Observatons on the growth and metabolic functions of cultured cells derived from human adipose tissue.

The growth and metabolic activity of cultured cells derived from human adipose tissue (CAT cells) were studied and compared to cultured skin fibroblasts. The morphological appearance of the CAT cells was distinctly different from that of fibroblasts. The growth rate of CAT cells as measured by 3H-thymidine incorporation was much slower than the fibroblast growth rate. Cultured CAT cells synthesized significantly 14C-glucose, while fibroblast cultures had a higher metabolic rate as measured by CO2 production. Insulin stimulated 3H-thymidine incorporation in both CAT and fibroblast cultures. The CAT cells did not show a consistent insulin response of lipid or CO2 production, but this may be a reflection of donor age or nutritional status. Even though the CAT cell may be a type of stromal cell peculiar to adipose tissue rather than a preadipocyte or adipocyte, it may prove useful in studies of human obesity.     

The timing of bud burst and its effect on tree growth

A phenology model for estimating the timings of bud burst – one of the most influential phenological phases for the simulation of tree growth – is presented in this study. The model calculates the timings of the leafing of beech (Fagus sylvatica L.) and oak (Quercus robur L.) and the May shoot of Norway spruce (Picea abies L.) and Scots pine (Pinus sylvestris L.) on the basis of the daily maximum temperature. The data for parameterisation and validation of the model have been taken from 40 climate and 120 phenological stations in southern Germany with time series for temperature and bud burst of up to 30 years. The validation of the phenology module by means of an independent data set showed correlation coefficients for comparisons between observed and simulated values of 54% (beech), 55% (oak), 59% (spruce) and 56% (pine) with mean absolute errors varying from 4.4 days (spruce) to 5.0 days (pine). These results correspond well with the results of other – often more complex – phenology models. After the phenology module had been implemented in the tree-growth model BALANCE, the growth of a mixed forest stand with the former static and the new dynamic timings for the bud burst was simulated. The results of the two simulation runs showed that phenology has to be taken into account when simulating forest growth, particularly in mixed stands.     

Effects of temperature on growth rate of cultured mammalian cells (L5178Y)

L5178Y cells were cultured in vitro at various temperatures. When the cells were in the exponential growth phase, the cells were in the "steady state of growth," i.e., the fraction of cells in the G₁, S, G₂, and M stages and the durations of each stage were constant. The life cycle analysis of the cells in the steady state of growth demonstrated that the G₁ stage and the S stage were affected the most by variation of temperature, and suggested that these two stages have considerable influence on the growth rate of the L5178Y cells. The calculated activation energies were positive in each stage of the life cycle, whereas the entropies of activation were negative throughout. The possible significance of these findings in our search for the regulatory mechanisms of cell growth is discussed.     

Specific growth stimulation of cultured smooth muscle cells from spontaneously hypertensive rats by platelet-derived growth factor A-chain homodimer.

Cultured vascular smooth muscle cells (VSMC)1 from spontaneously hypertensive rats (SHR) possess specific cell surface receptors for both homodimeric forms of platelet-derived growth factor (PDGF-AA and PDGF-BB), in contrast to cells from normotensive Wistar Kyoto (WKY) animals, which express receptors only for the B-chain form of PDGF. Stimulation of quiescent VSMC from SHR with PDGF-AA resulted in activation of S6-kinase and induction of phosphoinositide catabolism, as well as cellular proliferation when cultures were maintained for prolonged periods with daily supplementation of the growth factor. WKY-derived VSMC showed no response to PDGF-AA, which was consistent with their lack of specific receptors for this homodimer. The responsiveness of quiescent cells from SHR and WKY to the B-chain homodimer was similar. The enhanced growth responsiveness of SHR-derived cells to fetal calf serum, as compared with cells from their normotensive counterparts, may be accounted for in part by their expression of receptors for the AA homodimer of PDGF.     

