Showing papers by "Laval University published in 1989"

Heat shock resistance conferred by expression of the human HSP27 gene in rodent cells.

Abstract: Heat shock induces in cells the synthesis of specific proteins called heat shock proteins (HSPs) and a transient state of thermotolerance. The putative role of one of the HSPs, HSP27, as a protective molecule during thermal stress has been directly assessed by measuring the resistance to hyperthermia of Chinese hamster and mouse cells transfected with the human HSP27 gene contained in plasmid pHS2711. One- and two-dimensional gel electrophoresis of [3H]leucine- and [32P]orthophosphate-labeled proteins, coupled with immunological analysis using Ha27Ab and Hu27Ab, two rabbit antisera that specifically recognize the hamster and the human HSP27 protein respectively, were used to monitor expression and inducibility of the transfected and endogenous proteins. The human HSP27 gene cloned in pHS2711 is constitutively expressed in rodent cells, resulting in accumulation of the human HSP27 and all phosphorylated derivatives. No modification of the basal or heat-induced expression of endogenous HSPs is detected. The presence of additional HSP27 protein provides immediate protection against heat shock administered 48 h after transfection and confers a permanent thermoresistant phenotype to stable transfectant Chinese hamster and mouse cell lines. Mild heat treatment of the transfected cells results in an induction of the full complement of the endogenous heat shock proteins and a small increase in thermoresistance, but the level attained did not surpass that of heat-induced thermotolerant control cells. These results indicate that elevated levels of HSP27 is sufficient to give protection from thermal killing. It is concluded that HSP27 plays a major role in the increased thermal resistance acquired by cells after exposure to HSP inducers.

Role of Deep Abdominal Fat in the Association Between Regional Adipose Tissue Distribution and Glucose Tolerance in Obese Women

Abstract: Computed tomography (CT) was used to study the association between adipose tissue localization and glucose tolerance in a sample of 52 premenopausal obese women aged 35.7 +/- 5.5 yr (mean +/- SD) and with a body fat of 45.9 +/- 5.5%. Body-fat mass and the body mass index (BMI) were significantly correlated with plasma glucose, insulin, and connecting peptide (C-peptide) areas after glucose (75 g) ingestion (.40 less than or equal to r less than or equal to .51, P less than .01). Trunk-fat accumulation and the size of fat cells in the abdomen displayed highly significant correlations with postglucose insulin levels. The C-peptide area was also positively correlated with abdominal fat cell size (r = .76, P less than .01) and was more closely associated with the sum of trunk skin folds (r = .59, P less than .001) than with the extremity skin folds (r = .29, P less than .05). Subcutaneous and deep-abdominal-fat areas measured by CT displayed comparable associations with the plasma insulin area (r = .44 and .49, respectively; P less than .001) but marked differences in the associations with glucose tolerance. Indeed, subcutaneous abdominal fat was not significantly correlated with the glucose area, whereas deep abdominal fat showed a significant correlation (r = .57, P less than .001) with the glucose area. Midthigh fat deposition measured by CT was not, however, correlated with plasma glucose, insulin, or C-peptide areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Human variation in skeletal muscle fiber-type proportion and enzyme activities.

Abstract: The purpose of the present study was to describe the extent of the variation in some of the common characteristics of human skeletal muscle. A total of 418 biopsies was obtained from the vastus lateralis muscle of 270 healthy sedentary and 148 physically active individuals of both sexes. The lowest and highest proportion of type I muscle fiber observed were 15 and 85%, respectively. Coefficients of variation (CV) reached approximately 30% for the proportion of types I and IIA fibers and were two times higher for the proportion of type IIB fiber. The smallest and largest mean muscle fiber cross-sectional areas (CSA) were approximately 1,100 microns 2 and 9,500 microns 2, respectively. Mean CSA of the various fiber types exhibited CV of approximately 23%. CV reached 30% for the activity of creatine kinase, ranged between 28 and 41% for the glycolytic enzyme markers, and between 34 and 44% for the aerobic-oxidative enzyme markers. The mean proportion of type I fiber was lower in male than in female muscles, whereas the mean CSA of all fiber types was smaller in female than in male muscles. Levels of glycolytic enzyme markers were higher in male than in female skeletal muscles. However, activities of aerobic-oxidative enzyme markers were similar in males and females. These results reveal the existence of large interindividual variability and gender differences in the most common characteristics of the human skeletal muscle.

