Angiotensin converting enzyme inhibitors: first line therapy in patients with diabetic hypertension?
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Angiotensin-Converting Enzyme Inhibitors↗
Biomedical subjects
E M Levy
Publications and source records attributed to E M Levy.
Independent association between acute renal failure and mortality following cardiac surgery.
PURPOSE: To determine whether there is an independent association of acute renal failure requiring dialysis with operative mortality after cardiac surgery. PATIENTS AND METHODS: The 42,773 patients who underwent coronary artery bypass or valvular heart surgery at 43 Department of Veterans Affairs Medical Centers between 1987 and 1994 were evaluated to determine the association between acute renal failure sufficient to require dialysis and operative mortality, with and without adjustment for comorbidity and postoperative complications. Crude and adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were derived from logistic regression analysis. RESULTS: Acute renal failure occurred in 460 (1.1%) patients. Overall operative mortality was 63.7% in these patients, compared with 4.3% in patients without this complication. The unadjusted OR for death was 39 (95% CI 32 to 48). After adjustment for comorbid factors related to the development of acute renal failure (surgery type, baseline renal function, preoperative intraaortic balloon pump, prior heart surgery, NYHA class IV status, peripheral vascular disease, pulmonary rales, left ventricular ejection fraction below 35%, chronic obstructive pulmonary disease, systolic blood pressure, and the cross-product of systolic blood pressure and surgery type), the OR was 27 (95% CI 22 to 34). Further adjustment was made for seven postoperative complications (low cardiac output, cardiac arrest, perioperative myocardial infarction, prolonged mechanical ventilation, reoperation for bleeding or repeat cardiopulmonary bypass, stroke or coma, and mediastinitis), that were independently associated with operative mortality. The OR adjusted for comorbidity and postoperative complications associated with acute renal failure was 7.9 (95% CI 6 to 10). CONCLUSIONS: Acute renal failure was independently associated with early mortality following cardiac surgery, even after adjustment for comorbidity and postoperative complications. Interventions to prevent or improve treatment of this condition are urgently needed.
Acute Kidney Injury↗
The effect of acute renal failure on mortality. A cohort analysis.
OBJECTIVE: To determine if the high mortality in acute renal failure is explained by underlying illnesses (comorbidity). DESIGN: Cohort analytic study. SETTING: An 826-bed general hospital providing primary, secondary, and tertiary care. PATIENTS: From 16,248 inpatients undergoing radiocontrast procedures between 1987 and 1989, we identified 183 index subjects who developed contrast media-associated renal failure (defined as an increase in serum creatinine level of at least 25%, to at least 177 micromol/L [2 mg/dL], within 2 days of receiving contrast material) and 174 paired subjects, matched for age and baseline serum creatinine level, who underwent similar contrast procedures without developing renal failure. MAIN OUTCOME MEASURE: Death during hospitalization. RESULTS: The mortality rate in subjects without renal failure was 7%, compared with 34% in the corresponding index subjects with renal failure (odds ratio, 6.5; P<.001). After adjusting for differences in comorbidity, renal failure was associated with an odds ratio of dying of 5.5. Subjects who died after developing renal failure had complicated clinical courses characterized by sepsis, bleeding, delirium, and respiratory failure; most of these complications developed after the onset of renal failure. Deaths from renal causes were rare. CONCLUSIONS: The high mortality rate in acute renal failure is not explained by the underlying conditions alone. Renal failure appears to increase the risk of developing severe nonrenal complications that lead to death and should not be regarded as a treatable complication of serious illness.
APACHE↗
Inhibition of human immunodeficiency virus infection by agents that interfere with thiol-disulfide interchange upon virus-receptor interaction.
