Transient ischaemic attacks.
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Australia↗
Biomedical subjects
W J Carter
Publications and source records attributed to W J Carter.
Effect of anabolic hormones and insulin-like growth factor-I on muscle mass and strength in elderly persons.
The secretion of growth hormone and testosterone declines with age. Because these hormones have prominent anabolic effects on skeletal muscle, part of the age-related decrease in muscle mass and strength have been attributed to declining levels of these hormones; however, growth hormone replacement in healthy elderly people has produced side effects but no functional benefit. In contrast, short-term growth hormone and insulin-like growth factor 1 treatment have reduced protein loss and improved function during acute catabolic states. Although testosterone replacement has increased lean body mass and improved the sense of well being, functional benefit has not been clearly demonstrated, and the risks of long-term replacement have not been defined.
Adrenergic beta-Agonists↗
Comparison of the effects of salbutamol and clenbuterol on skeletal muscle mass and carcass composition in senescent rats.
Aging decreases skeletal muscle mass and strength, making elderly subjects particularly vulnerable to catabolic effects of age-related diseases. Clenbuterol, a muscle anabolic beta 2-adrenergic agonist, has reduced or restored skeletal muscle losses in experimental catabolic states. However, the doses of clenbuterol used to prevent or reverse muscle wasting in most animal models have exceeded the estimated safe dose in man. Recently, another beta 2-adrenergic agonist, salbuamol (albuterol), has been shown to increase muscle weight and protein content in young rats at a dose similar to that used clinically. In contrast to clenbuterol, salbutamol is currently approved for human use as a bronchodilator in the United States. This study has compared the muscle and protein anabolic effects of salbutamol at a clinically relevant dose with those of clenbuterol at a dose typically used in animal models of muscle wasting. Salbutamol and clenbuterol were administered by implanted osmotic minipumps to Fisher-344 rats aged 3 and 24 months at doses of 1.03 mg and 600 micrograms per kilogram per 24 hours for 3 weeks. The weights of five hindlimb muscles, as well as carcass protein and fat content, were determined. Salbutamol and clenbuterol increased combined hindlimb muscle weight 19% and 28% in young rats, with 19% and 25% increases in old rats. Similarly, these drugs increased gastrocnemius weight and protein content 19% and 24% in young rats, with 19% and 23% increases in old rats. Salbutamol and clenbuterol increased carcass protein content 20% and 30% in young rats, with 12% and 21% increases in old rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Adrenergic beta-Agonists↗
Insulin-like growth factor I as an indicator of protein-energy undernutrition among metabolically stable hospitalized elderly.
OBJECTIVE: The primary objective of this cross-sectional study was to test the hypothesis that the plasma concentration of insulin-like growth factor I (IGF-I) correlates with the risk of in-hospital morbidity among metabolically stable elderly. The secondary objective was to determine whether IGF-I correlates with other putative indicators of protein-energy nutritional status. SUBJECTS: To meet these objectives, 110 randomly selected admissions to a Geriatric Rehabilitation Unit (GRU) of a Veterans Administration hospital were studied. The average age of the study patients was 76 years; 98% were male, and 78% were white. OUTCOME MEASURES: At admission, each patient completed a comprehensive medical, functional, neuropsychological, and nutritional assessment including the attainment of a plasma IGF-I determination. While in the hospital, each subject was monitored daily for development of complications. RESULTS: Subsequent to GRU admission, 44 patients (40%) experienced at least one complication; 36 patients (33%) experienced an infectious complication, 8 patients (7%) experienced a life-threatening complication, and 5 patients (5%) experienced a life-threatening infectious complication. There was no correlation between IGF-I and development of a non-life-threatening complication ("any complication" or "any infectious complication"). However, IGF-I was a strong predictor of "life-threatening" and "life-threatening infectious" complications. The logistic regression model incorporating the independent variable IGF-I differentiated the patients who would develop a "life-threatening" complication from those who would not with a sensitivity of 75%, a specificity of 76%, and an overall predictive accuracy of 76%. IGF-I was highly correlated with admission serum albumin, transferrin, and cholesterol, triceps skinfold thickness, body weight expressed as a percent of ideal, and body mass index. There was no correlation between IGF-I and the Katz Index of Activities of Daily Living score, age, or anergy status. CONCLUSION: IGF-I is a strong predictor of "life-threatening" and "life-threatening infectious" complications and may be a clinically useful marker for protein-energy undernutrition among metabolically stable hospitalized elderly patients.
Aged↗
Effect of clenbuterol on recovery of muscle mass and carcass protein content following dietary protein depletion in young and old rats.
