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Biomedical subjects

J M Orenstein

Publications and source records attributed to J M Orenstein.

At least 55 records · Page 3Linked to original sources
PubMed1997

Macrophages as a source of HIV during opportunistic infections.

The source of increasing viremia that characterizes the latter stages of human immunodeficiency virus (HIV) disease has remained a paradox because it occurs at a time when lymphoid tissue is quantitatively and qualitatively impaired, and the patients' CD4 T lymphocytes are steadily declining. Here, macrophages, both infected and uninfected with common opportunistic pathogens of HIV disease such as Mycobacterium avium complex and Pneumocystis carinii, were identified as highly productive sources of HIV in coinfected lymph nodes. These observations indicate that tissue macrophages are not only infected with HIV, but that common pathogens of HIV disease can dramatically increase their production of virus. Thus, prevention or successful treatment of opportunistic coinfections, or both, potentially benefits the patient twofold by limiting the pathology caused by opportunistic infection and by controlling induction of HIV replication.

AIDS-Related Opportunistic Infections↗
PubMed1997

Isolation and purification of CD14-negative mucosal macrophages from normal human small intestine.

Mucosal macrophages play a fundamental role in the regulation of immunological events and inflammation in the small intestine. Because no information is available on normal small intestinal macrophages, we developed a technique for the isolation and purification of jejunal lamina propria macrophages in order to study their phenotype and activity. From sections of normal human jejunum, lamina propria mononuclear cells were isolated by neutral protease digestion and then subjected to counterflow centrifugal elutriation to purify the macrophages. The cells isolated by this procedure contained < 1% CD3+ lymphocytes and displayed the size distribution, morphological features, ultrastructure and phagocytic activity of mononuclear phagocytes. In contrast to blood monocytes, however, mucosal macrophages from the jejunum did not exhibit adherence properties or express CD14, a receptor for the lipopolysaccharide-binding protein. The purification of large numbers of lamina propria macrophages by this procedure offers the opportunity to define the role of this cell in the physiological inflammation characteristic of normal intestinal mucosa and the pathological inflammation associated with small intestinal diseases.

Cell Separation↗
PubMed1997

Immune stimulation and HIV-1 viral replication.

A biphasic early and late viremia is characteristic of HIV-1 infection. The first increase in circulating viral burden occurs within weeks after infection, before a host immune response, and the second, later peak emerges during the inevitable HIV-1 devastation of immune function. Recently, intermittent bouts of viremia have also been identified in HIV-1-infected individuals and found to be associated with episodes of immune challenge. Vaccinations, exposure to antigens, and infections often induce reversible increases in circulating viral levels, dependent on CD4+ T lymphocyte numbers. However, even with marked losses in CD4+ T cell counts, opportunistic infections appear to trigger a viremic response. In searching for the source of this virus, macrophages in tissues co-infected with opportunistic pathogens have been identified as prodigious producers of HIV-1. Thus, the fountain from which HIV-1 emerges may shift from CD4+ T lymphocytes in early HIV-1 infection to tissue macrophages later in the natural evolution of the disease, as the CD4+ T cells are depleted. Defining the mechanisms of this transitional event in HIV-1 infection may facilitate regulation and therapeutic control of both opportunistic infections and HIV-1.

AIDS-Related Opportunistic Infections↗
PubMed1997

Induction of apoptotic cell death by particulate lead chromate: differential effects of vitamins C and E on genotoxicity and survival.

