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Query: UMLS:C0020473 (hyperlipidemia)
 15,891 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

With a view to elucidating the physiologic role of hepatic triglyceride lipase (H-TGL), we studied the relationship between the activity of H-TGL and the concentrations of the lipids of ultracentrifugally separated lipoprotein fractions in sera from 81 cases of primary hyperlipidemia, 5 of hypothyroidism, and 31 normal subjects. The activity of H-TGL in postheparin plasma was determined by the sensitive, nonradioisotopic method that was recently developed by us. In the entire group of subjects including the normals, the activity of H-TGL had a significant inverse correlation with the concentration of the cholesterol (r = -0.443, P less than 0.001) and phospholipid (r = -0.433, P less than 0.001) of intermediate density lipoprotein (IDL). When the patients were divided into subgroups according to the phenotype of hyperlipidemia, it was found that the correlation was more significant in type IIb (r = 0.695, P less than 0.001) or type IV + V (r = -0.664, P less than 0.0001). In the five cases of hypothyroidism, the mean IDL cholesterol level was high (28.3 +/- 12.3 mg/dL) and the H-TGL activity was very low (4.6 +/- 4.5 mumol/h/mL). The H-TGL activity was also significantly correlated with the ratio of high density lipoprotein-2 to high density lipoprotein-3 cholesterol (r = 0.351, P less than 0.001) in the entire group.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The role of hepatic triglyceride lipase in the metabolism of intermediate-density lipoprotein--postheparin lipolytic activities determined by a sensitive, nonradioisotopic method in hyperlipidemic patients and normals. 394 9

High fat, high cholesterol diets do not produce atherosclerotic lesions in some animal species such as the rat; however, when combined with experimentally induced hypothyroidism, such diets do produce lesions. While the diets or hypothyroidism each induce significant alterations in plasma lipoproteins, the combination produces marked hypercholesterolemia. If the atherosclerosis is related to the hyperlipidemia, the combination regimen could be provoking changes in the structure or compositions of lipoproteins which are not noted with either regimen alone. To test this hypothesis, Sprague-Dawley male rats (approximately 250 g) were treated as follows: Diet(a) = chow + 5% lard and 0.3% Na taurocholate; Diet(b) = Diet(a) + 2% cholesterol; Diet(c) = Diet(b) + 0.1% propylthiouracil (PTU). The major findings were as follows. 1) With Diet(b), slow floating very low density lipoprotein (VLDL) (pre-beta) enriched in cholesteryl esters accumulated in plasma and low density lipoprotein (LDL) disappeared from its usual flotation position. 2) With Diet(c), changes in plasma concentration were more marked but were also qualitatively different. More VLDL accumulated, and distribution of VLDL was shifted toward even slower floating cholesteryl ester-rich particles. VLDL had "broad beta" mobility. Also, a beta-migrating intermediate density lipoprotein (IDL) population appeared. 3) Lipoprotein (d less than 1.019 g/ml) and zonal subfractions of d less than 1.019 g/ml lipoproteins (isolated from rats on cholesterol Diet (b] stimulated [3H]oleate incorporation into cholesteryl esters of fibroblasts and macrophages, while the d less than 1.019 g/ml fractions of 5% fat (Diet(a]-fed rats did not. 4) The major finding of this study was that identically prepared d less than 1.019 g/ml fractions of Chol + PTU-treated rats (Diet(c] were approximately 2.5-fold more stimulatory than the lipoproteins of cholesterol-fed rats. The results could not be explained by differences in cholesterol contents of the cholesterol-rich lipoproteins, but significant differences in the apoprotein compositions of the fraction were found which could be important. The most active fractions had higher apoBL/apoBS and apoE/apoC ratios than less active fractions. Thus, the combination regimen of cholesterol and PTU produced changes in lipoprotein structure and composition which enhanced the abilities of the lipoproteins to interact with cells. The results suggest that analysis of lipoprotein-cell interactions in vitro may be predictive of the atherogenic potential of lipoproteins in vivo and that euthyroidism in rat protects against atherogenic hyperlipidemia.
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PMID:Effects of high cholesterol diets on rat plasma lipoproteins and lipoprotein-cell interactions. 643 Oct 45

