Countervailing Effect Research Articles

Public health insurance and medical treatment: the equalizing impact of the Medicaid expansions

We investigate the impact of expanding public health insurance on the medical treatment received by women at childbirth, using Vital Statistics data on every birth in the US over the 1987–1992 period. The effects of insurance status on treatment are identified using the tremendous variation in eligibility for public insurance coverage under the Medicaid program over this period. Among low education mothers who were largely uninsured before being made eligible for Medicaid, eligibility for this program was associated with significant increases in the use of a variety of obstetric procedures. Among women with more education, however, there is a countervailing effect on procedure use. Most of these women had private insurance before becoming Medicaid-eligible, and some may have been ‘crowded out’ onto the public program, moving from insurance which reimburses medical care more generously to insurance with much less generous reimbursement. This movement was accompanied by reductions in procedure use. Thus, on net, the Medicaid expansions had an equalizing effect, increasing the treatment intensity of the previously uninsured while lowering it among the previously insured.

Erythropoietin regulates vascular smooth muscle cell apoptosis by a phosphatidylinositol 3 kinase-dependent pathway

Recent studies have shown that several cytokines could induce apoptosis in vascular smooth muscle cells (VSMCs) via the induction of nitric oxide (NO). In the present study, we explored whether human recombinant erythropoietin (rHuEPO) has a modulatory effect of apoptosis on interleukin-1beta (IL-1beta) or NO donor sodium nitroprusside (SNP)-induced apoptosis in rat cultured VSMCs. The quantitation of apoptosis among VSMCs was assessed by nuclear morphological analysis with fluorescent DNA-binding dye Hoechst 33258. Apoptotic changes were also confirmed by the detection of DNA fragmentation. The expression of EPO receptor (EpoR), cellular protein tyrosine phosphorylation, including EpoR and Janus kinase (JAK) 2, and the association of p85 subunit of phosphatidylinositol 3 kinase (PI3-kinase) to tyrosine-phosphorylated proteins, including EpoR, were explored by using Western blotting analysis combined in part with immunoprecipitation. rHuEPO inhibited the apoptosis induced by IL-1beta or SNP in a dose- and time-dependent manner. The anti-apoptotic effects of rHuEPO were diminished in the presence of a tyrosine kinase (TK) inhibitor genistein or anti-EpoR antibody. After stimulation with rHuEPO, EpoR and JAK 2 were tyrosine phosphorylated, and p85 subunits were associated with EpoR. Also, rHuEPO induced phosphorylation of Akt through a PI3-kinase-dependent pathway. The phosphorylation of Akt and the anti-apoptotic effects of rHuEPO were diminished in the presence of a PI3-kinase inhibitor, wortmannin. Our present study demonstrates that rHuEPO inhibites IL-1beta or SNP-induced VSMC apoptosis. The TK-dependent pathway, particularly the PI3-kinase-dependent pathway, seems to be critical to the countervailing effect of rHuEPO on IL-1beta and SNP-induced VSMC apoptosis.

Contract renegotiation and options in agency problems

This article discusses the ability of an agent and a principal to achieve the first-best outcome when the agent invests in an asset that has greater value if owned by the principal than by the agent. When contracts can be renegotiated, a well-known danger is that the principal can hold up the agent, undermining the agent's investment incentives. We begin by identifying a countervailing effect: Investment by the agent can increase his value for the asset, thus improving his bargaining position in renegotiation. We show that option contracts will achieve the first best whenever his threat-point effect dominates the holdup effect. Otherwise, achieving the first best is difficult and, in many cases, impossible. Copyright 2000 by Oxford University Press.

Contract Renegotiation and Options in Agency Problems

This paper studies the ability of an agent and a principal to achieve the first-best outcome when the agent invests in an asset that has greater value if owned by the principal than by the agent. When contracts can be renegotiated, a well-known danger is that the principal can holdup the agent, undermining the agent's investment incentives. We begin by identifying a countervailing effect: Investment by the agent can increase his value for the asset, thus improving his bargaining position in renegotiation. We show that option contracts will achieve the first best whenever this threat-point effect dominates the holdup effect. Otherwise, achieving the first best is difficult and, in many cases, impossible.