In vitro insulin-like growth factor I interaction with cartilage cells derived from postnatal animals

This paper reports data on the in vitro effects of insulin-like growth factor I (IGF-I) and basic fibroblast growth factor (bFGF) on the phenotypic expression of epiphyseal chondrocytes grown in serum-free (SF) culture medium. bFGF mostly stimulates chondrocyte DNA and inhibits sulfated proteoglycan synthesis and type II collagen mRNA. On the contrary, IGF-I is poorly mitogenic but strongly stimulates protein synthesis and type II collagen mRNA. In addition, IGF-I prevents the expression of type I collagen gene. Lastly, chondrocytes cultured in SF medium are able to locally produce IGF-I peptides. In conclusion, IGF-I and bFGF have opposite effects on the phenotypic expression of chondrocytes in vitro: bFGF is mostly mitogenic and IGF-I appears to be a differentiating factor.     

Specific subclones derived from a multipotential clone of rat anterior pituitary cells.

Several functional subclones of rat anterior pituitary cells were established from our 2A8 clone which apparently contains a heterogenous population of committed and uncommitted cells. On the basis of the hormones secreted into the culture media, as measured by radioimmunoassay, these subclones were divided into four categories, i.e., subclones which secrete (1) ACTH only, (2) prolactin only, (3) prolactin and GH or (4) ACTH, prolactin and GH. None of the subclones produced detectable amounts of thyrotrophic or gonadotrophic hormones. Subclones which secrete a single hormone have shown no change in the type of hormone produced, indicating that these subclones were each derived from a committed cell. The cells of all subclones exhibit a normal diploid karyotype and show good growth characteristics. The cells of the different subclones can be classified by phase contrast microscopy into four categories. However, no clear-cut ultrastructural features have been observed which can be correlated with the different categories of subclones. On the basis of the results a hypothesis is proposed relative to the functional cytodifferentiation of anterior pituitary cells.     

Role of oxygen on growth rate and gene activity in cultured chick-embryo heart cells.

Environmental oxygen is shown to have a regulatory role in growth rate and the mechanism of gene de-repression in chick-embryo heart cells; it modulates the intracellular concentration of polyamines, and this appears to be closely related to histone acetylation.     

DNA repair ability of cultured cells derived from mouse embryos in comparison with human cells

DNA repair in mouse cells derived from embryos of 3 inbred strains were investigated in comparison with that in human cells. The levels of unscheduled DNA synthesis after UV irradiation appeared to change at different passages, but capacities of host-cell reactivation of UV-irradiated herpes simplex virus were always reduced to the same levels as those in xeroderma pigmentosum cells. This implied that mouse cells are reduced in excision-repair capacities and that the apparently high levels of unscheduled DNA synthesis at certain passages are not quantitatively related to high levels of cell survival. Essentially no differences in DNA repair were noted among 3 strains — BALB/c, C3H/He and C57BL/10.     

The effect of temperature on the turnover of taste bud cells in catfish.

Renewal of taste bud cells on the barbels of channel catfish was studied. Groups of catfish, held in and acclimitized to 14 degrees C, 18 degrees C, 22 degrees C and 30 degrees C dechlorinated tap water were injected with [3H]thymidine (3.0 muCi/g body weight intraperitoneally). Barbels were sampled at various times after injection and prepared for light microscope autoradiography. Results show that epithelial cells surrounding the taste buds divide and some of their daughter cells migrate into the taste buds. The time at which 50% of the labelled cells have degenerated is taken as the average turnover time or average life span of the taste bud cells. The average life span as well as the time spent inside the taste buds is highly temperature-dependent. At 14 degrees C, 18 degrees C, 22 degrees C and 30 degrees C the average life span is on the order of 40, 30, 15 and 12 days respectively. Further studies indicate that both light and dark staining cells of the taste bud were labelled.     

The fertilising ability of spermatogenic cells derived from cultured mouse immature testicular tissue

