Biomedical subjects

J P Olano

Publications and source records attributed to J P Olano.

7 recordsLinked to original sources

PubMed2001

Animal model of fatal human monocytotropic ehrlichiosis.

Human monocytotropic ehrlichiosis caused by Ehrlichia chaffeensis is a life-threatening, tick-borne, emerging infectious disease for which no satisfactory animal model has been developed. Strain HF565, an ehrlichial organism closely related to E. chaffeensis isolated from Ixodes ovatus ticks in Japan, causes fatal infection of mice. C57BL/6 mice became ill on day 7 after inoculation and died on day 9. The liver revealed confluent necrosis, ballooning cell injury, apoptosis, poorly formed granulomas, Kupffer cell hyperplasia, erythrophagocytosis, and microvesicular fatty metamorphosis. The other significant histological findings consisted of marked expansion of the marginal zone and infiltration of the red pulp of the spleen by macrophages, interstitial pneumonitis, and increased numbers of immature myeloid cells and areas of necrosis in the bone marrow. Ehrlichiae were detected by immunohistology and electron microscopy in the liver, lungs, and spleen. The main target cells were macrophages, including Kupffer cells, hepatocytes, and endothelial cells. Apoptosis was detected in Kupffer cells, hepatocytes, and macrophages in the lungs and spleen. This tropism for macrophages and the pathological lesions closely resemble those of human monocytotropic ehrlichiosis for which it is a promising model for investigation of immunity and pathogenesis.

Animals↗

PubMed2001

Critical role of cytotoxic T lymphocytes in immune clearance of rickettsial infection.

Cytotoxic T-lymphocyte (CTL) activity developed against the major infected target cells of rickettsial infections, endothelial cells and macrophages. Spleen cells from mice immune to Rickettsia conorii exerted specific major histocompatibility complex (MHC) class I-matched CTL activity against R. conorii-infected SVEC-10 endothelial cells, with peak activity on day 10. Similarly, spleen cells from Rickettsia australis-immune mice exerted specific CTL activity against an R. australis-infected macrophage-like cell line. Gamma interferon (IFN-gamma) gene knockout mice were more than 100-fold more susceptible to R. australis infection than wild-type C57BL/6 mice. MHC class I gene knockout mice were the most susceptible, more than 50,000-fold more susceptible to a lethal outcome of R. australis infection than wild-type C57BL/6 mice. These results indicate that CTL activity was more critical to recovery from rickettsial infection than were the effects of IFN-gamma. The observation that perforin gene knockout mice were more than 100-fold more susceptible than wild-type C57BL/6 mice indicates that perforin-mediated activity accounts for a large component, but not all, of the CTL-mediated antirickettsial effect. CTL activity was expressed by immune CD8 T lymphocytes. Adoptive transfer of immune CD8 T lymphocytes from IFN-gamma gene knockout mice into R. australis-infected IFN-gamma gene knockout mice dramatically reduced the infectious rickettsial content in the organs, confirming that CD8 T lymphocytes provide immunity against rickettsiae besides that provided by the secretion of IFN-gamma. CTLs appear to be crucial to recovery from rickettsial infection.

Adoptive Transfer↗

PubMed2001

Rickettsial infection in murine models activates an early anti-rickettsial effect mediated by NK cells and associated with production of gamma interferon.

Natural killer (NK) cell activity was significantly increased on days 2-6 of infection in the Rickettsia conorii-infected C3H/HeN mice and on day 2 in the Rickettsia typhi-infected C57BL/6 mice. Depletion of NK cell activity utilizing anti-NK1.1 monoclonal antibody enhanced the susceptibility of normally resistant C57BL/6 mice to infection with R. typhi, and depletion of NK cell activity with antibody to asialo GM1 enhanced the susceptibility of C3H/HeN mice to infection with R. conorii. Serum gamma interferon was increased in R. conorii-infected C3H/HeN mice compared with NK cell-depleted, infected mice during the early course of infection. Additionally, the NK cell activating cytokine IL-12 was elevated in the sera of infected mice during the time period representing enhanced NK cell activity compared with uninfected mice. Thus, it appears that NK cells contribute to the early anti-rickettsial immune response, likely via a mechanism involving gamma interferon.

Animals↗

PubMed1998

Evaluation of the MycoAKT latex agglutination test for rapid diagnosis of Mycobacterium avium complex infections.