The importance of boundary-layer flows in supplying phytoplankton to the benthic suspension feeder, Mytilus edulis L.

Abstract: Measurements of vertical gradients in phytoplankton fluorescence over an intertidal mussel bed in the St. Lawrence River estuary (Qukbec) indicate a significant reduction in phytoplankton concentration close to the bed. Furthermore, measurements of near-bed fluorescence as a function of current speed, and of mussel consumption rate as a function of in situ fluorescence, suggest that consumption rate varies with flow speed. A steady, two-dimensional, finite-difference model was constructed to represent the balance between horizontal advection and vertical diffusion of phytoplankton over a mussel bed, in order to simulate the observed influence of mussels on the phytoplankton distribution. The vertical distribution of phytoplankton generated by the model shows a marked reduction close to the bed, consistent with the field measurements, and the model also confirms the depcndcnce of consumption rate on flow speed. Enhanced vertical diffusive transport at higher current speeds results in a higher rate of replenishment of phytoplankton to food-impoverished near-bottom waters. Model runs with different values of the bottom roughness parameter indicate that roughness due to the mussels themselves may significantly increase the food supply to the bed, due to enhanced turbulent transport. In addition, since there is a strong vertical gradient in food concentration above the seabed, the time-averaged food concentration obtained by the mussels is a strong function of the height from which they ingest.

Assessment of adipose tissue distribution by computed axial tomography in obese women: association with body density and anthropometric measurements.

Abstract: 1. Abdominal obesity is associated with numerous metabolic complications. Deep abdominal adipose tissue is critical in the association between the level of abdominal obesity and cardiovascular risk factors. 2. Adipose tissue localization was assessed by computed axial tomography (CAT), and its association with body density and anthropometric measurements was investigated in a sample of fifty-one obese women (percentage body fat 45.9 (SD 5.6)) aged 35.7 (SD 5.5) years. The CAT scans were performed at three levels: lower chest, abdomen and mid-thigh. 3. The total adipose tissue volume computed from these three scans was highly correlated with body fat mass (r 0.94, P less than 0.001). The proportion of deep abdominal fat as measured by the ratio of deep: total adipose tissue areas at the abdominal level was not significantly correlated with body fat mass, but it was moderately associated with the ratio of waist: hip circumferences (WHR) (r 0.49, P less than 0.001). The absolute amount of deep abdominal fat was, however, significantly correlated with body fat mass (r 0.72, P less than 0.001). 4. The subscapular (r 0.38) and the abdominal (r 0.38) skinfolds were the only two skinfolds that were significantly associated with the proportion of deep abdominal fat (P less than 0.01). These skinfolds were also those which showed the highest correlation with the absolute amount of deep abdominal fat (r 0.65, P less than 0.001, for both skinfolds). 5. A three-site CAT-scan procedure can be used for the estimation of body fat mass in premenopausal obese women. 6. In these obese women, there was no significant association between total adiposity and the proportion of deep adipose tissue at the abdominal level. 7. In premenopausal obese women, the absolute amount of deep abdominal fat can be predicted from anthropometric measurements with more accuracy than the relative amount of deep abdominal fat.

Genetic and environmental influences on level of habitual physical activity and exercise participation

Abstract: In order to quantify genetic and environmental determinants of physical activity level, 1,610 subjects from 375 families who lived in the greater Quebec city area completed a three-day activity record in 1978-1981. Level of habitual physical activity, which includes all the usual activities of life, and exercise participation, which includes activities requiring at least five times the resting oxygen consumption and more, were derived from this record. Familial correlations were computed in several pairs of biologic relatives and relatives by adoption after adjustment for the effects of age, sex, physical fitness, body mass index, and socioeconomic status, and analyzed with a model of path analysis that allows the separation of the transmissible effect between generations (t2) into genetic (h2) and cultural (b2) components of inheritance. The transmission was found to be statistically significant, but was accounted for by genetic factors for level of habitual physical activity (t2 = h2 = 29%), and by cultural factors for exercise participation (t2 = b2 = 12%). Although non-transmissible environmental factors remain the major determinants of these two physical activity indicators in this population, the results suggest that children can acquire from their parents certain customs regarding exercise behavior and that the propensity toward being spontaneously active could be partly influenced by the genotype.

