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PubMed1999

A novel resistance to thyroid hormone associated with a new mutation (T329N) in the thyroid hormone receptor beta gene.

Resistance to thyroid hormone (RTH) is a syndrome of elevated serum thyroxine, inappropriately "normal" serum thyrotropin (TSH) and reduced thyroid hormone responsiveness associated with point mutations in the thyroid hormone receptor-beta (TRbeta) gene. We describe a novel point mutation resulting in a cytosine for adenine substitution at nucleotide 1271 (exon 9) that results in the substitution of threonine for asparagine (T329N). This mutation was identified in a 30-year-old woman who was investigated for recurrent spontaneous abortions and was found to have RTH. Dextrothyroxine (D-T4) therapy was instituted. At 8 mg per day 2 pregnancies followed with the delivery of a healthy boy and an RTH-affected girl another miscarriage occurred on D-T4 treatment at 6 mg per day. The T329N mutation, which was also identified in the daughter, markedly reduces the affinity of TRbeta for triiodothyronine (T3). Formation of T329N mutant TR homodimers and heterodimers with RXRalpha on thyroid hormone response element F2 (TRE F2) was not affected, but the ability of T3 to interrupt T329N mutant TRbeta homodimerization was markedly reduced. The T329N mutant TRbeta was transcriptionally inactive in transient expression assays. In cotransfection assays with wild-type TRbeta1, the mutant TRbeta1 functioned in a dominant negative manner. The results suggest that the T329N mutation in the T3-binding domain of TRbeta is responsible for RTH in the proposita's family.

Abortion, Habitual↗
PubMed1995

Cholesterol reduction yields clinical benefit. A new look at old data.

BACKGROUND: There has been a continuing debate about the overall benefit of cholesterol lowering. We performed a novel meta-analysis of all randomized trials of more than 2 years' duration (n = 35 trials) to describe how coronary-heart-disease (CHD), non-CHD, and total mortality are related to cholesterol lowering and to type of intervention. METHODS AND RESULTS: The analytic approach was designed to separate the effects of cholesterol lowering itself from the other effects of the different types of intervention used. For every 10 percentage points of cholesterol lowering, CHD mortality was reduced by 13% (P < .002) and total mortality by 10% (P < .03). Cholesterol lowering had no effect on non-CHD mortality. Certain types of intervention had specific effects independent of cholesterol lowering. Fibrates (clofibrates, 7 trials; gemfibrozil, 2 trials) increased non-CHD mortality by about 30% (P < .01) and total mortality by about 17% (P < .02). Hormones (estrogen, 2 trials; dextrothyroxin, 2 trials) increased CHD mortality in men by about 27% (P < .04), non-CHD mortality by about 55% (P < .03), and total mortality by about 33% (P < .01). No specific effects independent of cholesterol lowering were found due to diet (n = 11) or other interventions (resins, 5; niacin, 3; statins, 2; partial ileal bypass, 1). CONCLUSIONS: The results suggest that cholesterol lowering itself is beneficial but that specific adverse effects of fibrates and hormones increase the risk of CHD (hormones only), non-CHD, and total mortality.

Cholesterol↗
PubMed1988

Hyperthyroidism due to selective pituitary resistance to thyroid hormones in a 15-month-old boy: efficacy of D-thyroxine therapy.

