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Biomedical subjects

L S Phillips

Publications and source records attributed to L S Phillips.

At least 91 records · Page 5Linked to original sources
PubMed1988

Nutrition and somatomedin. XVI: Somatomedins and somatomedin inhibitors in fasted and refed rats.

Nutritional deprivation is associated with poor growth and decreased levels of net circulating somatomedin activity, as measured by bioassay. Since somatomedin activity reflects the contributions both of somatomedins (which stimulate cartilage) and of somatomedin inhibitors (which antagonize the ability of the somatomedins to stimulate cartilage), we asked if changes in net somatomedin activity could involve progressive underlying alterations in levels of both somatomedins and somatomedin inhibitors. Groups of rats were killed during three days of fasting and 24 hours of refeeding. Fasting was associated with a rise in serum beta-hydroxybutyrate from 1.6 to 12.6 mmol/L after one day, followed by a decline to 4 mmol/L at three days. Somatomedins (low-MW) were separated from somatomedin inhibitors (high-MW) by gel permeation chromatography at acid pH on Sephadex G-50 and TSK-2000 HPLC. Somatomedins fell 35% after one day of fasting, and decreased to 59% below control levels after three days (P less than .05). Somatomedins did not change with six hours of refeeding, but then rose rapidly, reaching control levels after 24 hours. Somatomedins were correlated with change in weight (r = .41, P less than .05), but not with glucose or beta-hydroxybutyrate. Inhibitors rose to 195% above control-levels after one day of fasting, and continued to rise to 375% above control after three days (P less than .01). In contrast to the delayed change in somatomedins with refeeding, there was an abrupt fall in inhibitors (41% below three-day fasted levels after six hours), returning to control levels after 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗
PubMed1988

Nutrition and somatomedin. XIX. Molecular regulation of insulin-like growth factor-1 in streptozotocin-diabetic rats.

Poor growth in diabetes involves low circulating levels of somatomedins/insulin-like growth factors (IGFs), largely reflecting decreased growth factor release by the liver. To define regulatory mechanisms, circulating IGF-1 was compared with levels of a high mol wt putative hepatic IGF-1 precursor and hepatic IGF-1 mRNA in a model of progressive severity of diabetes in rats. Streptozotocin administered at 36, 72, 144, and 288 mg/kg produced graded metabolic decompensation 2 days later, from minimal hyperglycemia with continued weight gain at 36 mg/kg, to marked hyperglycemia, ketonemia, and weight loss at 288 mg/kg (all P less than 0.001). Total serum IGF-1 measured by RIA was unchanged with the 36 and 72 mg/kg doses of streptozotocin (471 +/- 19 and 439 +/- 27 ng/ml, respectively, vs. 517 +/- 27 ng/ml in controls) despite serum glucose greater than 400 mg/dl. With streptozotocin 144 and 288 mg/kg, serum IGF-1 fell to 131 +/- 27 and 142 +/- 10 ng/ml, respectively (both P less than 0.005 vs. controls). Serum IGF-1 was correlated strongly with serum beta-hydroxybutyrate and body weight (r = -0.88 and 0.91, respectively, P less than 0.0001), and less strongly with serum glucose (r = -0.59, P less than 0.0002). Extractable hepatic content of a high mol wt form of immunoreactive IGF-1 (a putative precursor) was unchanged at the two lowest doses of streptozotocin (68 +/- 4 and 83 +/- 9 ngeq/g vs. 67 +/- 4 in controls), but decreased to 16 +/- 3 and 29 +/- 4 ng/g at the two highest doses (both P less than 0.001 vs. controls).(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1987

Polyuria and refractory hypernatremia after cardiopulmonary arrest.

A patient exhibited brain damage, polyuria, and refractory hypernatremia after myocardial infarction and cardiopulmonary arrest. Serum vasopressin levels were relatively fixed and inappropriately low for the elevated serum osmolality. Hypernatremia persisted despite administration of vasopressin; after vasopressin was discontinued, serum sodium value was corrected with small doses of furosemide and replacement of free water. In her case, impairment of osmotic homeostasis could not be attributed to either simple resetting or complete destruction of osmoreceptors; metabolic normalization required an unusual therapeutic approach.

Diabetes Insipidus↗
PubMed1987

Nutrition and somatomedin. XV. Growth plate, growth factor and biologically active somatomedins in rats with streptozotocin-induced diabetes.