Certain hexavalent chromium compounds are documented human carcinogens. Exposure of cells to particulate forms of chromium results in cell-enhanced dissolution of particles in the extracellular microenvironment and chronic production of chromium oxyanions, which are taken up by the cell through an anion transport system and are genotoxic and clastogenic. It was previously shown that apoptosis is the mode of cell death of nearly all of the Chinese hamster ovary cells (CHO-AA8 cell line), which die after high-dose, short-term treatments with soluble sodium chromate. In this report the mode of cell killing by particulate lead chromate and of low-dose continuous treaments of soluble sodium chromate designed to mimic conditions of ionic chromate uptake after lead chromate exposure was examined. CHO-AA8 cells were treated for 24 hr with doses of sodium chromate or lead chromate which cause a 50% decrease in survival in colony-forming effeciency assays. Longer treatments (up to 72 hr) at the same doses did not decrease survival further than the 24-hr exposure. Morphological changes indicative of apoptosis, as well as internucleosomal DNA fragmentation, were detectable by 24 hr after treatment with lead chromate or soluble sodium chromate. All of the cells killed by treatments with lead chromate particles underwent apoptosis as the mode of cell death and this was accurately modeled in cell culture by continuous treatments with low-dose soluble sodium chromate. Exposure of cells to hexavalent chromium compounds causes a spectrum of DNA damage which can be selectively altered by pretreatment of cells with antioxidant vitamins prior to chromium exposure. Here we show that ascorbate and alpha-tocopherol markedly inhibited the chromosomal aberrations induced by both particulate and soluble chromate compounds, even though chromium adduct levels were not decreased by either vitamin pretreatment. Cell survival assays showed that ascorbate, but not alpha-tocopherol, protected cells from apoptosis induced by sodium chromate. The results differentiate chromium-induced apoptosis from both chromosomal damage and adduct levels and suggest that other lesions sensitive to ascorbate but not tocopherol are the proximal inducing signal for chromium-induced apoptosis.

Animals↗
PubMed1997

Activated cytotoxic lymphocytes in lymph nodes from human immunodeficiency virus (HIV) 1-infected patients: a light and electronmicroscopic study.

Persistent generalized lymphadenopathy often develops during HIV-infection. It is characterized by follicular hyperplasia which progresses over time to follicular involution and finally lymphocyte depletion. To determine whether activated cytotoxic T cells (CD8+) are present in the hyperplastic germinal centres, light and electronmicroscopic immunogold labelling with monoclonal antibodies were used to localize two cytotoxic molecules, perforin and TIA-1. Perforin and TIA-1-positive cells were detected in the follicles and paracortex of lymph nodes from HIV-infected patients, whereas labelling was seen only in cells of the paracortex in the hyperplastic lymph nodes from HIV-negative patients. Cytotoxic granules, staining positive for perforin and TIA-1, were identified by transmission electronmicroscopy, often in proximity to follicular dendritic cells within the hyperplastic germinal centres of only HIV-positive patients. These cytotoxic cells may play a role in the follicular dendritic cell loss and concomitant follicular involution that occur during the evolution of HIV disease.

Adult↗
PubMed1997

gp120 is present on the plasma membrane of apoptotic CD4 cells prepared from lymph nodes of HIV-1-infected individuals: an immunoelectron microscopic study.

OBJECTIVE: To study whether free gp120 can be detected on the plasma membranes of apoptotic CD4+ T lymphocytes in lymph nodes from HIV-positive patients. METHODS: Lymph-node cell suspensions prepared from three HIV-positive patients were studied by pre-embedding, double-immunogold-labeling to identify cell type, determine cell morphology, and detect the presence of bound gp120 molecules. Cells were classified by their surface antigens as helper/inducer T lymphocytes (CD4+), cytotoxic/suppressor T lymphocytes (CD8+), B cells (CD20+), and total lymphocytes [CD45+, leukocyte common antigen (LCA)+]. RESULTS: gp120 colabelled with both apoptotic and normal CD4+ T lymphocytes and LCA+ cells, but not with either apoptotic or normal CD8+ T lymphocytes or B cells. gp120 was more often identified on apoptotic than on normal CD4+ T lymphocytes. The gp120 and CD45 label were often colocalized. HIV particles were not identified to be associated with or budding from either normal or apoptotic lymphocytes. CONCLUSIONS: Free gp120 is found bound to CD4+ T cells in lymph nodes of HIV-infected individuals and potentially mark them for premature death by apoptosis.

Apoptosis↗
PubMed1997

Visualization of human herpesvirus type 8 in Kaposi's sarcoma by light and transmission electron microscopy.