Democratizing for Peace

The argument that democratization can bring about war is a powerful critique suggesting limits to the linkage between democracy and peace. This research examines this claim. Our findings demonstrate that democratizing polities are substantially less war prone than previously argued. By focusing on the characteristics of the transition process, we show that as contemporary polities become more democratic they reduce their overall chances of being involved in war by approximately half. We also find that rocky or especially rapid transitions or reversals are associated with a countervailing effect; namely, they increase the risk of being involved in warfare. Both in the long term and while societies undergo democratic change, the risks of war are reduced by democratization and exacerbated by reversals in the democratization process. To reach these conclusions, we developed and applied a logit model linking authority characteristics and war involvement using Polity III and Correlates of War databases.

Strategic Environmental Policy Under Incomplete Information

This paper introduces incomplete information into recent analyses of strategic environmental policy. It is shown how asymmetric information between planners and producers affects national incentives to impose strategic environmental standards on domestic industries in international oligopolistic competition. Relative to the full-information case, incomplete information is likely to mitigate allocative distortions originating from strategic behaviour. A countervailing effect, tending to raise distortion, is however revealed from the analysis. This effect is absent when governments intervene in free trade through direct production subsidies. The results suggest that incentives to capture foreign rents are less reduced due to private information, when environmental standards, rather than direct production subsidies, are the strategic instrument.

Contract Renegotiation in Agency Problems

This paper studies the ability of an agent and a principal to achieve the first-best outcome when the agent invests in an asset that has greater value if owned by the principal than by the agent. When contracts can be renegotiated, a well-known danger is that the principal can holdup the agent, undermining the agent's investment incentives. We begin by identifying a countervailing effect: Investment by the agent can increase his value for the asset, thus improving his bargaining position in renegotiation. We show that option contracts will achieve the first best whenever this threat-point effect dominates the holdup effect. Otherwise, achieving the first best is difficult and, in many cases, impossible. In such cases, we show that if parties have an appropriate signal available, then the first best is still attainable for a wide class of bargaining procedures. A noisy signal, however, means that the optimal contract will involve terms that courts might view as punitive and so refuse to enforce problems, and modern manufacturing.

Patent Length and the Rate of Innovation

This paper models the effect of patent length on the rate-of-innovation and consumer welfare. The authors find that the patent length that maximizes the rate-of-innovation exceeds that which maximizes consumer welfare. They show a countervailing effect of patent length upon the 'size' and 'frequency' of innovation. Longer patents increase the size, but decrease the frequency of innovation. The patent lengths that maximize the rate-of-innovation and welfare represent balance points between size and frequency. The divergence of the welfare maximizing and rate-of-innovation maximizing patent lengths has important policy implications that the authors briefly explore. Copyright 1996 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.

SCHUMPETERIAANSE ENTREPRENEURSKAP IN DIE LANDBOUSEKTOR VAN DIE NUWE SUID-AFRIKA

Abstract Schumpeter claims that the entrepreneur—who occasionally succeeds with a new bundle of innovations to set a process of Creative Destruction in motion—is in effect responsible for the dynamic character of capitalism. He was, nonetheless, of the opinion that entrepreneurial capitalism cannot survive its own success because it produced by virtue of its very success social and cultural by-products which will create circumstances that in the long run will not be conducive to providing that kind of protection, support and acknowledgement the entrepreneur needs. Because of the rise of large-scale corporative enterprises, the agricultural sector is today one of the few sectors in which the business form of owner-entrepreneur is still commonly in use. South Africa is at present experiencing a powershift toward a new dispensation. In the next 10 or 20 years a pluralistic network of power blocks must be brought about with the capacity to have a countervailing effect on one another. If this can be accomplish...

