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J Aaskov

Publications and source records attributed to J Aaskov.

5 recordsLinked to original sources
PubMed1993

Changes in levels of anti-dengue virus IgG subclasses in patients with disease of varying severity.

Extensive complement activation precedes onset of shock in dengue patients and complement "split products" C3a and C5a could be responsible, directly or indirectly, for the increased vascular permeability and disseminated intravascular coagulation which characterises dengue haemorrhagic fever (DHF) dengue shock syndrome (DSS). As IgG subclasses vary in their capacity to activate the classical complement pathway after combining with antigen, we have used an indirect enzyme linked immunosorbent assay (ELISA) to assess levels of IgG1-4 against each dengue serotype in acute and convalescent sera from patients with disease of varying severity. Acute phase sera from patients with dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS) contained higher levels of anti-dengue antibodies of the IgG1, complement fixing, subclass than similar sera from dengue fever (DF) patients. Conversely, acute phase sera from DHF and DSS patients contained lower levels of anti-dengue antibodies of the poor complement activating IgG2 subclass than acute phase sera from DF patients. No significant differences were detected between the levels of anti-dengue IgG3 and IgG4 antibody in acute phase sera from DF, DHF, and DSS patients. With the exception of levels of anti-dengue IgG2 antibody from DHF patients which were lower than those from DF and DSS patients, levels of anti-dengue IgG1, IgG2, IgG3, and IgG4 were similar in convalescent sera from all patients. These results provide a possible explanation for the activation of the serum complement system which precedes onset of shock in severe dengue infections.

Antibodies, Viral↗
PubMed1987

Dengue.

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Dengue↗
PubMed1984

Natural killer (NK) cell activity against human gingival fibroblasts exposed to dental plaque extracts.

Natural killer (NK) cell activity against plaque pretreated human gingival fibroblasts and against the erythroblastoid cell line K562 also pretreated with plaque extract was studied. Supra- and subgingival plaque was collected and extracts prepared by sonication for 10 to 15 minutes at room temperature. The erythroblastoid cell line K562 was given in RPMI (1640) medium, and served as the control. Gingival fibroblasts were grown from an explant of human gingiva. The K562 cells and gingival fibroblasts were incubated in subcytotoxic doses of both supra- and subgingival plaque for 18 hours prior to the NK cell assay in serum free medium. Pretreatment of the K562 cells with both supra- and subgingival plaque was found to reduce NK cell activity. On the other hand pretreatment of the human gingival fibroblasts with plaque extracts seemed to increase their sensitivity to NK cell activity. This suggests that the plaque pretreatment leads to a cytopathic change in the fibroblasts making them more sensitive to NK cell activity, or alternatively that by binding to target cells, plaque modulates the ability of NK cells to bind to, and kill these cells. Nevertheless, these results indicate that NK cell activity could play a role in tissue destruction in chronic inflammatory periodontal disease.

Cell Count↗
PubMedDate not supplied

Development of a simple indirect enzyme-linked immunosorbent assay for the detection of immunoglobulin M antibody in serum from patients following an outbreak of chikungunya virus infection in Yangon, Myanmar.

During 1984, 1548 children were admitted to the Yangon [Rangoon] Children's Hospital in Myanmar [Burma] with haemorrhagic fever. No evidence of recent dengue infection was found in 577 of the 803 children from whom paired sera were obtained, raising the possibility of reappearance of Chikungunya virus infection in Myanmar. An enzyme-linked immunosorbent assay (ELISA) for the detection of anti-Chikungunya virus immunoglobulin M (IgM) antibody was prepared and standardized using only reagents which are commercially available or which could be prepared without the use of sophisticated equipment. While there was 90% agreement between haemagglutination inhibition (HI) tests and the IgM ELISA in the diagnosis of acute Chikungunya virus infections, 12 additional patients with stationary anti-Chikungunya virus HI antibody titres could be identified as having acute Chikungunya infections using the ELISA. Furthermore, the ELISA could identify twice as many patients (31/103) at the time of admission to hospital as the HI test (15/103). There was no false positive IgM reaction with the ELISA which could be attributed to the presence of rheumatoid factor. Using the test, 103 of a sample of 163 children who presented to the Yangon Children's Hospital with fever/haemorrhagic fever were diagnosed as Chikungunya patients, 4 had possible dual Chikungunya and dengue infections, 16 had dengue, 30 had neither Chikungunya nor dengue infections, and a definitive diagnosis could not be made for 10 patients. Routine use of the ELISA would alert authorities to future outbreaks of Chikungunya virus infection and avoid admission to hospital of patients with a non-life-threatening viral disease.

Antibodies, Viral↗