A 15-month-old boy had clinical features of hyperthyroidism. In spite of elevated serum thyroid hormone levels (mean serum T4, 230 nmol/L; T3, 4.2 nmol/L), serum TSH levels ranged between 3.3-5.6 mU/L and rose to 35.4 mU/L after TRH stimulation. There was no abnormal serum thyroid hormone binding or any evidence of a pituitary tumor. The boy was treated with carbimazole for 6 months and became euthyroid. However, his thyroid size enlarged, and serum TSH rose to 45 mU/L. In an attempt to suppress TSH secretion, 3,5,3'-triiodothyroacetic acid was added to carbimazole in daily doses from 0.7-1.4 mg. This combined therapy failed to suppress TSH secretion (serum TSH, 10.2 mU/L) and led to recurrence of symptoms of hyperthyroidism. A trial using highly purified dextrothyroxine (contamination by L-T4, 0.05%) as sole therapy then was carried out. Serum TSH levels promptly declined to normal, both basally and after TRH stimulation (basal, 2.4 mU/L; peak, 13.8 mU/L). During a 24-month follow-up period, the boy remained euthyroid. Serum TSH levels remained in the normal range, as did his serum L-T4 levels (93 nmol/L). Complete remission was achieved using a 5-mg daily dose of D-T4. Temporary discontinuation of D-T4 led to prompt relapse of hyperthyroidism. Our patient's TSH hypersecretion appears to be due to selective pituitary resistance to thyroid hormones. Purified D-T4 effectively inhibited TSH secretion in this patient, without inducing significant side-effects, even when the daily dose was high. The cause of partial pituitary unresponsiveness to thyroid hormones is not known. We suggest that transport of thyroid hormones into the thyrotroph cells could be deficient in our patient.

Dextrothyroxine↗
PubMed1986

Contemporary recommendations for evaluating and treating hyperlipidemia.

The biochemistry, etiology, and evaluation of hyperlipidemia and its management, including dietary and drug therapies, are discussed. Strong evidence supports the role of increased cholesterol concentrations as an independent risk factor for coronary artery disease (CAD); however, evidence that elevated triglyceride concentrations are also an independent risk factor remains questionable. The cornerstone of the laboratory diagnosis of hyperlipidemia involves repeated measurement of serum or plasma cholesterol and triglyceride concentrations. The goals of therapy should be to reduce cholesterol or triglyceride concentrations or both to below the 75th percentile, modify co-existing risk factors, individualize the treatment, and minimize any adverse effects. Specific interventions must be determined on the basis of patient age, gender, etiology of hyperlipidemia, presence of other risk factors, and degree of lipid abnormality. The majority of patients may be managed with dietary therapy alone. The three-phase diet developed by the American Heart Association emphasizes a gradual reduction in cholesterol and fats with the substitution of polyunsaturated for saturated fats. Patients at risk for CAD with sustained elevations in plasma cholesterol concentrations above the 95th percentile or a triglyceride concentration above 500 mg/dL after an adequate dietary trial should be considered for drug therapy. The effects of cholestyramine and colestipol hydrochloride, niacin, dextrothyroxine, clofibrate, neomycin sulfate, probucol, gemfibrozil, and mevinolin and compactin on lipids and lipoproteins are reviewed. Hyperlipidemia should be managed systematically using information about the association between increased lipid concentrations and CAD, patient risk factors, and limitations of both diet and drug therapy.

Clofibrate↗
PubMed1975

Treatment of generalized scleroderma with inhibitors of connective tissue formation.

103 patients suffering from generalized scleroderma were studied in order to assess the effect of treatment with inhibitors of connective tissue formation. 93 patients with generalized scleroderma were given D-penicillamine, benzyl-penicillin-diethylamino-ethyl-ester hydroiodide, adrenal glucocorticoids, dextro-thyroxine, hydralazine, and "mixed treatment" (one or several of the drugs in consecutive courses, or concurrently). The effect of dextrothyroxine could not be evaluated in this study. No improvement could be seen after adrenocortical steroid therapy. Hydralazine seemed to be effective. D-penicillamine improved 25 of 34 treated patients; penicillin hydroiodide 12 out of 16. The dermal sclerosis of 6 patients regressed completely; in 16, sclerosis regressed with the exception of finger sclerosis; in 32, partial regression was registered; 20 had their progression arrested, but there was no regression; in 19 cases, there was no effect whatsoever. The prognosis seemed to be better for young than for old people. The age at onset was lower in the better groups. The higher the total dose, the better the results. The length of the treatment course is probably of some significance. The short-lasting cases had better prospects than the longer lasting. Ten untreated patients of this material and 11 patients seen earlier showed continued progression. Side effects leading to discontinuation of the drugs were seen in a substantial number of patients, especially after D-penicillamine. Twelve deaths could not be related to the treatments.