BACKGROUND: Human herpesvirus type 8 (HHV-8) has been associated with Kaposi's sarcoma, body cavity-based lymphoma (BCBL), and multicentric Castleman's disease through DNA, in situ hybridization, and serologic studies. HHV-8 has been visualized only in HHV-8-positive/Epstein-Barr virus (EBV)-negative/ cytomegalovirus (CMV)-negative BCBL cell lines, but not in HHV-8-positive/EBV-negative/ CMV-negative Kaposi's sarcoma lesions. DESIGN: Kaposi's sarcoma of the skin, lymph node, and spleen from three patients with AIDS were analysed for HHV-8, EBV and CMV DNA by polymerase chain reaction (PCR), for HHV-8 RNA (Tl.1 riboprobe) by in situ hybridization (ISH), for viral inclusions by light microscopy, and for herpesviruses by transmission electron microscopy (TEM). Sections were also labeled with Tl.1 counterstained with CD34, an endothelial cell marker. RESULTS: The skin lesion was DNA PCR-positive for HHV-8 and CMV (nested, but not single PCR), the lymph node was positive for HHV-8 and EBV, and the spleen was positive for only HHV-8. TEM revealed infection by a virus displaying the typical morphology and cytopathicity of herpesviruses. Hexagonal nucleocapsids and mature enveloped virions were present in vasoformative spindle cells and mononuclear cells, often resembling lymphocytes. Extrapolating from TEM to standard light microscopy on hematoxylin and eosin-stained paraffin sections, eosinophilic, targetoid intranuclear inclusions were identified within spindle cells which often lined vascular lumina. The Tl.1-riboprobe labeled CD34+ spindle cells containing intranuclear inclusions, as well as mononuclear cells within Kaposi's sarcoma and residual lymphoid tissue. CONCLUSION: The herpesvirus visualized in Kaposi's sarcoma lesions has morphologic and cytopathic features typical of human herpesviruses, productively infects vasoformative spindle cells and mononuclear cells, and is consistent with HHV-8. It can also form intranuclear inclusions that are identifiable by light microscopy in hematoxylin and eosin sections and by ISH.

Herpesvirus 8, Human↗
PubMed1997

Secretory leukocyte protease inhibitor (SLPI) in mucosal fluids inhibits HIV-I.

Despite the presence of HIV-1 in the oral cavity, transmission of the virus through saliva has not been proven. Consistent with these observations, we recently identified an endogenous 12 kD protein, secretory leukocyte protease inhibitor (SLPI), in saliva which blocks HIV-1 infection in vitro. Whereas other salivary proteins tested were inactive, purified native or recombinant SLPI inhibited HIV-1 infection of human monocytes at 100 ng ml-1. Levels of SLPI quantitated by ELISA in saliva from control and HIV-1 infected individuals exceeded this level, consistent with in vivo antiviral activity. As in saliva, levels of SLPI mRNA determined by Northern hybridization, and protein as assessed by immunohistochemistry in the salivary glands of control and infected populations were comparable. In contrast to adults, oral transmission occurs in infants, possibly due to their lack of fully developed salivary glands. To determine whether the inadequate antiviral protection might be compensated for by maternal sources, we evaluated breast milk samples obtained 6 months postpartum. Levels of SLPI were significantly lower than in saliva and not sufficient to provide antiviral protection in contrast to colostrum samples in which SLPI levels were equivalent to those in saliva and able to inhibit HIV-1 infection when tested in vitro. These data suggest that breast milk may provide transient antiviral activity in the newborn, but that this maternal source of SLPI is of insufficient duration to maintain protection against mucosal transmission of the virus over time. The high functional levels of SLPI in saliva and the low levels in mature breast milk correlate with negligible rates of HIV-1 transmission by saliva and higher rates by breast feeding.

Adult↗
PubMed1997

HEp-2 cell adherence patterns, serotyping, and DNA analysis of Escherichia coli isolates from eight patients with AIDS and chronic diarrhea.

Three morphologic patterns of interaction between bacteria and enterocytes have been observed in colonic biopsy specimens from AIDS patients with chronic diarrhea in the United States. The DNA encoding virulence factors and the HEp-2 cell adherence patterns of Escherichia coli strains isolated from the stools of eight symptomatic AIDS patients were compared with those of five control strains with known adherence patterns. One clinical isolate from a patient with attaching-and-effacing enteropathy displayed the localized adherence attaching-and-effacing pattern typical of enteropathogenic E. coli on HEp-2 cells, five isolates displayed the "stacked-brick" aggregative adherence pattern typical of enteroaggregative E. coli strains, and one isolate showed the pattern characteristic of diffusely adherent E. coli. One patient's isolate displayed features of all three patterns. No clinical isolate hybridized with standard probes for enteropathogenic, enteroaggregative, diffusely adherent, enterotoxigenic, and enteroinvasive E. coli strains. Thus, isolates from symptomatic AIDS patients in the United States can display the same interactive patterns with HEp-2 cells as the agents of pediatric or traveler's diarrhea, but lack their typical virulence factors.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Encephalitozoon cuniculi microsporidiosis: infection of the brain, heart, kidneys, trachea, adrenal glands, and urinary bladder in a patient with AIDS.

