-6 gene expression (P<0.05) were higher in CON group than CFC group at the end of 1^st week of dietary treatment. In conclusion, this study showed that CFC diet influences the hormones related to energy balance enhancing the welfare and growth of piglets. Furthermore, the increase in feed intake during 3 weeks of dietary treatment improved the feed efficiency over the entire post-weaning period.     

The A3 adenosine receptor as a new target for cancer therapy and chemoprotection

Adenosine, a purine nucleoside, acts as a regulatory molecule, by binding to specific G-protein-coupled A₁, A_2A, A_2B, and A₃ cell surface receptors. We have recently demonstrated that adenosine induces a differential effect on tumor and normal cells. While inhibiting in vitro tumor cell growth, it stimulates bone marrow cell proliferation. This dual activity was mediated through the A3 adenosine receptor. This study showed that a synthetic agonist to the A3 adenosine receptor, 2-chloro-N⁶-(3-iodobenzyl)-adenosine-5′-N-methyl-uronamide (Cl-IB-MECA), at nanomolar concentrations, inhibited tumor cell growth through a cytostatic pathway, i.e., induced an increase number of cells in the G0/G1 phase of the cell cycle and decreased the telomeric signal. Interestingly, Cl-IB-MECA stimulates murine bone marrow cell proliferation through the induction of granulocyte-colony-stimulating factor. Oral administration of Cl-IB-MECA to melanoma-bearing mice suppressed the development of melanoma lung metastases (60.8 ± 6.5% inhibition). In combination with cyclophosphamide, a synergistic anti-tumor effect was achieved (78.5 ± 9.1% inhibition). Furthermore, Cl-IB-MECA prevented the cyclophosphamide-induced myelotoxic effects by increasing the number of white blood cells and the percentage of neutrophils, demonstrating its efficacy as a chemoprotective agent. We conclude that A3 adenosine receptor agonist, Cl-IB-MECA, exhibits systemic anticancer and chemoprotective effects.