Biomedical subjects

C Gagné

Publications and source records attributed to C Gagné.

At least 19 recordsLinked to original sources

PubMed1992

Alterations in erythrocyte membrane lipid composition and fluidity in primary lipoprotein lipase deficiency.

Lipid composition of plasma lipoproteins and erythrocyte ghost membranes has been studied in 16 healthy normolipidaemic subjects and in 16 patients affected by primary lipoprotein lipase deficiency, resulting in severe chylomicronaemia and in cholesterol-depleted low-density lipoproteins and high-density lipoproteins. A significant decrease in membrane cholesterol/phospholipid ratio was observed in lipoprotein lipase deficient patients compared to controls (3.27 +/- 0.33 vs. 3.95 +/- 0.50, mean +/- S.D.; P less than 0.0001). There was also an increase in the erythrocyte membrane phosphatidylcholine/sphingomyelin ratio in lipoprotein lipase deficient patients compared to controls (1.53 +/- 0.10 vs. 1.05 +/- 0.13; P less than 0.0001) due to a concurrent increase in phosphatidylcholine and decrease in sphingomyelin relative concentrations in these patients. Erythrocyte ghost membrane fluidity was determined by fluorescence anisotropy and found to be higher in membranes from lipoprotein lipase deficient patients. This increase in membrane fluidity can be attributed in part to changes in membrane cholesterol and phospholipid concentrations in response to abnormal plasma lipoprotein composition.

Adolescent↗

PubMed1992

Geographic distribution and genealogy of mutation 207 of the lipoprotein lipase gene in the French Canadian population of Québec.

Mutations in the lipoprotein lipase (LPL) gene, leading to partial or total inactivation of the enzyme, result in a hereditary clinical syndrome called familial LPL deficiency. The French Canadian population, which is primarily and historically located in the province of Québec, has the highest worldwide frequency of LPL-deficient patients. We have analyzed the prevalence, spatial distribution, and genealogy in the Québec population of a LPL gene mutation, M-207 (P207L in conventional notation), which changes the amino acid proline to leucine in position 207 of the LPL protein and inactivates the enzyme. Our results show that M-207 is the most prevalent LPL gene mutation among French Canadians and accounts for the largest proportion of LPL-deficient patients in this population. Genealogical reconstruction of French Canadian LPL-deficient patients point to 16 founders of M-207, all of whom migrated to Québec in the early seventeenth century from the north-western part of France, especially from the region of Perche. Most of the carriers of M-207 are, at present, found in Charlevoix, Saguenay-Lac-St-Jean regions of eastern Québec. On the basis of the number of homozygote M-207 LPL-deficient patients so far identified, we estimate that there are at least 31,000 carriers of this mutation in the province of Québec. This constitutes a large pool of individuals at risk for atherosclerosis and other lipid-related diseases, since LPL deficiency is considered to be a significant contributing factor in the etiology and development of these diseases.

Alleles↗

PubMed1992

Influence of diets containing cow's milk or soy protein beverage on plasma lipids in children with familial hypercholesterolemia.

The present article summarizes the effects of diets containing either cow's milk or soy protein beverage on plasma lipids and lipoproteins in children with familial hypercholesterolemia. After a stabilization period of 6 weeks without any hypolipemic medication, 10 subjects aged 6-12 years were randomly assigned to either cow's milk or soy protein beverage with subsequent crossover after a washout period, each of 4 weeks duration. During the experimental periods, subjects were fed diets containing 20% of energy as protein, of which 35% was from cow's milk protein or soy protein isolate, 28% of energy as fat with a polyunsaturated:monounsaturated:saturated fat ratio of 1:3:3, and less than 200 mg/day of cholesterol. The soy protein beverage, compared to cow's milk, induced significant reductions in plasma triglycerides and very-low-density lipoprotein cholesterol, as well as a significant increase in high-density lipoprotein cholesterol, indicating that consumption of soy protein beverage may be beneficial for the prevention of coronary heart disease in children with familial hypercholesterolemia.

