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Biomedical subjects

R G McLean

Publications and source records attributed to R G McLean.

At least 73 records · Page 4Linked to original sources
PubMed1985

Quantitation of pulmonary gallium-67 uptake: comparison of computer-derived indices.

A variety of computer-derived indices of pulmonary gallium-67 were compared in 51 subjects with and without interstitial lung disorders. An index which quantitates lung uptake in relation to liver uptake, both being corrected for tissue background activity over the thigh, was the most reliable in differentiating between the two patient groups. The index is easily derived using standard computer techniques, so permitting further studies to assess its role in serial assessments of the progress of these disorders.

Computers↗
PubMed1985

Investigations of the vertebrate hosts of eastern equine encephalitis during an epizootic in Michigan, 1980.

A study was undertaken to investigate an increase in reported cases of clinical encephalitis due to eastern equine encephalitis (EEE) virus in horses and to determine the natural vertebrate hosts of that virus. Horses, birds, and small mammals were sampled at sites in a contiguous area in St. Joseph and Kalamazoo counties, Michigan, from 25 August to 5 September 1980. Serum samples from four horses acutely ill with encephalitis and 16 of 39 pasture mates of ill horses had neutralizing (N) antibody against EEE virus (46.5%); no viruses were isolated from these 43 sera. None of 24 draft horses from a site in St. Joseph County 12 km southeast of the affected sites had EEE antibody. A strain of Cache Valley virus was isolated from the blood of one of the 24 draft horses. No viruses were isolated, and no antibodies to EEE virus were detected in 28 blood samples from small mammals captured at sites where equine cases of encephalitis were occurring. Six strains of EEE virus, five of Highlands J virus, and one of Flanders virus were isolated from the blood of 401 wild birds belonging to 42 species captured at eight sites in both counties. A total of 29.9% of the wild birds had EEE antibody. Five species of domestic birds, mostly chickens and ring-necked pheasants, were sampled in both counties. Six strains of EEE virus were isolated from 152 ring-necked pheasants; these included three isolates from the brains of dead birds. About 13% of 51 pheasants tested from two small flocks in backyard pens in Kalamazoo County and 9% of 103 pheasants tested from a large game farm in St. Joseph County had antibody to EEE virus. The source of the EEE virus and the factors responsible for this epizootic are unknown; however, the epizootic probably represented an explosive expansion of an enzootic level of virus transmission.

Alphavirus↗
PubMed1985

Experimental studies of St. Louis encephalitis virus in vertebrates.

Serologically negative birds and mammals of species, known from other studies to be exposed naturally to St. Louis encephalitis (SLE) virus in Memphis, Tennessee, and other selected species were inoculated experimentally with strains of SLE virus to determine their potential as natural hosts. Mosquitoes (Culex sp.) were allowed to feed on some of the inoculated vertebrate species, held for 14 days, and tested for SLE infection. The cardinals (Richmondena cardinalis), robins (Turdus migratorius), and baby chicks (Gallus gallus) all became viremic; 97% of the bobwhites (Colinus virginianus) and 20% of the Japanese quail (Coturnix coturnix) became viremic. No viremia was detected in raccoons (Procyon lotor), opossums (Didelphis virginiana), or adult cotton rats (Sigmodon hispidus). Only 20% of cottontail rabbits (Sylvilagus audubonii), 50% of wood rats (Neotoma mexicana), and 75% of hamsters (Mesocricetus auratus) but all the young cotton rats and least chipmunks (Eutamias minimus) were susceptible. Robins had the highest titered viremia but were viremic for the shortest period of time. Bobwhites had lower peak viremia titers but for a longer duration. Biologic differences in the response of some vertebrates to different SLE strains were noted. Culex pipiens quinquefasciatus mosquitoes readily became infected after feeding on viremic cardinals. Comparisons of the experimental data with information obtained from field investigations provided a better understanding of the contributions of the various vertebrate species to the transmission and maintenance of SLE virus in nature.

Animals↗
PubMed1984

A pilot study of flutamide. A new agent in the treatment of advanced prostatic cancer.