Rapid diagnosis of Mycobacterium avium complex (MAC) bacteremia is important for management of patients with the acquired immunodeficiency syndrome who have disseminated MAC. The purpose of this study was to determine the reliability of the MycoAKT latex agglutination test for direct detection of MAC in positive mycobacterial blood cultures. First, colonies of isolates of previously identified mycobacteria, including 35 MAC, were tested. Of the 55 isolates evaluated, 33 were identified as MAC by the latex test, including 31 of the known MAC and 2 M. chelonae (sensitivity, 88.6%; specificity, 90.0%). Second, broth from 20 ESP II and 20 BACTEC 12B bottles seeded with isolates of MAC were tested. Aliquots from 19 (95%) ESP II cultures and 16 (80%) 12B cultures were positive by the latex test. In phase 3, broth from 115 signal-positive ESP II blood cultures were tested by latex agglutination. Forty-three subcultures from these bottles grew mycobacteria (41 MAC and 2 Mycobacterium tuberculosis complex); the remainder grew no organisms. Broth from 40 of the blood cultures (39 that grew MAC and 1 from which no organisms were recovered) were latex positive; thus, the sensitivity, specificity, and positive and negative predictive values of the latex test for direct identification of MAC in ESP II blood cultures were 95.1, 98.6, 97.5, and 97.3%, respectively. The mean time to detection of MAC was 14.6 days (range, 6-34 days) with the direct latex test, compared with 18.3 days (range, 9-36 days) with subculture and probe (p < 0.05).

AIDS-Related Opportunistic Infections↗

PubMed1996

Incarceration and the acquired immunodeficiency syndrome: autopsy results in Texas prison inmates.

The Texas Department of Criminal Justice (TDCJ) houses many subjects with acquired immunodeficiency syndrome (AIDS) who receive medical care in a comprehensive AIDS treatment center. In this case-control autopsy survey, we compared pathological outcomes of TDCJ inmates treated at the center (n = 155) with nonincarcerated patients who died during the same period (n = 155). Using multiple regression analysis and a proportional hazards model, survival time in the prisoners was equivalent to that in the controls. With few exceptions, the prevalences of opportunistic viral, fungal, protozoal, and bacterial infections contributing to mortality were equivalent between groups. Mycobacterium tuberculosis was isolated more frequently in the inmates, and M avium intracellulare was isolated less frequently (P < .0001). The inmates had a higher prevalence of bacterial infection of the central nervous system (CNS) (9.1% v 1.4%; P < .006); half of all CNS bacterial infections were caused by M tuberculosis. Inmates had significantly lower prevalences of vacuolar myelopathy (P < .006) and severe wasting disease (P < .0009). We conclude that survival of prison inmates with AIDS treated in a comprehensive AIDS treatment center was equivalent to that of nonincarcerated subjects with AIDS. Prevalences of certain complications of AIDS differed in the inmates, showing that the prison environment influenced some of the underlying causes of AIDS morbidity and mortality.

AIDS-Related Opportunistic Infections↗

PubMed1996

Quantifying apoptosis in banked human brains using flow cytometry.

Fragmentation of genomic DNA, a major biochemical feature of programmed cell death (apoptosis), is easily detected when apoptosis is prevalent. In brain tissue apoptotic cells are usually scarce and detection requires more sensitive techniques. We describe a highly sensitive method to quantify apoptosis in frozen human brain tissue using flow cytometry. Nuclei from homogenized brain specimens were isolated to purity using discontinuous isopyknic centrifugation through 2.2 M sucrose. DNA strand breaks in apoptotic nuclei were conjugated with biotinylated-dUTP using terminal deoxynucleotidyl transferase (TdT) and tagged with streptavidin-conjugated FITC (TUNEL). Negative controls excluding the TdT step, and positive controls using DNAase pretreatment to create 3'-OH strand breaks were run in parallel. The proportion of nuclei with TdT-dependent labeling in adult brain specimens was < 0.01% in 6 out of 7 specimens. In 3 fetal brains it averaged 0.86 +/- 0.11%. Apoptotic cells were readily detected in 2 malignant glial neoplasms and in a patient with HIV encephalitis. Comparable frequencies of stained nuclei were present in adjacent specimens embedded in paraffin and labeled in situ. By screening millions of nuclei cytometry detected very rare apoptotic events, producing quantitative results using banked frozen brains. The method has potential applications to studies of human brain development, neurodegenerative diseases, and brain tumors.

Adult↗

PubMed1995

Massive hepatic steatosis and lactic acidosis in a patient with AIDS who was receiving zidovudine.

Massive steatosis has recently been described among a few human immunodeficiency virus-seropositive patients who were receiving antiretroviral therapy. Although clinical and light-microscopic pathological findings were carefully described, no ultrastructural studies of the liver were performed in these cases. We report the light-microscopic and ultrastructural findings at autopsy of a 35-year-old woman with AIDS who developed severe lactic acidosis and hepatic failure. The patient had been receiving standard doses of zidovudine for 5 months when she was hospitalized because of the rapid onset of abdominal pain, nausea, and vomiting. The most significant findings at autopsy were massive hepatomegaly and steatosis. Ultrastructural examination of the liver and skeletal muscle showed slightly enlarged mitochondria in the liver but no mitochondrial changes in the skeletal muscle. The pathogenesis of mitochondrial toxicity associated with antiviral therapies is briefly discussed.

Acidosis, Lactic↗