Adult↗

PubMed1992

Prevalence, geographical distribution and genealogical investigations of mutation 188 of lipoprotein lipase gene in the French Canadian population of Québec.

Familial lipoprotein lipase deficiency (FLD) is of particular interest to the French Canadian population of Québec since the largest concentration of homozygotes and carriers of this genetic disease in the world resides in this area. We have previously described a missense mutation (M-188) in the lipoprotein lipase (LPL) gene which was present in FLD patients belonging to different ancestries, including a number of French Canadians (Monsalve MV et al. J Clin Invest 1990: 86: 728-734). In the present report, we show that this mutation, although found in largest absolute numbers among French Canadians as compared to other groups in the world, accounts for only a small proportion (24%) of all the LPL mutant alleles in this population. The M-188 occurs either in the homozygote state or as a compound heterozygote with another LPL mutation. Analysis of geographic distribution indicates that the M-188 is more prevalent in western Québec, with the highest carrier rate in the Mauricie region. Genealogical reconstruction leads to the recognition of four founders for M-188, all emigrants from France to Québec in the 17th century.

Base Sequence↗

PubMed1992

Adipose cell size and distribution in familial lipoprotein lipase deficiency.

To determine the effect of lipoprotein lipase deficiency on the size distribution of fat cell populations in human adipose tissues, abdominal and femoral subcutaneous fat tissue biopsies were obtained from seven patients affected by familial hyperchylomicronaemia. These patients were characterized by massive accumulation of chylomicrons in the fasting state due to defective catabolism of plasma triglyceride-rich lipoproteins. They had no post-heparin plasma lipoprotein lipase activity and their fat tissues were deficient in lipoprotein lipase activity. The size distribution of adipocytes examined by scanning electron microscopy were similar to distributions observed in control subjects. Patient fat cell diameters were not statistically different from control fat cells obtained from subjects of similar body mass index. Mature fat cells contributed to 99% of the total fat tissue mass in lipoprotein lipase deficiency. Normal adiposity in lipoprotein lipase deficiency can thus be attributed to mature adipocytes and not to hyperplastic growth of immature fat cells. It is concluded that normal adipose tissue homeostasis is maintained in these patients in spite of the deficiency in lipoprotein lipase activity.

Adipose Tissue↗

PubMed1992

Genetic epidemiology of lipoprotein lipase deficiency in Saguenay-Lac-St-Jean (Québec, Canada).

Familial hyperchylomicronemia due to the lipoprotein lipase (LPL) activity deficiency (Type I hyperlipoproteinemia) is an autosomal recessive disorder with a prevalence estimated at one case per million. Thirty-four type I individuals are known in Saguenay-Lac-St-Jean (SLSJ), a geographically isolated region of Quebec. The prevalence of type I and LPL deficient heterozygote in this region was estimated at 1/6382 and 1/46 inhabitants respectively. The mean inbreeding coefficient was slightly elevated in the type I group compared with three control groups. The mean kinship coefficient was 15.1 times higher in the type I group than in the control groups. The high prevalence of type I in SLSJ appears to be the result of the emigration of carriers of LPL deficiency from Charlevoix, another isolated region of quebec to the SLSJ region. Endogamy also played a crucial role in increasing the prevalence of type I in SLSJ.

Child↗

PubMed1991

A mutation in the human lipoprotein lipase gene as the most common cause of familial chylomicronemia in French Canadians.

