ISSN:0741-0581    

DOI:10.1002/jemt.1060080102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractWe compared the ultrastructure of the human retroviruses by thin‐section electron microscopy of infected lymphocytes. Virus particles form at the plasma membrane without involvement of a cytoplasmic precursor. Budding forms of human T‐cell leukemia virus types I and II (HTLV‐I and ‐II) consist of a crescent‐shaped nulceoid separated from the envelope by an intermediate layer. Mature forms of these viruses are about 100 nm in diameter. The nucleoid is electron lucent and almost completely fills the virion. There is about a 10‐nm space between the envelope and nucleoid. The envelope has fuzzy surface projections. HTLV‐I and ‐II resemble other type C retroviruses in morphology. Budding forms of human immunodeficiency virus (HIV, LAV, HTLV‐III) also have a crescent‐shaped nucleoid but not an intermediate layer between the core and envelope. The envelope has rod‐shaped surface projections. Mature forms of HIV have an electron‐dense nucleoid that is eccentric and bar‐ or cone‐shaped. Particles have the same ultrastructure as retroviruses of theLentivirusgenus. HIV is readily distinguishable from HTLV‐I and ‐II by thin‐section electron microscopy. HIV is usually found in extracellular spaces by transmission electron microscopy of thin sections, and scanning electron microscopy of HIV‐infected T4 lymphocytes also shows many particles on the surface of these cells. Lymphadenopathy‐associated virus type II (LAV‐II) has the same internal ultrastructure as HIV, but its surface projections are more prominent, being about three times the length of those of HIV. Human T lymphotropic virus type IV (HTL

ISSN:0741-0581    

DOI:10.1002/jemt.1060080103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractA novel human lymphotropic virus capable of crippling the immune system by infecting and destroying T4 antigen‐positive cells is now known to be the etiologic agent of the acquired immune deficiency syndrome (AIDS). The AIDS or human immunodeficiency virus (HIV) belongs to a family of RNA viruses called retroviruses. Several strains of HIV have been molecularly cloned, and DNA sequence comparisons have established that the proviral DNA genome is 9.7 kilobase pairs. The genome possesses characteristic retrovirus features including structural genes, flanked by long terminal repeats, in the ordergag, pol, andenvand, in addition, four unique nonstructural genes, several of which appear to be essential in regulating virus replication. Electron microscopy has played an important role in elucidating structural, genetic, and molecular properties of HIV and has aided in its classification as a member of the Lentivirnae retrovirus subfamily. Heteroduplex mapping methodologies pertinent to these findings are described. Although the relationships show considerable divergence, the similarities between HIV and lentiviruses are profound and encompass an indistinguishable morphology, genome sequence homology and topography, genomic diversity, and overlapping biology, including a preference for infecting cells of the immune system, a cytopathic effect in vitro, and the ability to produce a persistent, slowly progressing, degenerative disease in vivo. The newest HIV class (HIV‐2) has recently been molecularly characterized. HIV‐2 also bears all the hallmarks of a lentivirus but is more closely related to simian immunodeficiency viruses than the previously described HIV‐1, despite a similar biology. The HIV‐lentivirus phylogenetic relationship has broad implications for the AIDS disease process and has given new importance to the study of the natural history and pathogenesis of animal lentiviruses in searching for clues to prevent the sprea

ISSN:0741-0581    

DOI:10.1002/jemt.1060080104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe following communication is a tripartite synopsis of the role of viral infection in the acquired immunodeficiency syndrome (AIDS). The first section describes the impact of viral opportunistic infection in AIDS; for each virus, clinical presentation and diagnosis, laboratory diagnostic approaches (with emphasis on electron microscopy), and therapeutic interventions attempted to date are discussed. The second segment explores current theories on the pathogenesis of AIDS, and describes diagnostic and therapeutic approaches to the syndrome itself. The final section catalogues ultrastructural anomalies in the cells of AIDS patients, many of which have been mistakenly identified as etiologic agents.

