Cerebrotendinous xanthomatosis without neurological involvement.

BACKGROUND: Cerebrotendinous xanthomatosis (CTX) is an autosomal recessively inherited inborn error of metabolism. Neurological symptoms are considered to be a clinical hallmark of untreated adult patients. We describe a 'milder CTX phenotype', without neurological involvement. METHODS: We performed a retrospective patient file study in 79 genetically confirmed Dutch patients with CTX (55 patients aged ≥ 21 years) to study the clinical heterogeneity of CTX. We studied the frequency of adult patients with CTX without neurological involvement at diagnosis, in our Dutch cohort, and included a family from South Africa and patients from Italy, USA, Chile and Asia from the literature. RESULTS: In total, we describe 19 adult patients with CTX from 16 independent families, without neurological symptoms at diagnosis. A relatively small percentage (21%, n = 4) had a history of cataract. The majority, 84% (n = 16), presented with tendon xanthomas as the sole or predominant feature. The majority of patients showed increased plasma cholesterol levels. No correlation was found between this 'milder phenotype', the cholestanol levels and the CYP27A1 genotype. In addition, we describe three novel mutations in the CYP27A1 gene. CONCLUSIONS: This study shows the clinical heterogeneity of CTX, highlighting the existence of a 'milder phenotype', that is without neurological involvement at diagnosis. Adult patients with CTX may present with tendon xanthomas as the sole or predominant feature, mimicking familial hypercholesterolemia. It is important to realize that the absence of neurological symptoms does not rule out the development of future neurological symptoms. As CTX is a treatable disorder, early diagnosis and initiation of treatment when additional clinical signs occur is therefore essential.

Volanesorsen for treatment of patients with familial chylomicronemia syndrome.

Familial chylomicronemia syndrome (FCS) is a rare autosomal recessive disorder typically caused by mutations in genes for lipoprotein lipase (LPL), apolipoprotein C-II (Apo-CII), apolipoprotein A-V (Apo-AV), lipase maturation factor 1 (LMF1) and glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPI-HBP1). FCS is associated with severe morbidity that includes recurrent pancreatitis and other problems. Effective treatment to reliably prevent complications has been unavailable, so there is a quest to identify novel interventions to achieve sustained triglyceride lowering and prevention of pancreatitis. Apolipoprotein C-III (Apo-CIII) interferes with triglyceride clearance by blocking LPL and alternative pathways. Volanesorsen is an experimental antisense oligonucleotide that inhibits translation of Apo-CIII mRNA, thereby substantially lowering plasma levels of Apo-CIII and triglycerides. It is being developed for treatment of patients with FCS and refractory hypertriglyceridemia. Data from a variety of clinical trials have been very encouraging, with documentation of excellent triglyceride-lowering efficacy, but there have been concerns about the risk of drug-related thrombocytopenia and bleeding that contributed to the recent decision by the Food and Drug Administration (FDA) to not approve the drug for clinical use. Clinical trials testing the safety and efficacy of volanesorsen are ongoing, so there is hope that the drug ultimately will be approved and available for treatment of high-risk patients with FCS.

Nonenzymatic glycosylation of HDL and impaired HDL-receptor-mediated cholesterol efflux.

Previous studies have shown that nonenzymatic glycosylation of high-density lipoprotein (HDL) inhibits high-affinity binding to cultured cells and the candidate HDL-receptor protein. Because binding of HDL to its receptor is required for HDL-receptor-mediated cholesterol efflux from cells, we hypothesized that glycosylated HDL3 would have reduced ability to remove cholesterol from cells. HDL3 was glycosylated in vitro to achieve up to 40-50% reductions in free-lysine residues. Glycosylated HDL3 had a slightly greater ability than control HDL3 to sequester cholesterol directly from the plasma membrane, as predicted by changes in lipid composition. This process is independent of HDL-receptor binding and should not be influenced by reduced binding of HDL3. In contrast, efflux of intracellular cholesterol from cells, which is HDL-receptor dependent, was reduced 25-40%. The ability of glycosylated HDL3 to diminish cholesterol esterification was significantly reduced, indicating reduced net cholesterol efflux. Steady-state efflux of LDL-derived cholesterol was also markedly reduced. These findings suggest that nonenzymatically glycosylated HDL is functionally abnormal and might contribute to the accelerated development of atherosclerosis in patients with diabetes mellitus.