BACKGROUND: Lipoprotein lipase hydrolyzes the triglyceride core of chylomicrons and very-low-density lipoproteins and has a crucial role in regulating plasma lipoprotein levels. Deficiencies of lipoprotein lipase activity lead to aberrations in lipoprotein levels. Worldwide, the frequency of lipoprotein lipase deficiency is highest among French Canadians. We sought to determine the molecular basis of the disorder in this population. METHODS: The entire coding sequence of the lipoprotein lipase gene from one French Canadian patient was amplified by the polymerase chain reaction and sequenced. Exon 5 from 36 other French Canadian patients was amplified and analyzed by dot blot hybridization with allele-specific oligonucleotides. RESULTS: Sequence analysis revealed a missense substitution of leucine (CTG) for proline (CCG) at residue 207 in exon 5. This mutation was found on 54 of the 74 mutant alleles (73 percent) in the patients. Studies of site-directed in vitro mutagenesis have confirmed that this mutation generates inactive lipoprotein lipase and is the cause of lipoprotein lipase deficiency. CONCLUSIONS: We have identified a missense mutation at residue 207 of the lipoprotein lipase gene that is the most common cause of lipoprotein lipase deficiency in French Canadians. This mutation can be easily detected by dot blot analysis, providing opportunity for definitive DNA diagnosis of the disorder and identification of heterozygous carriers.

Base Sequence↗

PubMed1991

Effects of a soy-protein beverage on plasma lipoproteins in children with familial hypercholesterolemia.

The effects of soy protein (35% of protein energy) given as a beverage and those of cow-milk proteins were investigated on plasma lipoprotein concentrations in children with familial hypercholesterolemia (FH). Subjects were randomly assigned to either the soy-protein or cow-milk-protein experimental period, with subsequent crossover after a washout period, each period lasting 4 wk. Diets were planned to provide 20% energy as protein, 28% as fat (polyunsaturated:monounsaturated:saturated fatty acids, 1:3:3) and less than 200 mg cholesterol/d. No changes were observed in either plasma cholesterol, low-density-lipoprotein cholesterol, or apolipoprotein concentrations. However, the soy beverage significantly reduced the concentrations of triglyceride and very-low-density-lipoprotein cholesterol (P less than 0.05) and significantly increased the concentrations of high-density-lipoprotein cholesterol (HDL-C) and HDL3-C (P less than 0.04 and P less than 0.03, respectively). These results indicate that the administration of soy protein may induce clinically beneficial effects in children with FH.

Apolipoproteins↗

PubMed1991

Beneficial effects of the calcium antagonist isradipine on apolipoproteins in hypertensive patients.

The objective of the study was to assess the effects of the calcium antagonist isradipine on plasma lipids, lipoproteins, and apolipoproteins in patients with essential hypertension. After a four-week placebo wash-out period, 73 patients (41 men, 32 women) were studied in a double-blind, randomized, crossover study comparing sustained-release isradipine (isradipine SR) with the standard isradipine formulation. Nineteen patients received 5 mg/day and 54 patients 10 mg/day. Lipids were evaluated at the end of the placebo period and after 12 weeks of treatment with isradipine. In both treatment groups, lipid and lipoproteins were not modified. However, apolipoprotein A-I levels increased significantly (P less than .001) and the ratio of apolipoprotein B to apolipoprotein A-I concentration decreased significantly (P less than .01) irrespective of gender. These data show that the levels of plasma apolipoprotein A-I, a strong predictor of coronary heart disease, are favorably affected by isradipine of either formulation. The mechanisms of this effect remain to be elucidated.

Adult↗

PubMed1991

Founder effect in familial hyperchylomicronemia among French Canadians of Quebec.

Familial hyperchylomicronemia has reached a high prevalence in the French Canadian population of eastern Quebec. The birth places of 58 carriers identified through the birth of one affected child clustered in three regions. The genealogies of these 58 individuals showed that no founder was common to all of them. Three sets of founders were found, one for each region, with little overlapping between two regions. These results strongly suggest that more than one mutation, introduced by the French migrants in the 17th century, are segregating in the French Canadian population. Perche, a region situated between Paris and Normandy, appeared to be the most likely putative center of diffusion of at least one mutation in the lipoprotein lipase gene segregating in the modern-day French Canadian population of Quebec.

France↗

PubMed1989

Primary lipoprotein-lipase-activity deficiency: clinical investigation of a French Canadian population.