The cell surface of mammalian cells is capable of reductively cleaving disulfide bonds of exogenous membrane-bound macromolecules (for instance, the interchain disulfide of diphtheria toxin), and inhibiting this process with membrane-impermeant sulfhydryl reagents prevents diphtheria toxin cytotoxicity. More recently it was found that the same membrane function can be inhibited by bacitracin, an inhibitor of protein disulfide-isomerase (PDI), and by monoclonal antibodies against PDI, suggesting that PDI catalyzes a thiol-disulfide interchange between its thiols and the disulfides of membrane-bound macromolecules. We provide evidence that the same reductive process plays a role in the penetration of membrane-bound human immunodeficiency virus (HIV) and show that HIV infection of human lymphoid cells is markedly inhibited by the membrane-impermeant sulfhydryl blocker 5,5'-dithiobis(2-nitrobenzoic acid), by bacitracin, and by anti-PDI antibodies. The results imply that HIV and its target cell engage in a thiol-disulfide interchange mediated by PDI and that the reduction of critical disulfides in viral envelope glycoproteins may be the initial event that triggers conformational changes required for HIV entry and cell infection. These findings suggest additional approaches to impede cell infection by HIV.
Amino Acid Sequence↗
The effect of changes in thiol subcompartments on T-cell colony formation and cell cycle progression: relevance to AIDS.
Recently, it has been shown that intra- and extracellular thiol levels are significantly lower than normal even in the relatively early stages of human immunodeficiency virus (HIV) infection. It is plausible that this deficiency could contribute both to the loss of T-cell function and the ability to replenish T cells associated with HIV infection. We had previously reported that the T-cell colony-forming cell (T-CFC) is impaired in HIV infection and that it can be enhanced with the thiol compounds 2-mercaptoethanol (2-ME) and N-acetylcysteine (NAC). In this study, the effect of the thiol-depleting reagents buthionine sulfoximine, cyclohexene-1-one, and copper phenanthroline on T-CFC formation and cell cycle progression was determined in HIV+ subject and/or controls. All three reagents inhibited T-CFC formation and cell cycle progression with a suggestion that colony formation by cells from HIV+ subjects was more sensitive to the effects of thiol depletion. 2-ME and NAC enhanced effect of NAC did not appear to involve increased protein kinase C translocation. Our results suggest that oxidation of membrane thiols, as well as depletion of intracellular glutathione, inhibits T-CFC formation as well as cell cycle progression for mitogen-stimulated cells in bulk culture.
Acetylcysteine↗
Biological measures and cellular immunological function in depressed psychiatric inpatients.
Thirty depressed psychiatric inpatients, including 18 with a diagnosis of major depression, and 25 hospital staff controls were compared with respect to cellular immune function--that is, mitogen responsiveness to concanavalin A (con A), phytohemagglutinin (PHA), and pokeweed mitogen (PWM); natural killer cell (NK) activity; and T cell subsets, including helper/inducer T cells (CD4) and suppressor/cytotoxic cells (CD8). Only physically healthy subjects, who had not used psychoactive medications (except for low dose benzodiazepines) or other medications known to affect the immune system for at least 14 days, were included. Paired comparisons of the immune measures of patients with a DSM-III diagnosis of major depression (n = 18) with their controls demonstrated a statistically significant reduction of the patients' con A response. In addition, the patients with major depression had significantly lower con A and PHA responses than the combined patients with other forms of depression (atypical, dysthymic, or atypical bipolar). There was no indication that severity of depression, dexamethasone suppression test status, benzodiazepine use, or age accounted for the differences in immune function. A possibly important, unexpected finding was that antihistamine use was associated with lower immune function.
Adult↗
Immunosuppression in mice induced by cold water stress.
A number of studies indicate that stress can result in suppression of the immune system in animals and man. Most of the studies have focused on alterations of lymphocyte function while only a few have investigated alterations of macrophage function or macrophage cytokine production. Macrophages play an essential role in homeostasis of the immune response. Indeed, the earliest events of the immune response occur in cells of the monocytic lineage, and their secretion of various cytokines may have both immunological and nonimmunological effects. The present studies were undertaken to determine whether alterations in macrophage physiology occur in mice subjected to a stress stimulus. Our studies in mice exposed to cold water stress for 4 days indicated reduced numbers of thymocytes and splenocytes, decreased T-cell blastogenesis, and reduced NK activity. Examination of elicited peritoneal macrophages from stressed mice revealed increased prostaglandin E2 (PGE2) secretion and decreased immune region associated antigen (Ia) expression in response to interferon-gamma. Despite elevated PGE2 levels, indomethacin was generally unable to restore depressed immune function. Of special interest was the finding that cell-associated and secreted interleukin 1 were significantly higher from unstimulated elicited macrophages from stressed mice. These results suggest that early in the response to stress, functions of a variety of cells within the immune system, especially macrophages, are altered and that dysregulated macrophage function may well contribute to the generalized suppression of the immune response in cold water stressed mice.
