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Biomedical subjects

J D Almeida

Publications and source records attributed to J D Almeida.

At least 37 records · Page 2Linked to original sources
PubMed1978

The effect of trypsin on the growth of rotavirus.

It has been found that 1000-fold more bovine rotavirus is obtained when trypsin is incorporated in the maintenance medium and allowed to remain throughout the growth cycle. This holds true for primary calf kidney (CK) cells and also for several continuous and semi-continuous cell lines. In the presence of trypsin it has been possible to pass the virus serially on continuous cell lines seven times. Concentrations of 1 to 10 microgram/ml of trypsin are found to be effective. Preliminary results suggest that the same technique will be effective for the in vitro propagation of human rotavirus.

Animals↗
PubMed1978

Damaged membrane fragments and immune complexes in the blood of patients with Behcet's syndrome.

Electron microscopic examination of centrifuged pellets of serum from patients with Behcet's syndrome and recurrent oral ulcers revealed the presence of a large number of membrane fragments. Some of these membranes showed numerous 10 nm holes that were identical to lesions produced by the action of complement. An attempt was made to correlate complement levels, antibodies and cellular immunity with the presence of the membrane fragments, without success. However, a significant correlation was found between the membranes and the IgG class of immune complexes. The finding of membrane fragments with complement-induced damage predominantly in the blood of patients with Behcet's syndrome, and the association with soluble immune complexes suggest that the latter may generate C5b-9 complexes which may bind to the surface of cells in result in cell lysis.

Adult↗
PubMed1977

Antibody-modification of measles "in vitro" infection.

While the involvement of measles-like virus with subacute sclerosing panencephalitis (SSPE) has been shown in many laboratories, the possible mechanisms by which a normal measles infection may lead to the chronic condition are unclear. The work reported here demonstrates that the growth and maintenance of Vero cells infected with the MV 30 strain of measles, in the presence of multivalent antibody, results in a redistribution of the viral antigens within the cells and an alteration in the properties of this attenuated virus which persists even after removal of the antiserum from the culture medium. It is suggested that these in vitro findings could be parallel to the situation that occurs in vivo with measles encephalitis in hamsters and human SSPE.

Animals↗
PubMed1977

An antigenic subunit present in rotavirus infected faeces.

It has been found by immune electron microscopy that rotavirus-infected faeces, calf or human, contain an antigenic subunit associated with the inner of the two virus capsids. This internal component represents the group specific antigen for the rotavirus group and the subunit reacts with both homologous and heterologous antiserum. It can therefore be used in diagnostic tests and in this paper its use as a reagent for immunodiffusion is described.

Animals↗
PubMed1977

Human cytomegalovirus: purification of enveloped virions and dense bodies.

Enveloped virions and dense bodies of human cytomegalovirus have been purified by centrifugation, using combination negative viscosity: positive density gradients. Light-scattering bands of each component were obtained, and when these were examined by immune electron microscopy minimal cross contamination was observed.

Cell Line↗
PubMed1977

Studies on the structure of a coronavirus-avian infectious bronchitis virus.

When avian infectious bronchitis virus (IBV) is fixed in formaldehyde, negative stain is able to penetrate the particle and an internal component is visualized. This component is seen as a tongue or flask shaped structure attached at one point to the outer virus membrane. A model yielding transmission patterns similar to the virus has been made. Gradient centrifugation studies on IBV reveal that the RNP is associated with the internal sac.

Coronaviridae↗
PubMed1977

Hepatitis B antigen-positive obstetric patients.

In a period of six years (1971--77) 9400 sera taken at booking from antenatal patients were examined for hepatitis B antigen (HBsAg), and 40 patients were positive. These 40 patients had 45 pregnancies and were treated with special precautions so far as venepuncture and the management of delivery were concerned. No member of the hospital staff dealing with the patients developed hepatitis B. All infants born to these mothers were normal, two infants were HBsAg-positive at 7 months and 2 years, but are clinically well. No obstetric problems attributable to the HBsAg-positive state were encountered.

Adolescent↗
PubMed1976

Concurrent smallpox and chickenpox.

Three patients showing smallpox- and chickenpox-like lesions simultaneously were investigated virologically. Both infections were confirmed in the laboratory and, in one case, by electron microscopy.

Adolescent↗
PubMed1975

Formation of virosomes from influenza subunits and liposomes.

The surface haemagglutinin and neuraminidase projections of influenza virus were removed from the viral envelope, purified, and relocated on the surface of unilamellar liposomes. The resulting structures were examined in the electron microscope and found to resemble the original virus. Units of both the viral haemagglutinin and viral neuraminidase could be discerned. The name virosome is proposed for these new bodies.

Hemagglutinins, Viral↗
PubMed1975

A morphological study of the internal component of influenza virus.

Rapid treatment of influenza virus directly on the microscope grid with non-ionic detergent had allowed better visualization of the internal component. Many micrographs show that this ribonucleoprotein (RNP) is present as a continuous stand of 6 nm diam. arranged in the form of a double coil or helix. In spite of the minimal treatment to which the virus was subjected most helices still showed signs of degradation. The findings that we have obtained lead us to suggest that the RNP component of influenza virus must be very sensitive to both chemical and physical manipulations, any of which could cause it to fracture from one continuous strand into several pieces, although such breakages could possibly occur at specific points along its length.

Animals↗