THE IN VITRO DIFFERENTIATION OF DENSITY SUB-POPULATIONS OF COLONY-FORMING CELLS UNDER THE INFLUENCE OF DIFFERENT TYPES OF COLONY-STIMULATING FACTOR

The in vitro proliferation and differentiation of myeloid progenitor cells (CFU-c) in agar culture from CBA/Ca mouse bone marrow cells was studied. Density sub-populations of marrow cells were obtained by equilibrium centrifugation in continuous albumin density gradients. The formation of colonies of granulocytes and/or macrophages was studied under the influence of three types of colony-stimulating factor (CSF) from mouse lung conditioned medium CSF_MLCM), post-endotoxin mouse serum (CSF_ES) and from human urine (CSF_Hu). The effect of the sulphydryl reagent mercaptoethanol on colony development was also examined. The density distribution of CFU-c was dependent on the type of CSF. Functional heterogeneity was found among CFU-c with partial discrimination between progenitor cells forming pure granulocytic colonies and those forming pure macro-phage colonies. Mercaptoethanol increased colony incidence but had no apparent effect on colony morphology or the density distribution of CFU-c.     

Effect of organic matter on growth and cell yield of ammonia-oxidizing bacteria

The effect of various organic compounds on the growth of ammonia-oxidizing bacteria was examined.Nitrosococcus oceanus, a strongly halophilic bacterium, had a very low tolerance to organic matter compared with other organisms tested. Organic compounds scarcely affected the growth of theNitrosomonas strains whereas nitrite formation by bothNitrosococcus mobilis strains was inhibited by nearly all of the substances tested. The growth ofNitrosospira strain Nsp₁ was enhanced more than 30% by acetate and formate, but not growth was detectable in the presence of pyruvate. On the contrary,Nitrosospira strain Nsp₅ was stimulated only by pyruvate. Nitrite formation by the twoNitrosovibrio tenuis strains tested was similar. The growth of both strains was enhanced considerably by formate and glucose; acetate and, to a greater extent, pyruvate inhibited these bacteria.In batch culture, the energy efficiency of autotrophically grown ammonia-oxidizing bacteria varied from strain to strain. The cell yield of mixotrophically grown cultures, per unit of ammonia oxidized, was increased in comparison with autotrophic ones. No heterotrophic growth was detected.     

The serum growth and survival requirements of SV40-transformed 3T3 cells

Summary Simian virus 40-transformed 3T3 cells are dependent on serum for survival and growth. This growth activity can be separated on a pH 2 Sephadex G100 column into two fractions: a high molecular weight activity and a low molecular weight substance that has recently been characterized as containing as its major agent, biotin. To replace the remainder of the serum requirement, hormones and other growth factors were tested. Both insulin at high, nonphysiological concentrations (200 to 500 ng/ml) and transferrin (5×10⁻⁸ M) stimulate the growth rate in low serum medium (0.3% v/v bovine calf serum DME) individually and, when added together, are nearly as growth enhancing as 10% serum. The need for the residual serum in this medium can be eliminated by the use of crystalline trypsin during trypsinization. Under these serum-free conditions, biotin and transferrin supplementation provide for moderately good growth (20 to 30 hr population doubling time, 1×10⁶ cells/3.2-cm dish final cell density). Insulin addition further stimulates the growth rate (16 to 20 hr) and the final density (1.5×10⁶ cells). Although the protein growth factors, EGF (0.5 to 1.0 ng/ml) and FGF (4 to 10 ng/ml), also appear to enhance growth individually and additively, their effects are slight and very variable. Nevertheless, the complete serum-free medium (DME supplemented with biotin, transferrin, insulin, EGF and FGF) yields growth comparable but still inferior to 10% serum supplementation (14-versus 12-hr population doubling time, 1 to 2×10⁶ versus 2 to 3×10⁶ cells final cell density). This work was supported by NIH Grant CA 20040.     