Hyperlipidemia associated with hypothyroidism is well documented in man and several animal species. The effect of hypothyroidism on apolipoprotein metabolism in the absence of complicating factors such as high cholesterol or fat content in the diet is virtually unknown. Hypothyroidism was therefore induced in male Sprague-Dawley rats by radiothyroidectomy (RTx-treated) or treatment with propylthiouracil (PTU-treated). Both treatments resulted in an over 90% decrease in circulating thyroid hormone concentrations accompanied by a 50-100% increase in plasma cholesterol and a 20-40% reduction in plasma triglyceride concentrations. Plasma apo E and apo B concentrations increased by 100% in the PTU-treated group and 40-50% in the RTx-group. Apo A-I increased 10 and 30% in the RTx- and PTU-treated rats, respectively, while the concentration of apo A-IV was not altered. A large increase in the low-density (LDL) and high-density lipoprotein (HDL) protein was observed and accompanied by a marked reduction of very low density lipoprotein (VLDL) in the hypothyroid rats. The electrophoretic pattern of plasma lipoproteins in the hypothyroid rats was changed by the appearance of a slow pre-beta band shown to be beta-VLDL. A redistribution of apo B occurred within the lipoprotein fractions. Apo B content in the VLDL fraction decreased and a large increase was noted in LDL. The major portion of the apo E and apo A-I increment was recovered in the HDL and to a lesser degree in LDL. An accumulation of apo E-rich larger HDL particles, resembling HDLc in apolipoprotein composition and distinct from the apo A-I-containing species, was observed by column chromatography. The results presented are consistent with the hypothesis that hypothyroidism in the rat may induce an accelerated production of VLDL catabolic remnants, including LDL, but at the same time reduce the rate of removal of these lipoproteins from the circulation.
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PMID:Rat plasma lipoproteins and apolipoproteins in experimental hypothyroidism. 678 58

The clinical and laboratory data of a 5-year-old boy with the syndrome of essential hypernatremia are presented. In a four-year follow-up, no demonstrable hypothalamic structural lesion has been identified. Review of the literature has uncovered four similar cases, suggesting a distinct syndrome of altered hypothalamic function. The syndrome is characterized by: adipsia-hypodipsia (5/5 patients), recurrent hypernatremia (5/5), obesity (4/5), inability to excrete a water load (5/5), lack of growth hormone release in response to provocative stimuli (4/4), blunted thyrotropin releasing hormone responses (3/4), hypothyroidism (2/4), and hyperlipemia associated with hypernatremic crisis (1/1). In one of the patients the syndrome has been attributed to a disturbance of the opioid-peptide system.
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PMID:Hypothalamic adipsia without demonstrable structural lesion. 680 52

The clinico-hormonal course of acromegaly and the presence of the hyperlipemic syndrome were studied in relation to age, sex, associated hypothyroidism, diabetes, obesity and cardiovascular and atherosclerotic complications in 43 acromegalic patients (18 males and 25 females) of which 6 had received no treatment and 37 had been submitted 2 - 13 years to conventional roentgentherapy (31 cases), 90Y (5 cases) and hypophysectomy (1 case). Hyperlipemia (HLP), present in 24 acromegalic patients (55.8% of the cases) unrelated to age, was more frequent in women (64% as against 44% in males) and correlated with the clinico-hormonal evolution (GH greater than 20 mg) (60% of the cases), and associated hypothyroidism (79%), obesity (42%) and diabetes (25%). Of the hyperlipemic acromegalic patients, 62% had cardiovascular and atherosclerotic complications. The results of the study point to the need for a hypoglucidic, hypolipidic and associated treatment for hypothyroidism, diabetes and obesity in the prophylaxis of acromegalic atherosclerosis.
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PMID:The dyslipemic syndrome in acromegaly. 704 Dec 36

Hypothyroid rats fed an atherogenic diet (A) for 3 weeks developed a marked hyperlipidemia characterized by elevated very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol. Cholesterol concentrations of adipose tissue, liver, carcass and soleus muscle were significantly increased in rats fed the A diet versus rats fed a control diet (C). After 5 months on the A diet, cholesterol concentrations of adipose tissue, carcass and soleus muscle were not different from those measured in rats fed the A diet for 3 weeks; however, liver cholesterol concentration was 20-fold higher. To study the mechanisms by which the A diet increased adipocyte cholesterol content, in vitro binding studies were conducted with normal (N) and cholesterol enriched (CH) 125I-labeled VLDL. The inability of unlabeled N and CH VLDL to displace 125I-labeled VLDL supports the concept that VLDL was not specifically bound by rat adipocytes. The observation that adipocyte and other tissue cholesterol levels were similar at 3 weeks and 5 months suggests regulation of tissue cholesterol concentrations. The mechanism of regulation of adipocyte cholesterol was not related to VLDL binding or differential binding rates between N and CH VLDL.
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PMID:Studies on the etiology of increased tissue cholesterol concentration in cholesterol-fed hypothyroid rats. 714 14

Plerocercoid larvae of the tapeworm, Spirometra mansonoides produce a growth hormone-like factor that stimulates body growth of a variety of normal and hormone-deficient animals. Plerocercoid infection (15 per hamster) stimulated an increase in body weight, and markedly suppressed pituitary weight and growth hormone (GH) concentrations of serum and pituitaries of Syrian hamsters. The suppression of serum GH persisted for at least 4 mo after the initiation of infection. The presence of plerocercoids also resulted in a significant reduction (30-50%) in serum thyroxine (T4). The pronounced lipogenic effect associated with plerocercoid infection was not reversed by injection of the infected hamsters with high (10 or 20 micrograms/day) or low (1 or 2 micrograms/day) doses of L-thyroxine. These results suggest that the plerocercoid growth factor may function in a manner similar to high levels of endogenous GH by activating the feedback system that inhibits pituitary secretion of both GH and TSH. Whereas hypothyroidism may be associated with hyperlipidemia the resultant hypothyroid state induced by plerocercoid infection does not explain the hypertriglyceridemia and hypercholesterolemia which were a consistent observation in plerocercoid-infected hamsters.
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PMID:The lipogenic effect of the growth factor produced by plerocercoids of the tapeworm, Spirometra mansonoides, is not the result of hypothyroidism. 717 22

