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Biomedical subjects

A Rappaport

Publications and source records attributed to A Rappaport.

30 records · Page 2Linked to original sources
PubMed1983

Solubilization of active brain alpha 1-adrenoceptors by a zwitterionic detergent.

Solubilization of rat brain alpha 1-adrenoceptors was performed by treatment with 6 mM CHAPS (3-[(3-cholamidopropyl)dimethylammonio] - 1 - propanesulfonate). The alpha 1-adrenoceptor antagonist [3H]prazosin was shown to bind reversibly and specifically to the soluble extract obtained after centrifugation at 150,000 X g for 1 h. Separation of the soluble [3H]prazosin-bound complexes was performed by the polyethylene glycol precipitation technique followed by filtration. A Scatchard plot of the concentration-dependent binding curve showed only one class of binding sites, with a high affinity for [3H]prazosin. Affinity of the solubilized receptors for the ligand increased as the CHAPS concentration in the assay medium decreased; the number of binding sites remained unchanged (approximately equal to 70 fmol/mg protein). This corresponds to a 30% recovery of original membrane sites. The solubilized receptors presented the same characteristics of specificity and stereospecificity as membrane alpha 1-adrenoceptors. Moreover, 150 mM NaCl was found to modulate the affinity of epinephrine for the [3H]prazosin-bound soluble complex, as previously described for membrane preparations. Thus, CHAPS appears to be a suitable detergent for solubilizing rat brain alpha 1-adrenoceptors and preserving their functional activities.

Animals↗
PubMed1983

Biochemical analysis and solubilization of central alpha 1-adrenoceptors in the rat.

To study the structure and the molecular mechanisms of action of brain alpha-adrenoceptors, their solubilization was undertaken. alpha 1-Adrenoceptors were first successfully solubilized from fresh rat brain membranes by treatment with 0.3 percent deoxycholate, after prelabeling of the binding site by the highly specific tritiated antagonist 3H-prazosin. The complex thus solubilized underwent a rapid loss of activity at 25 degrees C. Direct solubilization of brain alpha 1-adrenoceptors was obtained by treatment with a new zwitterionic derivative of cholic acid (CHAPS) at a concentration of 5 to 10 mM. The soluble complex was detected by precipitation by polyethylene glycol 6,000 with gamma globulin as a carrier. Binding of 3H-prazosin at 25 degrees C was rapid; at 4 degrees C the steady state was obtained within two hours and remained unchanged for at least six hours. The affinity of the soluble binding site, determined by Scatchard analysis (congruent to 0.6 nM), varied with the concentration of detergent. Specificity of the membrane-bound receptor was preserved as demonstrated by incubation in the presence of alpha 1- and alpha 2-antagonists at various concentrations (by order of potency: prazosin greater than phentolamine greater than yohimbine). Stereoselectivity was also retained in the solubilized binding protein. The solubilization of an active brain alpha 1-adrenoceptor will allow further investigation at the molecular level.

Adrenergic alpha-Agonists↗
PubMed1982

A multivariate analysis of dichotomous opinions in dissensus disaster.

Despite the absence of evidence supporting either environmental or economic damages resulting from the Argo Merchant oil spill of 1976, a questionnaire administered 11 months afterward to 258 randomly selected heads of households in four towns contiguous to the spill revealed that 60 percent thought damages had occurred. In a secondary analysis of the original data to examine the causes of the damage perceptions, a discriminant function was developed on a randomly selected test group and evaluated on a control group. The results support the hypothesis that incorrect damage perceptions resulted from a priori views on the part of younger, socially conscious, higher-achieving heads of households. Support is indicated for the hypothesis that a priori perceptions were reinforced after the event. The index for total discriminating power was .43 for the test group and .38 for the control group. Television was the major media information source.

Adult↗
PubMedDate not supplied

Development of an HIV educational needs assessment tool.

The learning needs of persons with HIV/AIDS continue to grow more complex as new treatments are developed and HIV disease shifts from being a terminal to a chronic illness. Clinicians could use a simple tool to help them to focus on what clients think is important to know about living with HIV/AIDS. This article describes the development of the HIV Educational Needs Assessment Tool (HENAT). HIV+ persons (N = 363) who were receiving health care in a variety of ambulatory and institutional settings participated in this research during 1990 and 1993-1994. Factor analysis was used to shorten the instrument into a form that could be used in any nurse/client interaction. Principal axis factor extraction and varimax rotation deleted 16 items. The remaining 34 items were grouped into six factors: Treatments, Entitlements, Relationships, Preventing Infections, Social Support, and Working. Cronbach's alphas were computed and results ranged from .70 to .88. Two month test-retest correlations for a subset of participants (n = 195) ranged from .54 to .67. HENAT can be used (a) to examine differences in perception of learning needs between clients with HIV disease and their health care providers, (b) to measure shifts in learning needs over time, (c) to relate HIV-specific learning needs to length of time living with HIV disease, (d) to give clients an opportunity to assess their learning needs, and (e) as part of a larger intervention study that evaluates the effectiveness of patient education.

Adult↗
PubMedDate not supplied

The staying power of the public corporation.

