Biomedical subjects
J D Almeida
Publications and source records attributed to J D Almeida.
Letter: Virus-like particles in hepatitis-A-positive faecal extracts.
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Pitfalls in the study of hepatitis A.
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Hepatitis B core antigen: immunology and electron microscopy.
TWO DISTINCT VIRAL ANTIGENS ARE ASSOCIATED WITH THE HEPATITIS B VIRUS: the hepatitis B surface antigen (HB(s)Ag, Australia antigen) and the hepatitis B core antigen (HB(c)Ag). HB(s)Ag, purified from the serum of asymptomatic human HB(s)Ag carriers, and HB(c)Ag, purified from the liver of a chimpanzee acutely infected with hepatitis B virus, were examined by serological and immune electron microscopic methods. Antisera raised against HB(s)Ag reacted with the outer, surface component of the Dane particle and with the 20-nm spherical and tubular particles present in HB(s)Ag-positive serum, but not with the internal component of the Dane particle or with purified HB(c)Ag particles. Antisera raised against purified HB(c)Ag particles reacted with the internal component of the Dane particle and with HB(c)Ag, but not with the surface of the Dane particle or with the 20-nm spherical and tubular particles associated with HB(s)Ag. Purified HB(c)Ag particles, 27 nm in diameter, demonstrated distinct subunits. The infectious form of hepatitis B virus appears to be represented by the 42-nm Dane particle composed of a 27-nm nucleocapsid core component (HB(c)Ag) surrounded by an antigenically and morphologically distinct lipoprotein surface component (HB(s)Ag).
The unique morphology of the lactic dehydrogenase virus.
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Transmission of type B viral hepatitis to chimpanzees.
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Antigenically-related viruses associated with infectious bursal disease.
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Electron microscope study of a case of Australia antigen-positive chronic hepatitis.
The laboratory findings in a case of Australia antigen (Au-Ag) positive chronic hepatitis in a 4-year-old boy are given. Studies by the electron microscope technique of thin sectioning revealed the presence of 200A particles in the nuclei of hepatocytes. These particles are identical to those described previously in occasional specimens of Au-Ag-positive liver tissue. However, the pattern found here differs from previous descriptions inasmuch as no heavily infected nuclei could be found but almost all nuclei could be shown to contain extremely small numbers of these particles. The significance of this finding is discussed and the danger that it would be easy to obtain false negatives in similar tissue pointed out.
Deficiency of the second component of complement associated with anaphylactoid purpura and presence of mycoplasma in the serum.
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Control of Australia antigen-positive hepatitis within haemodialysis units.
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Australia antigen as a marker of propagation of the serum hepatitis virus in liver cultures.
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Individual morphological variations seen in Australia antigen positive sera.
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Relationship of Milan antigen to abnormal serum lipoprotein.
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Interaction of Sendai (HVJ) virus with human erythrocytes: a morphological study of haemolysis cell fusion.
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Immune electron microscopy of rhinoviruses.
Aggregates of three rhinovirus serotypes have been readily observed by utilizing the technique of immune electron microscopy. The aggregates generally fell into three categories: those with complete virions, those with "empty" capsids, and those in which the two types of particles were mixed.
Nonviral microbodies with viral antigenicity produced in cytomegalovirus-infected cells.
Masses of homogeneous electron-dense material accumulate in the cytoplasmic inclusions of cultured fibroblasts which have been infected with "wild" and "adapted" strains of human cytomegalovirus. The substance appears to be produced by microtubular membranes and the Golgi apparatus; ultrastructural histochemistry suggests that it is not lysosomal in nature nor is it comprised of lipids or polysaccharides. The dense material "buds" into cytoplasmic tubules forming circumscribed bodies having an investing membrane similar to the viral envelope. After transport to the extracellular milieu in cytoplasmic tubules and vesicles, virions and dense bodies can be demonstrated by immune electron microscopy. The homogeneous dense body appears to be a unique product of the cytomegalovirus-infected cell which possesses a limiting membrane having antigenic determinants common with the viral envelope.
Hepatitis-associated (Australia) antigen in Nigerians: an ultrastructural study.
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New antigen-antibody system in Australia-antigen-positive hepatitis.
After detergent treatment the 42 nm. Dane particles from the sera of patients with serum hepatitis separate into an outer coat of Australia antigen (Au-Ag) and an inner spherical 27 nm. diameter component resembling a rhinovirus. Antibody in post-hepatitic serum reacted with the inner component (but not with the outer) to yield aggregates resembling those seen in the liver of patients with serum hepatitis. Antibody to Au-Ag was not detected, before or after the attack of hepatitis. It is suggested that, in an attack of serum hepatitis, Au-Ag antibody develops but is subsequently cleared; antibody against the inner Dane component, however, persists.