We studied the effects of 6-week treatment with nifedipine (35 mg/kg/day orally, p.o.) on streptozotocin (STZ)-induced diabetic rats. Injection of STZ [45 mg/kg intravenously, (i.v.) single dose] produced a significant increase in blood pressure (BP), bradycardia, hyperglycemia, hypoinsulinemia, hyperlipidemia, hypothyroidism, depression in left ventricular developed pressure (LVDP), cardiomyopathy, and nephropathy. Treatment of diabetic rats with nifedipine normalized the BP and prevented bradycardia. Insulin levels were decreased after nifedipine treatment in diabetic as well as nondiabetic rats. However, serum glucose levels were also partially decreased in diabetic animals by nifedipine treatment. In control animals as well, glucose levels were in the normal range despite lower insulin levels observed after nifedipine treatment. Nifedipine treatment significantly prevented STZ-induced increase in cholesterol and triglyceride levels. Nifedipine treatment significantly prevented STZ-induced hypothyroidism and also prevented STZ-induced cardiac depression and cardiomyopathy. Our data indicate that nifedipine increases insulin sensitivity and has some beneficial effects on cardiovascular parameters. It may therefore be considered a preferred drug in the treatment of hypertension associated with diabetes mellitus.
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PMID:Effects of chronic nifedipine treatment on streptozotocin-induced diabetic rats. 756 66

Since in the literature basophilia is frequently related to myxedema, we evaluated basophilic leukocytes in patients with hypothyroidism, applying routine techniques used in clinical laboratories. The study included normal persons, untreated patients with hypothyroidism, and euthyroid subjects with hyperlipidemia. The number of circulating basophils was determined by differential counts of Pappenheim stained blood smears. No difference in relative and total basophil counts was detected in patients with hypothyroidism as compared to healthy controls (1.0% and 58.1 basophils/microliters vs. 0.8% and 50.8 basophils/microliters, respectively). The percentage of basophils in myxedema associated with hypercholesterolemia amounted to 1.0%, their absolute number to 57.6/microliters; in hypothyroid patients presenting normal serum cholesterol levels, the relative and absolute numbers of basophilic leukocytes was not statistically different (0.83% and 61.1 basophils/microliters, respectively). We conclude that in patients with hypothyroidism the number of basophils is not statistically different from the values of basophils in healthy controls. Furthermore, the number of peripheral blood basophils in hypothyroidism is not related to the serum cholesterol level.
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PMID:Basophilic leukocytes in hypothyroidism. 768 Sep 25

There is a general interest to know whether lipoprotein(a) [Lp(a)] is under hormonal control. Hypothyroidism is a well known cause of secondary hyperlipidemia, which mainly affects low density lipoprotein (LDL) cholesterol levels, but the result on the effects of L-T4 replacement therapy on the Lp(a) concentration is controversial. We studied 12 severely hypothyroid, hypercholesterolemic patients under basal conditions and during L-T4 treatment. We found a rapid decrease in both LDL cholesterol (5.71 +/- 0.62 vs. 4.37 +/- 0.44 mmol/L basally and after 1 month of thyroid replacement, respectively) and apolipoprotein-B (Apo-B) levels (1.89 +/- 0.02 vs. 1.52 +/- 0.17 g/L, respectively); these changes persisted for up 1 yr of analytical euthyroidism and paralleled the improvement in the thyroid status of the patients. In contrast, the plasma Lp(a) concentration did not change at any time (496 +/- 123, 464 +/- 128, and 441 +/- 110 mg/L under basal conditions and after 1 and 14-15 months of thyroid replacement, respectively), and the small fluctuations observed in some patients did not correlate with those in LDL cholesterol or Apo-B, and were not associated with any particular Apo(a) phenotype. In relation to HDL fractions, high density lipoprotein3 (HDL3) remained stable, but HDL2 cholesterol and phospholipid levels decreased during treatment, changes that were the inverse of those in postheparin plasma hepatic lipase activity. Patients in the present study were normotriglyceridemic, except one who was hypertriglyceridemic at diagnosis, but even in this patient, triglyceride levels were unaffected by T4 substitution therapy, as was postheparin plasma lipoprotein lipase activity. The changes observed in LDL, HDL2, and hepatic lipase activity delineate the lipoprotein-related response to T4 replacement therapy, whereas potential individual fluctuations in Lp(a) levels are probably more dependent on other factors, such as the production rate, which are not affected by thyroid hormones.
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PMID:Long-term thyroid replacement therapy and levels of lipoprotein(a) and other lipoproteins. 785 21


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