Flutamide, a new non-steroidal antiandrogenic agent, was administered in the treatment of five assessable patients with advanced carcinoma of the prostate. Two patients showed significant clinical benefit, one showed a reduction in his requirement for analgesia and two failed to benefit; side-effects were minimal. These results indicate the need for a controlled clinical trial of flutamide in patients with prostatic cancer.

Anilides↗
PubMed1984

Scintigraphic patterns in certain primary malignant bone tumours.

The diagnosis of solitary bone lesions can be difficult. Skeletal scintigraphy has not achieved a major role for this purpose, being used primarily to determine the presence of metastatic disease. The scintigraphs of 52 patients, comprising 22 with osteogenic sarcoma, 16 with Ewing's sarcoma and 14 with chondrosarcoma, were reviewed. This comparison revealed that each tumour tends to be associated with a characteristic pattern permitting a particular diagnosis to be suggested, thus improving specificity and contributing to patient management.

Adolescent↗
PubMed1984

Three-phase skeletal scintigraphy for suspected bone tumors.

The advantage of using three-phase skeletal scintigraphy rather than merely conventional delayed imaging in the investigation of suspected bone tumors is illustrated by two cases in which this procedure provided greater information on the site and extent of the lesion than other single modalities.

Adolescent↗
PubMed1984

Unexpected gallium uptake in benign pulmonary pathology. Report of two cases.

Two cases in which pulmonary gallium uptake was demonstrated in benign conditions are reported. In one, the abnormality permitted localization of a benign mesothelioma, while in the other patient it was associated with pulmonary fibrosis resulting from therapeutic irradiation. These cases extend the causes of gallium accumulation in which neither malignancy nor infection is responsible.

Aged↗
PubMed1984

Cholescintigraphy in acute cholecystitis: use of intravenous morphine.

Conventional cholescintigraphy (60 patients) and a modified protocol (59 patients) were compared in 74 females and 45 males with acute cholecystitis. In the modified protocol, intravenous morphine (0.04 mg/kg) was administered whenever the gallbladder was not seen 40 minutes after injection of Tc-99m-pyridoxylideneglutamate (36/59). Accuracy was 98% with morphine, compared with 88% for the conventional protocol; specificity improved from 83% to 100% with no loss of sensitivity (96% in both groups). Low doses of morphine are well tolerated and can result in a highly accurate diagnosis of acute cholecystitis without the need for delayed imaging.

Acute Disease↗
PubMed1983

Persistence of rabies antibody in free-ranging raccoons.

The immune status of a wildlife population to rabies virus probably influences the occurrences of epizootics among that species in a given geographical area. This is not to say that enzootic transmission of the virus will not occur, but rather that attainment of epizootic levels may be hampered through herd immunity. After an epizootic of rabies in a raccoon population in the Fall of 1970, a serologic surveillance program was initiated from November 1970 through August 1974. The surveillance provided the opportunity to determine the persistence of antibody in individual animals as well as to compare the sensitivity of intracerebral mouse inoculation and the RFFIT. The average point prevalence of neutralizing antibody was 20.9% (range, 15.5% [1970] to 25.0% [1974]). Fifty-one (18%) of the 476 raccoons monitored during the study period were trapped more than once. The testing of sequential serum samples from individual seropositive raccoons indicated that serum neutralizing antibody can persist for at least 37 months. It cannot be stated with certainty that these antibody titers resulted from a single exposure to rabies virus and were not boosted by further experience with the virus. Serial serology tests on three young raccoons (less than 15, 30, and 52 weeks of age) suggest that endemic rabies virus was circulating in or near the study area between June 1972 and February 1974. Thirty-six raccoons trapped in November 1970 were shipped to the Centers for Disease Control, Lawrenceville, Ga, where they were held in captivity for observations and serologic monitoring.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

The house sparrow (Passer domesticus) as a sentinel for St. Louis encephalitis virus.

