Angiopoietin-like-4 is a potential angiogenic mediator in arthritis.

Our previous studies of gene expression profiling during collagen-induced arthritis (CIA) indicated that the putative angiogenic factor Angptl4 was one of the most highly expressed mRNAs early in disease. To investigate the potential involvement of Angptl4 in CIA pathogenesis, Angptl4 protein levels were assessed at early stages of disease and its cellular sources were determined. In addition, the functional effects of mouse Angptl4 on endothelial cells were assessed. Angptl4 protein levels were higher in arthritic joints as compared to normal joints. In situ hybridization localized Angptl4 mRNA to stromal fibroblast-like cells within the inflamed synovium. Temporal expression of Angptl4 mRNA during CIA was similar to that of key angiogenic factors, including structurally related angiopoietin 1. Recombinant mouse Angptl4 promoted endothelial cell survival and formation of tubule-like structures. These functional effects of Angptl4, combined with very high expression at early stages of CIA, suggest a role for Angptl4 in angiogenesis in arthritis.

Pathogenic potential of filoviruses: role of geographic origin of primate host and virus strain.

African filoviruses have caused outbreaks of fulminating hemorrhagic fever among humans. In 1989, related filoviruses were isolated from cynomolgus monkeys imported into the United States from the Philippines. The pathogenic potential of these new filoviruses was compared in 16 Asian monkeys (Macaca fascicularis-cynomolgus) and 16 African monkeys (Cercopithecus aethiops-African green) using African filoviruses from Zaire (Ebola virus) and Sudan or Asian filoviruses (Reston and Pennsylvania). African filovirus infections resulted in earlier death (P = .005), had a shorter duration of disease and median incubation period (3-4 vs. 7 days), and had earlier peak viremia (5-7 vs. 7-9 days). African green monkeys showed significantly higher survival than cynomolgus monkeys (P less than .01), and some were asymptomatic as have been humans accidentally infected with Asian filovirus. Rechallenge experiments showed that protection in survivors of filovirus infections against fatal challenge with Ebola (Zaire) virus is unpredictable. The minimal clinical disease observed in humans infected with the Reston strain is consistent with host- and virus-dependent pathogenicity.

Filovirus clearance in non-human primates.

There has been concern in the USA and Europe about filovirus outbreaks in recently imported monkeys, and possible transmission to human beings. Healthy monkeys have been found to have low-titre immunofluorescence antibody (IFA) to Asian filoviruses (Reston and Pennsylvania viruses) as well as to the African filoviruses that caused fulminating human outbreaks in the 1970s (Ebola [Zaire] and Sudan viruses). We have assessed whether such monkeys are a risk to man. We studied 42 non-human primates; 31 were experimentally infected with African and Asian filoviruses, 6 were infected during a documented Reston filovirus outbreak, and 5 had serological evidence suggestive of recent filovirus infection. During the first 15 days after infection, virus could be routinely recovered from serum or biopsy or necropsy tissue, and Asian filovirus RNA could be detected by polymerase chain reaction. 20 to 600 days after challenge, filovirus could no longer be recovered nor viral RNA detected in 141 serum, liver, spleen, or kidney specimens. Animals surviving filovirus infection develop high-titre, cross-reacting filovirus-specific antibody 14 to 21 days after infection, and this coincides with virus clearance. Healthy monkeys with low-titre filovirus antibody may be regarded as uninfected.

SIV, STLV-I and type D retrovirus antibodies in captive rhesus macaques and immunoblot reactivity to SIV p27 in human and rhesus monkey sera.

The prevalence of simian immunodeficiency virus (SIV), simian T-cell lymphotropic virus type 1 (STLV-I), and type D retrovirus (SRV-D) antibodies was determined for 1229 rhesus monkeys (Macaca mulatta) from two research colonies. Serum samples were tested by using enzyme-linked immunosorbent assay (ELISA), immunoblot (IB), and radioimmunoprecipitation assay (RIPA). Seropositive results for the three retroviruses tested were 0 for SIV, 270 (22%) for STLV-I, and 103 (8.4%) for type D retrovirus. Of the rhesus monkey sera, 61 (5.0%) were reactive to SIV gag p27 only, when tested by IB, but were negative when further tested by RIPA. Virus isolation was attempted from cultured peripheral blood mononuclear cells of 35 monkeys whose sera contained only p27 reactivity and none were positive by reverse transcriptase and core antigen assays to detect SIV. No overt clinical signs of immunodeficiency disease or unexplained deaths were evident in either monkey colony. Additionally, 63 of 165 (38%) human sera from various groups (primate center workers, normal donors, health care workers) had weak to moderate IB reactivity only to SIV p27, but 31 of 31 sera tested were negative by RIPA. These sera remained reactive to SIV p27 following absorption with an uninfected cell lysate, after blocking IB strips with various blocking solutions and were reactive to different SIV antigen preparations while remaining negative to human immunodeficiency virus type 1 (HIV-1) by IB and negative to HIV-2 by ELISA. These data underscore the need to adopt criteria for a positive SIV serologic test requiring reactivity against more than one viral gene product. These results also illustrate a potential problem in the testing of human sera for antibodies against simian retroviruses and demonstrate the need for caution in the interpretation of immunoblot results.

Percutaneous trephine biopsy of the vertebral body in the rhesus monkey (Macaca mulatta).

Two methods of percutaneous vertebral body biopsy were performed in the Rhesus monkey, using a 3-mm diameter trephine and a pneumatic driver placed at a 30 degrees angle of approach to the transverse plane of the spine. The freehand method involved placing needle landmarks in the spine, followed by examination of a lateral radiograph of the lumbar region to verify landmark positioning and to estimate placement of the trephine. In the 2nd method, a pneumatic trephine guide was oriented according to a trigonometric calculation based on radiographic data. The pneumatic trephine guide allowed precise placement of the driver and steadied the trephine as it passed through the bone.

Prolonged exposure to acid, chlorine, or tetracycline in the drinking water: effects on delayed-type hypersensitivity, hemagglutination titers, and reticuloendothelial clearance rates in mice.

Water treated with hydrochloric acid, alkaline and acidic solutions of sodium hypochlorite, or tetracycline was given to outbred mice for 120 days. Significant experimental variability was found in the delayed-type hypersensitivity responses in the mice drinking tetracycline treated water (1 mg/ml). One group of mice consuming tetracycline treated water had suppressed foot pad responses to sheep erythrocytes which may have been related to a change in the enteric microflora or a variation in tetracycline resistance. There was a significant reduction in uncorrected reticuloendothelial clearance rates (K) in the mice consuming acidified water (pH 2.0), and this appeared to be a result of reduced spleen weight and spleen to body weight ratios. However, there were no significant differences in the carbon clearance rates that were corrected for spleen, liver, and body weights. Responses in other treatment groups were not significantly affected. The findings of this study suggest that the routine use of additives in drinking water for rodents should be considered as a potential source of variation in immune responses.