Brian Wong

Evidence for a role of a tumor necrosis factor-α (TNF-α)-converting enzyme-like protease in shedding of TRANCE, a TNF family member involved in osteoclastogenesis and dendritic cell survival

Tumor necrosis factor (TNF)-related activation-induced cytokine (TRANCE), a member of the TNF family, is a dendritic cell survival factor and is essential for osteoclastogenesis and osteoclast activation. In this report we demonstrate (i) that TRANCE, like TNF-α, is made as a membrane-anchored precursor, which is released from the plasma membrane by a metalloprotease; (ii) that soluble TRANCE has potent dendritic cell survival and osteoclastogenic activity; (iii) that the metalloprotease-disintegrin TNF-α convertase (TACE) can cleave immunoprecipitated TRANCE in vitro in a fashion that mimics the cleavage observed in tissue culture cells; and (iv) that in vitro cleavage of a TRANCE ectodomain/CD8 fusion protein and of a peptide corresponding to the TRANCE cleavage site by TACE occurs at the same site that is used when TRANCE is shed from cells into the supernatant. We propose that the TRANCE ectodomain is released from cells by TACE or a related metalloprotease-disintegrin, and that this release is an important component of the function of TRANCE in bone and immune homeostasis.

Central-Nervous-System Toxoplasmosis in Homosexual Men and Parenteral Drug Abusers

Central-nervous-system toxoplasmosis developed in 7 of 269 patients with the acquired immunodeficiency syndrome reported to the New York City Health Department through July 1982. Focal neurologic abnormalities, mass lesions on computed-tomographic brain scans, lymphocytic cerebrospinal fluid pleocytosis, and detectable IgG antibody to Toxoplasma gondii were common; but IgG titers of 1:1024 or more, IgM antibody to T. gondii, and positive open brain biopsies were uncommon. Serologic findings suggested that the disease resulted from recrudescent rather than primary infection. Four of five patients improved when treated with sulfonamides and pyrimethamine, but 2 had relapses. An aggressive diagnostic approach and sometimes even empiric therapy are warranted when central-nervous-system toxoplasmosis is suspected in a seropositive patient with the acquired immunodeficiency syndrome.

Continuous high-grade mycobacterium avium-intracellulare bacteremia in patients with the acquired immune deficiency syndrome

Serial quantitative blood cultures were performed before and during treatment in four patients with the acquired immune deficiency syndrome (AIDS) and Mycobacterium avium-intracellulare bacteremia. Initial colony counts were 350 to 28,000 cfu/ml, the counts declined substantially with treatment in two patients, and they declined modestly with treatment but rose when it was stopped in the other two. In one patient who was studied in detail, most of the circulating organisms were within the leukocytes, colony counts in blood subjected to lytic agents were 1.9- to 5.2-fold higher than in unlysed blood, and there were 10(5) to 10(6) times more organisms per gram in several tissue specimens obtained at autopsy than per milliliter of blood. It is concluded that continuous high-grade bacteremia is common in patients with AIDS and severe M. avium-intracellulare infections and that serial quantitative blood cultures provide a potential means for studying treatment in these patients.

Parasitic diseases in immunocompromised hosts.

In patients with compromised host defenses, diseases caused by protozoans and nematodes appeared, a few years ago, to be declining in importance. However, the outbreak of the acquired immunodeficiency syndrome (AIDS) among homosexual men, parenteral drug abusers, and other groups has made it necessary for physicians to familiarize themselves again with the manifestations of these diseases in abnormal hosts. The groups of patients at greatest risk, the usual clinical syndromes in abnormal hosts, and current approaches to diagnosis, treatment, and prevention of infections due to Pneumocystis carinii, Toxoplasma gondii, Strongyloides stercoralis, and organisms of the genus Cryptosporidium are reviewed. Because so many cases of these infections have recently occurred among patients with AIDS, recent experience with these diseases in AIDS patients at Memorial Sloan-Kettering Cancer Center is summarized.

Mucormycosis following bone marrow transplantation

Disseminated mucormycosis, presenting with a cutaneous lesion, developed in a 20-year-old woman following bone marrow transplantation. The infecting organism was identified as Rhizopus rhizopodiformis. Despite early diagnosis and therapy with amphotericin B, the patient died.

Flavobacterium meningosepticum bacteremia in an adult with acute leukemia use of rifampin to clear persistent infection

A case of Flavobacterium meningosepticum bacteremia complicating the course of a patient with leukemia is described. The patient was treated successfully when rifampin was added to the antibiotic therapy. Unusual organisms should be considered as agents of infection in immunocompromised hosts and susceptibility testing with drugs not commonly employed for gram-negative rods should be performed in complicated cases.