Birds are the primary hosts for St. Louis encephalitis (SLE) virus in most of North America. Because the increased prevalence of antibody in House Sparrows (Passer domesticus) has been related to human cases, this species has been frequently used as a sentinel of SLE virus activity in urban areas. This study investigated the susceptibility of House Sparrows to two strains of SLE virus, measured antibody profiles, and evaluated the use of House Sparrows in an urban surveillance system. House Sparrows were susceptible to both strains of SLE virus inoculated, although not equally, and produced viremias sufficient to infect vector mosquitoes. Both hemagglutination-inhibiting (HI) and neutralizing (N) antibody developed rapidly and to high titers within 2 weeks after inoculation. Detectable humoral antibody began to disappear by 3 months, but persisted for 2 years in 27% for HI and 36% for N antibody of the surviving birds. However, all of the surviving birds were resistant to reinfection with SLE virus at 2 years after inoculation. The titer of HI antibody appeared to be useful in determining recent exposure to SLE virus. The experimental data on HI antibody development and persistence was related to field serologic data from House Sparrows. The monthly prevalences of SLE antibody for independent samples of sera from House Sparrows collected in Memphis, Tennessee, in 1980 were similar. SLE amplification in the House Sparrow population was delayed until September. The Memphis arbovirus surveillance system detected the amplification quickly, and responded with increased adult mosquito control in the focal areas. Urban surveillance of SLE utilizing House Sparrows as sentinels is discussed.

Animals↗
PubMed1983

Experimental infections of birds with Turlock virus.

Two experiments were conducted with five gallinaceous and one passerine bird species to determine their responses to Turlock (TUR) virus inoculations. Inoculation of TUR strain 847-32 into bobwhites, chukars, ring-necked pheasants, chickens, and Japanese quail did not product detectable viremias. The first four species, however, did respond with neutralizing antibody. Inoculation of chickens with strain 69V-1095 resulted in a viremia which lasted 5 days and had a peak mean titer of 2.0 log 10 PFU per 0.2 ml of blood on the third day after infection. The observation that viremic birds exhibited no noticeable virus-associated morbidity or mortality suggested that TUR virus does not have a detrimental effect on free-ranging populations of the avian hosts studied during this investigation.

Animals↗
PubMed1982

Experimental studies of Rio Grande virus in rodent hosts.

Rio Grande (RG) virus, a new member of the Phlebotomus fever serogroup, was inoculated into wild wood rats (Neotoma micropus) and laboratory-reared cotton rats (Sigmodon hispidus) to determine if these potential hosts could be experimentally infected. Nine of 14 (64%) wood rats became viremic, with titers of circulating virus ranging from 10(2.3) to 10(5.3) plaque-forming units (PFU)/ml and a geometric mean titer of 10(3.7) PFU/ml. Virus was not detected in urine specimens from inoculated wood rats but was found in a single saliva specimen. RG virus was detected in the blood of 1 of 12 (8%) cotton rats. Neutralizing (N) antibody developed in 8 of 9 inoculated wood rats which survived for 30 days postinoculation and in 11 of 12 cotton rats. N antibody was still detectable in 4 of 7 wood rats which survived for 1 year, and all 7 were resistant to rechallenge with the virus, as were 3 wood rats with naturally-acquired antibody. High mortality (36%) occurred in inoculated wood rats; whereas low mortality (8%) occurred in cotton rats. The specific cause of death of the rats was not determined. Modes of transmission of the virus in nature are discussed.

Animals↗
PubMed1982

Potentiation of keystone virus infection in cotton rats by glucocorticoid-induced stress.

Cotton rats (Sigmodon hispidus) were treated daily with corticosteroids and then inoculated with keystone virus. Viremia and neutralizing antibody profiles were determined in treated and untreated rats. Compared to untreated rats, the treated rats were substantially more susceptible to infection, and their viremia lasted much longer. This experimental model suggests that stress associated with excess glucocorticoid synthesis within a natural population could cause an increase in transmission of arboviruses. It also suggests that the effects of stress should be considered when experimental laboratory studies are designed.

Animals↗