Hierarchy in picture segmentation: a stepwise optimization approach

Abstract: A segmentation algorithm based on sequential optimization which produces a hierarchical decomposition of the picture is presented. The decomposition is data driven with no restriction on segment shapes. It can be viewed as a tree, where the nodes correspond to picture segments and where links between nodes indicate set inclusions. Picture segmentation is first regarded as a problem of piecewise picture approximation, which consists of finding the partition with the minimum approximation error. Then, picture segmentation is presented as an hypothesis-testing process which merges only segments that belong to the same region. A hierarchical decomposition constraint is used in both cases, which results in the same stepwise optimization algorithm. At each iteration, the two most similar segments are merged by optimizing a stepwise criterion. The algorithm is used to segment a remote-sensing picture, and illustrate the hierarchical structure of the picture. >

Fungal Growth Stimulation by CO(2) and Root Exudates in Vesicular-Arbuscular Mycorrhizal Symbiosis.

Abstract: Transformed roots of carrot were used to determine the effects of root metabolites on hyphal development from spores of the vesicular-arbuscular mycorrhizal fungus Gigaspora margarita. Hyphal growth of this obligately biotrophic symbiont was greatly stimulated by a synergistic interaction between volatile and exudated factors produced by roots. Root volatiles alone provided little stimulation, and root exudates alone had no effect. For the first time, carbon dioxide was demonstrated to be a critical root volatile involved in the enhancement of hyphal growth. C-labeled root volatiles were fixed by the fungus and thus strongly suggested that CO(2) served as an essential carbon source.

Adipose tissue distribution and plasma lipoprotein levels in obese women. Importance of intra-abdominal fat.

Abstract: Prospective studies have shown that excess abdominal fat is associated with an increased risk of coronary heart disease and related death. We used computed axial tomography (CAT) to assess the association between deep and subcutaneous abdominal adipose tissue and plasma lipoprotein levels in a sample of 52 premenopausal obese women aged 35.7 +/- 5.5 years (mean +/- SD). Whereas the plasma lipoprotein concentration were not significantly correlated with fat mass, the data obtained by CAT indicated that the absolute amount of deep abdominal fat was negatively correlated with high density lipoprotein cholesterol (HDL-CHOL) levels (r = -0.35, p less than 0.01), as well as with HDL-CHOL/low density lipoprotein (LDL)-CHOL, HDL-apoprotein-(apo) A-I/LDL-apo B, and HDL2-CHOL/HDL3-CHOL ratios (-0.32 less than or equal to r less than or equal to -0.40, 0.05 greater than p less than 0.01). Adipose tissue deposition at the mid-thigh region determined by CAT did not show any significant relationship with plasma lipoprotein levels. When subgroups of women with comparable ages and adiposity but with high and low intra-abdominal fat accumulation were compared, women with a high accumulation of intra-abdominal fat displayed significantly lower HDL-CHOL (p less than 0.001), HDL2-CHOL (p less than 0.001), HDL3-CHOL (p less than 0.01), and HDL-apo A-I (p less than 0.05) levels, as well as reduced HDL-CHOL/LDL-CHOL (p less than 0.01), HDL-apo A-I/LDL-apo B (p less than 0.05), and HDL2-CHOL/HDL3-CHOL ratios (p less than 0.05) in comparison with obese women with low accumulations of intra-abdominal fat.(ABSTRACT TRUNCATED AT 250 WORDS)

Mixed‐interpolated elements for Reissner–Mindlin plates

Abstract: DCpartement de Mathtmatiyue, L'nit,ersitt 1aral Quthec, Canado SUMMARY We present in this paper a procedure to establish Reissner-Mindlin plate bending elements The procedure is based on the idea to combine known resuits on the approximation of Stokes problems with known results on the approximation of elliptic problems The proposed elements satisfy the mathematical conditions of stability and convergence, and some of them promise to provide efficient elements for practical solutions

Impact testing of concrete using a drop-weight impact machine

Abstract: A detailed description of the instrumented dropweight impact machine is presented. The instrumentation, the calibration, the inertial loading correction, and the dynamic analysis of a concrete beam specimen undergoing three-point impact flexural loading are described. Some results, using such an impact testing machine, obtained from tests done on plain concrete, fiber-reinforced concrete, and conventionally reinforced concrete are presented. It is concluded that the use of such a testing machine may be successfully made in order to test cementitious materials under impact.