There is a need for new therapeutic agents designed to prevent or restore skeletal muscle loss in frail, elderly subjects resulting from injury or disease and associated catabolic stresses such as malnutrition. Since the beta 2-adrenergic agonist clenbuterol increases skeletal muscle mass in rats, the effect of this agent on recovery of muscle mass and carcass protein content following protein malnutrition was studied in young and old rats. The 3-week period of severe dietary protein restriction reduced body weight 21%, hind-limb muscle weight 24 and 15%, and carcass protein content 31 and 19%, respectively, in 3- and 24-month-old rats. During the 3-week recovery period induced by feeding a complete diet, 10 mg clenbuterol per kg diet increased hind-limb muscle weight 34 and 30% and carcass protein content 27 and 25%, respectively, in 3- and 24-month-old rats. Restoration was complete in animals of both ages fed clenbuterol and incomplete in animals fed the control diet. These observations suggest that clenbuterol or similar beta 2-adrenergic agonists may be useful in hastening the recovery of muscle mass and body protein stores lost because of malnutrition in frail, elderly humans.
Aging↗
Selective accumulation of MyoD and myogenin mRNAs in fast and slow adult skeletal muscle is controlled by innervation and hormones.
Each of the myogenic helix-loop-helix transcription factors (MyoD, Myogenin, Myf-5, and MRF4) is capable of activating muscle-specific gene expression, yet distinct functions have not been ascribed to the individual proteins. We report here that MyoD and Myogenin mRNAs selectively accumulate in hindlimb muscles of the adult rat that differ in contractile properties: MyoD is prevalent in fast twitch and Myogenin in slow twitch muscles. The distribution of MyoD and Myogenin transcripts also differ within a single muscle and correlate with the proportions of fast glycolytic and slow oxidative muscle fibres, respectively. Furthermore, the expression of a transgene consisting of a muscle-specific cis-regulatory region from the myoD gene controlling lacZ was primarily associated with the fast glycolytic fibres. Alteration of the fast/slow fibre type distribution by thyroid hormone treatment or by cross-reinnervation resulted in a corresponding alteration in the MyoD/Myogenin mRNA expression pattern. These findings show that the expression of specific myogenic helix-loop-helix regulators is under the control of innervation and humoral factors and may mediate differential control of contractile protein gene expression in adult muscle.
Animals↗
Modifications of platelet phospholipid fatty acid composition in streptozocin-induced diabetic rats.
Increased thromboxane A2 (TXA2) generation by platelets has been reported both in diabetic patients and streptozocin-induced diabetic rats. This increase is in contrast to the decreased prostacyclin (PGI2) synthesis by endothelial cells in diabetes. An imbalance in the ratio of TXA2/PGI2 has been implicated in increased platelet aggregation and a high incidence of vascular disease in human diabetes. The mechanism for this imbalance, however, remains elusive. In a previous study from our laboratory, we reported unchanged arachidonic acid levels in platelet membrane phospholipids of 3-week diabetic rats, but a decreased arachidonic acid level in platelet membrane phospholipids of 6-week diabetic rats. In the present communication, we report the role of enzymes that are involved in remodeling arachidonic acid levels of platelet membrane phospholipids in both 3- and 6-week diabetic rats. No alterations were observed in the activities of arachidonoyl-CoA synthetase, acyl-CoA: lysophosphatidylcholine acyltransferase, or phospholipase A2 in platelets from both 3- and 6-week diabetic rats. However, both increased uptake and incorporation of [14C]arachidonic acid into platelets were observed in the diabetic platelet-rich plasma. In conclusion, increased TXA2 formation in diabetic platelets is not due to alterations in the activities of enzymes involved in the incorporation into or release of arachidonate from the diabetic platelet membrane phospholipid, but may be due to increased efficiency of uptake, incorporation or possibly redistribution of this fatty acid among phospholipid classes in diabetic platelets.
1-Acylglycerophosphocholine O-Acyltransferase↗
Cystocerebral syndrome: a possible explanation.
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Aged↗
Effects of clenbuterol on skeletal muscle mass, body composition, and recovery from surgical stress in senescent rats.
Aging decreases skeletal muscle mass and strength, which may be exacerbated by age-related diseases. There is a need for therapeutic agents to prevent or restore loss of skeletal muscle in elderly subjects with muscle wasting disorders. Clenbuterol, a beta 2-adrenergic agonist, dramatically increases skeletal muscle mass in young animals and partially prevents or restores muscle loss in experimental models of muscle wasting. However, the protein anabolic and fat catabolic effects of clenbuterol have not been studied in senescent animals. To determine whether this drug has potential for preventing or repairing muscle loss in elderly subjects, we have examined its effects in young and old rats. Clenbuterol was administered by implanted osmotic minipumps to Fischer-344 rats ages 3, 12, and 23 months, at a dose of 1.5 mg/kg/24 h for 3 weeks. The weights of five hindlimb muscles and carcass protein and fat content were determined. Clenbuterol treatment increased the weight of skeletal muscles 22% to 39% in 3-month-old rats, 19% to 35% in 12-month-old rats, and 22% to 25% in 23-month-old animals. Likewise, clenbuterol increased carcass protein content 19% in 3-month-old rats, 16% in 12-month-old rats, and 24% in 23-month-old animals. Conversely, the drug reduced carcass fat content 36% in 3-month-old rats, 32% in 12-month-old rats, and 38% in 23-month-old rats. Therefore, clenbuterol had similar anabolic and catabolic effects in all age groups. In addition, clenbuterol stimulated recovery of skeletal muscle protein lost following pump implantation in senescent rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Aging↗
Decreased incorporation of long-chain fatty acids into erythrocyte phospholipids of STZ-D rats.