Animals↗
Psychological and immunological associations in men with AIDS pursuing a macrobiotic regimen as an alternative therapy: a pilot study.
A group of men with AIDS who chose to follow a macrobiotic regimen as an alternative form of therapy was studied for the possible influence of psychological factors on their clinical progression. In this group, men with Kaposi's sarcoma (KS) had an estimated survival time of 60% at 3 years. Moreover, there was a tendency for lymphocyte number to increase during the first 3 years following diagnosis with KS. A subset of eight of these men with KS and one man with Pneumocystis carinii pneumonia (PCP) agreed to fill out a battery of psychological questionnaires. The results suggest low levels of fatigue, negative affect, and confusion, but high levels of vigor in this subgroup. Additionally, there was significant positive associations of CD4 positive lymphocyte numbers with trait curiosity and hardiness scores and significant negative associations with anxiety and depression. Mitogen responsiveness followed a similar pattern, but only a positive association with curiosity reached significance. Caution has to be used in interpreting such data, especially in view of the size of the sample and the complexity of the cohort. Nonetheless, these findings clearly suggest the need for prospective studies on the influence of psychological factors on the progression of AIDS.
Acquired Immunodeficiency Syndrome↗
Increased T-cell colony formation in AIDS patients treated with zidovudine: a possible mechanism for increased lymphocyte number.
Treatment of AIDS patients with zidovudine is associated with an increase in lymphocyte counts. The mechanism for this increase is unclear and somewhat surprising in view of the myelosuppressive effect of zidovudine. To investigate this further, we measured lymphocyte numbers, T-cell subsets, and the ability of peripheral blood mononuclear cells (PBMC) to form T-cell colonies (T-CFC) in agar formation, in a group of patients with AIDS, before and during the first 6 months of zidovudine treatment. Eight patients were treated for an average of 11 weeks. There was a significant increase in T-CFC with zidovudine treatment (11.5 +/- 4.7% versus 29.8 +/- 6.9%, P less than 0.02 using a paired Student's t-test). There was a non-significant trend in the improvement of lymphocyte counts in these patients (872 +/- 117 versus 1102 +/- 204, NS). In vitro exposure of lymphocytes to zidovudine (200 mumol/l) resulted in modest suppression of T-CFC formation, suggesting that the effect of zidovudine treatment is indirect. Given that we have previously shown that inactivated HIV can inhibit T-CFC formation, we suggest that zidovudine treatment indirectly allows an increase in lymphocyte number by decreasing virus load, thereby permitting greater T-cell repopulation.
Acquired Immunodeficiency Syndrome↗
2-Mercaptoethanol and n-acetylcysteine enhance T cell colony formation in AIDS and ARC.
One contributing factor to the loss of T cells in AIDS may be the impaired ability of T cell precursors to expand, as reflected in a decreased ability of patient cells to form T cell colonies in agar. We and others have noted such a defect in people with AIDS and ARC, and have found that suppressor cells and suppressive plasma contribute to decreased T-CFC formation. We report here that the reducing agents 2-mercaptoethanol (2-ME) and n-acetyl cysteine (NAC) can enhance colony formation in vitro. In part, 2-ME can reverse the defect in T cell colony-forming cells (T-CFC) formation by overcoming the effect of suppressor cells. In a group of 46 AIDS patients, T-CFC formation was initially 42 +/- 8% (mean +/- s.e.) that of control levels. 2-ME caused an increase of 401 +/- 76% in T-CFC formation which was significantly greater than the increase in control T-CFC formation; it also significantly enhanced T-CFC formation by cells from ARC patients. Suppressor cell activity from ten AIDS patients decreased from 58 +/- 21% to 12 +/- 10% when 2-ME was added. Similar data were obtained from 14 ARC patients. NAC, a related antioxidant with low toxicity, also enhanced T-CFC in cells of AIDS and ARC patients. Vitamin C generally did not increase T-CFC formation. The data suggest that certain antioxidants such as 2-ME and NAC may be useful in treatment protocols to enhance T cell numbers in patients with AIDS or ARC.
