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J D Almeida

Publications and source records attributed to J D Almeida.

At least 19 recordsLinked to original sources
PubMed1998

Hand, foot, and mouth disease: a case report.

Hand, foot, and mouth disease is a viral infection related to coxsackieviruses A5, A6, A9, and A10, coxsackieviruses B2 and B5, and echovirus 11. It generally affects children, but this article presents a clinical case of a young woman with hand, foot, and mouth disease. Patients with this disease have oral and skin lesions that may be confused with other diseases. The differential diagnosis is very important because both dental and medical professionals may misdiagnose the disease and sometimes prescribe an inappropriate medication.

Adult↗
PubMed1990

Electron microscopic detection of human parvovirus (B19) in a patient with HIV infection.

We report the findings on an HIV-positive patient found to be infected with human parvovirus B19. In a comparative study of sequential sera, direct electron microscopy (EM) had the same sensitivity as DNA hydridization for the detection of the virus. EM did not require specific reagents and also yielded information on the state of the virus; i.e., whether random or complexed, and the type of antibody involved. The presence of parvovirus complicated the judgement as to drug treatment. This case also highlighted the importance of diagnosing the presence of opportunistic viral infections that have no, or low-grade, pathogenic activity.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Recovery of antigenically reactive HIV-2 cores.

Negative staining studies of human immunodeficiency virus (HIV) have been hampered by the fragile nature of the particles. Although detergent treatment is capable of releasing cores from HIV-2 particles, these are unstable and do not retain morphological integrity. Addition of glutaraldehyde will stabilise these structures but, if used at too high a concentration, will destroy their antigenicity. This study shows that if both detergent and glutaraldehyde are used in correct proportions, antigenically reactive cores can be recovered from HIV-2 cell cultures. More specifically we show that a mixture of 0.1% Nonidet P40 and 0.1% glutaraldehyde produces preparations of HIV-2 cores that are suitable for immune electron microscopy. These cores reacted positively, that is, formed immune complexes, with both human HIV-2 antisera and a mouse monoclonal antibody that, although directed against p24 (HIV-1), reacts also with p25 (HIV-2).

Antigens, Viral↗
PubMed1988

The morphology of human immunodeficiency virus (HIV) by negative staining.

We have examined preparations of human immunodeficiency virus 1 (HIV-1) and HIV-2 by negative staining electron microscopy. HIV-2 cultures contained large numbers of 130-200 nm particles containing a 130-nm-long by 30-70 nm-wide core. This core is probably of conical or pear-shaped morphology. Some particles exhibited a short fringe that could be seen to comprise a regular arrangement of repeating subunits when visualised end on. Identical particles were found in HIV-1 cultures but in much lower numbers. Attempts to carry out negative staining immune EM were unsuccessful. Also detected in both HIV-1 and HIV-2 cultures were small (70-80 nm) fringed viruslike particles. The possible significance of these particles is discussed.

Antibodies, Monoclonal↗
PubMed1988

Further studies of HIV morphology by negative staining.

Thin-section studies of HIV-1- and HIV-2-infected cells were used to establish peak virus productivity and distribution of virus on and around infected cells. Maximum virus yields occurred 7 days after passage; cells at that stage were used as a source of virus for negative staining. Various methods of separating virus and cells were assessed: results showed that gentle homogenization in a Tenbroek-type homogenizer yielded considerably more virus than other techniques. Virus obtained in this way mainly appeared in the form of large clumps. Because of the large numbers of virus particles obtained it was possible to visualize what is probably the immature form of the virus. The inner component of this particle is spherical and, as is discussed, is a transient form proceeding to the now well established, mature, cone-shaped virus core.

Cell Line↗
PubMed1986

Rapid diagnosis and management of parainfluenza I virus infection in common marmosets (Callithrix jacchus).

During 1983 a severe episode of respiratory infection occurred in a marmoset colony at these laboratories. Of 91 marmosets, 69 showed clinical signs of disease, one died and nine were so ill that euthanasia was necessary. Eight were examined post mortem and all showed consolidation of the lungs. Laboratory studies were carried out in an attempt to establish the cause of the outbreak and an interstitial pneumonia was found in seven animals which were examined histologically. Direct electron microscopy of nasal swabs and lung samples revealed the presence of a high titre of a paramyxovirus, and subsequent immunofluorescence studies established that the particular paramyxovirus involved was parainfluenza virus type I. Subsequent studies showed that surviving affected animals had seroconverted to parainfluenza I virus while animals that had not been implicated in the outbreak had not.

