Journal Club. HIV-associated bacterial pneumonia

Bacterial pneumonia is the most common cause of death from pneumonia in patients with HIV disease, causing greater mortality than Pneumocystis carinii pneumonia. The challenge for the clinician evaluating the HIV-infected patient with pneumonia is to quickly distinguish clinically among all possible causes and to initiate therapy based on the most likely diagnosis. While an understanding of typical clinical and radiographic presentations is essential, bronchoscopy is the preferred test for reliably identifying the causative organism.

Interactions between American Indian ethnicity and health care

Interventions in health care must be sensitive to the part that culture plays in treatment, recovery and healing of the American Indian patient. Cultural factors play an important part in how the family participates and copes with the intervention program. Interpreting communication and behavior from the perspective of the family's culture contributes to positive family-professional interaction. This paper addresses the most important cultural factors impinging on positive health care for American Indian families and addresses a process for assessment of cultural conflicts which may prevent positive outcomes in the delivery of health care to this population. In addition, this paper offers strategies throughout that can be used by health care professionals to assure culturally sensitive service delivery to American Indians.

Professionalism in emergency medicine. SAEM Ethics Committee. Society for Academic Emergency Medicine

The Society for Academic Emergency Medicine (SAEM), with the support and participation of the American Board of Emergency Medicine (ABEM), the Council of Residency Directors (CORD), the American College of Emergency Physicians (ACEP), the Emergency Medicine Residents Association (EMRA), the American Academy of Emergency Medicine (AAEM), and the Association of Academic Chairs of Emergency Medicine (AACEM), initiated a project entitled Professionalism in Emergency Medicine. Its concepts were developed by the SAEM Ethics Committee, and are intended to describe proper behaviors and attitudes of the successful practitioner of emergency medicine. The behaviors described are not primarily scientific or technical, since those are defined by the core curriculum for residency training and are tested through certification examinations. This document identifies attitudes and behaviors that enhance trust by placing the patient's interest above other interests. This concept serves as the operative definition of professionalism. The purpose of this article is to clarify the professional attitudes and knowledge that are important to the emergency physician (EP). While no physician is likely to meet idealized standards, all EPs must meet basic standards while striving for the ideal. Awareness of these standards must begin early in the socialization process of emergency medical professionals. The standards must be integrated into residency training as well as the clinical practice of all EPs.

Effects of liposome-encapsulated drugs on macrophages: comparative activity of the diamidine 4',6-diamidino-2-phenylindole and the phenanthridinium salts ethidium bromide and propidium iodide

Liposomes can be used for the intracellular delivery of drugs into macrophages. Previously, we developed a liposome-mediated macrophage 'suicide' technique based on the intraphagocytic accumulation of the liposomally delivered bisphosphonate clodronate. Later we found that the diamidine propamidine is even more effective in this approach. In the present study it is shown that liposome-encapsulated 4', 6-diamidino-2-phenylindole (L-DAPI), another well known DNA-binding diamidine, is the most effective drug in killing liver macrophages (Kupffer cells), when intravenously administered in rat. Compared to liposome-encapsulated propamidine (L-propamidine) it showed about 10-fold more activity on a molar basis. Furthermore, L-DAPI was found to induce cell death by inducing apoptosis. The structurally strongly related phenanthridinium salts ethidium bromide (EB) and propidium iodide (PI) exert marked differences in their efficacy. Whereas liposome-encapsulated PI (L-PI) was about 5 times more active in killing macrophages than L-propamidine, liposome-encapsulated EB (L-EB) showed a strongly reduced activity (10 times less than L-PI). As is shown here, PI remains mainly encapsulated in liposomes, while substantial amounts of EB leak out of liposomes. This may very well explain the differences in in vivo activity between L-EB and L-PI.

Gender and history of suicidality: are these factors related to U.S. college students' current suicidal thoughts, feelings, and actions?

Gender and history of suicidality (HS vs. NoHS) were related to current symptoms of depression, reasons for living, and reports of self-destructive and life-threatening behavior in a college student sample. Overall, college men reported engaging in more life-threatening and potentially suicidal behavior than college women on the Life Attitudes Schedule (LAS). No gender effects were obtained on the symptoms of depression and reasons for living measures. Results suggest that the LAS may be a particularly effective way to identify college students at risk for self-destructive and suicidal behavior. As expected, HS individuals were more depressed, had fewer reasons for living, and reported engaging in more current suicidal and life-threatening behavior than NoHS participants. However, gender and history of suicidality were found to interact. NoHS women reported avoiding a variety of injury-producing and health-diminishing behaviors that were common for all other groups of college students. Meanwhile, HS women endorsed fewer current reasons for living than did NoHS women, NoHS men, and NoHS men. These findings were interpreted both with regard to cultural and gender-specific expectations for the expression of self-destructive, suicidal, and life-threatening behavior. Implications for the prevention of college women's and men's suicidal behavior were also noted.