AIDS-Related Complex↗
Defective T-cell differentiation in acquired immune deficiency syndrome (AIDS).
A decline in T-cell lymphocyte number is the central characteristic of acquired immune deficiency syndrome (AIDS). The reason for the loss of these cells is not well understood. We investigated the hypothesis that defects in T-cell differentiation contributed to T-cell loss using an in vitro colony assay that measures T-cell precursor (CFU-T) frequency. The results indicate a substantial generalized decrease in CFU-T in people with AIDS (P less than 0.01), most of whom have Kaposi's sarcoma, and an occasionally severe decrease in CFU-T in people with ARC. Some of the cells from low colony formers suppressed colony formation by control cells. In addition, plasma from people with AIDS was less supportive of colony growth than control plasma. Decreased Ia expression on adherent mononuclear cells did not correlate with colony formation. A defect in T-cell repopulation can help explain the loss of T cells associated with AIDS.
Acquired Immunodeficiency Syndrome↗
Elevation of circulating beta-endorphin levels with concomitant depression of immune parameters after traumatic injury.
Immunosuppression is frequently observed after traumatic injury, and is associated with the subsequent development of sepsis. Although a number of factors such as age, nutritional status, and the degree of injury have been related to the severity of the immunosuppression that occurs, the physiologic alterations leading to immunosuppression are not well defined. We hypothesized that changes in the endogenous opiate peptides, such as beta-endorphin, might contribute to changes in the immune system following injury. Levels of circulating beta-endorphin, responsiveness to the mitogen PHA, and the frequency of circulating T11, T4, and T8 cells were measured in trauma patients hospitalized in a surgical intensive care unit. beta-endorphin levels were elevated during the first 4 days after trauma (134.1 +/- 22.5 vs. 49.3 +/- 4.3 pg/ml, mean +/- S.E., patient vs. control; p less than 0.001). During the same time period patient PHA response (10,852 +/- 3,775 vs. 28,147 +/- 12,078; p less than 0.05), and the per cent of T4 positive (31.2 +/- 2.6 vs. 47.0 +/- 1.4; p less than 0.001) cells were lower than controls. These parameters were not significantly different from control values when measured at later times. Thus we conclude there is a temporal association of depressed immune parameters and elevated beta-endorphin levels after traumatic injury.
Endorphins↗
In vitro effect of foscarnet on expansion of T-cells from people with LAS and AIDS.
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Acquired Immunodeficiency Syndrome↗
Patients with Kaposi sarcoma who opt for no treatment.
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Humans↗
Membrane vesicles shed by murine melanoma cells selectively inhibit the expression of Ia antigen by macrophages.
We previously demonstrated that membrane vesicles shed by the F10 variant of the murine B16 melanoma cell line inhibited the induction by interferon-gamma (IFN) of murine macrophage immune response region-associated (Ia) antigen expression. In this paper we present evidence that the inhibition of macrophage Ia antigen expression is a selective effect of vesicles and characterize its temporal requirements. Membrane vesicles shed from F10 cells did not affect the expression of macrophage H-2K or H-2D antigens under conditions shown to profoundly inhibit Ia antigen expression. Similarly, the induction of plasminogen activator and interleukin 1 from macrophages was not inhibited by the vesicles. The vesicles did not measurably decrease total cellular RNA or protein synthesis. Macrophages were sensitive to the inhibitory effects of the vesicles during the induction and maintenance phases of Ia expression. Pretreatment of macrophages with vesicles before culture with IFN did not reduce the induction of Ia. The rate of decline of Ia expression after removal of IFN was unaffected by the presence of vesicles. Removal of vesicles from cultures of IFN-treated macrophages resulted in only a partial recovery of Ia expression, suggesting that the inhibition of Ia expression may be a slowly reversible process. The selective and partially reversible inhibition of Ia expression by vesicles shed from the plasma membrane of tumor cells is a possible mechanism whereby tumor-bearing hosts may become immunocompromised.