A female AIDS patient, dying with widely disseminated Encephalitozoon cuniculi microsporidiosis, cytomegalovirus (CMV) disease, and Pneumocystis carinii infection, is described. Indirect immunofluorescent antibody staining studies and molecular analyses identified the microsporidian as the dog strain of E. cuniculi. Autopsy revealed necrotizing microsporidiosis of the adrenal glands and kidneys, with lesser involvement of the brain, heart, trachea, urinary bladder, spleen, and lymph nodes. Cellular targets included macrophages, epithelium, endothelium, and cardiac myocytes. Spore detection was enhanced by Gram-staining, polarization, and fluorescence chitin stains. Central nervous system microglial nodules were present and either contained microsporidia, CMV, or no identifiable pathogen. CMV disease was most severe in the central nervous system, trachea, adrenal glands, and colon, whereas the Pneumocystis carinii infection was focal in the lungs, lymph nodes, and spleen. This is the first demonstration of Encephalitozoon microsporidiosis of the brain, heart, and adrenal glands in a patient with AIDS. E. cuniculi should be included in the differential diagnosis of disseminated opportunistic infections in patients with AIDS.

AIDS-Related Opportunistic Infections↗
PubMed1997

Anatomic dissociation between HIV-1 and its endogenous inhibitor in mucosal tissues.

The rarity of oral transmission of human immunodeficiency virus (HIV)-1 by saliva suggests the absence of HIV-1 in the oral cavity and/or the presence of viral inhibitory molecules. We analyzed salivary gland tissues from 55 individuals with acquired immune deficiency syndrome (AIDS) for the presence of HIV-1 by in situ hybridization and detected the virus in more than 30% of these salivary glands. These data, together with previous demonstrations of HIV-1 in oral secretions, implicate a key role for an anti-viral molecule(s) in suppressing transmission. Thus, we focused on the characterization and localization of the endogenous antiviral molecule secretory leukocyte protease inhibitor (SLPI), which inhibits HIV-1 infection in vitro. Expression of SLPI transcripts was evident in submandibular, parotid, and minor salivary glands from both HIV-1-infected and seronegative subjects. Gene expression was reflected by similar levels of SLPI protein by immunohistochemical analysis in the tissues and by enzyme-linked immunosorbent assay in the saliva. However, although SLPI accumulated in acinar cells or ductal epithelium, HIV-1 transcripts did not, and these viral transcripts were identified only in mononuclear cells within the salivary gland stroma. By in situ hybridization, we found no evidence of productive HIV-1 infection of salivary gland epithelium. Thus, HIV-1 was frequently identified in salivary gland tissue, but the virus was found in interstitial mononuclear cells only and did not co-localize with SLPI. Once within the oral cavity, HIV-1 exposure to antiviral levels of SLPI may impede infection of additional target cells, contributing to the virtual absence of oral transmission of HIV-1 by saliva. These studies emphasize the importance of innate, endogenous inhibitors of HIV-1, particularly SLPI, as effective inhibitors of HIV-1 transmission.

Acquired Immunodeficiency Syndrome↗
PubMed1997

A patient with acquired immunodeficiency syndrome and untreated Encephalitozoon (Septata) intestinalis microsporidiosis leading to small bowel perforation. Response to albendazole.

