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Biomedical subjects

D M McLean

Publications and source records attributed to D M McLean.

At least 55 records · Page 3Linked to original sources
PubMed1970

Gastroenteritis of infants in two Canadian communities.

Enteroviruses were isolated from 11 of 1391 rectal swabs collected from 1103 infants aged less than 2 years who were hospitalized in Toronto, Ontario, and New Westminster, British Columbia, between April 1966 and March 1969. Viruses were recovered from 23 of 1231 rectal swabs obtained from 1076 age-matched control patients without gastroenteritis. The dominance of coxsackievirus and echovirus strains in Toronto patients with and without gastroenteritis contrasted sharply to their extremely low incidence in New Westminster where the Sabin attenuated strains of poliovirus composed the majority of isolates from both categories of patient. Although enteropathogenic bacteria were identified in 36 cases of gastroenteritis and 11 control subjects, no patient excreted a bacterial pathogen and a virus simultaneously.

British Columbia↗
PubMed1967

Myxovirus dissemination by air.

Myxoviruses including 150 strains of parainfluenza 1, 15 of parainfluenza 3 and five of influenza B virus were isolated from nasopharyngeal secretions obtained from 300 children less than 3 years of age who developed acute laryngotracheobronchitis during the preceding 48 hours. The patients were examined between October 1966 and January 1967, the peak monthly rate of virus isolation (67%) occurring during January. Parainfluenza 1 virus was isolated from air obtained in the vicinity of one of 30 children whose nasopharyngeal secretions yielded this agent. Samples comprising 150 litres of air were collected for virus assay by placing an Andersen sampler about 60 cm. from the child's face inside an oxygen tent which surrounded the patient. These findings confirm previous observations that parainfluenza 1 virus is the dominant agent associated with acute laryngotracheobronchitis in children in Toronto, and they show that this virus is disseminated in the air.

Air Microbiology↗
PubMed1967

Mumps and enteroviral meningitis in Toronto, 1966.

Of 52 children admitted to hospital for apparently typical mumps meningitis in 1966, 50 had their cerebrospinal fluid (CSF) examined. In only 17 was the mumps virus isolated from the CSF. Mumps antihemagglutinin conversions or increments were detected in 32 subjects including 10 whose CSF yielded virus. Antibody conversions were found in 16 patients and fourfold increments in another nine whose serum pairs were collected only one to four days apart. Initial sera from 20 patients were obtained three days or less after the onset of meningitis. Antibody increments were frequently noted about one day after defervescence and clinical improvement. Interferon was detected in CSF from two of eight patients, both of whom yielded virus. Enteroviruses were isolated from CSF and/or feces in seven of 15 cases of aseptic meningitis which occurred between July and October. Six patients including three virus excretors showed enteroviral neutralizing antibody increments during convalescence. The dominant enteroviral serotype was coxsackievirus A9.

Child↗
PubMed1967

Powassan virus: persistence of virus activity during 1966.

Powassan virus isolations were achieved from three of 60 pools of Ixodes cookei ticks removed from 286 groundhogs (Marmota monax) which were collected some 200 miles north of Toronto between May 5 and September 5, 1966. Virus yields per pool of one to 11 ticks ranged from 10(2.5) to 10(6.0) TCD(50) for primary swine kidney tissue cultures, and positive pools were collected on June 24, July 15 and August 10. Powassan neutralizing antibodies were detected by mouse inoculation tests in 143 of 362 animals including 127 of 286 groundhogs, 14 of 45 red squirrels (Tamiasciurus hudsonicus) and two of 31 other forest mammals. The monthly prevalence of antibody in the current season's groundhogs increased from 0 to 25% with the progression of summer, but in older animals the incidence remained between 38 and 62% throughout the season. These results substantiate earlier findings which pointed towards the maintenance of Powassan virus in nature by a cycle involving groundhogs and squirrels as reservoirs, with ticks as vectors, from which human infections occurred tangentially.

Animals↗
PubMed1966

Rubella virus infections during pregnancy, Toronto, 1963-66.

Among 670 pregnant women who attended the antenatal clinics of two Toronto city hospitals and one suburban hospital between May 1963 and January 1966, 29 of 550 patients apparently acquired rubella neutralizing antibodies, including 12 whose initial sera were collected during the first trimester. None developed overt rubella. Although rubella antibodies were detected in 61 to 79% of mothers aged 20 years or more, and antibody conversions were detected in 4 to 10% of mothers in each five-year age group between 16 and 39 years, tho rubella syndrome did not appear among any of their offspring. Five of seven other infants, aged 4 to 22 weeks, with the rubella syndrome excreted rubella virus. Rubella neutralizing antibodies were detected in all seven of these infants; these persisted at least 56 weeks in one subject. One mother who received gamma globulin during the first trimester was delivered of an infant who showed signs of the rubella syndrome.

Adolescent↗
PubMed1966

Viral infections of Toronto children during 1965: II. Measles encephalitis and other complications.

Among 16 cases of measles encephalitis observed in Toronto during 1964 and 1965, including six who were stuporous or comatose on admission and five who presented with convulsions, measles virus was isolated from CSF of one patient, rising titres of measles antihemagglutinin were detected in another patient, and 14 showed high antibody titres in sera collected as early as two to five days after onset of the measles rash. Increasing levels of measles antibody were detected in paired sera from three of seven patients with uncomplicated measles, and elevated antihemagglutinin titres were found in 16 cases of measles without neural involvement. Measles virus was isolated from lung tissue of a fatal case of giant cell pneumonia. Administration of pooled human gamma globulin to one leukemic patient, and of leukocytes from a convalescent donor to another leukemic child, may have assisted their recovery from measles.

Child↗
PubMed1966

Viral infections of Toronto children during 1965. I. Enteroviral disease.

Enteroviruses were isolated from feces and/or cerebrospinal fluid of 29 of 43 Toronto children who contracted aseptic meningitis, pleurodynia, abdominal pain or febrile upsets between June and October, 1965. Coxsackie A9 virus was the dominant agent in aseptic meningitis and Coxsackie B1 virus in pleurodynia and other syndromes. Sero-logical evidence of recent Coxsackie B1 and Echo 6 infection was obtained in two additional patients with aseptic meningitis who did not yield virus, and elevated Coxsackie B1 antibody titres were found in one patient with pericarditis. A newborn infant died with myocarditis due to Coxsackie B1 virus following infection of the mother during the immediate antenatal period. Paired sera collected only two to four days apart from patients with enteroviral syndromes or mumps meningoencephalitis frequently showed four-fold or greater increases of antibody levels.

Blood↗
PubMed1966

Powassan virus: vernal spread during 1965.

Powassan virus was isolated from seven pools of Ixodes cookei ticks removed from groundhogs (Marmota monax) collected near North Bay, Ontario, between May and August 1965, including five pools obtained during spring. Tick pools, each comprising one to nine ticks, contained 2.0 to 5.5 log(10) TCD(50) of virus upon titration in monolayer cultures of primary swine kidney cells. Powassan virus neutralizing antibody prevalence in sera of the current season's groundhogs increased steadily from zero during May to 25% during August but remained relatively unchanged (42% to 58%) in the previous season's groundhogs, thereby confirming that active infection had occurred particularly amongst juvenile groundhogs mainly during spring 1965. Isolation of one strain of Silverwater virus from Haemaphysalis leporis-palustris ticks and detection of neutralizing antibody in three of nine snowshoe hares (Lepus americanus) confirmed the active spread of this agent during 1965.

Animals↗