Animals↗
Inhibition of recombinant interferon-gamma-induced Ia antigen expression by shed B16 F10 melanoma cell membrane vesicles.
The expression of immune region-associated (Ia) antigens by macrophages is a prerequisite for antigen presentation, which is necessary for the activation of T helper cell function. A decrease in macrophage Ia expression is associated with a decrease in immune function in vitro. However, the effect of diseases accompanied by immunosuppression, such as cancer, on macrophage Ia expression has not been studied. The expression of Ia antigen was induced by the culture of murine peritoneal macrophages with recombinant interferon-gamma (IFN). Maximal expression was achieved after 4 days of culture. Membrane vesicles shed from the murine B16 F10 melanoma cell line inhibited the in vitro induction of Ia expression by 40 to 90% in allogeneic and syngeneic systems. Inhibition was not due to toxicity, a reduction in IFN activity, phagocytosis or contamination of the vesicle preparation with endotoxin, which is an inhibitor of Ia expression. Inhibition exerted by vesicles was prostaglandin-dependent and was over-come by increasing concentrations of IFN. It is possible that the reduction of macrophage Ia antigen expression by tumor cell products, such as shed membrane vesicles, contributes to the immunosuppression of tumor-bearing hosts. Employing IFN to reverse the inhibition provides a strategy for improving the therapy of patients with cancer.
Animals↗
Changes in mitogen responsiveness lymphocyte subsets after traumatic injury: relation to development of sepsis.
Head injury and multiple trauma patients were evaluated for mitogen responsiveness and lymphocyte subset frequencies within the first few days after injury. The profile obtained was compared to the patient's clinical course to see if there was a relation between early immune abnormalities and the subsequent development of unanticipated sepsis. Lymphocytes from multiple trauma patients were generally hyporesponsive to in vitro stimulation with a suboptimal dose of the mitogen phytohemagglutinin (PHA). In contrast, the response of head injured patients was comparable to that of the control group. There was a significant decrease in the relative number of multiple trauma patient's T4 (29.3 vs 48.6%) and T11 (48.9 vs 74.7%) positive populations (P less than 0.01). There was no change in the percentage of T8-positive cells (19.0 vs 20.5%). Patients with head injuries also had a decrease in T4-positive cells (35.9%). The percentage of cells with B cell and natural killer (NK) markers remained normal. Thus trauma patients appeared to have an increase in null cells. Six patients whose PHA responses were among the lowest developed sepsis early after trauma. The changes in subset distributions although possibly contributing to a decreased responsiveness did not predict the ability to respond to PHA or the development of sepsis.
Adult↗
Adherent cell requirement for the effect of vitamin E on in vitro antibody synthesis.
Mice deficient in dietary vitamin E are impaired in their humoral and cell-mediated immunological responses. The basis for this impaired immunocompetence was investigated by using the in vitro antibody response as an assay system. Spleen cells from mice fed vitamin E-deficient diets were low responders to the antigens, sheep red blood cells (SRBC) and dinitrophenyl-L-lysine-Ficoll (DNP-Ficoll). However, they responded as well as mice fed vitamin E-supplemented diets to the relatively macrophage-independent antigen trinitrophenylated-lipopolysaccharide (TNP-LPS). This suggested that the macrophage was the cell most affected by the vitamin E deficiency. The involvement of macrophages was confirmed directly by mixing experiments, in which it was shown that macrophages from vitamin E-deficient mice were unable to support an antibody response by macrophage-depleted spleen cells from vitamin E-supplemented mice. Macrophages from vitamin E-deficient mice expressed less Ia antigen, and seemed less able to present antigen to nonadherent cells. However, it was found that macrophages from vitamin E-deficient mice not only lacked accessory cell function, but could act instead as suppressor cells. The effect of dietary vitamin E was noted with either saturated or unsaturated sources of fat in the diet.
Animals↗