On the Spectral Subtraction of Water from the FT-IR Spectra of Aqueous Solutions of Proteins

Abstract: A method is described for the quantitative subtraction of water from the transmission infrared spectra of aqueous solutions of proteins. The 2125-cm−1 association band of water is used as an internal intensity standard, and the scaling factor is determined with the use of a second-order least-squares fit. This method eliminates the user bias encountered with interactive methods and takes into account small baseline variations due to instrument drift. Statistical analysis of the results obtained demonstrates that at 10% w/w protein concentration, the error is of the order of 2% in the region of the amide I and II bands.

A new approach for the FEM simulation of viscoelastic flows

Abstract: We present a finite element method for the simulation of viscoelastic flow. A decoupled approach is employed for the computation of the velocity field and of the components of the extra-stress tensor. The high Weissenberg number problem is addressed by using together two different types of upwinding namely the streamline upwinding technique and the Lesaint-Reviart method. Numerical results are presented for the case of the 4 to 1 plane contraction.

High levels of PCBs in breast milk of Inuit women from arctic Quebec.

Abstract: In the last twenty years polychlorinated biphenyls (PCBs) have been identified as major contaminants of the natural environment. More recently, the presence of such toxic compounds was described in arctic regions. In this regions, PCBs have been found in water, snow, ice and air. The level of PCB contamination was significantly lower than that found at midlatitudes. PCB levels are often monitored because they could also reflect exposure to several other chemical contaminants such as other organochlorines. Other highly toxic compounds such as polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were found in the blubber from arctic ringed seals caught near the west coast of Spitzbergen. Since the closest known sources of PCDD and PCDF were several thousands of kilometers away, these results were surprising. The consumption of fish and marine mammals by the Inuit people is markedly higher than in the rest of the Canadian population and in some communities, sea mammals represent a significant part of the diet. It is possible that Inuit are exposed to an undesirably high of PCBs and other organochlorinated compounds. Levels of PCBs in the Inuit diet were assessed in Broughton Island, North West Territories, Canada. The present study was designed to assess themore » PCB levels in the breast milk of lactating Inuit women from the Hudson Bay region of Northern Quebec and of women from Southern Quebec.« less

Genetic effect in resting and exercise metabolic rates

Abstract: Two studies dealing with the contribution of the genotype in individual differences for resting metabolic rate (RMR), thermic effect of a 4.2 MJ carbohydrate meal (TEM), and energy cost of submaximal exercise are reported. The genetic effect for RMR and TEM was studied in 31 pairs of parent-child, 21 pairs of dizygotic (DZ) twins, and 37 pairs of monozygotic (MZ) twins, whereas the heritability of the energy cost of submaximal exercise was determined from data on 22 pairs of DZ twins and 31 pairs of MZ twins. The heritability of RMR reached approximately 40% of the variance remaining after adjustment for age, gender, and fat-free mass, (FFM). The genetic effect for TEM was equivalent to at least 40% to 50% of the variation in the energy expended during four hours after the meal test. A highly significant genetic effect was found for fasting plasma glucose (greater than .72), but the results for fasting plasma insulin are unclear. No significant genetic variance was seen for the glucose and insulin response to the carbohydrate meal. Finally, heritability for the metabolic rate during cycle exercise was high (greater than or equal to .46) at low power output, but it became nonsignificant when the energy cost reached about 6 times the RMR.

