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Biomedical subjects

J H Joncas

Publications and source records attributed to J H Joncas.

At least 55 records · Page 3Linked to original sources
PubMed1977

Viral attributes and host factors in carcinogenesis: herpesviruses.

This paper describes two different experiments of nature: 1) the persistence of unusual virus strains of Epstein-Barr virus (EBV) (which proved oncogenic in vitro) and cytomegalovirus (CMV) in lymphoid cells following congenital or early acquired infection; 2) the occurence of multiple cases of Burkitt's lymphoma and nasopharyngeal carcinoma in one family. All the members of this family were EBV viral capsid antigen (VCA) and nuclear antigen (EBNA) antibody positive. The two patients with nasopharyngeal carcinoma had high titers of EBV-VCA, EA, and EBNA antibodies. The only member of this family having EBV early antigen (EA antibodies in addition to the patients with tumors was the mother. Borderline IgA deficiency was documented in 3 members of this family. These findings illustrate the importance of host factors (intracellular resistance to transformation and secondarily, immunological surveillance) in the outcome of the host-virus challenge whether cancer or infectious disease is the outcome. Extensive studies of these cases may provide the best insight into the mysteries of viral oncogenesis.

Antibodies, Viral↗
PubMed1976

Nasopharyngeal carcinoma and Burkitt's lymphoma in a Canadian family. I. HLA typing, EBV antibodies and serum immunoglobulins.

Two nasopharyngeal carcinomas of the lymphoepithelioma type and two Burkitt's lymphomas with the characteristic histopathologic features developed in three siblings and one first-degree cousin in a large French-Canadian family. Epstein-Barr virus antibody titres in the two lymphoepithelioma cases but not in the Burkitt's lymphoma cases were, as expected, greatly elevated. HLA typing of the family members failed to disclose HLA antigens A2 and B Sin-2, which have been associated with lymphoepithelioma in Asia. The occurrence, however, of a plasmacytoma in one other first-degree cousin and low serum IgA values in several siblings and cousins suggests the possibility of a genetically determined predisposing B-cell dysfunction in the development of these tumours.

Adolescent↗
PubMed1976

Herpes encephalitis. Rapid diagnosis and treatment with antiviral drugs.

The use of specific IgM antibodies and direct electron-microscopic examination of brain biopsies or vesicle fluid was tested as means of raped diagnosis in 6 cases of herpes simplex encephalitis seen consecutively in Montreal. In 2 of 3 biopsies herpes viruses were seen by negative staining of a cell extract within 1 hr. In the negative case, the biopsy was done almost 1 month after onset. In 2 additional cases herpes virus particles were found directly in the fluid of isolated vesicles. In the last 2 cases, who survived, the diagnosis of herpes encephalitis rested upon the demonstration of a greater than 4-fold rise in complement fixing herpes simplex virus antibodies in convalescent sera and upon the appearance late in the course of the encephalitis of specific antibodies in the cerebrospinal fluid. The early appearance of specific IgM antibodies contributed to the diagnosis in 4 of the 6 cases. Antiviral therapy was attempted in alternate cases (3 cases) but was not successful. Brain biopsy is rarely performed for diagnostic purposes but when prompt antiviral therapy is contemplated, the examination of the biopsy material for herpes virus particles by electron microscopy in negative staining and thin sections can rapidly and reliably confirm the diagnosis.

Aged↗
PubMed1975

Interpretation of the PPD skin test in BCG-vaccinated children.

Skin testing with 5 tuberculin units (TU) of purified protein derivative (PPD) of tuberculin stabilized with polysorbate (Tween) 80 was done 3 months and 1 year after immunization with bacille Calmette-Guérin (BCG) vaccine in two groups of children: one group vaccinated at birth and another group at age 6 years. Interpretation of the PPD skin test with 5 TU is possible in children 1 year and older vaccinated with BCG at birth: if the diameter of induration is more than 10 to 12 mm the reaction cannot be ascribed to BCG vaccination and is highly suggestive of supervening infection with Mycobacterium tuberculosis or occasionally atypical mycobacteria. In contrast, the interpretation of a PPD test in children vaccinated at age 6 years is extremely difficult.

BCG Vaccine↗
PubMed1975

Improved Epstein-Barr virus immunoglobulin M antibody test.

The successful demonstration of Epstein-Barr virus immunoglobulin M (EBV IgM) antibody in human sera has been accomplished to date by at least four groups of workers. Many, however, including ourselves, have had difficulty in getting reproducible results with the techniques described. The three-coat technique described by H. Schmitz and M. Scherer (1972) on both fractionated and unfractioned sera was adopted with minor modifications. The Hyland antihuman IgM antiserum used in the second coat was made specific by absorption on Cohn fraction II. This step in the procedure was found to be the single most important factor in arriving at reproducible results in the IgM test. The EBV IgM antibodies from our results to date with this method in 14 cases of heterophil-positive cases of mononucleosis appear short lived, lasting 2 months or less. These antibodies were found in only 2 of 18 selected non-mononucleosis cases, in both associated with EBV-viral capsid antigen antibody rise or seroconversion. The successful elimination of nonspecific fluorescence by a simple, inexpensive procedure and the possibility of testing unabsorbed, unfractionated sera directly will facilitate the use oe the EBV IgM antibody test in the future.

Absorption↗
PubMed1974

Limitations of immunofluorescence tests in the diagnosis of infectious mononucleosis.

The relative value of heterophil agglutinins (HA) and of specific EBV antibodies in the diagnosis of infectious mononucleosis (IM) was assessed in 108 cases of the disease and in 280 controls. Among the 108 cases 93 were HA-positive by sheep cells in at least one of their sera, while 15 were HA-negative by the same test. Among the 280 controls false-positive HA tests were not encountered except in eight cases with the horse cell microtitre tests. With one of the two slide tests at least two false-positive tests and 12 false-negative tests were also found but these sera had low titres in microtitre tests. The HA life-span was found to be unexpectedly long in a few cases, sheep cell HA lasting up to 8 to 10 months and horse cell HA up to 21 to 23 months.Many false-positive tests may therefore not be true false-positives and may result from the persistence of HA following unrecognized mononucleosis months before. Virtually all cases of IM had (or developed) antibodies to Epstein-Barr virus, viral capsid antigen (EBV-VCA), whereas only half of the controls were EBV-VCA-positive. The comparative analysis of nonspecific and specific test results in mononucleosis allows the following conclusions: (1) horse cell microtitre tests and the monospot test are more sensitive than sheep cell microtitre tests and the monotest; (2) false-negative results are occasionally seen with the latter tests but not with the former; (3) more false-positive results, however, are probably seen with the former tests; and (4) specific EBV-IgM and EBV-EA antibody tests are useful in the diagnosis of selected borderline cases of mononucleosis.

Adult↗