Biomedical subjects

J M MacLean

Publications and source records attributed to J M MacLean.

15 recordsLinked to original sources

PubMed1997

Monoclonal origin of concordant T-cell malignancy in identical twins.

Acute leukemia has a high concordance rate in young identical twins and in infants this is known, from molecular analysis, to reflect an in utero origin in one twin followed by prenatal metastasis to the other twin via intraplacental anastomoses. The situation in older twins with leukemia has been less clear. We describe a pair of identical twins who were diagnosed with a T-cell malignancy at 9 and 11 years of age, one with T-cell non-Hodgkin's lymphoma and the other with T-cell acute lymphoblastic leukemia. Leukemic cells from the twins shared the same TCR beta gene rearrangement with an identical 11 bp N region. The most plausible interpretation of this result is that these malignancies were initiated in one twin fetus in utero, in a single T-lineage cell that had stable bi-allelic TCR beta rearrangements. Progeny of this cell then spread to the other twin before birth via shared placental vasculature. This was then followed by a 9- and 11-year preleukemic latent period before clinical disease manifestation as leukemia or lymphoma. This result has considerable implications for the etiology and natural history of pediatric leukemia.

Alleles↗

PubMed1991

Pathophysiological studies on Dicrocoelium dendriticum infection in sheep.

Red cell kinetics and plasma protein metabolism were investigated in two experiments using 20 adult sheep naturally infected with Dicrocoelium dendriticum, but free of other liver and gastrointestinal helminths. In the first experiment, where groups of animals with low to high Dicrocoelium burdens were injected with 51Cr-labelled red cells and 125I-labelled albumin, the results indicated that there were no significant differences in the turnover rate of labelled red cells or albumin between any of the groups. In the second experiment, two groups of sheep with low and high worm burdens were studied using the same radioisotope tracers; in addition, 59Fe-citrate was used to assess red cell iron incorporation rates in the two groups. Although the red cell half-lives of the infected sheep were just significantly longer, both were within normal limits and the difference was attributed to random variation within the two small groups of sheep. No significant differences were found in the other parameters. It was concluded that burdens of up to 4000 D. dendriticum do not cause significant blood or plasma protein loss in sheep.

Animals↗

PubMed1991

Pathophysiology of Haemonchus placei infection in calves.

This study was conducted to investigate the pathophysiology of Haemonchus placei infection in Friesian calves. Seven calves were divided into two groups, three uninfected calves (control group) and four infected animals. The latter group were infected orally with 500 H. placei larvae kg-1 body weight. Five weeks after infection they were all housed in metabolic crates and injected with 125I-bovine albumin. 51Cr-red cells and 59Fe-transferrin, to study albumin metabolism, erythrokinetics and ferrokinetics. The results showed that there was a significant reduction in the mean haematocrit values and reduced weight gains in the infected calves compared with the controls. There was also a change in the distribution of albumin from the extravascular to the intravascular pool and a significant increase in the plasma and blood volumes of infected calves although the blood and albumin loss via the gastrointestinal tract recorded in this study was similar in both groups.

Age Factors↗

PubMed1976

Cerebral embolism, marantic endocarditis, and cancer.

Two subjects with cerebral embolism were found at autopsy to have marantic (nonbacterial thrombotic) endocarditis (NBTE) and an unsuspected carcinoma. A additional 16 subjects with marantic endocarditis and cancer were found on reviewing the autopsy records of 22 subjects with NBTE. Of these 18 subjects with NBTE and cancer, eight developed a stroke during their illness, in five as the initial manifestation of cancer. Although the association of cancer and marantic endocarditis is generally well recognized, cerebral embolism from this source should be more seriously considered as one of the "remote effects" of cancer on the nervous system.

Carcinoma↗

PubMed1973