Synaptophysin expression during synaptogenesis in the rat cerebellar cortex

Abstract: In order to study the mechanisms of synaptogenesis in the rat cerebellar cortex, a library of monoclonal antibodies has been generated against proteins of the isolated synapse. One recognizes a glycosylated 38 kDa protein that is concentrated in the synaptic vesicle fraction and resembles synaptophysin biochemically in its molecular weight, charge, and pattern of glycosylation. In the adult cerebellar cortex, the antisynaptophysin(mabQ155) immunoreactivity is codistributed with synapses. Immunoreactivity is strongest in the molecular layer where punctate deposits of reaction product outline the Purkinje cell dendrites. Discrete small profiles, consistent with the distribution of basket cell axon terminals, surround the Purkinje cells, and in the granular layer the synaptic glomeruli are intensely stained. There is no immunoreactivity in the white matter axon tracts. Electron microscope immunocytochemistry confirms the synaptic location of the antigen and suggests that the reaction product is associated with synaptic vesicles. Both round and flat vesicle populations are immunoreactive. Antisynaptophysin(mabQ155) has been used to follow synaptogenesis in the developing rat cerebellum. In the newborn rat (P0), despite the paucity of synapses, there is some specific immunoreactivity, especially in the subcortical white matter. Electron microscopy shows that the antigenicity is associated with vesicles within growth cones, filopodia, and immature axon profiles. During development, antisynaptophysin immunoreactivity increases progressively, along with the maturing cell populations, for both the granule cell-Purkinje cell and the mossy fiber-granule cell synapses. Quantitative biochemical analysis confirms the cytochemical results. These data suggest that neuronal growth cones express a synapse-specific antigen before complete morphological synapses are present.

Peer status and self-perception among early elementary school children: the case of the rejected children.

Abstract: Etude des relations entre le statut sociometrique et les perceptions de la competence sociale des autres et de soi-me-me chez 222 enfants âges de 9 et 11 ans

Diet, mammographic features of breast tissue, and breast cancer risk

Abstract: This case-control study was designed to reevaluate the association of the morphology of breast tissue seen on mammograms with breast cancer risk and to assess the relation of diet, especially intake of fat and vitamin A, to the high-risk mammographic images. The cases included 290 patients with newly diagnosed breast cancer who were first treated in Quebec in 1982-1984. The controls included 645 women who participated in the Canadian National Breast Screening Study. Risk of breast cancer was higher among women with the P2 or DY parenchymal pattern (relative risk (RR) = 3.7, 95% confidence interval (Cl) 2.0-7.0) than it was among those with the N1 pattern. Moreover, risk increased regularly with the extent of nodular and homogeneous densities on the mammogram. Relative risk was 5.5 (95% Cl 2.3-13.2) for women in whom 60% or more of the volume of the breast showed either nodular or homogeneous densities compared with women without such densities. Among controls, increase in energy-adjusted saturated fat intake was associated with an increase in extent of high-risk mammographic features. Energy-adjusted polyunsaturated fat or cholesterol intake did not, however, appear to influence the morphology of breast tissue seen on the mammogram. Increasing carotenoid and fiber intakes were associated with a reduction of the extent of densities on the mammogram, but retinol intake seemed to have little or no effect on mammographic features. These data suggest that elevation in saturated fat intake and reduction in carotenoid and fiber intakes may be related to an increase in breast cancer risk through effects of these nutrients on breast tissue morphology.

Expertise in auditing: Myth or reality?☆

Abstract: This article presents a critical review of the existing research literature on expertise in auditing and explores useful avenues for future research The review is organized around the two main approaches that have been used to study expertise in auditing—the behavioral and the cognitive approaches The concept of expertise within these two approaches is examined Results from studies using the behavioral approach indicate that expert auditors do not behave differently from novice auditors Possible reasons for this lack of significant difference are discussed in the article Results from studies using the cognitive approach are more encouraging They indicate that there may be knowledge differences between expert and novice auditors and that these differences might lead expert auditors to use decision processes that differ from those used by novice auditors Our knowledge about expertise in auditing is, however, still embryonic and there is a need for more research

Role of hepatic-triglyceride lipase activity in the association between intra-abdominal fat and plasma HDL cholesterol in obese women.