Has the publicly held corporation out-lived its usefulness? In HBR's September-October 1989 issue, Michael C. Jensen of the Harvard Business School said "yes." The institutional shortcomings of the public corporation are so grave, he argued, that it must be considered fatally flawed. He described the emergence of a new form of enterprise-the LBO Association-that releases much of the untapped value and corrects many of the inefficiencies of large public companies. Alfred Rappaport, a professor and consultant who advises large public companies, joins the debate with a rebuttal to Jensen. Rappaport shares many of Jensen's criticisms of current strategic and financial practices among public companies. But he does not believe leveraged buyouts and other going-private transactions can replace the public corporation. This is so, he asserts, for two reasons: LBOs have a limited demand and a limited life. Rappaport argues that the publicly held corporation is worth saving. It is inherently flexible and self-renewing-properties that are fundamental to stability and progress in a market-driven economy and that transitory organizations like LBOs cannot replicate. Rappaport advances a four-point program to overhaul strategic planning, compensation, and governance to maximize shareholder value in public companies: 1. Find the highest valued use for all assets. 2. Limit investment to opportunities with credible potential to create value. 3. Return cash to shareholders when such value-creating investments are not available. 4. Establish incentives for managers and employees to focus on the critical business drivers that create value.

Governing Board↗
PubMedDate not supplied

CFOs and strategists: forging a common framework.

Companies have become increasingly polarized into two divergent camps: those who consider shareholder value the key to managing the company and those who put their faith in gaining competitive advantage. Indeed, that age-old debate between investing for the long term and showing outstanding short-term results is back - only this time the camps are flying banners with the new buzzwords of corporate America: competitive advantage and shareholder value. In this article, Alfred Rappaport attempts to settle the debate once and for all, arguing forcefully that establishing competitive advantage and creating shareholder value both stem from a common economic framework. In fact, long-term productivity is the hinge from which both sustainable competitive advantage and consistent results for the shareholder hang. But many managers refuse to accept this theory and cling to the mistaken belief that the market does not actually value the long-term productivity of their company but judges it only by its short-term performance. They then jump to a second mistaken conclusion: assuming they must depart from the shareholder-value model to improve their competitive position. Rappaport attacks these mistaken beliefs, showing that the stock market does value the long-term productivity of a company and that it is not necessary to depart from the shareholder-value model to improve a company's competitive position. Maximum returns for current shareholders will materialize only when managers maximize long-term shareholder value and deliver interim results that attest credibly to sustainable competitive advantage.

Administrative Personnel↗
PubMedDate not supplied

New thinking on how to link executive pay with performance.

As the stock market began its ascent in the mid-1990s, executive pay--always the subject of heated debate--mounted along with it. That's because among the largest U.S. companies, stock options now account for more than half of total CEO compensation and about 30% of senior operating managers' pay. One problem became particularly clear during the bull market's astonishing run: even below-average performers reap huge gains from stock options when the market is rising rapidly. The author proposes steps to close the gap between existing compensation practices and those needed to promote higher levels of achievement at all levels of the corporation. For top managers, he recommends replacing conventional stock options with options that are tied to a market or peer index. Below-average performers would not be rewarded under such plans; superior performers could, depending on the way plans were structured, receive even more. He notes that managers at the business unit level should not be judged on the company's stock price--over which they have little control--and advocates an approach that accurately measures the value added by each unit. Finally, he suggests how certain indicators of value can be used to measure the contribution of frontline managers and employees. The concept of pay for performance has gained wide acceptance, but the link between incentive pay and superior performance is still too weak. Reforms must be adopted at all levels of the organization. Shareholders will applaud changes in pay schemes that motivate companies to deliver more value.

Administrative Personnel↗
PubMedDate not supplied

Stock or cash? The trade-offs for buyers and sellers in mergers and acquisitions.

In 1988, less than 2% of large deals were paid for entirely in stock; by 1998, that number had risen to 50%. The shift has profound ramifications for shareholders of both the acquiring and acquired companies. In this article, the authors provide a framework and two simple tools to guide boards of both companies through the issues they need to consider when making decisions about how to pay for--and whether to accept--a deal. First an acquirer has to decide whether to finance the deal using stock or pay cash. Second, if the acquirer decides to issue stock, it then must decide whether to offer a fixed value of shares or a fixed number of them. Offering cash places all the potential risks and rewards with the acquirer--and sends a strong signal to the markets that it has confidence in the value not only of the deal but in its own stock. By issuing shares, however, an acquirer in essence offers to share the newly merged company with the stockholders of the acquired company--a signal the market often interprets as a lack of confidence in the value of the acquirer's stock. Offering a fixed number of shares reinforces that impression because it requires the selling stockholders to share the risk that the value of the acquirer's stock will decline before the deal goes through. Offering a fixed value of shares sends a more confident signal to the markets, as the acquirer assumes all of that risk. The choice between cash and stock should never be made without full and careful consideration of the potential consequences. The all-too-frequent disappointing returns from stock transactions underscore how important the method of payment truly is.

Decision Making, Organizational↗