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Severe acute respiratory syndrome (SARS) is a significant emerging infectious disease. Humans infected with the etiological agent, SARS-associated coronavirus (SARS-CoV), primarily present with pneumonitis but may also develop hepatic, gastrointestinal, and renal pathology. We inoculated common marmosets (Callithrix jacchus) with the objective of developing a small nonhuman primate model of SARS. Two groups of C. jacchuswere inoculated intratracheally with cell culture supernatant containing SARS-CoV. In a time course pathogenesis study, animals were evaluated at 2, 4, and 7 days after infection for morphological changes and evidence of viral replication. All animals developed a multifocal mononuclear cell interstitial pneumonitis, accompanied by multinucleated syncytial cells, edema, and bronchiolitis in most animals. Viral antigen localized primarily to infected alveolar macrophages and type-1 pneumocytes by immunohistochemistry. Viral RNA was detected in all animals from pulmonary tissue extracts obtained at necropsy. Viral RNA was also detected in tracheobronchial lymph node and myocardium, together with inflammatory changes, in some animals. Hepatic inflammation was observed in most animals, predominantly as a multifocal lymphocytic hepatitis accompanied by necrosis of individual hepatocytes. These findings identify the common marmoset as a promising nonhuman primate to study SARS-CoV pathogenesis.

Surface stimulation of fresh or cultured human mononuclear cells by latex particles causes an increase in the accumulation of cyclic AMP that is inhibited by preincubation with calcitonin (CT). Preincubation of cultured monocytes with 500 ng/ml pertussis toxin totally blocks the inhibitory effects of CT at low concentrations of this hormone. The effects of pertussis toxin are dose‐related and eliminated by boiling the toxin. Similar preincubations with cholera toxin have no significant effects on subsequent inhibition of surface‐stimulated cyclic AMP by CT. Membranes prepared from cultured human monocytes contain a 41,000‐dalton protein that is ADP‐ribosylated by pertussis toxin and may be the inhibitory guanine nucleotide regulatory protein (N) mediating this inhibition.

Lymphocytes are implicated in the pathogenesis of bone disease in chronic inflammation, osteoporosis, transplantation and osteopetrosis. The effects of lymphocytes and lymphocyte-conditioned medium on bone-resorbing activity and osteoclast function have been well studied, but there are few studies of the effects of LCM on bone formation and osteoblast function. The effects of LCM on the function of the MG-63 human osteosarcoma cell line were studied, which, when stimulated with 1,25-(OH)2D3, demonstrates many of the properties of the mature human osteoblast. Lymphocytes contain oestrogen receptors and the model was also used to test the hypothesis that the effects of oestrogen on bone cells may be mediated indirectly via lymphokines. Lymphokines were measured by ELISA in human lymphocyte conditioned medium (LCM) collected following incubation of mixed lymphocytes with or without stimulation for 72 h. Unstimulated LCM increased proliferation of MG-63 cells and this increase was not affected by neutralization of interleukin 1 (IL-1), IL-3, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), tumour necrosis factor (TNF), lymphotoxin α, or interferon γ (IFN-γ). Phytohaemagglutinin-stimulated LCM decreased proliferation of MG-63 cells, as well as induced expression of IL-6 mRNA, increased alkaline phosphatase production, and inhibited osteocalcin production. The decrease in proliferation was abolished by neutralization of IFN-γ but was unaffected by neutralization of IL-1, IL-2, IL-3, IL-4, IL-6, GM-CSF, TNF, or lymphotoxin α. Neutralization of IFN-γ in stimulated LCM also partially inhibited the increase in alkaline phosphatase production but had no effects on the decrease in osteocalcin production. Although oestrogen inhibited lymphocyte proliferation, the effects of LCM collected from lymphocytes in the presence of oestrogen on MG-63 cell proliferation and function was no different than the effects of LCM collected in the absence of oestrogen.