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Biomedical subjects

D A Morgan

Publications and source records attributed to D A Morgan.

148 records · Page 9Linked to original sources
PubMedDate not supplied

Transmural regulation of myocardial perfusion by neuropeptide Y.

In vivo studies have shown that sympathetic nerve stimulation improves the transmural distribution of myocardial perfusion by increasing the endocardial/epicardial flow ratio; however, the mechanism of this effect is unknown. During nerve stimulation both norepinephrine (NE) and neuropeptide Y (NPY) are released, either or both of which may exert vasoconstrictor effects. The present studies were performed to examine the effects of these two cotransmitters on the transmural distribution of myocardial perfusion in a canine model. In anesthetized open-chest dogs, during maximal coronary vasodilation with intracoronary adenosine, both neuropeptide Y (29.7 micrograms/min) and norepinephrine (0.5-2.0 micrograms/min) reduced myocardial perfusion to a greater extent in the epicardium than in the subendocardium. The endo/epi ratio with adenosine alone was 1.11 +/- 0.02. Norepinephrine increased this by 80%, neuropeptide Y by 20%, and the combination of the two by 76% (P < 0.05 for all three vs. adenosine). Neuropeptide Y alone constricted the coronary vasculature but did not alter transmural flow. Thus neuropeptide Y preferentially reduces myocardial perfusion in the epicardium. We speculate that neuronally released neuropeptide Y contributes importantly to the transmural distribution of myocardial perfusion during sympathetic nerve stimulation.

Animals↗
PubMedDate not supplied

p24 antigen screening to reduce the risk of HIV transmission by seronegative bone allograft donors.

BACKGROUND: During the last decade, more than 2000 bone allografts harvested from 888 donors and processed by the Queensland Bone Bank have been transplanted in over 1500 patients in Australia and New Zealand. A strict protocol to eliminate HIV transmission by fresh frozen allografts is followed; and not a single case of HIV transmission has been reported. METHODS: All donors were screened and strict donor exclusion criteria were used. All donor blood samples were subjected to double testing including antibody to HIV-1, HIV-2 and HTLV-1 and p24 antigen. The allografts negative for these tests were subjected to processing, including removal of extraneous tissue, pulsatile lavage to remove marrow elements, and immersion in 97% alcohol for 20 minutes. Allografts were subjected to 25 cGy irradiation before transplantation. RESULTS: Allografts were retrieved from a total of 950 donors and 51 were discarded after screening for contamination by organisms other than HIV-1. Eleven donors negative for HIV-1 antibodies tested positive for p24 antigen and were discarded. Allografts from donors testing negative for both the tests (n = 888) were irradiated and used for transplantation. CONCLUSIONS: Routine p24 antigen testing and irradiation of allograft should be mandatory for bone banks, especially those freezing fresh allografts. p24 antigen testing is inexpensive, rapid and easy. Certain guidelines must be followed to avoid misleading results of p24 testing.

Bone Transplantation↗