Nonenzymatic glycosylation of HDL resulting in inhibition of high-affinity binding to cultured human fibroblasts.

Nonenzymatic glycosylation of plasma proteins may contribute to the excess risk of developing atherosclerosis in patients with diabetes mellitus. Because high-density lipoprotein (HDL) is believed to protect against atherosclerosis and is glycosylated at increased levels in diabetic individuals, the effects of nonenzymatic glycosylation of HDL3 on binding of HDL3 to cultured fibroblasts and to the candidate HDL-receptor protein were examined. HDL3 was glycosylated in vitro with glucose alone or in combination with sodium cyanoborohydride. With this catalyst, up to 40-50% of the lysine residues could be glycosylated, resulting in a progressive drop to nearly 60% in high-affinity binding to cultured fibroblasts at 4 degrees C. Binding to the 110,000-Mr candidate HDL-receptor protein was reduced by almost 75%. At levels of HDL glycosylation equivalent to the 3-5% observed in diabetes, high-affinity binding to fibroblasts at 4 degrees C was diminished by up to 15-20%. Binding kinetic studies paradoxically suggested that glycosylated HDL3 binds with higher affinity to a reduced number of binding sites. The findings in this study suggest that nonenzymatically glycosylated HDL may be functionally abnormal and might contribute to the development of atherosclerosis in patients with diabetes mellitus.

Exacerbation of rheumatoid arthritis by sodium fluoride treatment of osteoporosis.

Recent studies have suggested that sodium fluoride therapy may be an effective treatment for vertebral osteoporosis. Unfortunately, the high frequency of side effects may limit the use of this treatment modality. This report documents the repeated exacerbation of rheumatoid arthritis on three occasions after the initiation of sodium fluoride therapy. This apparent complication of sodium fluoride treatment may be mediated by stimulation of leukocyte production of reactive oxygen species and other mediators of the acute inflammatory response. We suggest that sodium fluoride should be used cautiously in patients with rheumatoid arthritis.

Inappropriate thyroid gland ablation in patients with generalized resistance to thyroid hormone. A common sequela of a rare disorder.

Generalized resistance to thyroid hormone is one of several rare disorders of thyroid metabolism that can be associated with confusing symptoms and signs. Five cases of generalized resistance to thyroid hormone that were misdiagnosed with thyrotoxicosis, leading to unnecessary thyroid gland ablation and iatrogenic hypothyroidism, are reviewed herein. These cases illustrate the point that a careful review of the history, physical examination, and laboratory data, as well as an understanding of hormonal feedback relationships, will greatly benefit the practitioner in evaluating the patients with thyroid dysfunction. Consultation with an endocrinologist may be helpful to establish the correct diagnosis and avoid unnecessary treatments.

Henoch-Schönlein purpura following thiram exposure.

Henoch-Schönlein purpura (HSP) is an uncommon, nonthrombocytopenic hypersensitivity vasculitis that is often idiopathic, but may be induced by infectious agents, drugs, foods, environmental chemicals, or insect bites. To our knowledge, we report the first recognized case of HSP following exposure to the widely used industrial and agricultural agent, tetramethylthiuram disulfide. Few reports of HSP or other vasculitides resulting from exposure to structurally similar compounds are available. Despite the widespread use of tetramethylthiuram disulfide, many cases of exposure may remain unrecognized, resulting in a subsequent failure to properly identify sequelae.

The relationship between sex hormones and high-density lipoprotein cholesterol levels in healthy adult men.

