Simian immunodeficiency virus infection of CD4+CD8+ T cells in a macaque with an unusually high peripheral CD4+CD8+ T lymphocyte count

We assessed the possible role in vivo CD4(+) CD8(+) T cells as a viral reservoir for simian immunodeficiency virus (SIV), in a macaque with 50% CD4(+) CD8(+) T cells in peripheral blood. During primary infection (day 14) of this rhesus macaque with the pathogenic SIVmac251 strain, proviruses were detected at similar frequencies in CD4(+) CD8(+) T cells (1/10) and CD4(+) T cells (1/10) and at a lower frequency in CD8(+) T cells (1/800). On day 235, no viral DNA was detected in CD8(+) cells, despite the persistent high viral load, indicating that CD8(+) cells do not constitute a reservoir during the chronic phase of SIV infection. Infection induced early lymphopenia of CD4(+), CD4(+) CD8(+), and CD8(+) cells; only the CD8(+) cell population returned to initial levels and expanded further. We found that CD4(+) CD8(+) T cells expressed the costimulatory CD28 molecule less and were more prone to die in vitro after phytohemagglutinin/interleukin 2 stimulation than were CD4(+) T cells. Taken together, massive death of CD4(+) CD8(+) T cells during acute stages of SIV infection may explain why CD8(+) T cells did not represent a major reservoir for SIV at the onset of infection.     

Cardiac valves in patients with Whipple endocarditis: microbiological, molecular, quantitative histologic, and immunohistochemical studies of 5 patients

The pathological features of Whipple endocarditis, which is caused by Tropheryma whipplei, were histologically evaluated in cardiac valves from 5 patients. We used quantitative image analysis to compare the valvular fibrosis, calcifications, vegetations, inflammation, and vascularization due to Whipple endocarditis with those due to non-Whipple endocarditis and degenerative valves. We also studied the presence of T. whipplei in valves by immunohistochemical analysis, culture, and polymerase chain reaction (PCR). In histologic analysis, Whipple endocarditis was characterized by significant fibrosis, a lack of calcifications, slight inflammation and vascularization, and vegetations of intermediate size. Inflammatory infiltrates consisted mainly of foamy macrophages and lymphocytes. We found that the detection of T. whipplei in cardiac valves, by immunohistochemical analysis, was correlated with the detection of the bacterium by culture and PCR. We report, for the first time, the immunodetection of T. whipplei in a surgically removed arterial embolus. Pathological and immunohistologic analyses may contribute to the diagnosis of Whipple endocarditis.     

Increased presence of anti-HLA antibodies early after allogeneic granulocyte colony-stimulating factor-mobilized peripheral blood hematopoietic stem cell transplantation compared with bone marrow transplantation

We have recently shown that the use of allogeneic granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood hematopoietic stem cell transplantation (PBHSCT), as compared with bone marrow transplantation (BMT), is associated with increased titers of antibodies (Abs) directed against red blood cell ABO antigens. To further evaluate the influence of a G-CSF-mobilized PBHSCT graft on alloimmune Ab responses, we examined the frequency of anti-HLA Abs after transplantation in the setting of the same randomized study, comparing PBHSCT with BMT in adults. Anti-HLA Ab presence was determined by complement-dependent cytotoxicity assay (CDC) and flow cytometry in the recipient before and 30 days after transplantation as well as in the donor before graft donation. The use of PBHSCT was significantly associated with increased detection of anti-HLA immunoglobulin G (IgG) Abs early after transplantation as evidenced by flow cytometry (11 of 24 versus 4 of 27 transplant recipients, P =.03) and, less so, by CDC (5 of 24 versus 1 of 27 transplant recipients, P =.09). The difference between PBHSCT and BMT was further heightened when analysis was restricted to anti-HLA IgG Ab-negative donor/recipient pairs. In such a setting, early anti-HLA Ab was never detected after BMT but was repeatedly detected after PBHSCT (flow cytometry, 6 of 18 versus 0 of 17 transplant recipients, P =.02; CDC, 4 of 23 versus 0 of 26 transplant recipients, P =.04). Importantly, the PBHSCT-associated increase in anti-HLA Ab detection was observed despite a reduction in the median number of platelet-transfusion episodes per patient in PBHSC transplant versus BM transplant recipients (3 platelet-transfusion episodes [range, 1-21] in PBHSCT group vs 6 platelet-transfusion episodes [range, 3-33] in the BMT group; P =.02). In conclusion, this study strongly suggests that G-CSF-mobilized PBHSCT results in an increased incidence of circulating anti-HLA Abs and further confirms that the use of such a graft alters alloimmune Ab responses.     

Late perforation of a thoracic aortic dacron graft by a metallic stent-graft component.

PURPOSE: To describe a case involving perforation of a previously placed aortic Dacron graft by the uncovered proximal stent of a thoracic stent-graft. CASE REPORT: A 76-year-old man with a surgically treated type A dissection presented with residual type B dissection. Thoracic stent-grafting of the entry site was performed successfully. After 2 years, the patient was admitted for evaluation of a non-pulsating parasternal mass. Computed tomography showed a large, hypodense liquid-like mass affecting the mediastinum up to the subcutaneous tissue. A false aneurysm at the proximal end of the stent-graft was observed arising from an aortic perforation by the uncovered stent. One week later, the mass had almost completely resolved, and the patient has been scheduled for close surveillance. CONCLUSION: This case illustrated the importance of thoroughly examining the long-term durability and compatibility of prosthetic materials.     

Longitudinal Study of Extended-Spectrum-β-Lactamase- and AmpC-Producing Enterobacteriaceae in Household Dogs

A longitudinal study was performed to (i) investigate the continuity of shedding of extended-spectrum-beta-lactamase (ESBL)-producing Enterobacteriaceae in dogs without clinical signs, (ii) identify dominant plasmid-mediated ESBL genes, and (iii) quantify ESBL-producing Enterobacteriaceae in feces. Fecal samples from 38 dogs were collected monthly for 6 months. Additional samples were collected from 7 included dogs on a weekly basis for 6 weeks. Numbers of CFU per gram of feces for non-wild-type Enterobacteriaceae were determined by using MacConkey agar supplemented with 1 mg/liter cefotaxime (MCC), and those for total Enterobacteriaceae were determined by using MacConkey agar. Cefotaxime-resistant isolates were screened by PCR and sequence analysis for the presence of bla_CTX-M, bla_CMY, bla_SHV, bla_OXA, and bla_TEM gene families. Bacterial species were identified by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) analysis. PCR-negative isolates were tested by a double-disk synergy test for enhanced AmpC expression. A total of 259 samples were screened, and 126 samples were culture positive on MCC, resulting in 352 isolates, 327 of which were Escherichia coli. Nine dogs were continuously positive during this study, and 6 dogs were continuously negative. Monthly or weekly shifts in fecal shedding were observed for 23 dogs. Genotyping showed a large variety of ESBL genes and gene combinations at single and multiple consecutive sampling moments. The ESBL genes bla_CTX-M-1, bla_CTX-M-14, bla_CTX-M-15, bla_SHV-12, and bla_CMY-2 were most frequently found. The mean number of CFU of non-wild-type Enterobacteriaceae was 6.11 × 10⁸ CFU/g feces. This study showed an abundance of ESBL-producing Enterobacteriaceae in dogs in the Netherlands, mostly in high concentrations. Fecal shedding was shown to be highly dynamic over time, which is important to consider when studying ESBL epidemiology.