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Biomedical subjects

J D Almeida

Publications and source records attributed to J D Almeida.

At least 19 recordsLinked to original sources
PubMed1979

A simple immunofluorescent technique for the detection of human rotavirus.

If trypsin is incorporated in the tissue culture medium it is possible to carry out a sensitive immunofluorescence assay for the presence of human rotavirus. The enhanced effect of trypsin is negated by serum. It has also been established that naturally occurring enzymes in faeces enable some virus to penetrate tissue culture cells. The role of these naturally occurring enzymes in the pathogenesis of rotavirus infection is discussed.

Animals↗
PubMed1979

The effect of sodium thiocyanate on virus structure.

A study of two different virus types after elution from immunosorbent columns by sodium thiocyanate has shown that virus degradation occurs. The two virus types studied were hepatitis B and rotavirus. Hepatitis B antigen (HBAg) was only slowly degraded and retained many of its morphological features, although in an altered form; rotavirus was highly sensitive to the chaotropic agent, losing both its viability and its morphological integrity. During the process of disassembly a previously undetected inner component of rotavirus could be visualised, which was termed the "core."

Capsid↗
PubMed1979

A solid-phase system (SPACE) for the detection and quantification of rotavirus in faeces.

This report describes the development of a solid-phase haemadsorption system using chromic chloride-linked, antibody coated erythrocytes. It is proposed to call this technique solid phase aggregation of coupled erythrocytes (SPACE). The system is suitable for the detection of virus antigens, such as from rotavirus infections, which are present in 'dirty' or 'mixed' preparations such as faeces, urine or exudates. The test uses microtitre U-form plates coated with specific antivirus antibody; faecal suspensions are added and virus or antigen allowed to adsorb. The plates are then washed and adsorbed antigens are detected by the addition of virus-specific IgG-coated erythrocytes. The resultant settling pattern is read in the same manner as a conventional haemagglutination test. The system is compared with electron microscopy and fluorescent antibody techniques.

Animals↗
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↗