Delayed diagnosis of pediatric cervical spine injury.

We report on nine patients in whom there were delays in establishing a diagnosis of cervical spine injury and discuss the causes that contributed to the delays, their clinical significance, and whether or not asymptomatic injury occurs.

Dual regulation of silent and productive infection in monocytes by distinct human immunodeficiency virus type 1 determinants.

The regulation of human immunodeficiency virus type 1 infection and replication in primary monocytes was investigated by mutagenesis of recombinant proviral clones containing an env determinant required for the infectivity of monocytes. Virus replication was assayed by determination of reverse transcriptase activity in culture fluids and by recovery of virus from monocytes following cocultivation with uninfected peripheral blood mononuclear cells. Three virus replication phenotypes were observed in monocytes: productive infection, silent infection, and no infection.

No direct neuronotoxicity by HIV-1 virions or culture fluids from HIV-1-infected T cells or monocytes.

Macrophages and microglia are the principal target cells for human immunodeficiency virus (HIV) in brain, and as such, are likely participants in the neuropathology of HIV infection. In a model system for this process, we found that fluids from human monocyte cultures enhanced survival and differentiation of the neurons in fetal rat brain explants. In contrast, fluids from HIV-infected monocyte cultures were strongly toxic to neurons and paradoxically enhanced the proliferation of glial cells.

Localization of infection by the microsporidian Enterocytozoon bieneusi in the gastrointestinal tract of AIDS patients with diarrhea.

Objective: We compared the level of Enterocytozoon bieneusi infection at different sites within the small intestine among patients with AIDS.

Design: The level of E. bieneusi infection of each patient biopsy was determined and compared using semi-thin plastic section light microscopy and transmission electron microscopy (TEM).

Cell-to-cell spread of HIV-1 occurs within minutes and may not involve the participation of virus particles.

Although virus infections have been classically studied with "cell-free" virion preparations, many animal viruses are able to spread both in vitro and in vivo by inducing cell-cell fusion. An efficient system to monitor the cell-to-cell spread of HIV-1 has been developed employing chronically infected H9 donor cells. Under appropriate conditions of cocultivation with uninfected cells, the synthesis of unintegrated viral DNA, monitored by Southern blot hybridization, occurred between 2 and 4 hr following infection; viral proteins were detected 8 to 12 hr following cocultivation and progeny virions were released into the medium by 16 hr.

Ultrastructural pathology of human immunodeficiency virus infection.

The electron microscope has been used with great skill in many aspects of the acquired immunodeficiency syndrome. It has played a critical role in classifying the human immunodeficiency virus, in characterizing the morphogenesis and gene products of the virus, and in elucidating the host cell targets and interactions. With the aid of the electron microscope, new opportunistic pathogens are being identified, and particularly difficult diagnoses are being made.

A comparison of two microsporidian parasites in enterocytes of AIDS patients with chronic diarrhea.

Enterocytozoon bieneusi was first described by electron microscopy in 1985 in intestinal biopsies from an AIDS patient. It has subsequently been observed in many AIDS patients with chronic diarrhea from the U.S.

Fine structure of a new human microsporidian, Encephalitozoon hellem, in culture.

Encephalitozoon hellem is a new human microsporidian isolated from corneal biopsies and conjunctival scrapings of three AIDS patients and cultured in Madin Darby canine kidney (MDCK) cells. Encephalitozoon hellem and Encephalitozoon cuniculi display different protein profiles with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and unique antibody binding patterns with murine antisera against Western blots of each organism. Developmental stages of E.

Epidermal Langerhans cells are not principal reservoirs of virus in HIV disease.

Several reports implicate Langerhans cells of skin as susceptible targets, reservoirs, and vectors for transmission of HIV: 1) numbers of Langerhans cells in skin of HIV-infected patients were decreased about 50% of that in control skin; 2) as many as 30% of Langerhans cells in the skin of HIV-infected patients were morphologically abnormal; 3) viral particles typical for HIV were identified in or around 2 to 5% of these cells; and 4) infectious HIV was isolated from skin biopsies of infected patients. These results were consistent with similar observations of HIV-infected macrophages in such tissues as brain, lung, and lymph node. Despite these findings, other investigators find no evidence for virus infection in the epidermis of HIV-infected patients by any of several immunohistochemical or ultrastructural criteria.