Adult↗
PubMed1983

Pharmacologic therapy for the hyperlipidemic patient.

Drug therapy should be instituted only after appropriate diet treatment has been started and adequate baseline lipid and lipoprotein values are established. Nicotinic acid is useful in treating most lipoprotein disorders and the cutaneous flushing that develops during the early part of treatment is usually alleviated by aspirin. Cholestyramine and colestipol are nonabsorbable resins whose use is limited to type II hyperlipoproteinemia. Clofibrate is primarily effective in lowering triglyceride levels, but its clinical use has considerably declined following the World Health Organization study results that reported increased morbidity and mortality rates among patients receiving this drug. Based on the finding of increased mortality among a subset of patients participating in the Coronary Drug Project, dextrothyroxine is only recommended for treating patients who do not have clinically evident atherosclerotic heart disease. Probucol lowers total and low-density lipoprotein cholesterol levels, but has the undesirable effect of simultaneously reducing high-density lipoprotein levels.

Bile Acids and Salts↗
PubMed1991

Hyperthyroidism due to familial pituitary resistance to thyroid hormone: successful control with 3, 5, 3' triiodothyroacetic associated to propranolol.

We herein describe a family with thyroid hormone resistance. Thyroid hormones and basal TSH were elevated. Pituitary tumor or abnormality in thyroid hormone binding proteins were ruled out by appropriate tests. Mother and sister of the propositus presented similar abnormal hormonal features but no hyperthyroidism. Initially the patient was treated with carbimazole (30 mg/day): three months later a dramatic increase in the size of the thyroid gland and in TSH levels (12.5 to 28 mU/l) were noted. Thereafter, dextrothyroxine (D-T4) and 3, 5, 3'-triiodothyroacetic acid (TRIAC) were given consecutively and treatment was accompanied by a decrease of TSH levels (2 mU/l) but thyroid hormone remained elevated. The symptoms and signs of hyperthyroidism improved with the addition of propranolol (30-60 mg/day). In conclusion, the present report describes a new family with the syndrome of THR and variable degrees of involvement among relatives. We suggest the usefulness of TRIAC therapy to decrease TSH levels and propranolol to improve thyrotoxicosis due to pituitary resistance to thyroid hormone.

Adolescent↗
PubMed1981

Practical aspects of decision making in clinical trials: the coronary drug project as a case study. The Coronary Drug Project Research Group.

Arriving at a decision for early termination of a treatment group or of an entire clinical trial, due to either beneficial or adverse results, is a complex process. It may involve, among other things, the necessity to (1) determine whether the observed treatment differences are likely to represent real effects and are not due to chance; (2) weigh the importance of many different response variables, some possible trending in favor of the treatment and some against it; (3) adjust for differences in distributions of baseline characteristics among the treatment groups; (4) discern possible biases (due to the study not being double-blind) in the medical management of patients or in the diagnosis of events; and (5) evaluate treatment effects in subgroups of the study participants. Experiences in the Coronary Drug Project are described in making decisions for early termination of treatment groups. Special methods applied in conjunction with reaching these decisions included: (1) analyses designed to detect possible biases in diagnosing a major endpoint--nonfatal myocardial infarction, e.g.--biases that may have arisen because of unblinding by side effects of the estrogen treatment group; (2) a simulation study to assess the statistical significance of mortality differences between the dextrothyroxine and placebo participants in certain subgroups identified a posteriori; and (3) the development, on the basis of the accumulated data, or new hypotheses relating to treatment differences in specific subgroups and the testing of these hypotheses a few months later on the basis of new events occurring during that interval.

Clinical Trials as Topic↗
PubMed2005

Diet, lifestyle, and nonstatin trials: review of time to benefit.