ISSN:0741-0581    

DOI:10.1002/jemt.1060080105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractSeveral protozoa have emerged as the major opportunistic infections and cause of death in patients with acquired immunodeficiency syndrome (AIDS).Pneumocystis cariniipneumonia is the leading cause of death in AIDS patients. Electron microscopy (EM) usually shows numerous trophozoites and cysts ofPneumocystisfilling up the entire alveolar space, while only cysts are seen under the light microscope. The focal thickening of cyst wall ofPneumocystis, as demonstrated by EM and manifested as a “parentheses” shaped structure with silver stain, serves as a diagnostic marker forPneumocystis.Freeze‐fracture EM has demonstrated the intimate contact betweenPneumocystistrophozoites and the type I pneumocytes, which may contribute to the alveolar‐capillary block, leading to severe respiratory distress. However, EM is seldom needed for the diagnosis of this infection.Toxoplasmaencephalitis, which is an unusual clinical manifestation in cases of toxoplasmosis reported previously, has become a common complication and one of the major causes of death in patients with AIDS. Because subclinical infection byToxoplasmais common, serologic tests usually offer no definite answers as to whether the infection is acute or chronic, active or past. The small size and its non‐specificity in both morphology and tissue affinity make light microscopic diagnosis of toxoplasmosis difficult. Only immunologic staining, such as immunoperoxidase and immunofluorescence, can help to achieve a definite positive identification of the organism. When special antibodies or facility for such staining is not available, EM is the final resort for identifyingToxoplasmaby showing the apical complex with the characteristic sausageshaped rhoptries.Cryptosporidiosis, practically unknown before the AIDS outbreak, has become one of the most common intestinal protozoa in both immunocompromised and immunocompetent patients. The protracted and sometimes fatal course of cryptosporidiosis in immunocompromised patients can be explained by the presence of autoinfective oocysts (thin‐walled oocysts), as detected by EM, and by recycling of first‐generation schizonts observed experimentally. While diagnosis of cryptosporidiosis can be made by detection of oocysts in stools in most cases, EM is still the last resort for a definitive identification ofCryptosporidiumspecies.While the incidence of isosporiasis is still low, it has been found more frequently in patients with AIDS than in the general population. The parasite,Isospora belli, being a coccidian as is theCryptosporidiumspecies, is similar to the latter in its life cycle and clinical manifestations. However, the morphology of its diagnostic stage, the oocyst, is quite different from Cryptosporidium and it is much larger than the latter. The oocyst of Isospora belli, usually containing one sporoblast, can be detected by light microscopy in stools.Microsporidiosis, having been known only recently, is also relatively common in immunocompromised patients, including four patients with AIDS. Although this protozoan can be detected by light microscopy and its polar granules, identified by the periodic acid‐Schiff or methenamine silver stain, are characteristic, a definitive diagnosis of microsporidiosis stil

ISSN:0741-0581    

DOI:10.1002/jemt.1060080106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThis reviw examines an important bacterial infection in acquired immunodeficiency syndrome (AIDS). Despite occasional infections with bacteria such asStreptococcus pneumoniae, Haemophilus influenzae, Salmonella, and Nocardiain patients with AIDS, the primary problems of AIDS and invading bacterial infections center around mycobacteropsos. A unique feature of AIDS has been the common identification of disseminated infections withMycobacterium avium‐intracellulare.The following discussion examines our present understading of this group of organisms and how they interact with the compromised hos

ISSN:0741-0581    

DOI:10.1002/jemt.1060080107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractDefects in cell‐mediated immunity caused by infection with the human immunodeficiency virus (HIV) render AIDS patients particularly susceptible to fungal pathogens. Signs and symptoms of serious infection may be nonspecific, and early diagnosis and institution of antifungal therapy is essential to decrease morbidity and mortality in this patient population. In a symptomatic individual, invasive procedures are often required to establish a microbiologic diagnosis, and histopathologic examination of tissue by light and electron microscopy is often the first indication of a serious fungal infection in an AIDS patien

ISSN:0741-0581    

DOI:10.1002/jemt.1060080108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractStrongyloides stercoralis, the only helminthic parasite that can complete its life cycle in the human host, is also the only helminthic parasite that has been reported with any frequency in AIDS patients. Symptoms include hives, skin eruptions, abdominal pain, perianal pruitis, diarrhea, and pneumonitis. Diagnosis is made by demonstrating rhabditiform larvae in the stool or female parasitic worms and eggs in the small intestinal mucosa; in disseminated cases, rhabditiform or filariform larvae can be found in liver, heart, lungs, thyroid, kidneys, adrenals, pancreas, lymph nodes, and central nervous system. Successful treatment has been achieved with thiabendazol. Strongyloidiasis is uncommon, but since cell‐mediated immunity is important in combatting this organism, and since T‐lymphocyte function is impaired in AIDS patients, strongyloidiasis should not be overlooked in the diagnosis of opportunistic illnesses in these individu

ISSN:0741-0581    

DOI:10.1002/jemt.1060080109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractMalignancies frequently arise in patients infected with human immunodeficiency virus (HIV), including those patients classified as having the acquired immunodeficiency syndrome (AIDS). Currently, Kaposi's sarcoma and certain types of lymphoma are considered to develop as a result of HIV infection, and other cancers have also been reported in these patients. For the most part, ultrastructural study of HIV‐associated malignancies has been limited to Kaposi's sarcoma; the ultrastructural features of the epidemic form of this disease are generally the same as those of the classical form. The occurrence of these cancers in HIV‐infected individuals appears to be related to the immunodeficiency caused by this virus, but the basic etiologic mechanisms remain unknown. In general, only palliative treatments are presently available for HIV‐associated maligna

ISSN:0741-0581    

DOI:10.1002/jemt.1060080110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0741-0581    

DOI:10.1002/jemt.1060080101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY