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Biomedical subjects

R E Morgan

Publications and source records attributed to R E Morgan.

At least 19 recordsLinked to original sources

National and international health agencies. Profile of key players.

The major players in international health and health policy have a tremendous potential to contribute to the wellbeing of humankind. Multilateral organizations, such as WHO, have universal areas of concern. The financial multilateral agencies play a key role in influencing development through the leverage of financial resources. Bilateral agencies of donor countries influence health policy direction by the magnitude of their financial resources. Private organizations, including universities, foundations, professional associations, nongovernmental organizations, and US industry, play an important role in identifying important policy issues through research, designing and developing appropriate technology, and acquiring the knowledge base necessary to form sound international health policy decisions.

Global Health

Failure of BCAA supplementation to promote nitrogen retention in injured patients.

The purpose of this study was to determine if supplementing total parenteral nutrition (TPN) with lipids or the branched chain amino acids (BCAA) leucine, isoleucine, and valine influences nitrogen balance in the injured patient. Four TPN study solutions were used, with each patient receiving two of the solutions for 4 days each. Group A received solutions consisting of 19% and 44% BCAA, with nonnitrogen calories supplied by 100% carbohydrate. Group B received a 7:3 carbohydrate-to-lipid ratio of nonnitrogen calories as a fuel source. Neither BCAA supplementation nor varying fuel substrates promoted a difference in nitrogen retention. The added cost of BCAA supplementation, along with the lack of an effect upon nitrogen accretion, indicates that greater benefits must be demonstrated before widespread use of BCAA supplementation can be recommended in the injured patient.

Amino Acids, Branched-Chain

Carnitine femoral arterial-venous differences in the stressed critically ill.

Femoral arterial and venous carnitine concentrations from critically ill patients were measured in order to determine if the large urinary carnitine excretions seen in these patients was associated with a net loss of carnitine from skeletal muscle. Bloods were drawn two or three times during the 7-day study period. A 24-hr urine sample was obtained on the same day. The arterial-venous difference for free carnitine plus short chain acylcarnitine was -2.8 +/- 0.9 microM (means +/- SEM), and -2.7 +/- 1.0 microM for total carnitine. Both values were significantly less than zero (p less than 0.05). Median urinary free carnitine excretion was 1237 mumol/day while the median acylcarnitine excretion was 544 mumol/day. We conclude that skeletal muscle in these patients is in negative carnitine balance, and is at least one source of the increase in carnitine excretion seen in critically ill patients.

Adult

Increased plasma carnitine in trauma patients given lipid-supplemented total parenteral nutrition.

The purpose of this study was to determine the effects of altering the fuel substrate mix of total parenteral nutrition (TPN) on plasma and urinary carnitine in trauma patients. TPN solutions were either 100% carbohydrate (CHO) based or lipid based (70% CHO, 30% lipid). There were statistically significant (p less than 0.05) increases in plasma levels of free carnitine, short-chain acyl carnitine, and total carnitine in trauma patients receiving lipid-based TPN. No significant differences in urinary carnitine excretion were noted between groups. We conclude that the use of lipids in the TPN of trauma patients leads to an alteration in plasma carnitine metabolism.

Adult

Addition of branched-chain amino acids to parenteral nutrition of stressed critically ill patients.

We compared the efficacy of a total parenteral nutrition solution supplemented with 44.6% branched-chain amino acids (BCAA) to standard total parenteral nutrition (19.0% BCAA) in the support of critically ill patients. After a 4-day administration of a randomly assigned solution, amino acids were assayed from femoral venous and arterial samples. The BCAA-supplemented solution caused increases in arterial concentrations of valine, isoleucine, and leucine compared to the control solution. The femoral arteriovenous differences for these BCAA were more positive in patients given the control solution. There were no significant differences in nitrogen balance. Since previous studies showing promotion of nitrogen balance with BCAA did not use a balanced substrate for nonprotein caloric support, the lack of a significant difference in the present study may be due to effective utilization of lipid as a fuel source by both groups.

Adult

Maturation of sympathetic neurotransmission in the rat heart. IV. Effects guanethidine-induced sympathectomy on neonatal development of synaptic vesicles, synaptic terminal function and heart growth.

Sympathetic nerve input has been proposed to regulate cardiac growth and differentiation. In the present study, this hypothesis was tested by giving the neurotoxic adrenergic neuron blocking agent, guanethidine (50 mg/kg, s.c.), daily to rats for 21 consecutive days to produce long-term peripheral sympathectomy in neonatal rats. Ontogeny of the sympathetic nerve terminal was measured by the ablity of synaptic vesicle preparations to take up radiolabeled norepinephrine, and heart growth in the sympathectomized animals was monitored by organ weight as well as by RNA and protein synthesis. Guanethidine treatment produced a massive sympathectomy, as synaptic vesicle development was totally arrested; the functional consequence of this treatment was confirmed by the attenuation of chronotropic responses to tyramine, a drug which acts by displacement of norepinephrine from the noradrenergic terminal. Despite the clear-cut effectiveness of guanethidine to prevent formation of functional sympathetic innervation of the heart, no significant alterations in heart growth or RNA and protein synthetic capabilities were observed in the developing rats. These results suggest that the presence of sympathetic innervaton is not obligatory for normal growth of the heart to occur.

Aging

Vasectomy.

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Follow-Up Studies