We studied the mechanisms for the altered fatty acid composition in erythrocytes (RBCs) derived from streptozocin-induced diabetic (STZ-D) rats. After 3-wk duration of diabetes, blood glucose, plasma triglyceride, and plasma free-fatty acid levels were all significantly increased. In the diabetic platelet-poor plasma (PPP), the most significant increases in free fatty acids were stearate, linoleate, eicosatrienoate (n-6), and docosahexaenoate (n-3). Fatty acid composition of RBC phospholipids was also altered, with significant decreases in arachidonate, docosatetraenoate (n-6), and docosapentaenoate (n-6) and increases in linoleate and docosahexaenoate. Insulin treatment of the diabetic rats resulted in normalization of docosapentaenoate, arachidonate, and linoleate levels in RBC phospholipids but not of docosahexaenoate or docosatetraenoate levels. The incorporation of [5,6,8,9,11,12,14,15-3H]arachidonate into diabetic RBC phospholipids was significantly decreased compared with the corresponding control RBC, regardless of the incubation medium used, which was the PPP derived either from the control or diabetic rats. Therefore, the decreased incorporation of [5,6,8,9,11,12,14,15-3H]arachidonate into diabetic RBC phospholipids was independent of the altered lipid composition of the PPP incubation media. Furthermore, the decreased incorporation was not specific for arachidonate, because the incorporation of other long-chain fatty acids such as [9,10-3H]oleate, [1-14C]palmitate, [2-14C]eicosatrienoate (n-6), and [1-14C]linoleate into RBC phospholipids was also comparably decreased. More important, the decreased fatty acid incorporations were reversed by insulin treatment of the diabetic rat.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
My spastic patients.
Managing patients with severe cerebral palsy can be very challenging due to communication difficulties and unusual presentations. The tribulations and rewards of a general practitioner dealing with these patients are detailed in this article.
Cerebral Palsy↗
Effects of dietary fats on fatty acid composition and delta 5 desaturase in normal and diabetic rats.
We have studied the effect of various diets on the phospholipid fatty acid composition and in vitro delta 5 desaturase activity of hepatic microsomes derived either from the normal or streptozotocin-induced diabetic rat. The diets studied were the standard rat chow diet and a basal fat-free diet supplemented either with 20 percent saturated fat, 20 percent unsaturated fat, or 20 percent menhaden oil. Phospholipid fatty acid composition analysis revealed that the normal rat fed the saturated fat or menhaden oil diet had significantly decreased arachidonate levels, consistent with decreased delta 5 desaturase activities and decreased 18:2n-6 intake. On the contrary, the unsaturated fat diet decreased dihomo-gamma-linolenate and increased arachidonate levels, without increased delta 5 desaturase activity. Streptozotocin-induced diabetes resulted in decreased arachidonate and delta 5 desaturase activity. The unsaturated fat diet fed to the diabetic rat also failed to correct this decreased delta 5 desaturase activity. The unsaturated fatty acids in this diet also displaced a substantial amount of n-3 fatty acids in both normal and diabetic microsomes, due to the competition between these two fatty acid families for incorporation into the membrane phospholipids. Conversely, the menhaden oil diet fed to the normal and diabetic rats displaced n-6 fatty acids, reduced delta 5 desaturase activity, and enhanced 22:6n-3 incorporation into diabetic microsomes.
Animals↗
Effects of experimental hypo- and hyperthyroidism on hepatic long-chain fatty acyl-CoA synthetase and hydrolase.
The effects of T3 treatment and thyroidectomy on rat liver microsomal long-chain fatty acyl-CoA (LCFA-CoA) synthetase and LCFA-CoA hydrolase activities were determined. Hyperthyroid rats had a 36-42% decrease in LCFA-CoA synthetase with no change in hydrolase activity. This may contribute to the redirection of fatty acids from esterification to oxidation reactions in hyperthyroidism. Thyroidectomized rats had a 40-44% decrease in synthetase and a 27-42% decrease in LCFA-CoA hydrolase activity. The decrease in both LCFA-CoA synthetase and hydrolase activities in hypothyroidism may indicate that the LCFA-CoA turnover in this futile cycle is decreased in the liver.