There are many reports about the in vitro culture of spermatogenic cells, but no-one has succeeded in inducing the differentiation from spermatogonia to intact sperm. Also the study of in vitro testicular tissue culture has hardly advanced. We studied the culture of mouse immature testicular tissue derived from 5-day-old mice. We aimed to achieve the differentiation of spermatogenic cells in order to observe spermatogenesis in testicular tissue in vitro. We also froze mature testicular tissue and immature testicular tissue cultured for 2 weeks. Furthermore, spermatogenic cells differentiated by culturing were injected into metaphase II oocytes to determine whether these differentiated cells and frozen-thawed testicular tissue have fertilising and developmental ability. Under the culture conditions employed, secondary spermatocytes and a few round spermatids differentiated from spermatogonia were observed in the immature testicular tissue cultured for 2 weeks. When spermatogenic cells derived from cultured immature testicular tissue, cultured frozen immature testicular tissue and frozen-thawed mature testicular tissue were injected into ooplasm, the oocytes were fertilised and fertilised oocytes developed to the 8-cell stage. We suggest that spermatogenic cells derived from cultured immature testicular tissue have fertilising and developmental abilities equivalent to that of sperm. Also these abilities of spermatogenic cells obtained from cultured frozen immature testicular tissue and frozen-thawed mature testicular tissue were better than those of the same cells before freezing.     

Differential temperature sensitivity of cultured cells from cartilaginous or bone origin.

The effects of long-term exposure to hyperthermia were studied on several cell cultures of cartilaginous or bone origin after a 4-day treatment at 40 degrees C. Chondrocytes proliferation, as well as mitochondrial activity were not modified by these culture conditions (40 degrees C) but protein content and cell volume were increased. In contrast, the proliferative capacity of osteoblasts, MC3T3.E1 a and ROS 17/2.8 was decreased and their protein content, cell volume and mitochondrial activity were increased. Chondrocytes appeared to be thermoresistant, and osteoblastic cells thermosensitive. Furthermore, temperature sensitivity was greater for the continuous established osteoblastic cell line MC3T3.E1 and for the cancerous established osteoblastic cell line ROS 17/2.8 than for chondrocytes.     

Secretion of a new growth factor, smooth muscle cell derived growth factor, distinct from platelet derived growth factor by cultured rabbit aortic smooth muscle cells

In attempts to determine the mechanism of proliferation of arterial smooth muscle cells (SMC) in intimal atheromatous lesions, autocrine secretion of growth factors by SMC has recently received much attention. Here we report a new growth factor named smooth muscle cell derived growth factor (SDGF). Cultured rabbit medial SMC secreted SDGF for 1 week during their incubation in serum-free media only after at least 4 passages. SDGF differed from platelet derived growth factor (PDGF) physicochemically, immunologically, and biologically. The properties of SDGF also seemed different from those of other known growth factors that stimulate the proliferation of mesenchymal cells.     

Body dimensions and birth and organ weights of calves derived from in vitro produced embryos cultured with or without serum and oviduct epithelium cells

Body dimensions, birth and organ weights of calves derived from embryos produced in 2 in vitro culture systems (modified SOFaa with 20% cattle serum and co-cultured with oviduct-epithelium cells [IVPserum, n=8], and modified SOFaa with 3 mg/mL PVA [IVPdefined, n=6]) were compared with calves originating from artificial insemination (AI, n=85). Three additional IVP calves were included which had been vitrified as mature oocytes by the open pulled straw (OPS) method, warmed, fertilized and cultured to the blastocyst stage in modified SOFaa with 5% cattle serum, then again OPS-vitrified and warmed prior to transfer (IVPops, n=3). At birth, gestation length and birth weights were registered for all calves. At 1 wk of age all 17 IVP and 7 of the AI calves were killed, and their body dimensions and organ weights recorded. Birth weight was higher for the IVPserum and IVPops calves than for AI control calves (kg +/- SEM: IVPserum 46.9+/-1.8, IVPops 50.6+/-2.4, AI 41.8+/-0.8; P < 0.002). There was no difference between IVP and AI calves regarding gestation length and no effect of culture conditions on body dimensions or organ weights, except for longer hind legs in IVPdefined calves compared with AI calves (cm +/- SEM: IVPdefined 93+/-2, AI 87+/-2; P < 0.04). The IVPops calves had an increased liver weight compared with AI and the other IVP calves (g +/- SEM: IVPops 1.457+/-59; AI 1,117+/-37; IVPserum 1,159+/-34, IVPdefined 1,073+/-39; P < 0.0003). It is concluded that in vitro culture of bovine embryos in the presence of serum and oviduct epithelium cells increased birth weight but not organ weight and body dimension in 1-wk-old calves. However, vitrification of the ova as oocyte and again as blastocysts increased birth weight and liver size. This possible effect of cryopreservation of oocytes on subsequent fetal development awaits further investigation.