Roger B. McDonald

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The Sinorhizobium meliloti BacA ABC transporter protein plays an important role in its nodulating symbiosis with the legume alfalfa (Medicago sativa). The Mycobacterium tuberculosis BacA homolog was found to be important for the maintenance of chronic murine infections, yet its in vivo function is unknown. In the legume plant as well as in the mammalian(More)
Collagen biosynthesis was analyzed in C57BL/6J mice homozygous for the high-growth locus. Plasma levels of insulin-like growth factor-1 (IGF-1) were significantly elevated in high-growth mice at all ages studied (3 wk-6 mo); IGF-binding proteins were also elevated. Skin biopsies were obtained from mice aged 3, 6, and 9 wk under halothane anesthesia. Mice(More)
We assessed whether alterations in endogenous circadian rhythm of core temperature (CRT) in aging rats are associated with chronological time or with a biological marker of senescence, i.e., spontaneous rapid body weight loss. CRT was measured in male Fischer 344 (F344) rats beginning at age 689 days and then continuously until death. Young rats were also(More)
The inability of old rats to maintain body temperature during cold exposure has been well documented. This study evaluated the effect of exercise on the rates of cold-induced O2 consumption and the contribution of nonshivering thermogenesis (NST) to these rates. Younger (12 mo) and older (24 mo) male Fischer 344 (F344) rats were divided into exercised and(More)
The anorexia of aging is a syndrome characterized by unexplained losses in food intake and body weight that occur near the end of life. Proposed etiologies cover a wide range of biological and psychological conditions. The observation of this phenomenon in older laboratory animals suggests that physiological changes play a significant causal role. Research(More)
We evaluated nutrient intake (as measured by a 3-day food record) and nondietary factors that may influence nutrient intake in urban (n = 48) and rural (n = 47) elderly clients in the Title III C home-delivered meal program. Mean nutrient intake did not differ significantly between the two populations; each population met or exceeded 100% of the Recommended(More)
Nutritional requirements for mature rodents used in long-term investigations are virtually unknown. The limited knowledge of the dietary needs of mature rodents is due in part to overreliance on weanling animals fed an experimental diet for relatively short periods. Generalizations made from observations of weanling rodents are not appropriate for all ages.(More)
The anorexia of aging syndrome in humans is characterized by spontaneous body weight loss reflecting diminished food intake. We reported previously that old rats undergoing a similar phenomenon of progressive weight loss (i.e., senescent rats) also display altered feeding behavior, including reduced meal size and duration. Here, we tested the hypothesis(More)
We previously showed that, although cold-induced thermoregulation is attenuated in 26-mo-old male Fischer 344 (F344) rats, not all rats this age exhibit the same degree of cold-exposed hypothermia or diminished brown adipose tissue nonshivering thermogenic capacity. Examination of this heterogeneity suggested the hypothesis that it was associated with a(More)
OBJECTIVE This study was designed to evaluate whether participation in a congregate-site meal program influenced the nutritional status of a group of healthy elderly. DESIGN Nutritional status, as defined by dietary intake and biochemical indexes, was assessed in free-living persons (aged 60 to 89 years) who either did (n = 70) or did not (n = 65)(More)