Kinetic study of littorine rearrangement in Datura innoxia hairy roots by (13)C NMR spectroscopy

The kinetics of tropane alkaloid biosynthesis, particularly the isomerization of littorine into hyoscyamine, were studied by analyzing the kinetics of carbon-13 ((13)C) in metabolites of Datura innoxia hairy root cultures fed with labeled tropoyl moiety precursors. Both littorine and hyoscyamine were the major alkaloids accumulated, while scopolamine was never detected. Feeding root cultures with (RS)-phenyl[1,3-(13)C(2)]lactic acid led to (13)C spin-spin coupling detected on C-1' and C-2' of the hyoscyamine skeleton, which validated the intramolecular rearrangement of littorine into hyoscyamine. Label from phenyl[1-(13)C]alanine or (RS)-phenyl[1,3-(13)C(2)]lactic acid was incorporated at higher levels in littorine than in hyoscyamine. Initially, the apparent hyoscyamine biosynthesized rate (v(app)()hyo = 0.9 micromol (13)C.flask(-1).d(-1)) was lower than littorine formation (v(app)()litto = 1.8 micromol (13)C.flask(-1).d(-1)), suggesting that the isomerization reaction could be rate limiting. The results obtained for the kinetics of littorine biosynthesis were in agreement with the role of this compound as a direct precursor of hyoscyamine biosynthesis.

Diversification and selection mechanisms for the production of protein repertoires: lessons from the immune system

The physiological mechanism for producing antigen-specific antibodies is based on a two-phase neo-Darwinian process: the first phase consists of diversity generation (formation of the repertoire), and the second phase is antigen-mediated selection. In this article, we consider how the natural immunoglobulin gene-diversification processes can be exploited both in vivo and in vitro in order to allow the generation of novel antibody (and heterologous protein) repertoires.

Allelic inclusion of T cell receptor alpha genes poses an autoimmune hazard due to low-level expression of autospecific receptors

Organ-specific autoimmune disease can be caused by alphabeta T cells that have escaped self-tolerance induction. Here we show that one of the causes of escape from self-tolerance is the coexpression of two different T cell receptors by the same cell, which can occur in up to 30% of all T cells in normal mice and can lead to low-level surface expression of an autospecific TCR. We found that double receptor-expressing T cells can escape tolerance even to ubiquitously expressed antigens but can nevertheless induce autoimmune diabetes when the relevant protein is expressed in pancreatic tissue. Such diabetogenic T cells are absent, however, among T cells expressing the autospecific TCR as the sole receptor.

Interleukin 10 secretion and impaired effector function of major histocompatibility complex class II-restricted T cells anergized in vivo

Continuous antigenic stimulation in vivo can result in the generation of so-called "anergic" CD4(+) or CD8(+) T cells that fail to proliferate upon antigenic stimulation and fail to develop cytolytic effector functions. Here we show that class II major histocompatibility complex-restricted T cells specific for influenza hemagglutinin (HA) that become anergic in mice expressing HA under control of the immunoglobulin kappa promoter exhibit an impaired effector function in causing diabetes in vivo, as compared to their naive counterparts, when transferred into immunodeficient recipients expressing HA under the control of the insulin promoter. Furthermore, HA-specific T cells anergized in vivo contain higher levels of interleukin (IL)-4 messenger RNA (mRNA) than naive and recently activated T cells with the same specificity and more than a 100-fold higher levels of IL-10 mRNA. The higher expression of the IL-10 gene is also evident at the protein level. These findings raise the interesting possibility that T cells rendered anergic in vivo have in fact become regulatory T cells that may influence neighboring immune responses through the release of IL-10.

Changes in function of antigen-specific lymphocytes correlating with progression towards diabetes in a transgenic model

Mice that express influenza hemagglutinin under control of the rat insulin promoter (INS-HA) as well as a class II major histocompatibility complex (MHC)-restricted HA-specific transgenic TCR (TCR-HA), develop early insulitis with huge infiltrates, but progress late and irregularly to diabetes. Initially, in these mice, INS-HA modulates the reactivity of antigen-specific lymphocytes, such that outside the pancreas they do not cause lethal shock like their naive counterparts in single transgenic TCR-HA mice, when stimulated with high doses of antigen. Inside the pancreas, the antigen-specific cells do not initially attack the islet cells, and produce some IFN-gamma as well as IL-10 and IL-4. Spontaneous progression to diabetes, which can be accelerated by cyclophosphamide injection, is accompanied by a 10-fold increase in IFN-gamma and a 3-fold decrease in IL-10 and IL-4 production by the locally residing antigen-specific T cells. Also, total islets from non-diabetic mice contain more TNF-alpha, compared with diabetic mice. This scenario is consistent with the view that beta cell destruction depends upon the increased production of certain pro-inflammatory cytokines by infiltrating T cells. Our inability to detect Fas expression on beta cells, but not on lymphoid cells, in diabetic and non-diabetic mice, puts some constraints on the role of Fas in beta cell destruction.