Diabetic children may exhibit poor growth, yet levels of growth hormone and somatomedins measured by specific radioligand assays usually are normal. In the present studies, biological assays based on costal cartilage from hypophysectomized rats were used to test the possibility that diabetes is associated with decreases in circulating growth-related factors. 'Growth plate growth factor' activity was evaluated with tissue from the osteochondral junction (which resembles epiphyseal cartilage), and 'somatomedin' activity was measured with resting cartilage distant from the growth plate. Diabetes was induced in rats by administration of streptozotocin (STZ) at 40, 80, 160 and 310 mg/kg. Two days later, animals receiving STZ 40 mg/kg exhibited slight hyperglycemia but normal beta-hydroxybutyrate and weight gain; glucose and beta-hydroxybutyrate rose, and weight fell progressively with higher dosage. Gel filtration on Sephadex G-75 at pH 2.4 was used to separate rat serum into somatomedins (KAv 0.50-0.75) and growth plate growth factor (KAv 0.38-0.50). Somatomedins were 102, 92, 83 and 68% of control in STZ-treated animals, i.e. unchanged from control at 40 mg/kg STZ and falling only with higher dosage. In contrast, the growth plate growth factor declined at all doses of STZ to 93, 84, 69 and 57% of control. Thus, the growth plate growth factor began to fall with mild hyperglycemia alone (glucose 190 mg/dl), while a comparable fall in somatomedins was not seen until glucose was greater than 400 mg/dl and beta-hydroxybutyrate was three times normal. Only the growth plate growth factor was correlated with changes in body weight (r = 0.44, p less than 0.025). We conclude that decreases in levels of a circulating growth plate growth factor may contribute to growth impairment in diabetes. Measurements of this factor may be useful in examining underlying mechanisms.

Animals↗
PubMed1987

Nutrition and somatomedin. XVII. Circulating somatomedin C during treatment of diabetic ketoacidosis.

Although somatomedin levels may be low in animals with experimental diabetes, values in humans have generally been normal. Because humans with severely decompensated diabetes have not been studied, we characterized somatomedin C responses during metabolic restoration in 21 patients with diabetic ketoacidosis. Somatomedin C values were compared with those of 25 outpatient controls. Somatomedin C in controls (mean +/- SE) was 0.72 +/- 0.09 U/ml, 69% of the mean sex-adjusted normal level; 28% of patients had values below the lower limit of normal. In ketoacidotic subjects, initial somatomedin C was 0.43 +/- .06 U/ml, 33% of the mean normal level; 52% of subjects had somatomedin C below the lower limit of normal. Initial levels in ketoacidotic subjects were unrelated to presenting levels of glucose, bicarbonate, ketones, or blood urea nitrogen but were significantly lower in patients of less than ideal body weight (0.30 vs. 0.58 U/ml, P less than .03). Presenting levels of somatomedin C in ketoacidotic subjects were significantly lower than in controls (P less than .02). During insulin-infusion therapy, somatomedin C rose to a peak of 1.16 +/- 0.21 U/ml after 28 h, significantly higher than initial levels (P less than .05). With continued subcutaneous insulin, somatomedin C fell to a nadir after an additional 22 h then rose more slowly to a final value of 0.75 +/- 0.12 U/ml, significantly higher than the nadir (P less than .05) but lower than peak values; final values in the ketoacidotic subjects were comparable to outpatient somatomedin C levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Nutrition, somatomedins, and the brain.

Conditions of decreased nutrient supply (malnutrition) and/or decreased nutrient utilization (diabetes) are attended by impairment of growth despite an increase in circulating levels of growth hormone (GH). Growth involves the actions of somatomedins, circulating insulinlike polypeptides with anabolic effects on cartilage, fat, and muscle. In malnutrition and diabetes, mechanisms of growth impairment appear to include a decrease in GH-induced generation of somatomedins, together with an increase in somatomedin inhibitors, factors which antagonize somatomedin action. Brain mediation of these alterations involves a rise in GH secretion due to decreased negative feedback from somatomedins, perhaps accentuated by blunting of feedback via actions of somatomedin inhibitors. In combination these processes lead to shunting of metabolic fuels toward vital processes and away from growth (via decreased somatomedin action) and to protein-sparing and increase in alternate metabolic fuels (via direct GH actions on muscle and fat). Further study of involved hypothalamic and pituitary mechanisms should yield additional insights into the role of the brain in metabolic homeostasis.

