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Biomedical subjects

A C Allen

Publications and source records attributed to A C Allen.

95 records · Page 6Linked to original sources
PubMedDate not supplied

Perinatal listeriosis: report of an outbreak.

From April to August, 1981, 15 cases of perinatal listeriosis were seen in Halifax, Nova Scotia, Canada. Nine of the 15 mothers presented with 'flu-like' symptoms, 3 had symptoms of an upper respiratory infection and 2 a history of fever alone. During labor 11 mothers had fevers greater than 38 degrees C and 9 had stained amniotic fluid. Twelve delivered prematurely. Among the 15 infants the most common clinical features were perinatal depression, respiratory distress, fever, hematologic abnormalities and rash. There were 7 deaths (case fatality rate of 46.7%). A transplacental route of infection for the fetus was suggested by the signs of systemic illness in most mothers, the lack of positive maternal vaginal cultures and evidence of chorioamnionitis, premature labor, severe fetal disease and intrauterine death prior to membrane rupture. The delivery of healthy infants to two mothers who had received antepartum treatment for listeriosis suggests that earlier recognition and treatment of maternal disease will improve perinatal outcome.

Disease Outbreaks↗
PubMedDate not supplied

Response to mucosal antigen challenge in IgA nephropathy.

While IgA nephropathy (IgAN) is characterized by the deposition of glomerular IgA, the source of the deposited IgA is not known, with both the mucosal and systemic IgA systems being implicated. In order to investigate mucosal and systemic antibody production to mucosal antigen challenge in IgAN, 9 patients and 11 controls were immunized intranasally with tetanus toxoid (TT). There was no significant difference in the serum or saliva IgG, IgA, IgA1, or IgA2 antibody production to TT. However, in IgAN there was an increase of in vitro IgA anti-TT production in Epstein-Barr virus transformed cultures of peripheral blood lymphocytes taken after mucosal immunization. This increase in traffic of immunocompetent cells between the systemic and mucosal systems could play a role in the link between the mucosa and glomerulus in IgAN. Systemic immunization with TT following mucosal priming did not result in any difference in the antibody response between patients and controls. There was no evidence from this study that mucosal immunization results in an enhanced antibody response in IgAN or that mucosal priming alters the subsequent systemic antibody response.

Administration, Intranasal↗
PubMedDate not supplied

In vitro immunoglobulin isotype suppression in immunoglobulin A nephropathy.

IgA nephropathy (IgAN) is characterized by mesangial IgA deposition, and up-regulation of the IgA system is frequently described. This study investigated in vitro immunoglobulin isotype production by peripheral blood mononuclear cells from patients with IgAN and controls, without mitogenic stimulation and under the influence of cell cycle inhibitors and cyclosporin A (CyA). In controls, only IgM production was suppressed by cell cycle inhibitors, and no isotype was affected by CyA. This suppressible IgM production may represent antigen-independent 'natural antibody'. In IgAN, IgM, IgA and IgG were all suppressed by cell cycle inhibitors, and CyA suppressed IgA production. This state of altered immune activation in IgAN demonstrates T-cell-independent IgA production, suggesting that it is IgA 'natural antibody'. In conclusion, we suggest that mesangial IgA deposition may not be antigen dependent but due to some non-immune characteristic of the IgA molecule.

Adult↗
PubMedDate not supplied

Increased IgA and decreased IgG production by Epstein-Barr virus transformed B cells in culture in IgA nephropathy.

Despite many studies describing IgA upregulation both in vivo and in vitro in IgA nephropathy (IgAN), the underlying mechanism of increased IgA production is not known. In this study, Epstein-Barr virus was used to transform B cells in vitro in a T-cell-independent manner in order to investigate immunoglobulin production by B cells in IgAN. B cells from patients with IgAN produced more IgA and less IgG in culture than controls. While both IgA subclasses contributed to the increase in IgA production, only IgA1 synthesis was significantly higher than controls. These results of increased IgA production in patients with IgAN, with a concomitant decrease in IgG production, demonstrate hyperactivity of B cells restricted to the IgA isotype in IgAN.

Adolescent↗