We examined 56 French Canadians, aged 1 week to 54 years, from eastern Quebec who were referred to the Laval University Lipid Research Centre and in whom coincidental finding (in 46% of the cases), abdominal pain (in 32%) or family screening (in 22%) led to the diagnosis of primary lipoprotein-lipase-activity deficiency (familial hyperchylomicronemia). Half of the patients had one or more of the following signs: lipemia retinalis, eruptive xanthomas, splenomegaly and hepatomegaly; the plasma triglyceride concentrations were significantly higher (greater than 40 mmol/L) among these patients than among those without clinical signs (mean 21.7 [standard deviation 13.5] mmol/L). The prevalence rate of this disorder was 30 times higher than the previously published rate and was highest in the counties of Charlevoix and Saguenay-Lac-St-Jean (200 and 100 cases per million respectively) because of the distinct demographic history of these areas. Because of a founder effect an autosomal recessive gene involved in lipoprotein-lipase expression or activation has probably been disseminated among this isolated French Canadian population.

Adolescent↗

PubMed1989

Familial lipoprotein lipase-activity deficiency: study of total body fatness and subcutaneous fat tissue distribution.

Total body fatness and subcutaneous fat tissue distribution were evaluated in 19 hyperchylomicronemic patients. Eleven were males, aged 10 to 57 years, and eight were females, aged 13 to 46 years. Familial lipoprotein-lipase-activity deficiency was diagnosed by the absence of lipoprotein-lipase activity in the plasma withdrawn ten and 20 minutes after intravenous injection of ten units of heparin per kilogram of body weight. The 19 patients had skin-fold measurements for evaluation of subcutaneous fat distribution. Fifteen also underwent body density measurements by underwater weighing. Percent body fat was calculated from body density. These anthropometric data were plotted against the regression curves of 1638 normal controls of both sexes (aged 10 to 54 years) for fat tissue weight, percent body fat, subcutaneous fat/total fat mass ratio and trunk/extremity skin-fold ratio. Impairments in the process of building fat tissue reserves could not be shown in the 19 hyperchylomicronemic patients, in spite of the absence of lipoprotein-lipase activity in their postheparin plasma. It is hypothesized that normal fat tissue mass in these patients could be due partly to de novo synthesis of fatty acids by adipocytes, hydrolysis of plasma triglycerides by hepatic lipase, and/or contribution of a specific fat-tissue lipase to the catabolism of plasma triglyceride-rich lipoproteins.

Adipose Tissue↗

PubMed1989

Hypertriglyceridemia and lower LDL cholesterol concentration in relation to apolipoprotein E phenotypes in myotonic dystrophy.

Plasma lipid, lipoprotein levels and apolipoprotein apo E phenotypes were determined in 70 patients with myotonic dystrophy (MyD) and 81 controls. Marked differences were noticed in the apo E phenotype frequencies between the two groups. Plasma triglycerides and VLDL cholesterol were higher in MyD than controls, but only the latter was related to differences in the apo E phenotypes between two groups. Accordingly, the ratio of VLDL cholesterol/plasma triglycerides was increased significantly in MyD, suggesting accumulation of intermediary density particles due to lower affinity of E2 containing lipoproteins for lipoprotein cell receptors. The LDL cholesterol concentration was lower in MyD than controls and was related to differences in the apo E phenotype frequencies between the two groups. These results indicate increased removal of LDL particles in the apo E2 phenotypes, perhaps due to upregulation of LDL (B, E) receptor activity. Plasma cholesterol and HDL cholesterol concentrations were similar in both groups. Another feature of the study was lower levels of plasma cholesterol, triglycerides, VLDL and LDL cholesterol in the homozygous E4:E4 phenotype. These results suggest increased clearance rate of both VLDL and LDL particles and support the concept that apo E4-containing lipoproteins have higher in vivo affinity for ape E and/or B, E receptors.

Adolescent↗

PubMed1989

Influence of zofenopril and low doses of hydrochlorothiazide on plasma lipoproteins in patients with mild to moderate essential hypertension.