Animals↗
PubMed1984

Monoclonal antibodies to herpes simplex virus type 1 glycoproteins show that epitope location influences virus neutralization.

Three monoclonal antibodies, G8D1 , C2D2 , and TI57 , reacting with herpes simplex virus type 1 glycoproteins have been characterised according to the location of their epitope and ability to neutralize infective virus. Immune electron microscopy and a blocking radioimmunoassay were used to locate the epitopes. The results indicate that the epitope recognised by G8D1 is located on the surface of the glycoprotein fringe, whereas those recognized by C2D2 and TI57 are interior with respect to this. Only G8D1 has neutralizing activity alone, whereas C2D2 can neutralize when antiglobulin is added. Thus, epitope location and density determine the neutralizing capacity of individual antibody molecules.

Antibodies, Monoclonal↗
PubMed1984

An electron microscope study of three-component immune complexes.

Immune electron microscopy has been used to examine the appearance of three-component complexes. The three components are antigen, supplied by two dissimilar viruses, antibody, and a secondary immune reactant. Secondary reagents used in the study are antispecies immunoglobulin (anti-IgG), rheumatoid factor (RF), and complement. Each of these secondary reagents produced cross-linking between antigenically unrelated immune complexes, and it was found possible to distinguish visually the mixed complexes produced by each of them. The significance of the appearance of these mixed complexes is discussed and related to the neutralisation enhancement that can occur in the presence of secondary immune reactants. The appearance of the complexes is also related to the false positive results that can be obtained in carrying out solid phase immunoassays.

Antibodies, Anti-Idiotypic↗
PubMed1984

A regular subunit pattern seen on non-infectious Newcastle disease virus particles.

A pseudo-crystalline array of subunits has been observed on particles of the La Sota, in contrast to the Ulster , strain of Newcastle disease virus (NDV) grown in MDBK tissue culture without trypsin. This regular arrangement of subunits was associated with the semi-permissive nature of the tissue culture system, as it disappeared when trypsin, which allows infectious virus to be made, was added. The phenomenon described was considered to be related to the crystalline array of matrix protein which has been described inside the envelope of Sendai virus and NDV by others.

Animals↗
PubMed1981

The use of markers in immune electron microscopy.

Immune electron microscopy (IEM) cannot be used successfully for structures that do not have recognisable morphology. However, at least some of these structures or components are related antigenically to recognisable antigens or viruses. We have therefore mixed unknown antigens with known markers and looked for the presence of mixed aggregates. The present study examined a low molecular weight subunit of rotavirus and a micellar form of hepatitis B surface antigen. In both cases mixed immune aggregates were found showing that the unknown components had antigens in common with the established virus or antigen.

Antigen-Antibody Complex↗
PubMed1980

The role of rheumatoid factor in an electron microscope study of hepatitis B antigens.

An immune electron microscopic (IEM) study of the hepatitis B e antigen (HBeAg) system has shown that rheumatoid factor (RE) can be an important complicating factor when examining preparations containing multiple antigenic specificities. For example, in the presence of RF, mixed immune complexes were produced that suggested HBeAg might be antigenically related to either Dane particles or cores. When RF was removed, however, the putative HBeAg--anti-Hbe complexes showed no relationship with any other hepatitis B component. It has been shown that RF can have a positive practical application in IEM by using it to link preformed marker complexes to immune complexes which do not contain morphologically recognizable antigen.

Antigen-Antibody Reactions↗
PubMed1980

A new phenomenon (SMOG) associated with solid phase immune electron microscopy.

Solid phase immune electron microscopy (SPIEM) has been used to study the interaction of virus and antibody both quickly and with economy of reagents. Unexpectedly, the present study shows that when virus-coated grids are floated on drops of specific antibody the virus particles migrate to form complexes. This has been termed specific migration on the grid (SMOG) and it is suggested that it can be used both to assess the properties of an antiserum and to make virus more readily detectable. The mechanism by which SMOG occurs is not understood but various possibilities are discussed.

Antibodies, Viral↗
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↗