Animals↗
Red blood cell and plasma fatty acid composition in diabetes mellitus.
Arachidonic acid deficiency and increased linoleic acid levels have been a consistent finding in a variety of tissues in experimental diabetes. To determine if patients with type II non-insulin-dependent diabetes show changes in red blood cell and plasma fatty acid composition, a group of non-insulin-dependent diabetic patients were studied prior to and following treatment with glyburide which substantially improved their diabetic control. Red blood cell and plasma fatty acid composition was compared with that of a group of nondiabetic subjects and to red cell fatty acid composition in normal and streptozotocin diabetic rats. The diabetic patients had no changes in linoleic or arachidonic acid levels prior to treatment and no changes following glyburide therapy. These studies and the available literature suggest to us that either more severe diabetes is required to produce the fatty acid abnormalities described in the diabetic rat or that there is a fundamental species difference in the mechanism of diabetes or in fatty acid metabolism between the human and the rat which allows the human diabetic to more easily maintain normal tissue fatty acid composition.
Diabetes Mellitus, Type 2↗
Altered fatty acid composition in the plasma, platelets, and aorta of the streptozotocin-induced diabetic rat.
Decreased arachidonate levels have been described in various tissues of the streptozotocin-induced diabetic rat. However, reported arachidonate changes in platelets from diabetic patients have been variable. In this communication, we describe experiments that indicate that in the short-term streptozotocin diabetic rat (2 to 3 weeks), the fatty acid composition of plasma and red blood cell lipids was altered but remained unchanged in platelet and aorta phospholipids. The altered fatty acid composition of the diabetic red blood cells and plasma cholesterol esters and phospholipids was similar to that previously found in the diabetic liver. However, in long-term diabetes (6 weeks), the phospholipid fatty acid composition of the platelet and aorta became significantly altered. Thus, in the 6-week diabetic platelet, there were increases of linoleate, dihomo-gamma-linolenate, docosapentaenoate (C22:5n-3), and docosahexaenoate, and decreases of oleate, arachidonate, and docosatetraenoate. In the aorta, there were increases of linoleate, eicosapentaenoate, and docosahexaenoate, and decreases of arachidonate, docosatetraenoate, and docosapentaenoate (C22:5n-6). Results from these experiments indicate that the fatty acid composition of plasma and red blood cell lipids was altered in short-term diabetes (2 to 3 weeks), but that of platelet and aorta phospholipids was not changed until more prolonged diabetes was present. Insulin treatment of the diabetic rat increased the levels of palmitoleate and oleate and decreased the levels of linoleate in platelet and aorta lipids from insulin-treated diabetic rats, suggesting an overcorrection of diminished delta 9 and delta 6 fatty acid desaturation as compared with the nondiabetic control.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
The dental health of Lyndon B. Johnson.
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Famous Persons↗
Effect of graded doses of tri-iodothyronine on ventricular myosin ATPase activity and isomyosin profile in young and old rats.
Ventricular myosin ATPase activity, V1 isomyosin content and serum T3 (tri-iodothyronine) values decrease with age in male Fischer 344 rats. To determine if the age decrement in ATPase activity and V1 isomyosin content are caused by decreased T3 levels or an age-related decrease in V1 isomyosin induction by T3, 3-, 12- and 24-month-old male Fischer 344 rats were given constant T3 infusions by osmotic minipump. Rats at all ages were given 0.75, 5 and 15 micrograms(/100 g per 24 h) doses of T3, whereas 12- and 24-month-old rats were given an additional 0.4 microgram dose. In control rats, T3 levels decreased from 97 +/- 2.7 at 3 months to 75 +/- 4.7 ng/100 ml at 24 months. Likewise, Ca2+-activated myosin ATPase activity decreased from 1.04 +/- 0.05 to 0.68 +/- 0.05 mumol of Pi/min per mg of protein, and the relative proportion of V1 of isomyosin decreased from 90 +/- 4.0 to 26 +/- 2.0%. The lowest (0.4 microgram) T3 dose, which was sufficient to restore T3 levels in 24-month-old animals to 3-month control values, abolished the age decrement in myosin ATPase activity and markedly increased the proportion of V1 isomyosin present in the ventricle. These findings indicate that the senescent ventricle responds readily to small doses of T3 and strongly suggest that the age decrement in serum T3 levels is sufficient to contribute to the age-related decrease in myosin ATPase activity and V1 isomyosin content. Since these parameters correlate with ventricular contractility, the age decrement in T3 levels may also contribute to the decreased ventricular contractility and cardiac output observed in senescent rats.
Adenosine Triphosphatases↗