The effects of zofenopril (ZOF) calcium, an anticonverting enzyme inhibitor, and of hydrochlorothiazide (HCT) on plasma lipids, lipoproteins and apoproteins were compared in 37 patients with sitting diastolic blood pressure (SDBP) of 95 to 110 mm Hg at the end of a placebo period of 4 weeks. In the randomized double-blind experiment, 16 males and 21 females were treated with either ZOF, 30 mg (n = 18) or HCT, 25 mg (n = 19), once daily. When a SDBP of less than 90 mm Hg was not reached after 4 weeks, the dose of the initial treatment was doubled. Lipoprotein determinations were repeated after 12 weeks of active treatment. Statistically significant decrease in blood pressure (P less than .001) was demonstrated in both treated groups. Total, low density (LDL) and high density (HDL) lipoprotein, cholesterol and triglyceride concentrations were not modified either by ZOF or HCT. Furthermore, LDL/HDL and HDL-2/HDL-3 ratios, apoproteins B, A and A-1 levels did not show any significant differences. Thus, ZOF and small doses of HCT do not cause deleterious effects in lipoprotein composition as reported in previous studies with higher dosage.

Adolescent↗

PubMed1988

Changes in plasma lipoproteins during various androgen suppression therapies in men with prostatic carcinoma: effects of orchiectomy, estrogen, and combination treatment with luteinizing hormone-releasing hormone agonist and flutamide.

Cardiovascular complications are a well recognized side-effect of antihormonal therapy in men with prostatic carcinoma. We studied changes in plasma lipoproteins in patients with prostate cancer during treatment with several androgen suppression therapies. Estrogen, orchiectomy, and a combination of LHRH agonist and antiandrogen (flutamide) reduced plasma testosterone concentrations (89-92%) and plasma estradiol decreased by 85%, 44%, and 54%, respectively. Estrogen induced hypertriglyceridemia and elevation of plasma HDL cholesterol, phospholipid, and apolipoprotein A-I and A-II concentrations. Low density lipoprotein (LDL) cholesterol decreased but LDL apolipoprotein B did not. These results suggest that the cardiovascular complications that occur during estrogen administration are not mediated through changes in lipoprotein profile, other than the hypertriglyceridemic effect. Orchiectomy caused hypercholesterolemia and an increase in both total and LDL apolipoprotein B, all of which are strong determinants of cardiovascular disease. The high density lipoprotein (HDL) concentration was not affected despite a reduction in plasma testosterone, perhaps due to a simultaneous decrease in estradiol. Combination therapy had no effect on plasma lipid and apolipoprotein B concentrations, but very low density lipoprotein (VLDL) apolipoprotein B decreased, and LDL apolipoprotein B increased. The HDL cholesterol and apolipoprotein A-I concentrations increased but A-II and phospholipids did not. These results suggest enhanced lipoprotein lipase activity, consistent with the reciprocal changes in VLDL and LDL apolipoprotein B levels, apolipoprotein B enrichment of LDL particles, and increase in HDL cholesterol. The higher apolipoprotein A-I to A-II ratio indicates an increase in HDL2 subfraction due to inhibition of endothelial hepatic lipase, increased secretion of apolipoprotein A-I, or both. These effects are attributed to estradiol, which decreased less than after orchiectomy, and to additional adrenal androgen inhibition by flutamide. We conclude that estradiol plays an important role in determining plasma lipoprotein concentrations in men, and androgens exert an antagonist effect. The lipoprotein profile resulting from the combination treatment is more beneficial than that resulting from orchiectomy or estrogen administration.

Aged↗

PubMed1987

Increase in plasma high-density lipoprotein concentration following complete androgen blockage in men with prostatic carcinoma.