How rapidly benefits accrue from nonstatin, lipid-lowering therapies is a 21st-century question posed to data collected in the 20th century. The 3 early dietary trials conducted in institutional settings where diet was strictly controlled demonstrate that, compared with a control diet, cholesterol-lowering diets reduce coronary event rates over several years. These data do not reveal whether a more homogeneous high-risk population would demonstrate an earlier time to benefit. Dietary counseling trials of men with coronary disease conducted in the 1950s and 1960s failed to demonstrate a consistent benefit from dietary therapy, in part because of confounding factors from methodologic flaws in trial design. By the 1980s and 1990s, improvements in trial design, such as larger numbers of subjects, control of confounding risk factors, and limiting trial end points to those directly attributable to atherosclerotic events, were in place. Subsequently, 5 randomized clinical trials showed a consistent benefit of dietary therapy, with significant reductions by 1 to 2 years in fatal events, nonfatal events, and total mortality; 2 of these studies, each including omega-3 fatty acids as part of the dietary intervention, reported a rapid and significant time to benefit (within 3 to 6 months). Additional lifestyle benefits of cardiac rehabilitation (a surrogate for physical activity) and smoking cessation clearly show long-term benefit at 1 and 5 years, respectively. Nonstatin drug and surgical therapies either have shown no significant benefit (estrogen, dextrothyroxine) or benefit after 1 to 5 years of therapy (intestinal bypass surgery, cholestyramine, clofibrate, niacin, and a combination of niacin and clofibrate). In conclusion, rapid time to benefit has been observed in older lifestyle and nonstatin trials that have included omega-3 fatty acids as a component of dietary therapy. Lifestyle changes in diet, physical activity, weight loss, and smoking cessation remain important and effective therapies with which significant long-term benefits can be expected.

Diet, Fat-Restricted↗
PubMed1990

Review of clinical trials: proving the lipid hypothesis.

The Lipid Hypothesis, which states that lowering blood cholesterol levels should significantly reduce the incidence of coronary heart disease (CHD), has been repeatedly tested in primary and secondary intervention trials. Viewed as a whole, it is apparent that the incidence of CHD in treated groups decreased in proportion to the degree of plasma cholesterol reduction. An early study at the Wadsworth Hospital in Los Angeles showed that a diet high in polyunsaturated fat and low in cholesterol reduced the incidence of CHD. The Oslo study of diet and smoking intervention demonstrated a significant decrease in CHD concomitant with a 13% reduction in serum cholesterol achieved through a low saturated-fat diet and cessation of smoking. In the World Health Organization primary prevention trial, clofibrate reduced serum cholesterol by 9% and first clinical episodes of myocardial infarction by 20%. There was a 37% rise in total mortality, but no causal link with clofibrate has been found, and this was not significant when corrected for age at death. A secondary trial, the Coronary Drug Project, demonstrated that oestrogen and dextrothyroxine were clearly toxic. In this trial, niacin produced a 10% fall in serum cholesterol and mortality was 11% lower than in the placebo group after long-term follow-up. The Lipid Research Clinics-Coronary Primary Prevention Trial (LRC-CPPT) found an 8% reduction in plasma cholesterol and a 19% reduction in the incidence of CHD in the group treated with cholestyramine compared with placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Coronary drug project: experience with niacin. Coronary Drug Project Research Group.

Niacin was one of the treatments compared in the Coronary Drug Project, a placebo-controlled, multicenter trial of lipid-lowering drugs in the secondary prevention of coronary heart disease. A total of 1119 men, aged 30-64 at entry, were randomized to niacin and 2789 to placebo by the end of recruitment in March 1969. Although side-effects interfered with adherence to the niacin regimen, it was the most effective agent in achieving cholesterol-lowering (10% overall); other agents in the trial were clofibrate, dextrothyroxine, and conjugated equine estrogens. At the scheduled conclusion of the trial in February 1975, the niacin-treated group exhibited a statistically significantly lower incidence of definite, non-fatal myocardial infarction (MI) than the placebo group. There was a trend toward improvement in the life-table mortality curve, but this was not statistically significant. In 1981 an extended follow-up was carried out concerning vital status for the 6008 men who were still alive at the end of treatment and active follow-up in the trial in 1975 (827 in the niacin group and 2008 in placebo groups). Vital status was determined for 99.1% of these men after a mean of 9 years from conclusion of the trial. In the group previously randomized to niacin, there were 69 (11%) fewer deaths than were expected on the basis of mortality in the placebo group. This difference was significant (z = -3.52; P = 0.0004). The data also suggested that patients with a higher baseline cholesterol experienced greater benefit from niacin therapy, as did those with the best response to the drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Prescribed use of cholesterol-lowering drugs in the United States, 1978 through 1988.