The objective of this study was to clarify the complex and uncertain relationship between endogenous sex hormones and high-density lipoprotein (HDL) cholesterol levels in healthy men. Fifty-five healthy adult men were consecutively recruited from an ongoing cross-sectional study of cardiovascular disease risk factors from a lipid research clinic at the University of Washington, Seattle. Subjects receiving medication were excluded. Multiple linear regression analysis identified several factors that correlated highly significantly with HDL cholesterol levels, including alcohol intake; frequency of strenuous exercise; age; levels of total cholesterol, low-density lipoprotein cholesterol, and triglyceride; and carbohydrate intake. Nearly 80% of the heterogeneity in HDL cholesterol levels could be accounted for by these factors. Despite finding significant correlations with factors known to influence HDL cholesterol levels, no correlation with estradiol level, testosterone level, or the ratio of estradiol to testosterone levels was apparent. In conclusion, endogenous sex hormones do not appear to influence HDL cholesterol levels in healthy adult men. Alternatively, a large proportion of the heterogeneity in HDL levels in this group of men can be accounted for by environmental factors. The disparity between this conclusion and others may be partially due to differences in accounting for these confounding variables.

The relationship between serum lipoprotein(a) and insulinemia in healthy nondiabetic adult men.

OBJECTIVE: To test the hypothesis that variations in serum insulin concentrations and insulin action may influence serum concentrations of lipoprotein(a) [Lp(a)]. RESEARCH DESIGN AND METHODS: A cross-sectional analysis of fasting serum insulin and Lp(a) concentrations were conducted in a group of 54 healthy adult men 23-61 years of age. Measures of dietary intake, exercise, smoking, alcohol ingestion, body mass index (BMI), fasting plasma lipoprotein lipid concentrations, and serum sex hormone and fasting glucose levels were also determined. RESULTS: The fasting serum concentrations of insulin and Lp(a) were negatively correlated (r = -0.339, P = 0.014) by univariate regression analysis. Several confounding variables were also significantly correlated with Lp(a) concentrations: testosterone (r = 0.348, P = 0.012), strenuous exercise (r = 0.287, P = 0.041), and BMI (r = -0.276, P = 0.050). As expected, these additional variables and serum insulin concentrations were highly interrelated. In a stepwise regression model, the serum insulin level was identified as the single best predictor of Lp(a) levels. Nearly 25% of the heterogeneity in serum concentrations of Lp(a) could be predicted by serum levels of insulin and testosterone, BMI, and the amount of strenuous exercise. CONCLUSIONS: The results of these studies have shown that serum concentrations of insulin and testosterone, BMI, and strenuous exercise appear to account for the majority of predicted nongenetic variability in serum levels of Lp(a). These observations suggest the possibility in this group of healthy men that serum concentrations of Lp(a) may be modulated by a complex interplay between insulin action, obesity, androgen levels, and strenuous exercise.

A new point mutation (C446R) in the thyroid hormone receptor-beta gene of a family with resistance to thyroid hormone.

Resistance to thyroid hormone (RTH) is a condition of impaired end-organ responsiveness to thyroid hormone characterized by goiter and elevated thyroid hormone levels with an inappropriately normal TSH. RTH has been associated with mutations in the thyroid hormone receptor-beta (TR beta) gene. We report studies carried out in 21 members of a family (F119), 12 of whom exhibited the RTH phenotype. A point mutation was detected in the T3-binding domain of the TR beta gene. It resulted in replacement of the normal cysteine-446 with an arginine (C446R) that has not been previously reported. The clinical characteristics of this family are similar to those reported in other families with RTH, namely goiter, tachycardia, and learning disabilities. Thyroid function tests are also typical of other subjects with RTH. The mean values (+/- SD) in untreated affected subjects compared to those in unaffected family members were: free T4 index, 250 +/- 21 vs. 108 +/- 13; total T3, 4.3 +/- 0.4 vs. 2.4 +/- 0.4 nmol/L; and TSH, 4.5 +/- 1.1 vs. 2.4 +/- 1.1 mU/L. DNA samples from 18 family members were screened for the TR beta mutation, which results in the loss of a BsmI restriction site, and each of the 11 subjects with abnormal thyroid function tests were heterozygous for the mutant allele. The mutant TR beta expressed in Cos-I cells did not bind T3 (Ka of C446R/wild-type, < 0.05). T3 at a concentration up to 100 nmol/L failed to enhance the transactivation of a reporter gene, and the mutant receptor inhibited the T3-mediated transcriptional activation of the wild-type TR beta.