Pneumococcal bacterial tracheitis.

Bacterial tracheitis is an uncommon cause of acute respiratory distress in children. The authors present a case of bacterial tracheitis in a 6-year-old girl caused by an unusual pathogen, Streptococcus pneumoniae. Her clinical presentation and radiographic findings are typical for an older child.

Maturation of human immunodeficiency virus particles assembled from the gag precursor protein requires in situ processing by gag-pol protease.

The vaccinia virus expression system was used to determine the role of human immunodeficiency virus type 1 (HIV-1) protease in viral morphogenesis and maturation. The unprocessed p55 gag precursor polyprotein alone was assembled to form HIV-1 particles which budded from cells. The particles were spherical and immature, containing an electron-dense shell in the particle submembrane; there was no evidence of core formation.

Macrophage- and astrocyte-derived transforming growth factor beta as a mediator of central nervous system dysfunction in acquired immune deficiency syndrome.

The multifunctional cytokine, transforming growth factor beta (TGF-beta), was identified by immunocytochemistry in the brain tissues of four patients with acquired immune deficiency syndrome (AIDS), but not in control brain tissue. The TGF-beta staining was localized to cells of monocytic lineage as well as astrocytes, especially in areas of brain pathology. In addition, the brain tissues from the AIDS patients contained transcripts for human immunodeficiency virus 1 (HIV-1) by in situ hybridization, suggesting a correlation between the presence of HIV-1 in the brain and the expression of TGF-beta.

Adenovirus colitis in the acquired immunodeficiency syndrome.

Adenovirus was identified in colonic tissue by transmission electron microscopy or culture in 5 of 67 (7.4%) homosexual men seropositive for human immunodeficiency virus (51 with the acquired immunodeficiency syndrome) with diarrhea. Colonoscopy showed the mucosa to be normal in 3 cases and mildly inflamed in 2.

Infection of CD8+ T lymphocytes with HIV. Requirement for interaction with infected CD4+ cells and induction of infectious virus from chronically infected CD8+ cells.

In this study, we have investigated the basic requirements for HIV-1 infection of CD8+ lymphocytes in vitro. Unfractionated PBL obtained from healthy HIV-1 seronegative donors were activated with PHA and infected in vitro with HIV-1LAV. Based on immunofluorescent labeling, the vast majority of cells (85 to 97%) surviving peak virus replication belonged to the CD8+ subset and only a small percentage (0.

Isolation and characterization of a new human microsporidian, Encephalitozoon hellem (n. sp.), from three AIDS patients with keratoconjunctivitis.

A new human microsporidian was isolated from cultures of Madin-Darby canine kidney cells incubated with conjunctival scrapings or corneal tissues from three AIDS patients with keratoconjunctivitis. The three isolates were morphologically similar to Encephalitozoon cuniculi. The spores averaged 1 x 1.

Regulation of HIV replication in infected monocytes by IFN-alpha. Mechanisms for viral restriction.

In a survey of 15 different virus isolates, no IFN-alpha or IFN-beta activity was detected in culture fluids of HIV-infected T cells or monocytes. Exogenous rIFN-alpha added to T lymphoblast or monocyte cultures induced restriction in replication of the amphotropic HIV that infect both cell types. With IFN-treated HIV-infected T cells, levels of reverse transcriptase (RT) activity in culture fluids were half those in control cultures, but the frequency of infected cells or the levels of p24 Ag released in culture fluids were unchanged.

A mutant of human immunodeficiency virus with reduced RNA packaging and abnormal particle morphology.

A deletion of 30 bases was created in the noncoding region of the human immunodeficiency virus type 1 genome that extends between the 5' splice donor and the start of the gag gene. Viral particles produced after transfection of this mutant provirus had a normal protein pattern but a reduced RNA content. The infectivity of the mutant virus was also markedly reduced but not completely abolished.