Conditions that induce tolerance in mature CD4+ T cells

Establishment of antigen-specific tolerance among mature T cells has been a long debated, yet poorly understood issue. In this study we have used transgenic mice bearing a class II--restricted TCR specific for the hemmagglutinin of the influenza virus in order to test the behavior of CD4+ T cells upon exposure to antigen in different forms and doses. We first studied the fate of T cells expressing the transgenic TCR (6.5) in double transgenic mice where HA was expressed as a self antigen by hemapoietic cells. In these mice, we found some mature T cells in periphery that had escaped thymic deletion and that showed signs of activation but which were anergic. Mature CD4+6.5+ cells that were transferred into antigen-containing recipients went through an initial phase of expansion after which most cells were deleted and those remaining became unresponsive, as previously described for CD8+ cells. Inducing tolerance in CD4+6.5+ cells in situ in single transgenic mice proved a difficult task: classical protocols using single doses of soluble or deaggregated antigen as well as feeding antigen all failed to induce antigen-specific unresponsiveness. It was only after decreasing cell numbers by CD4 antibody treatment and by repeatedly reintroducing antigen thereafter that unresponsiveness of 6.5+ cells was achieved and maintained. In no case could we observe the appearance of antigen-specific T cells with a Th2 cytokine profile among the remaining cells and therefore conclude that deletion and anergy represent the major mechanisms of tolerance in our studies.

A pain management documentation tool

PURPOSE/OBJECTIVES

To describe the development, implementation, and evaluation of a tool to standardize assessment, monitoring, management, and documentation of acute and chronic pain in hospitalized patients.

DATA SOURCES

A multidisciplinary hospital committee, nursing staff, a pain consultant, published standards, and hospital standards.

DATA SYNTHESIS

A comprehensive pain flow sheet and pain protocol was developed to assess, monitor, document, and evaluate clients at risk for or with actual pain. The tool was designed to assess and document acute and chronic pain in patients with cancer.

CONCLUSIONS

Based on an initial review of quality assurance indicators, the tool has demonstrated increased consistency in documentation of pain management activities.

IMPLICATIONS FOR NURSING PRACTICE

The use of a pain assessment and management flow sheet with a pain protocol provides an organized, consistent approach that maximizes quality, cost-effective care.

Survival of patients with severe congestive heart failure treated with oral milrinone

The safety and efficacy of long-term oral milrinone therapy were evaluated over a 2 1/2 year period in 100 patients who had severe congestive heart failure despite conventional therapy. Long-term oral milrinone therapy (27 +/- 8 mg/day initial dose) was well tolerated; drug-related side effects occurred in only 11% of patients and led to drug withdrawal in only 4% of patients. Of 94 patients evaluated after 1 month of therapy, 51% had improved by at least one New York Heart Association functional class. Despite hemodynamic and clinical improvements, life table analysis showed a 39% mortality rate at 6 months and a 63% mortality rate at 1 year of therapy. Characteristics at study entry that predicted death within 6 months included more advanced functional class, impaired renal function, lower right ventricular ejection fraction, presence of nonsustained ventricular tachycardia on 24 hour ambulatory electrocardiography, more impaired baseline hemodynamic function and absence of clinical improvement after 1 month of milrinone therapy. Multivariate analysis selected lower baseline cardiac index and aortic systolic pressure as the most significant variables in predicting death; patients who died of progressive heart failure had less frequent use of antiarrhythmic drugs and greater increases in furosemide and milrinone doses during long-term follow-up than did those who died suddenly. Thus, although milrinone is well tolerated and produces early symptomatic benefits in approximately half of patients with congestive heart failure refractory to conventional therapy, there is no evidence that it improves the high baseline mortality in this disorder.

Effects of milrinone on coronary hemodynamics and myocardial energetics in patients with congestive heart failure

To examine the effect of milrinone on myocardial energetics in patients with congestive heart failure, we measured systemic, pulmonary, and coronary hemodynamics in 18 patients before and after intravenous administration of milrinone (125 +/- 36 micrograms/kg). There was a 45% increase in cardiac index (2.1 +/- 0.5 to 3.0 +/- 0.6 liters/min/m2; p = .0001), a 39% fall in the pulmonary capillary wedge pressure (28 +/- 8 to 17 +/- 8 mm Hg; p = .0001), and a 42% increase in left ventricular external work (3758 +/- 1419 to 5340 +/- 1598 g-m/min; p = .0001). Both the heart rate-blood pressure product (9624 +/- 2272 to 9380 +/- 2428 mm Hg-beats/min; p = NS) and regional left ventricular myocardial oxygen consumption (7.6 +/- 2.9 to 8.1 +/- 3.1 ml O2/min; p = NS) were unchanged after milrinone, resulting in a 45% increase in calculated left ventricular external efficiency (p = .004). Although myocardial oxygen consumption did not change, regional great cardiac venous blood flow increased significantly (73 +/- 32 to 85 +/- 34 ml/min; p = .02) as a result of a 30% reduction in regional coronary vascular resistance (1.32 +/- 0.99 to 0.93 +/- 0.54 mm Hg-min/ml; p = .004), a decrease comparable to the concurrent 37% and 38% falls seen in systemic and pulmonary vascular resistance, respectively. These changes were associated with an 11% fall in the transcoronary arterial-venous oxygen difference (111 +/- 24 to 99 +/- 21 ml/O2/liter; p = .0001), which is consistent with a primary coronary vasodilator effect of milrinone.(ABSTRACT TRUNCATED AT 250 WORDS)