Effect of fasting, refeeding, and dietary fat restriction on plasma leptin levels.

The factors responsible for the variability in plasma leptin levels observed among individuals with similar body compositions remain unclear. To examine the impact of dietary variables, we compared the changes in leptin levels induced by fasting and dietary fat restriction with the expected decrease following a significant loss in adipose mass. A 21.4 +/- 3.7% weight loss led to a 76.3 +/- 8.1% decrease in mean plasma leptin level (25.2 +/- 9.3 to 6.1 +/- 3.4 ng/mL, P = 0.0001) in a group of 9 obese males. Despite a weight loss of only 2.6 +/- 0.8%, mean plasma leptin levels fell by 61.9 +/- 25.2% (8.5 +/- 4.5 to 2.4 +/- 0.5 ng/mL, P < 0.01) in 7 nonobese females subjected to 3 days of fasting. Leptin levels in fasted subjects returned to baseline within 12 h of refeeding. Individual high- and low-fat meals given to 19 subjects after an overnight fast had no effect on plasma leptin levels. Reduction in dietary fat content from 37-10% of total calories for 7 weeks was also without effect on plasma leptin levels in these subjects. We conclude that plasma leptin levels primarily reflect total adipose mass, rather than meal consumption or dietary energy source, but that the reduction in leptin levels with ongoing fasting is disproportionate to the reduction in adipose mass. The ability of fasting to deactivate this presumed physiological satiety system may have been advantageous in environments characterized by rapid changes in food availability.

High plasma homocyst(e)ine levels in elderly Japanese patients are associated with increased cardiovascular disease risk independently from markers of coagulation activation and endothelial cell damage.

Elevated plasma homocyst(e)ine is a risk factor for cardiovascular disease (CVD) in many populations, but the relationship between homocyst(e)ine and CVD in Japanese subjects has been unclear. It has been hypothesized that the link between homocyst(e)ine and CVD may be mediated in part by activation of coagulation and endothelial cell injury in the elderly Japanese subjects. To further evaluate this hypothesis, the present cross-sectional study was designed to assess the relationships among plasma homocyst(e)ine concentrations, risk of CVD, and markers of coagulation (fibrinogen, FVII, F1+2, FVIIa and FXIIa) and endothelial cell damage (vWF and thrombomodulin) in 146 elderly Japanese subjects (79 healthy controls and 67 patients with CVD). The geometric mean (range) of plasma homocyst(e)ine concentrations was 10.2 (3.2--33) micromol/l in 79 Japanese healthy elderly subjects. As expected, healthy female and male elderly subjects had homocyst(e)ine levels that were 2.5 and 5.3 micromol/; higher, respectively, compared to healthy young control subjects (n=62). Healthy young and elderly men had homocyst(e)ine levels that were 1.7 and 4.5 micromol/l higher, respectively, compared to values in women. This higher plasma homocyst(e)ine levels in the elderly subjects were negatively correlated with levels of folic acid, albumin and total cholesterol, but were not significantly related to markers of coagulation or endothelial cell-damage. The results of multiple logistic regression analyses suggested that high homocyst(e)ine levels were independently related to CVD risk. In addition, levels of FVIIa, and F1+2 were significantly higher in elderly Japanese patients with CVD compared to elderly subjects without CVD, but were unrelated to plasma homocyst(e)ine concentrations. In summary, elevated plasma concentrations of homocyst(e)ine, FVIIa, and F1+2 were associated with increased risk of CVD in elderly male and female Japanese subjects, but the association between homocyst(e)ine and CVD was unrelated to abnormalities in markers of coagulation and endothelial cell damage in this population.

Rhabdomyolysis after taking atorvastatin with gemfibrozil.