Adipose Tissue↗
PubMed1986

The 1986 McCollum award lecture. Fuel-mediated teratogenesis during early organogenesis: the effects of increased concentrations of glucose, ketones, or somatomedin inhibitor during rat embryo culture.

Whole rat embryos were explanted at head-fold, late pre-somite stage (day 9.5 of gestation) and cultured in rat sera varyingly supplemented with glucose (3, 6, 9, or 12 mg/mL), D,L sodium beta-hydroxybutyrate (2, 4, 8, or 16 mM), or both (6 mg/mL D-glucose plus 8 mM beta-hydroxybutyrate). During 48 h culture, increasing glucose alone or beta-hydroxybutyrate alone effected growth retardation and faulty neural and extraneural organogenesis in dose-dependent fashion. Synergistic dysmorphogenic effects occurred when minimally teratogenic concentrations of glucose and beta-hydroxybutyrate were combined. Sera from diabetic animals containing somatomedin inhibitor bioactivity were also able to produce growth retardation and major developmental lesions in presence of amounts of glucose and ketones which of themselves were not teratogenic. Thus, aberrant fuels and fuel-related products can impair growth and organogenesis in early post-implantation embryo. Such fuel-mediated teratogenesis may be multifactorial and include possibilities for synergistic and additive interactions.

3-Hydroxybutyric Acid↗
PubMed1986

Circulating somatomedin activity during hepatic regeneration.

Liver disease in humans and partial hepatic resection in animals are associated with decreased circulating somatomedin activity, suggesting that the liver may be an important site of somatomedin regulation. However, in both circumstances, concomitant alterations in nutrition could contribute to changes in somatomedin activity. To distinguish the consequences of reduced liver mass from those of decreased food intake, we examined the effects of partial hepatic resection in rats with controlled nutrition. Animals were first subjected to 65% partial hepatectomy, and fed ad libitum. At death, circulating somatomedin activity was measured in a bioassay using costal cartilage from hypophysectomized rats. After partial hepatectomy, somatomedin activity was decreased for 2 days, then rose toward normal. Somatomedin activity returned to control levels by 6 days after partial hepatectomy. Food intake also decreased (11 g/100 g over 48 h vs. 24 g in controls; P less than 0.001), and animal weight remained below control levels for 10 days (P less than 0.001) despite full liver regeneration. To control for the effects of nutrition, we then provided partially hepatectomized and sham-operated animals with equicaloric restricted diets (approximately 80% of ad libitum diet) based on spontaneous food intake after partial hepatectomy. With this paradigm, both groups exhibited a transient decrease in somatomedin activity. However, despite equal food intake, partially hepatectomized animals had higher somatomedin activity than sham-operated controls over a 7-day period (P less than 0.03, by analysis of variance). Differences were greatest after 72 h, when regeneration was 80% complete (somatomedin activity, 79% of normal after partial hepatectomy vs. 63% after sham procedures; P less than 0.02). In hypophysectomized rats, liver regeneration was retarded (29% at 72 h), and serum somatomedin activity remained at posthypophysectomy levels. We conclude that when rats are provided equicaloric restricted diets, somatomedin activity is higher after partial hepatectomy than after sham operation. Under these conditions, the regenerating liver may produce more somatomedins and/or less somatomedin inhibitors. Pituitary factors may be important in the regenerative response to partial hepatic resection in the rat.

Animals↗
PubMed1986

Somatomedin inhibitors from diabetic rat serum alter growth and development of mouse embryos in culture.

Offspring of diabetic humans and laboratory animals have been shown to have a higher incidence of congenital malformations with attendant growth retardation. These defects have been attributed to alterations in the intrauterine environment and specifically to changes in maternal serum factors, e.g., glucose and ketone bodies. Our investigation examines the potential teratogenicity of a low-molecular-weight (940) serum fraction with demonstrated somatomedin inhibitory activity isolated by column chromatography from streptozocin-induced diabetic rats. Mouse embryos were exposed to control or the inhibitor fraction at concentrations of 0.25-0.6% vol/vol (0.9-3.0 micrograms protein/ml culture medium) in whole embryo culture and evaluated for the presence of malformations and growth retardation. Embryos exposed to inhibitor during the period of neurulation (3-5 somites) exhibited neural tube and craniofacial defects, whereas those exposed during early limb bud stages (18-19 somites) exhibited abnormalities of the forebrain and face. In addition, both stages were growth retarded. Control fractions produced no abnormalities. These results demonstrate a potential role for somatomedin inhibitors in diabetic embryopathy and suggest that factors other than hyperglycemia and hyperketonemia may contribute to the higher incidence of malformations among infants of diabetic mothers.