Balbiani ring RNA in the cytoplasm of Chironomus thummi salivary gland cells

In this paper experimental results on the size, transport and stability of cytoplasmic Balbiani ring RNA and on its appearance in polysomes are presented. Cytoplasmic RNA of salivary gland cells from Chironomus thummi contains two large RNA fractions of about 20×10⁶ dalton and 10×10⁶ dalton in size. These RNA fractions correspond both to Balbiani ring BR 1 RNA and BR 2 RNA and are apparently transported from nucleus into cytoplasm without a significant size reduction. Chase experiments illustrate a great stability of giant cytoplasmic Balbiani ring RNA molecules and exclude the possibility of a precursor-product relationship between these and smaller BR RNA molecules also found in cytoplasm. A part of giant cytoplasmic Balbiani ring RNA molecules is bound to poly(U)-sepharose columns and should, therefore, contain poly(A)-sequences. — Polysomes of salivary gland cells extracted by a gentle lysis procedure and centrifuged through sucrose gradients are characterized by a rather broad sedimentation profile. Polysome sizes up to about 800 S have been detected, but in no case a distinct polysome fraction corresponding in size to Balbiani ring RNA has been observed. Hybridization of polysomal RNA with salivary gland chromosomes in situ resulted in labelling of both Balbiani rings BR 1 and BR 2.     

Head posture and craniofacial morphology

The associations between craniofacial morphology and the posture of the head and the cervical column were examined in a sample of 120 Danish male students aged 22–30 years. Two head positions were recorded on lateral cephalometric radiographs, one determined by the subject's own feeling of a natural head balance (self balance position), and the other by the subject looking straight into a mirror (mirror position). Craniofacial morphology was described by 42 linear and angular variables, and postural relationships by 18 angular variables. A comprehensive set of correlations was found between craniofacial morphology and head posture. The correlations were similar for both head positions investigated. Of the postural variables, the position of the head in relation to the cervical column showed the largest set of correlations with craniofacial morphology. Extension of the head in relation to the cervical column was found in connection with large anterior and small posterior facial heights, small antero-posterior craniofacial dimensions, large inclination of the mandible to the anterior cranial base and to the nasal plane, facial retrognathism, a large cranial base angle, and a small nasopharyngeal space. The possible role of functional factors in mediating the relationship between morphology and posture was discussed.     

PRFS-Based MR Thermometry Versus an Alternative T1 Magnitude Method – Comparative Performance Predicting Thermally Induced Necrosis in Hepatic Tumor Ablation

Objective

To compare the accuracy of a semi-quantitative proton resonance frequency shift (PRFS) thermal mapping interface and an alternative qualitative T1 thermometry model in predicting tissue necrosis in an established routine setting of MRI-guided laser ablation in the human liver.

Materials and Methods

34 cases of PRFS-guided (GRE) laser ablation were retrospectively matched with 34 cases from an earlier patient population of 73 individuals being monitored through T1 magnitude image evaluation (FLASH 2D). The model-specific real-time estimation of necrotizing thermal impact (above 54 °C zone and T1 signal loss, respectively) was correlated in size with the resulting necrosis as shown by lack of enhancement on the first-day contrast exam (T1). Matched groups were compared using the Mann-Whitney test.

Results

Online PRFS guidance was available in 33 of 34 cases. Positive size correlation between calculated impact zone and contrast defect at first day was evident in both groups (p < 0.0004). The predictive error estimating necrosis was median 21 % (range 1 % - 52 %) in the PRFS group and 61 % (range 22 - 84 %) in the T1 magnitude group. Differences in estimating lethal impact were significant (p = 0.004), whereas the real extent of therapy-induced necrosis showed no significant difference (p > 0.28) between the two groups.

Conclusion

PRFS thermometry is feasible in a clinical setting of thermal hepatic tumor ablation. As an interference-free MR-tool for online therapy monitoring its accuracy to predict tissue necrosis is superior to a competing model of thermally induced alteration of the T1 magnitude signal.