BACKGROUND: Encephalitozoon (Septata) intestinalis is a common disseminating opportunistic intestinal microsporidian affecting patients with acquired immunodeficiency syndrome. This microsporidian does respond to albendazole therapy. A patient with acquired immunodeficiency syndrome and chronic diarrhea presented to George Washington University Hospital in January of 1996. Despite appropriate surgical specimens, no etiology had been found to explain his cholecystitis, cystitis, and enteritis 3 months previously at another hospital. DESIGN: Tissue specimens were analyzed by light microscopy, using hematoxylin-eosin and the Armed Forces Institute of Pathology Brown-Brenn microsporidia stain, and by transmission electron microscopy. Urine and stool specimens were analyzed by modified chromotrope 2R trichrome and chitin fluorochrome stains and by transmission electron microscopy. RESULTS: At George Washington University Hospital, disseminated E intestinalis was diagnosed from duodenal biopsy, urine, and stool specimens. On the 14th day of oral albendazole therapy, a partial small bowel resection was performed to correct a perforation (air under the diaphragm). There was no enterocyte microsporidian infection at that time, only spores undergoing macrophage digestion. Review of previous specimens showed severe E intestinalis cholecystitis, cystitis, and enteritis. Albendazole was restarted and, after 2 weeks, the patient had negative stool and urine specimens. CONCLUSIONS: Encephalitozoon intestinalis symptomatically targets many organs, including the urinary bladder. To our knowledge, this is the first tissue-documented case of cystitis. Left untreated with albendazole, small bowel infection can lead to perforation and peritonitis.

AIDS-Related Opportunistic Infections↗
PubMed1996

Fas mediates apoptosis in human monocytes by a reactive oxygen intermediate dependent pathway.

Monocyte apoptosis has emerged as a central regulatory event in hemopoiesis and inflammation. Inflammatory cytokines can either promote or prevent monocyte apoptosis. To study the possible role of Fas Ag, a member of the TNF/nerve growth factor receptor family, in monocyte apoptosis, human peripheral blood monocytes activated by IL-1 beta or TNF-alpha were exposed to anti-Fas mAb. Engagement of the Fas Ag resulted in apoptosis of monocytes, as monitored by propidium iodide uptake, decrease in cell size, DNA fragmentation, and characteristic ultrastructural changes. The apoptotic action of Fas was abolished completely by antioxidants such as N-acetylcysteine and glutathione, suggesting a role for reactive oxygen intermediates (ROI) in the death process. Consistent with this observation, Fas stimulation enhanced the fluorescence associated with oxidation of 2',7'-dichlorofluorescein, indicating increased levels of intracellular ROI. Moreover, the exogenous addition of hydrogen peroxide or menadione, an intracellular generator of superoxide anion, was sufficient for the induction of monocyte apoptosis. These data indicate that ROI are key mediators of Fas-induced apoptosis. In contrast to IL-1 beta and TNF-alpha, LPS-treated monocytes were resistant to the apoptotic action of Fas. Under these conditions, LPS did not down-regulate Fas, but inhibited the Fas-dependent elevation of ROI. Therefore, monocytes appear to have a protective mechanism that can interfere directly with the Fas-induced pathway of cell suicide, thereby controlling their destiny.

Antioxidants↗
PubMed1996

Disseminated microsporidiosis especially infecting the brain, heart, and kidneys. Report of a newly recognized pansporoblastic species in two symptomatic AIDS patients.

Microsporidia have emerged as important opportunistic AIDS pathogens of the alimentary, respiratory, and urinary tracts. Although nonhuman mammalian microsporidia infections typically include encephalitis, CNS microsporidiosis has not been reported in patients with AIDS. A 33-year-old white male and an 8-year-old black girl presented with seizures and declining mental status. Central nervous system (CNS) imaging studies revealed small peripherally and diffusely enhancing lesions present for at least 2 and 4 months before death, respectively. Both patients expired despite empirical anti-toxoplasma therapy. Their brains contained innumerable soft gray matter lesions that consisted of central areas of necrosis, filled with free spores and spore-laden macrophages, surrounded by microsporidia-infected astrocytes. The complete autopsy of the child also revealed necrotizing and sclerosing cardiac and renal microsporidiosis and infection of the pancreas, thyroid, parathyroids, liver, spleen, lymph nodes, and bone marrow. Infected cells included astrocytes, cardiac myocytes, epithelium, endothelium, vascular smooth muscle cells, hepatocytes, adipocytes, Schwann cells, and macrophages. Light and electron microscopic studies revealed pansporoblastic development within thick-walled sporophorous vacuoles of parasite origin. Although most similar to Pleistophora sp and Thelohania sp, this microsporidian is different from any known species. Microsporidiosis should be considered as the possible cause of a wide range of diseases in AIDS patients, including CNS, cardiac, and renal.

AIDS-Related Opportunistic Infections↗