The effect of financing decisions on the choice of manufacturing technologies

This paper demonstrates the importance of jointly considering financing and technology choices when making manufacturing investments. We show that considerable value can be added to investments through financing decisions, and that the gains due to financing are sensitive to technology choice. A model of financing and technology choice is presented that considers differences in cost structure and product flexibility, and applies it to an example involving flexible manufacturing systems (FMSs). Three main results emerge. First, optimal financing decisions are different for different technologies and the choice of technology can change when financing and technology decisions are made simultaneously. Second, if one technology's fixed and variable costs are lower or its initial investment higher than another technology's the former has higher value added due to financing. Since empirical data shows that FMS and conventional technologies have this pattern, ignoring the benefits of debt financing leads to undervaluation of new technology. Third, product flexibility can add considerable value through its effect on financing decisions because product flexibility reduces variability of cash flows. A major conclusion is that financing and technology choice are long-term strategic decisions that should be made jointly. Firms that make these decisions separately, not considering the effect of one on the other, may make suboptimal technology decisions.     

Loss of self-tolerance to single-stranded deoxyribonucleic acid (sDNA) in vitro.

The spleens of many normal and autoimmune-susceptible strains of mice mount a specific, IgM, anti-sDNA plaque-forming cell (PFC) response in vitro in the absence of an exogenous source of antigen. This response was not related solely to levels of xenotropic or ecotropic virus and was generated from a small number of precursor cells capable of binding sDNA. Small numbers of anti-sDNA PFC were also apparent in serum-free medium and the response of low-responder strains could be augmented with pokeweed mitogen. T cells and macrophages were not essential and cell division was required early in culture to obtain a peak response on day 5. These results suggest that autoantigen-sensitive cells may escape normal regulatory mechanisms in vitro and differentiate into clones of autoantibody secreting cells.     

Peroxidase activities in relation to plant height and grain weight in bread wheat (Triticum aestivum L.)

Summary The relationship of peroxidase activity with plant height and grain weight has been studied in seven different varieties of bread wheat belonging to diverse genotypes, and their F₁ crosses. The association between plant height and peroxidase activity was highly significant and negative. Based on the similarity index values of peroxidase isoenzymes, the seven wheat genotypes could be classified into two groups: the first group consisting of triple and quadruple dwarf varieties and the other of tall, single and double dwarf. A negative correlation between peroxidase activity and grain weight was also observed. However, the results of this study indicate a possibility of developing a dwarf plant type with low peroxidase activity and well filled grains.     

Modification of guanine to queuine in transfer RNAs during development and aging

The degree of modification of guanine to queuine in the four queuine-containing tRNAs (Q-tRNAs) has been studied from rats of various age groups, and bacterial cells in different growth phases by measuring the amount of G-tRNA present in these tRNA preparations by tRNA-guanine transferase. In very young (one-week old) animals, only a small amount of G to Q modification was observed. However, this modification was essentially complete in the tRNAs of nine-month old animals, thereafter, the amount of Q decreased steadily. Studies of tRNAs from leukemic lymphocytes and bacterial cells indicated that the degree of G to Q modification was related to the metabolic state of the cell. The possible role of the Q-deficient isoacceptors in translation control is discussed.     

Changes in transfer ribonucleic acids of Bacillus subtilis during different growth phases

The transfer ribonucleic acids (tRNAs) of B. subtilis at different growth phases are examined for changes in the composition and the methylation of minor constituents. The composition of the tRNAs indicates about equal amounts of adenosine and uridine, and of guanosine and cytidine. About 3-4 residues are present as modified bases in the average tRNA molecule. The net composition of tRNAs appears to remain unaltered during different growth phases. In vitro methylation of tRNAs indicates lack of methyl groups in both exponentially growing cells and spores. In vivo methylation studies show tRNA methylation occurs during the stationary phase in the absence of net tRNA synthesis. Thus, both in vitro and in vivo methylation indicates that the tRNAs in exponentially growing cells do not contain their full complement of modified bases. More complete modification is noted in tRNAs from stationary cells or spores. Hence, tRNA modifications in general are preserved with fidelity even in the dormant spore but the possibility is left open that specific modifications of selected isoacceptors of tRNAs may occur.     

Evidence for the role of brain biogenic amines in depressed motor activity seen in chemically thyroidectomized rats.