Animals↗
PubMed1985

Nutrition and somatomedin. XIII. Usefulness of somatomedin-C in nutritional assessment.

Malnutrition is common in hospitalized patients, but current measures of nutritional status are limited. Because levels of somatomedins are regulated by nutrition, the utility of somatomedin-C measurement in nutritional assessment was studied. Thirty-seven malnourished patients had measurement of somatomedin-C and conventional nutritional indexes. In 28 patients seen before therapy, the somatomedin-C level was reduced (38 percent of normal) and was lower than the albumin level (66 percent, p less than 0.01), transferrin level (59 percent, p less than 0.05), and lymphocyte count (43 percent, p = NS). Somatomedin-C level was lowest with combined "kwashiorkor-marasmus" (25 percent of normal) and also reduced with "kwashiorkor" (51 percent) or "marasmus" (57 percent) alone. Somatomedin-C was correlated with albumin, transferrin, and lymphocyte count (p less than 0.02 for each). In six patients given nutritional therapy, somatomedin-C levels rose by more than 70 percent in each (mean increase 181 percent), whereas lymphocyte counts rose in four (increase 78 percent for all patients), transferrin levels rose in four (increase 33 percent), and albumin levels rose in one (-6 percent). In 20 patients with detailed dietary analysis, only somatomedin-C was correlated with intake of protein and calories (p less than 0.005 for each). Somatomedin-C may be a sensitive marker of malnutrition and the response to nutritional therapy.

Adult↗
PubMed1985

Nutrition and somatomedin--XII. Fractionation of somatomedins and somatomedin inhibitors in normal and diabetic rats.

Bioassayable somatomedins and somatomedin inhibitors were examined after chromatographic separation, using serum from normal rats (enriched in somatomedins) and diabetic rats (enriched in somatomedin inhibitors). At neutral pH, gel filtration on Sephacryl S-300 revealed somatomedins at mol. wt approximately 140,000 (presumably carrier-bound) and inhibitors at mol. wts approximately 250,000, approximately 24,000 and approximately 1,000. At acid pH, gel filtration on Sephadex G-50 revealed somatomedins at mol. wt approximately 8,000 (presumably carrier-free) and a single inhibitor at mol. wt approximately 21,000. Ion exchange chromatography revealed that the inhibitor(s) may be more acidic than the somatomedins, but only low quantities of somatomedins were recovered. Sephadex G-50 fractionation was applied to pathophysiologic models in rats: 3 days of fasting were associated with a 62% fall in somatomedins and a 159% rise in inhibitors; 2 days of diabetes were associated with a 60% fall in somatomedins and a 344% rise in inhibitors. Since chromatography on Sephadex G-50 at pH 2.4 appears to provide adequate separation of somatomedins and somatomedin inhibitors with good estimated recovery of biological activity, this simple approach may be a probe useful in examining the regulation of somatomedins and somatomedin inhibitors in vivo.

Animals↗
PubMed1985

Nutrition and somatomedin. XIV. Altered levels of somatomedins and somatomedin inhibitors in rats with streptozotocin-induced diabetes.