Prostaglandin E 2 Receptors of Monocytes/Macrophages: Regulation by Insulin and Interleukin-1α

The regulation of receptors for prostaglandin E 2 (PGE 2) in monocyte/macrophage-like cells, P388D 1, by interleukin-1α (IL-1α) and insulin has been investigated. Many of the effects of IL-1, such as fever and other inflammatory activities, are linked to the stimulation of PGE 2 synthesis. On the other hand, PGE 2 exhibits suppressive effects on many steps in the immune response, including IL-1 production. The binding of PGE 2 to monocytes is reported to be essential for the inhibition of IL-1 production and activity. This inhibition occurs through the stimulation of cyclic AMP synthesis by the activation of PGE 2 receptor-linked adenylate cyclase. Although IL-1α stimulates PGE 2 synthesis in monocytes/macrophages during immunoactivation, it inhibits the binding of PGE 2 to these cells and may thereby exert a countervailing effect on the immunosuppressive action of this prostanoid. By contrast, insulin at physiological concentrations enhances the PGE 2 binding to these cells. This suggests that insulin at physiological concentrations may enhance the immunosuppressive action of PGE 2. Since the stimulation of cAMP synthesis in cells is regulated by PGE 2 binding, it is possible that these hormonal factors may control the immune response by modulating the PGE 2 receptor activity of monocytes/macrophages. This article focuses on the interactions of insulin and IL-1 with PGE 2 receptors of monocytes/macrophages.

The effect of vapour pressure on the reaction of water vapour with siderite and its relevance to retorting of Australian Tertiary oil shales

The thermal decomposition reaction of siderite mineral samples in water vapour/nitrogen atmospheres was studied using thermogravimetry. A reduction of about 120 °C in the decomposition temperature in 60 kPa water vapour, compared to that in nitrogen, was found for both siderite and ferroan magnesite. A different reaction mechanism in water vapour accounts for the differences in temperature. The effect of water vapour pressure between 0 and 80 kPa was non-linear, being relatively greater at low vapour pressures, and the inverse relationship between the peak decomposition temperature and water vapour pressure has been established. The results imply that the siderites and magnesian siderites present in Australian Tertiary oil shales will decompose during steam-retorting, although the possible countervailing effect of carbon dioxide remains to be defined.

Enantiodivergent synthesis of steroidal side chains. Stereocontrol via SN1 vs. SN2 type cleavage of acetal templates

The chiral steroidal acetals 2(S–R, R isomer) and 3(S–S, S isomer) were prepared from the reaction of the steroidal aldehyde 1 with (2R, 4R)-(–)-pentane-2,4-diol and with (2S, 4S)-(+)-pentane-2,4-diol, respectively. The TiCl4 mediated reaction of 2 and 3 with organometallic reagents, such as allylsilane, allyltin, allyl-9-BBN, 1-tributylstannylalk-1-ynes, and 1-trimethylsilylhex-1-yne gave a mixture of the Cram, 4 and 6, and anti-Cram, 5 and 7, adducts. The organometallic compounds with lower nucleophilicity (the Me3Si and 9-BBN derivatives) gave the Cram isomer predominantly or exclusively regardless of the chirality of the acetal, whereas the reagents with higher nucleophilicity (the tributylstannyl derivatives) produced the anti-Cram isomer with good diastereoselectivity in the case of the S–S, S isomer 3. This synergistic or countervailing effect of the acetal template and Cram rule is understood by considering that the chiral induction is controlled by the timing of bond breaking and bond making in the acetal template. This stereodivergent synthetic method was applied to the preparation of an α-ecdysone type steroid 17.

Inhibition of thromboxane A2 synthesis in human platelets by coagulation factor Xa.