Abstract— The effects of exposure to an antithyroid drug, methimazole, on brain tyrosine hydroxylase and tryptophan hydroxylase activity, as well as the levels of norepinephrine, dopamine, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid have been investigated in maturing brain. Daily treatment of neonatal rats with methimazole for 30 days induced chemical thyroidectomy as evidenced by significant impairment of body and brain growth. The activities or brain tyrosine hydroxylase and tryptophan hydroxylase and the levels of norepinephrine, dopamine and 5-hydroxytryptamine were markedly altered in a dose- and time-dependent manner in methimazole-treated rats. Conversely, the concentration of brain 5-hydroxyindoleacetic acid was elevated (46%) by methimazole administration. Treatment with the antithyroid drug failed to exert any significant effect on the endogenous levels of brain tryptophan, as well as on the activity of the deaminating enzyme, monoamine oxidase. Administration of triiodothyronine (25 or 100 μg/100 g) to hypothyroid rats for 30 days did not produce any appreciable effect upon the neurochemical parameters related to either norepinephrine or 5-hydroxytryptamine mctabolism. However, increasing the dose of triiodothyronine to 250 μg/100 g significantly elevated the levels of norepinephrine and 5-hydroxytryplamine as well as the activities of the two synthesizing enzymes, tyrosine hydroxylase and tryptophan hydroxylase. Brain 5-hydroxyindoleacetic acid levels were restored to normal values in thyroid hormone-deficient rats treated with this higher dose of triiodothyronine. Evidencc also was obtained to show that chemical thyroidectomy suppressed the spontancous locomotor activity in neonatal rats; the changes being apparent at 15 days of age. Our data support the view that thyroid hormone in neonatal life displays an important regulatory effect on the metabolism of norepinephrine, dopamine and 5-hydroxytryptamine. Since certain amines have been known to be implicated as the neurochemical substrates for behavioural arousal, it is conceivable that the observed hypoactivity in methimazolc-treated rats may, at least in part, be related to impaired maturation of norepinephrine and dopamine-synthesizing systems in brains of cretinous rats.     

Characterization of a novel alpha-class anionic glutathione S-transferase isozyme from human liver

A novel, alpha-class glutathione S-transferase (GST) isozyme has been isolated from human liver using glutathione (GSH) affinity chromatography, DEAE-cellulose ion-exchange chromatography, and immunoaffinity chromatography. The isozyme is a dimer of approximately 25,000 Mr with blocked N termini. Structural, kinetic, and immunological properties of this enzyme indicate that it belongs to the alpha class of GSTs. Noticeable differences between the properties of this enzyme and the other alpha-class GSTs of human liver are its anionic nature (pI 5.0), GSH peroxidase activity toward hydrogen peroxide, and relatively higher GSH conjugating activities toward CDNB and epoxide substrates as compared to other alpha-class GSTs. Results of these studies indicate that anionic GST omega characterized previously (Y. C. Awasthi, D. D. Dao, and R. P. Saneto, 1980, Biochem. J. 191, 1-10) from human liver is a mixture of GST pi and a novel alpha-class GST. We have, therefore, reassigned the name GST omega to this new alpha-class anionic GST of human liver.     

Block of outward current in cardiac purkinje fibers by injection of quaternary ammonium ions

We have studied the effects of iontophoretic injection of the quaternary ammonium compounds tetraethylammonium (TEA) and tetrabutylammonium (TBA) in cardiac purkinje fibers. We find that TBA(+) is a more effective blocker than TEA(+), but injection of either compound reduces the time-dependent outward plateau currents, transient outward current (I(to)), and the delayed rectifier (I(x)). Our findings provide evidence that these outward cardiac currents are carried by channels that in some respects are pharmacologically similar to squid axon potassium channels. We demonstrate that this procedure is a new tool that can be useful in the analysis of membrane currents in the heart.     

Regulatory cells in human bone marrow: Suppression of an in vitro primary antibody response

Human bone marrow (BMC) contains regulatory cells that can suppress the in vitro primary PFC response of normal allogeneic spleen or tonsillar cells and autologous peripheral blood cells. Suppression is dependent upon the dose of BMC added, but is not due to cell crowding nor to excessive cytotoxicity, and requires the presence of viable, metabolically active BMC. BMC are maximally inhibitory when added during the first 24 hr of culture and do not cause an induced shift in the kinetics of the response. Thus, suppression reflects inhibition of early inductive events in the antibody response. The target of suppression is the non-T cell, with either polyclonal activator or Ag being required for maximal suppression. DNA synthesis of normal tonsillar cells is not inhibited by BMC. Characterization of the human bone marrow-suppressor cell has shown it to be radiosensitive, E-rosette negative, Fc receptor positive, and to reside in the large, weakly adherent cell population after velocity sedimentation and in the lymphocyte-depleted fraction after sucrose density gradient separation. Pretreatment of the bone marrow-suppressor cell with anti-human thymocyte serum does not abrogate suppression. We speculate on a possible physiologic role for this cell.