Diabetes is associated with poor growth despite elevated levels of growth hormone (GH). Skeletal GH effects are mediated by somatomedins; in diabetes, somatomedins measured by radioassay are normal, yet somatomedin activity measured by bioassay is low. Since bioassay measurements reflect the presence of both somatomedins and somatomedin inhibitors, we asked if diabetes might be associated with discordant regulation of these circulating factors. Graded severity of diabetes was induced in rats by injection of streptozotocin at 37, 73, 146, and 293 mg/kg. After two days, metabolic derangement varied from normal serum beta-hydroxybutyrate with slight increase in glucose and minimal weight loss at 37 mg/kg streptozotocin to beta-hydroxybutyrate 10.6 mmol/L, glucose 447 mg/dL, and 33 g weight loss at 293 mg/kg streptozotocin. After fractionation of serum on Sephacryl S-300 pH 7.0, somatomedins and somatomedin inhibitors were measured by rat cartilage bioassay. Somatomedins (Kav 0.25 to 0.50) were comparable to control levels despite beta-hydroxybutyrate 2 mmol/L, glucose 534 mg/dL, and weight loss 11 g at 73 mg/kg streptozotocin and fell only at higher streptozotocin dosage. In contrast, somatomedin inhibitors (Kav 0.62 to 0.88) began to rise at 37 mg/kg streptozotocin and increased with higher dosage. Levels of somatomedins were correlated weakly only with beta-hydroxybutyrate (r = 0.48, P less than 0.05), while somatomedin inhibitors were correlated significantly with all indices, particularly beta-hydroxybutyrate (r = 0.78, P less than 0.0001). The early rise in somatomedin inhibitors but late fall in somatomedins could explain low somatomedin activity (and poor growth) despite normal levels of somatomedins measured by radioassay; measurement of somatomedin inhibitors may provide an index of growth potential in diabetes mellitus.

3-Hydroxybutyric Acid↗
PubMed1985

Glucocorticoid effects on somatomedins and somatomedin inhibitors.

Glucocorticoid excess may be associated with poor growth despite normal levels of GH and adequate nutrition. Steroid-induced growth failure could be mediated by defective generation and/or action of somatomedins. To probe potential mechanisms, we examined the effect of corticosteroid administration on net somatomedin activity, immunoreactive somatomedin-C, and separated biologically active somatomedins and somatomedin inhibitors. Twelve children receiving alternate day steroid therapy had circulating somatomedin activity measured by porcine cartilage bioassay. Somatomedin activity fell 6 h after steroids [from 1.02 +/- 0.09 (+/- SEM) to 0.35 +/- 0.07 U/ml; P less than 0.001] and then rose toward normal. No significant change in somatomedin activity occurred during the day off therapy. Further studies were conducted in normal subjects given a single 60-mg dose of prednisone. Six hours after prednisone, somatomedin activity (rat cartilage bioassay) decreased by 46% (P less than 0.01), yet somatomedin-C did not change. To pursue this discrepancy, serum was fractionated on Sephadex G-50, pH 2.4, and separated somatomedin and somatomedin inhibitory bioactivity was measured. Biologically active somatomedins (Kav, 0.50-0.63) were comparable before and after prednisone treatment, as was inhibitory activity found at Kav 0.13-0.25. In contrast, somatomedin inhibitory activity at Kav 0.25-0.38 doubled (111 +/- 8% inhibition of somatomedin action vs. 54 +/- 11%; P less than 0.005) after prednisone therapy. The somatomedin inhibitor in these fractions blunted serum stimulation of sulfate, thymidine, and uridine uptake by test cartilage. These inhibitory effects could not be attributed to direct steroid action, as levels were less than 2 micrograms/dl in inhibitory fractions and addition of cortisol and prednisolone to the bioassay system failed to decrease somatomedin activity. We conclude that glucocorticoid administration is followed by an increase in circulating somatomedin inhibitors. Such inhibitors may explain the steroid-induced fall in net somatomedin activity and contribute to impaired growth.

Adolescent↗
PubMed1984

Nutrition and somatomedin. X. Comparison of insulin-like activity of somatomedins extracted from liver and serum.

Uncontrolled diabetes in rats is associated with reduced levels of both serum somatomedins and hepatic somatomedins. Hepatic somatomedins are recognized after extraction with 5 mol/L acetic acid, have a higher molecular weight (about 30,000) than serum somatomedins (about 8,000), despite acid conditions that dissociate somatomedins from circulating carrier proteins, and stimulate cartilage when given in vivo. To determine if hepatic somatomedins--as potential prohormones--have insulin-like activity comparable with serum somatomedins, their effects on rat epididymal adipose tissue were examined. Somatomedins were prepared from serum and liver extracts by gel filtration on Sephadex G-75, pH 2.4. In initial studies with fat pad segments, extracted hepatic somatomedins increased glucose oxidation only 64 +/- 11% above buffer (mean +/- SEM), while stimulation of 372 +/- 48% was provided by extracted serum somatomedins of comparable cartilage-stimulating potency (P less than 0.01, liver v serum). Further examination was performed with isolated adipocytes in a system sensitive to insulin at a concentration of 10 microU/mL (stimulation 100% above buffer). In dose-response studies measuring glucose oxidation, hepatic somatomedins had insulin-like activity of 16 microU/mL versus 55 microU/mL for serum somatomedins equipotent on cartilage (P less than 0.05); measuring glucose incorporation into total lipids, hepatic somatomedins had undetectable activity while serum somatomedins had activity of 28 microU/mL. It is concluded that hepatic somatomedins with potent cartilage-stimulating activity have greatly reduced insulin-like activity. The apparent dissociation in biologic activity of hepatic somatomedins suggests that while they may be prohormones, they may also represent a class of growth factors separate from the circulating somatomedins.