Data from two pharmaceutical marketing research databases, the National Prescription Audit and the National Disease and Therapeutic Index, were used to study trends in outpatient use of cholesterol-lowering drugs in the United States from 1978 through 1988. Retail pharmacies dispensed an estimated 4.4 million prescriptions for cholesterol-lowering drugs in 1978. This declined to 2.6 million in 1983 and increased dramatically to nearly 13 million in 1988. This fivefold increase between 1983 and 1988 was accounted for primarily by the introduction and use of two new drugs, gemfibrozil and lovastatin, and, to a lesser extent, by the increasing use of some older drugs. In 1988, after 1 full year of marketing, lovastatin was the leading cholesterol-lowering drug, followed closely by gemfibrozil; both drugs are currently considered second-line agents. Clofibrate and dextrothyroxine, drugs that ranked first and second in 1978, declined to ranks of sixth and eighth out of eight in 1988. Cholestyramine, gemfibrozil, and lovastatin accounted for about 75% of all lipid-lowering prescriptions in 1988. From 1978 through 1988, an average 54% of individuals using cholesterol-lowering drugs were 60 years of age or older. The 13 million prescriptions for cholesterol-lowering drugs in 1988 represent a maximum estimate of 13 million treated individuals. This number compares with the 60 million Americans with high cholesterol levels who are candidates for dietary advice, and, if cholesterol levels do not improve, for combined diet and drug intervention.

Anticholesteremic Agents↗
PubMed1983

Secondary prevention of myocardial infarction with drugs.

Clinical trials in the field of secondary prevention of myocardial infarctions are reviewed, with emphasis on those studies that were randomized and included at least 100 patients. Standardized total mortality data, when available, are provided. Five groups of drugs are reviewed: 1) antiarrhythmic drugs, including studies of phenytoin, tocainide, mexiletine and aprindine. Important, commonly used drugs in this group, which apparently have not been submitted to clinical trials, include procainamide and lidocaine; 2) lipid-lowering drugs, including estradiol, conjugated equine estrogen, dextrothyroxine, clofibrate and nicotinic acid; 3) anticoagulant drugs, the oldest and most controversial preventive drug measure. In this group, only the oral drug derivatives of indandione or coumarin have been tested, and no appropriate studies of parenteral heparin were found; 4) platelet-active drugs--six studies dealing with aspirin alone, one combining aspirin and dipyridamole, and one study of sulfinpyrazone are reviewed; and 5) beta-adrenergic blocking drugs, including practolol and timolol.

Adrenergic beta-Antagonists↗
PubMed1980

Aspirin in coronary heart disease. The Coronary Drug Project Research Group.

The Coronary Drug Project Aspirin Study (CDPA), started in late 1972 and terminated in early 1974, involved men selected from three groups originally receiving dextrothyroxine or estrogen therapy in the Coronary Drug Project. All patients had a history of myocardial infarction, most of them several years earlier. Length of follow-up ranged from 10-28 months (average 22 months). A total of 1529 patients were recruited and were randomly assigned on a double-blind basis to aspirin therapy -- one 324-mg tablet three times daily or a corresponding placebo treatment. Data indicate a high level of adherence to the study protocol. No major differences were recorded in use of nonstudy medications in the two treatment groups. Overall mortality was 5.8% in the aspirin group and 8.3% in the placebo group (an observed difference of 30%). This difference, suggestive of a beneficial effect for aspirin in the treatment of post-myocardial infarction men, was not large enough to be conclusive.

Aspirin↗