The findings in this case indicate that atorvastatin, like other DL-3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, may increase the risk of myositis and rhabdomyolysis when used in combination with gemfibrozil.

Differential effects of subcutaneous estrogen and progesterone on low-density lipoprotein size and susceptibility to oxidation in postmenopausal rhesus monkeys.

OBJECTIVE: To study the differential effects of subcutaneous E2 alone or in combination with P on the susceptibility of low-density lipoprotein (LDL) cholesterol to oxidation in naturally postmenopausal diet-controlled rhesus monkeys. DESIGN: Prospective, longitudinal controlled study. SETTING: Oregon Health Sciences University, Portland, Oregon, and Oregon Regional Primate Research Center, Beaverton, Oregon. PATIENT(S): Five naturally postmenopausal rhesus monkeys. INTERVENTION(S): Estradiol was administered subcutaneously for the first 4 weeks, followed by E2 plus P for 4 weeks, followed by a third 4-week washout period. MAIN OUTCOME MEASURE(S): Changes in plasma lipoprotein levels and oxidation of LDL and serum concentrations of E2 and P. RESULT(S): Levels of LDL cholesterol fell after 4 weeks of treatment with E2, compared with baseline. The lag time to half maximal light absorbancy after 4 weeks of E2 treatment was significantly increased compared with baseline. The maximal absorbance values and the slope of the propagation phase after 4 weeks of treatment with E2 were decreased compared with baseline. After 4 weeks of combined E2 and P treatment, all values were comparable to baseline. CONCLUSION(S): These results suggest that subcutaneous E2 therapy appears to enhance LDL resistance to oxidation and that this effect is attenuated by the addition of the P.

High glucose levels do not directly impair cellular binding of HDL3 or HDL-mediated efflux of cholesterol from human skin fibroblasts.

The excess risk of atherosclerosis that is associated with diabetes mellitus cannot be completely accounted for by other known risk factors. Recent studies have suggested that increased glycation of high density lipoproteins (HDL) at high glucose concentrations causes functional abnormalities that might contribute to accelerated atherosclerosis. Other investigators also have shown that elevated glucose concentrations can stimulate the activity of protein kinase C in cultured cells. Because protein kinase C appears to be involved in HDL receptor-mediated efflux, the hypothesis that a high glucose concentration in vitro might modulate HDL-mediated efflux of cholesterol from human fibroblasts was tested. These studies indicate that a high glucose level alone does not affect the interaction of normal HDL3 with cultured human skin fibroblasts.

Short-term folic acid supplementation induces variable and paradoxical changes in plasma homocyst(e)ine concentrations.

Folic acid is presently the mainstay of treatment for most subjects with elevated plasma homocyst(e)ine concentrations [Plasma or serum homocyst(e)ine, or total homocysteine, refers to the sum of the sulfhydryl amino acid homocysteine and the homocysteinyl moieties of the disulfides homocystine and homocystein-cysteine, whether free or bound to plasma proteins.] Changes in homocyst(e)ine in response to folic acid supplementation are characterized by considerable interindividual variation. The purpose of this study was to identify factors that contribute to heterogeneity in short-term responses to folic acid supplementation. The effects of folic acid supplementation (1 or 2 mg per day) for 3 wk on plasma homocyst(e)ine concentrations were assessed in 304 men and women. Overall, folic acid supplementation increased mean plasma folate 31.5 +/- 98.0 nmol/L and decreased mean plasma homocyst(e)ine concentrations 1.2 +/- 2.4 micromol/L. There was evidence of substantial interindividual variation in the homocyst(e)ine response from -18.5 to +7.1 micromol/L, including an increase in homocyst(e)ine in 20% of subjects (mean increase 1.5 +/- 1.4 micromol/L). Basal homocyst(e)ine, age, male gender, cigarette smoking, use of multivitamins, methylene tetrahydrofolate reductase, and cystathionine beta-synthase polymorphisms accounted for 47.6% of the interindividual variability in the change in homocyst(e)ine after folic acid supplementation, but about 50% of variability in response to folic acid was not explained by the variables we studied.