Factor Xa binds to platelets provided that factor Va is present on the platelet surface, an interaction that results in a striking acceleration of the conversion of prothrombin to thrombin. Thrombin then initiates fibrin formation, induces platelet aggregation, and stimulates the intraplatelet synthesis of thromboxane A2 (TXA2). Addition of thrombin (2.4-14.4 nM) to platelet-rich plasma increased the basal level of TXA2, measured as thromboxane B2, from less than 0.5 pmol per 10(8) platelets to (mean +/- SEM) 100 +/- 22 and 250 +/- 10 pmol per 10(8) platelets, respectively. Treatment of platelet-rich plasma with increasing concentrations of factor Xa (1-12 nM) prior to the addition of thrombin progressively inhibited the production of TXA2. Thrombin (9.6 nM), which produced 93% of the maximal formation of TXA2, was inhibited 70% by factor Xa (10 nM). To identify which of these steps in thromboxane synthesis was inhibited by factor Xa, platelets labeled with [14C]arachidonic acid were exposed to thrombin and products of prostaglandin synthesis were separated by thin-layer chromatography. In contrast to the inhibition of TXA2 synthesis, prostaglandin E2 and prostaglandin F2 alpha synthesis were not inhibited suggesting that neither phospholipase(s) nor cycloxygenase was involved. The inhibition of TXA2 formation by factor Xa could be reversed by increasing the molar ratio of thrombin to factor Xa to 5.5. Incubation of platelets with an IgG fraction of a human monoclonal antifactor V antibody, previously shown to inhibit factor Xa binding, was found to block factor Xa inhibition of TXA2 synthesis. The inhibition of TXA2 synthesis requires the presence of the active site serine of factor Xa and is not specific for TXA2 formation induced by thrombin because it is also demonstrable when the agonist is ADP. Further, factor Xa does not require additional plasma components for its action because its inhibitory effects are detected in gel-filtered platelets. The effect of factor Xa was evident at physiological (1.3 mM) calcium concentrations. These results indicate that factor Xa binding to platelets through factor Va not only stimulates thrombin formation but also has a countervailing effect by inhibiting TXA2 formation.

Surface silanols in silica-bonded hydrocarbonaceous stationary phases : I. Dual retention mechanism in reversed-phase chromatography

“Irregular” retention behavior of crown ethers in reversed-phase chromatography with silica-bonded hydrocarbonaceous stationary phases is interpreted by using a dual binding model. It is assumed that retention is caused not only by the usual solvophobic interactions but also by “silanophilic” interactions between the eluite and the accessible silanol groups at the surface of various alkyl-silica bonded phases. Minima observed in the dependence of the retention factor of dibenzo-18-crown-6 on the composition of methanol-water mixtures used as the eluent are in agreement with the theory. The model also correctly predicts the temperature dependence of retention under various conditions as far as the nature of the stationary phase and the eluent composition are concerned. Thus curved Van 't Hoff plots of the experimental data are attributed to the sufficiently dissimilar enthalpies involved in the solvophobic and silanophilic binding. It is likely that minima exhibited by plots of retention factor against eluent composition in reversed-phase chromatography are in most cases manifestations of the countervailing effect of the solvophobic and silanophilic forces on retention.

The dependence of phosphofructokinase kinetics upon protein concentration

It is well established that mammalian phosphofructokinases show concentration-dependent association and dissociation phenomena [l--5]. The minimum fully active form of the enzyme from skeletal muscle has a molecular weight of 380,000 and can be dissociciated into units of molecular weight 192,000 by dilution at pH 6.7, or lowering the pH to 5.0 [l] . The dissociated enzyme has at most two percent of the activity of the associated form. Similar observations have been made on the enzyme from sheep heart [2]. In the latter case ATP was found to favour dissociation, and the other substrate of the reaction, fructosed-phosphate (F6P) exerted a countervailing effect, tending to favour the associated form of the enzyme. The results presented here indicate that the effector modulated dissociation of phosphofructokinase is capable of accounting for almost the entire range of control properties of the enzyme. These may be summarised as (1) inhibition by high concentrations of ATP, (2) synergistic inhibition by citrate in the presence of inhibitory concentrations of ATP, (3) the counteraction of inhibition by adenosine monophosphate (AMP) and fructose-1-6diphosphate (FDP), and (4) cooperativity of the F6P kinetics in the presence of inhibitors. In relation to (3) it should be noted that although the kinetic order of AMP activation appears to be two, whilst that of FDP activation is one, both compounds are capable of completely counteracting ATP inhibition.