Adipose Tissue↗
PubMed1984

Somatomedin inhibitor in uremia.

In uremia, poor growth occurs despite normal to increased levels of insulin and GH. Since serum somatomedin levels measured by RIA and radioreceptor assay are normal in patients with renal failure, while serum somatomedin activity measured by bioassay is low but increased by dialysis, we asked if somatomedin activity could be decreased due to the presence of a low mol wt inhibitor(s). Serum was obtained from eight normal adults and eight uremic patients before hemodialysis treatment and was fractionated by gel filtration. Somatomedins and high mol wt inhibitors were separated on Sephadex G-50, pH 2.4, and high and low mol wt inhibitors were separated on Sephadex G-25, pH 7. Somatomedins were measured by stimulation of SO4 uptake by hypophysectomized rat costal cartilage in vitro, and inhibitor levels were determined by the blunting of stimulation produced by somatomedins in normal serum. Total biologically active somatomedin levels were comparable in uremic and normal sera. High mol wt somatomedin inhibitors (as found in malnutrition and diabetes) also were detected at similar levels in uremic and normal sera. In contrast, serum from uremic patients had increased levels of a low mol wt somatomedin inhibitor(s) [151 +/- 23% (mean +/- SEM) of serum stimulation inhibited vs. 47 +/- 9%; P less than 0.001]. Peak inhibitory activity was found at approximately 940 mol wt (range, 800-1100); an inhibitor of similar size was found in normal urine. Uremic serum fractions blunted cartilage sulfate uptake that was stimulated by whole serum, somatomedins (dissociated from serum carrier proteins), and insulin and lowered uridine and thymidine uptake that was stimulated by whole serum (all P less than 0.005). Lineweaver-Burk analysis indicated that somatomedin-inhibitor interactions on cartilage were noncompetitive, consistent with observations that direct exposure of cartilage to inhibitor decreased SO4 uptake to 30 +/- 3% below buffer levels (P less than 0.001). Despite these marked effects on cartilage, no alterations in basal or insulin-stimulated glucose oxidation occurred after addition of inhibitory serum fractions to adipose tissue incubations. Exposure of the inhibitor to proteolytic enzymes led to a significant decrease in inhibitory activity, indicating that the inhibitor may be a peptide. These studies suggest that decreased circulating somatomedin activity and impaired growth in uremia may reflect the accumulation of a circulating peptide inhibitor that would normally be cleared by the kidneys. Measurements of this factor may provide an index of growth potential in uremic children and help guide therapy of renal failure in both children and adults.

Adult↗
PubMed1984

Metabolic regulation of somatomedin activity in rat liver.

We have compared circulating and hepatic somatomedin (SM) activity in rats with diabetes or malnutrition of varying severity. Somatomedin activity was measured by the hypophysectomized rat costal cartilage bioassay. In both moderate diabetes and moderate malnutrition, mean serum SM activity was not significantly lower than normal (79 +/- 13% (S.E.M.) and 95 +/- 11% vs normal controls respectively). In contrast, liver perfusate SM activity was significantly reduced in both groups (51 +/- 12% for moderate diabetes and 44 +/- 12% for moderate malnutrition). Liver extract SM activity was also significantly decreased in both moderate diabetes and malnutrition (74 +/- 4% and 75 +/- 6% vs normal controls respectively). In severe diabetes and malnutrition, both liver and serum activities were low, consistent with previous reports. Our studies showed that liver SM activity fell in response to metabolic stress before a decrease in circulating levels occurred, supporting the concept that the liver regulates serum SM activity and growth in diabetes and malnutrition.

Animals↗