There is evidence that endogenous estrogens have a positive effect on plasma high density lipoprotein (HDL) concentration, whereas the relation between HDL and male sex hormones is unclear, since both positive and negative effects have been reported. This study examined the effects of LHRH agonist in combination with an antiandrogen on plasma lipids and lipoproteins in 17 elderly men with prostatic carcinoma. Subjects were examined prior to and after therapy at 4-week intervals up to 16 weeks. Prior to therapy, their lipid and lipoprotein profiles were not significantly different from a control group composed of individuals of similar age and living in the same community area. Following therapy plasma levels of testosterone and dihydrotestosterone were markedly decreased (above 90%) and their residual activity neutralized through effective use of an antiandrogen. Plasma estradiol decreased between 65% and 85% and the concentration of cortisol was unaffected. The very low density lipoprotein (VLDL) apo-B decreased and low density lipoprotein (LDL) apo-B increased; thus, no change was observed in the total plasma apo-B levels. Total plasma cholesterol increased by 6% (baseline v peak values, mg/dL, mean +/- SEM; 219 +/- 9 v 233 +/- 9, P less than 0.05) due to a significant rise in HDL cholesterol concentration (45.5 +/- 2.8 v 56.5 +/- 3.6, P less than 0.01). Both VLDL and LDL cholesterol levels remained unchanged. The mean elevation of 21% in HDL cholesterol was accompanied by a significant rise in HDL apo-A concentration (161 +/- 6 v 193 +/- 10, P less than 0.01), thus suggesting an increase in HDL mass and/or particle number.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗

PubMed1986

Severe lipemia induced by tamoxifen.

A 61-year-old woman was treated with tamoxifen for breast cancer and had marked hyperlipoproteinemia: high plasma triglyceride levels (2790 mg/dl); increased very low density lipoprotein (VLDL) cholesterol levels (241 mg/dl); and high VLDL apoprotein B levels (126 mg/dl). Low density lipoprotein (LDL) cholesterol was decreased (104 mg/dl) and LDL apoprotein B was at 107 mg/dl. A low activity of both postheparin plasma lipoprotein lipase (LPL) and hepatic triglyceride lipase (h-TGL) was also noted. All these observations were reversed following tamoxifen withdrawal. Plasma triglyceride levels fell to 361 mg/dl. VLDL cholesterol and VLDL apoprotein B decreased to 41 mg/dl (83%) and 21 mg/dl (83%), respectively. Meanwhile, LDL cholesterol rose to 194 mg/dl (86%) and LDL apoprotein B increased to 138 mg/dl (29%). LPL and h-TGL activities did increase following tamoxifen withdrawal. Our observations show that, in some patients, the previously described weak hypertriglyceridemic effect of tamoxifen is amplified. That observation supports the concept and helps to explain that, in such severe induced lipemia, reduction of the activities of LPL and h-TGL might impede the conversion of VLDL to LDL, thus causing an amplification of the effect.

Breast Neoplasms↗

PubMed1986

Plasma triglycerides related decrease in high-density lipoprotein cholesterol and its association with myocardial infarction in heterozygous familial hypercholesterolemia.

Recent studies suggest that decreased levels of high-density lipoprotein (HDL) may contribute to the risk of premature occlusive atherosclerosis in familial hypercholesterolemia (FH). To investigate further, we have analyzed the concentration as well as distribution of HDL cholesterol in relation to plasma triglycerides and their influence on ischaemic heart disease in FH subjects. The study was carried out in 71 men with heterozygous FH and 46 matched controls. FH subjects were relatively young with a mean age of 38 +/- 11 years. Tendon xanthomatas were observed in 57% of the subjects, whereas ischemic heart disease was identified in 33%. Compared to normals, the mean value of HDL cholesterol is significantly reduced by 21% in FH heterozygotes (42 +/- 12 v 33 +/- 9 mg/dL, P less than 0.001). The decrease in HDL cholesterol is highly correlated to the levels of plasma triglycerides (r = -0.50, P less than 0.001) and VLDL cholesterol (r = -0.53, P less than 0.001). Moreover, HDL cholesterol decrease is not associated with elevated levels of LDL cholesterol (r = -0.20, NS), which is the primary characteristic feature of FH subjects. However, HDL cholesterol decrease is weakly related to total plasma cholesterol concentration (r = -0.24, P less than 0.05). The body weight is also contributory to the reduction of HDL cholesterol (r = -0.42, P less than 0.01), probably due to its strong positive correlation to plasma triglycerides (r = +0.54, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