The role of macrophages in the induction and regulation of immunity elicited by exogenous antigens

Different delivery vehicles may target to different antigen presenting cells (APC) because of their composition, size and/or physical properties. In this study, we examined the priming of cytotoxic T lymphocyte (CTL) responses to a soluble exogenous protein in vivo, using various delivery vehicles. In addition, we determined the role of macrophages as APC in vivo for each of these delivery vehicles by comparing the induction of antigen-specific CTL and serum antibodies in normal and macrophage-depleted mice. Influenza A virus-derived virosomes, liposomes and monophosphoryl lipid A/squalene (MPLSQ) efficiently induced antigen-specific CTL as well as antibody responses, of which virosomes proved to be the most efficient inducers. In mice that were immunized with cell-associated antigen, strong CTL responses but no antigen-specific antibodies were detectable, while aluminium hydroxide and aluminium phosphate elicited antigen-specific antibodies but no CTL responses. Elimination of macrophages in vivo before immunization abrogated CTL responses induced with liposomes and MPL/SQ, but did not affect induction of antigen-specific CTL with virosomes or cell-associated antigen. Importantly, serum antibody levels were not altered after macrophage depletion, regardless of the delivery vehicle used, suggesting that in the absence of macrophages, other APC may phagocytose the exogenous antigens for major histocompatibility complex (MHC) class II processing and presentation. These results suggest that soluble exogenous antigens delivered in different carrier systems may be processed differently by different APC in vivo for MHC class I- or class II-restricted presentation.

Elimination, blocking, and activation of macrophages: three of a kind?

In mammals, macrophages are multifunctional cells. Apart from their scavenger role in the clearance of non-self materials such as microorganisms and altered-self materials such as apoptotic cells, senescent erythrocytes, immune complexes, and inflammatory products, they play a crucial role in the regulation of both innate and acquired immunity. Whereas the former activity is based on phagocytosis and intracellular degradation, the latter activity largely depends on the production and secretion of a panel of regulatory molecules such as cytokines, chemokines, and nitrogen oxide (NO). Depletion of macrophages and blocking of phagocytosis form important approaches to study the role of these cells in various host defense mechanisms. Moreover, the efficacy of drug- and gene-targeting, based on the application of particulate carrier devices, can be improved in this way. However, compounds originally described as efficacious blockers of phagocytosis simultaneously activate their production of cytokines and NO. Moreover, elimination, blocking, as well as activation of macrophages are all dependent on the concentration of such compounds. When administered in vivo, they will reach some macrophages in a high and others in a low concentration. As a consequence, the former cells may be eliminated or blocked, whereas the latter are activated by the same treatment. In this review, the various methods for suppression of macrophage functions are compared and requirements for the development of new, selective, and organ-specific macrophage-suppressing devices are discussed.

Conjugation of unprotected trisuccin, N-[tris[2-[(N-hydroxyamino)carbonyl]ethyl]methyl]succinamic acid, to monoclonal antibody CC49 by an improved active ester protocol

For the conjugation of the trihydroxamate bifunctional chelating agent N-[tris[2-[[N-(benzyloxy)amino]-carbonyl]ethyl]methyl]succinamic acid (trisuccin, 1) to antibodies, we originally used the corresponding 2,3,5,6-tetrafluorophenyl active ester followed by the postconjugation removal of the benzyl protecting groups by catalytic hydrogenation. It was of interest to us to design a conjugation protocol capable of incorporating deblocked hydroxamates into peptides and proteins. Reported procedures that were expected to be compatible with the functionalities present in trisuccin were used with no success, as judged by the lack of ability of the products to radiolabel with 188Re. A simple conjugation method was then developed utilizing the o-nitrophenol (ONP) activated ester of the unprotected trisuccin, N-[tris[2-[(N-hydroxyamino)carbonyl]ethyl]methyl]succinamic acid, 3, which eliminates the need for the postconjugation deblocking. An assay for indirect estimation of the active ester content, based on the concentration of its decomposition byproduct, ONP-OH, was developed. Comparison of the indirectly estimated concentrations with those obtained directly from purified products showed > 90% accuracy for this assay. This procedure has the advantage of rapidly using the unpurified active ester, eliminating the possibilities of its decomposition through solvolysis or self-condensation by the unprotected hydroxamate functions. A colorimetric assay was developed for estimation of the number of ligands per molecule of protein. This assay and the fact that all conjugates consistently radiolabeled with 188Re show that this procedure conjugated the unprotected hydroxamate ligands to the CC49 monoclonal antibody. These results indicate the potential applicability of this technique to conjugation of unprotected hydroxamate derivatives with other proteins and peptides.

Transient suppression of macrophage functions by liposome-encapsulated drugs

Macrophages play an important role in host defense reactions, for example, by phagocytosis of particulate materials. This process also results in the rapid removal of targeting devices such as liposomes and adenovirus vectors and of non-autologous grafted cells and materials. Another aspect of macrophage function is their production and secretion of proinflammatory cytokines. Transient and organ-specific suppression of macrophage function by liposome-mediated manipulation has been shown to improve the efficacy of drug and gene targeting and to reduce the symptoms of inflammatory reactions.