Growth requirements of endothelial cells in culture: variations in serum and amino acid concentrations

Endothelial cell growth in vitro is limited to the availability of nutrients from commercially available media and added serum. Nutrients, such as amino acids, are chiefly derived from the cell culture medium, rather than from added serum, and optimal endothelial cell growth may be dependent on amino acid levels in the culture media. To test this hypothesis, porcine pulmonary artery-derived endothelial cells were exposed to culture medium 199 (M199), amino acid-deficient M199 (dM199), as well as dM199 supplemented with amino acids. Cell protein was similar in cells cultured for 3 d in M199 supplemented with 1, 3, 5 or 10% bovine calf serum, respectively. Addition of amino acid solutions (L-amino acids [Laa], DL-amino acids [DLaa], 2Laa, or Laa+glutamine) to dM199 demonstrated a cell dependence for optimal growth on the type of amino acids as well as on the total available nitrogen in the media. Compared with M199, dM199 supplemented with Laa only partially supported long-term growth of endothelial cells in culture. On the other hand, dM199 supplemented with either 2Laa, DLaa, or Laa+ glutamine was superior over M199 with regard to endothelial cell growth. The addition of Laa+glutamine to dM199 was most growth-supporting, with an increase of over 2.6-fold in total cell protein compared with cells cultured with M199. These results suggest that, in addition to the presence of essential amino acids, total available nitrogen in culture media may be a critical factor for optimal endothelial cell growth.     

Measurement of boundaries using a digitizer tablet

The perimeter is the most error prone of the primary measurements (length, perimeter and area) made when using a device such as a digitizer tablet to trace profiles on micrographs. To allow for minimization of this error an expression is developed relating the error in the perimeter to the digitizer resolution plus other errors in the entry process. The predictions of this expression are shown to be in good agreement with the results of computer simulation of the tracing process, as well as results from manual tracing using a digitizer tablet. This analysis of the digitizer entry process also provides a method by which an optimal choice of the sample spacing between digitizer coordinates can be made.     

Synthesis and properties of fluorinated polyimides and fluorinated poly(imide amide)s containing pendent cyano groups

A series of fluorinated polyimides and fluorinated poly(imide amide)s containing pendent cyano groups were prepared and investigated to determine their dielectric constants as a function of relative humidity and thermal characteristics. The fluorinated polymides and fluorinated poly(imide amide)s containing pendent cyano groups were prepared by reaction of bis(4-aminophenoxy) benzonitriles with a fluorinated dianhydride and with a fluorinated di(acid chloride) containing preformed imide rings. The properties of the fluorinated polyimides and fluorinated poly(imide amide)s containing pendent cyano groups were compared with those of fluorinated polyimides and fluorinated poly(imide amide)s prepared from 1,3-bis(4-aminophenoxy)benzene. The introduction of the pendent cyano groups caused an increase in the dielectric constant and an increase in the glass transition temperature of the polymers compared with the polymers prepared without pendent cyano groups.     

Analysis of the distribution of Cu, Fe and Zn and other elements in brindled mouse kidney using a scanning proton microprobe

An analysis of the distribution of trace metals in the kidney cortex in normal and brindled male mice has been carried out with a scanning proton microprobe. Enzyme histochemical staining techniques were used to distinguish between proximal and distal tubules. Average copper levels were increased in brindled kidney tissue sections, with the above-normal Cu accumulation found to occur entirely within the proximal tubules. Therefore, the proximal tubule is now regarded as the location where the defect in Cu transport in brindled mice is manifested the most clearly. The distribution of Fe was found to be non-uniform with some tubule cross-sections exhibiting high concentrations in both genotypes. The distribution of Zn was found to be uniform, and the concentration was similar for each genotype.     

Histochemistry in rat brain and spinal cord with an antibody directed at the cholecystokininA receptor

The role of D2/D3 receptors in striatum was electrophysiologically examined in vitro in chloralose-anesthetized rats. In addition, in vitro patch clamp method with rat brain slices was followed. Stimulations of the substantia nigra pars compacta (SN) in vivo elicited spike generation which was inhibited by microiontophoretically applied domperidone, a D2 antagonist. These domperidone-sensitive neurons were activated by microiontophoretic application of D2 agonists such as talipexole, quinpirole and bromocriptine as well as the D2 agonist, 7-OH-DPAT. They were also excited by either intravenous injection of bromocriptine or talipexole in a dose-dependent manner. Furthermore, the SN-induced increases in neuronal firing were blocked during microiontophoretic application of domperidone. In patch clamp whole-cell recording large-sized cells, identified visually under Ramanosky microscope, were depolarized with repetitive firing on bath application of talipexole and 7-OH-DPAT at a current clamp mode. Talipexole-induced depolarization in the large-sized cell was similarly observed in the presence of TTX and high Mg2+ in Ca(2+)-free physiological solution. In contrast, the medium-sized cells were hyperpolarized on bath application of talipexole without being affected by 7-OH-DPAT. These findings suggest that the large-sized cells, which were presumably cholinergic interneurons, are activated by dopamine derived from the SN via D2 and/or D3 receptors, while the medium-sized cells are inhibited by dopamine via D2 receptors.     

Evaluation of a predictive mathematical model of di-(2-ethylhexyl) adipate plasticizer migration from PVC film into foods

The diffusion coefficient of the plasticizer di-(2-ethylhexyl)adipate (DEHA) in Cheddar cheese (Df) was determined by measuring the extent to which DEHA penetrated cheese that was placed in intimate contact with artificially DEHA-contaminated cheese. Slices (20 microns) of cheese from the boundary layer, into which DEHA had migrated, were microtomed at -40 degrees C, and analyzed for DEHA by gas chromatography (GC). Mean values of Df determined by graph fitting experimental and calculated data were 1.5 x 10(-9) cm2 s-1 at 5 degrees C and 3.0 x 10(-8) cm2 s-1 at 25 degrees C. The partition coefficient (K) of DEHA between cheese and PVC film was derived from the partition coefficients of DEHA between acetonitrile (ACN) and cheese lipid, ACN and cheese solid, and ACN and PVC film. The mean values of K between cheese and PVC film were estimated to be 0.70 at 5 degrees C and 0.58 at 25 degrees C. The estimated values of Df and K were then used in a mathematical model (Till et al. 1982) to predict migration levels of DEHA into cheese. Good agreement with previously published experimental data was obtained. Extrapolation of the prediction of DEHA migration into fatty foods, such as salami and avocado, was also successful (ratio of experimental to predicted results within a factor of two). The values of Df and K for cheese are, however, inappropriate for modelling non-fatty foods such as meat, cakes, fruit and vegetables. Predicted values for these foods were typically 3-10-fold too high. More accurate predictions would probably be obtained if values of Df more relevant to these foods are used. The predictions were relatively insensitive to the value of K.