Abstract: Intra-abdominal fat content is an important variable in the association between regional body fat distribution and plasma high density lipoprotein (HDL) cholesterol levels. In the present study, we report on the role of plasma postheparin lipases as well as abdominal and femoral adipose tissue lipoprotein lipase activities in the association between body fat distribution and plasma lipoprotein levels. Postheparin plasma lipoprotein lipase (LPL), hepatic-triglyceride lipase (H-TGL), abdominal and femoral adipose tissue (AT)-LPL activities and plasma lipoprotein levels were measured after an overnight fast in a sample of 16 obese women (ages 36.0 +/- 6.1 years [mean +/- SD], percent body fat 46% +/- 6%). Computed axial tomography was used to assess body fat distribution. Plasma postheparin LPL activity was neither correlated with total adiposity nor with the level of intra-abdominal fat. Intra-abdominal fat deposition was, however, positively correlated with H-TGL activity (r = 0.66, p less than 0.005). Furthermore, covariance analysis showed that the association between intra-abdominal fat and H-TGL was independent from total adiposity. Plasma postheparin LPL and abdominal AT-LPL activities showed no significant correlation with plasma lipoprotein levels, whereas femoral AT-LPL activity was positively correlated with the HDL2 cholesterol/HDL3 cholesterol ratio (r = 0.51, p less than 0.05). H-TGL activity was, however, negatively correlated with HDL2 cholesterol (r = -0.60, p less than 0.05), but not with HDL3 cholesterol (r = -0.28, NS). These results suggest that the high H-TGL activity in obese women with excess deep abdominal fat could be responsible for the reduction in plasma HDL2 cholesterol levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological activities of outer membrane vesicles

Abstract: Article de synthese sur les vesicules extracellulaires (vesicules de la membrane externe) des bacteries gram negatif avec mise en relief des especes bacteriennes de la cavite buccale: conditions de formation, methodes d'isolement, composition et activites biologiques (capacite de fixation, activite bacteriocine, activites enzymatiques, activite toxique, et role possible dans la transformation genetique

The effect of leisure time physical activity on the risk of pre-eclampsia and gestational hypertension.

Abstract: STUDY OBJECTIVE: To assess the relation between leisure time physical activity (LTPA) during the first 20 weeks of pregnancy and the risk of developing pre-eclampsia and gestational hypertension. DESIGN: Case-control study carried out over a 28 month period with retrospective data collection. SETTING: Six hospitals in Quebec City and four hospitals in Montreal. PARTICIPANTS: 172 women with pre-eclampsia, 254 with gestational diabetes, 505 controls. All were primiparous, with no history of high blood pressure before pregnancy (unless due to oral contraceptive use), or during the first 20 weeks of gestation. Cases were defined using recognised criteria, and 97% of those eligible agreed to be interviewed. Controls delivered in same hospital immediately after cases and had no more than one reading of elevated blood pressure during pregnancy; 96% of those eligible agreed to be interviewed. MEASUREMENTS AND MAIN RESULTS: Participants were interviewed in hospital a few days after delivery using a questionnaire. Information was collected on type, frequency and average duration of any LTPA performed regularly during the first 20 weeks of pregnancy, together with medical, obstetric and sociodemographic details. It was found that women who performed regular LTPA had a reduced risk of pre-eclampsia (adjusted RR 0.67, 95% CI 0.46-0.96) and gestational hypertension (aRR 0.75, 95% CI 0.54-1.05), and the relative risks decreased as the average time spent in LTPA increased (aRR for pre-eclampsia among women with low, moderate and high energy expenditure: 1.00, 0.77 and 0.57, p = 0.01). The same trend was present for gestational hypertension (1.00, 0.80 and 0.71, respectively, p = 0.08). CONCLUSIONS: Leisure time physical activity during the first half of pregnancy is likely to reduce the risk of pre-eclampsia and gestational hypertension.

Acclimation of Two Tomato Species to High Atmospheric CO2 I. Sugar and Starch Concentrations

Abstract: Lycopersicon esculentum Mill. cv Vedettos and Lycopersicon chmielewskii Rick, LA 1028, were exposed to two CO2 concentrations (330 or 900 microliters per liter) for 10 weeks. Tomato plants grown at 900 microliters per liter contained more starch and more sugars than the control. However, we found no significant accumulation of starch and sugars in the young leaves of L. esculentum exposed to high CO2. Carbon exchange rates were significantly higher in CO2-enriched plants for the first few weeks of treatment but thereafter decreased as tomato plants acclimated to high atmospheric CO2. This indicates that the long-term decline of photosynthetic efficiency of leaf 5 cannot be attributed to an accumulation of sugar and/or starch. The average concentration of starch in leaves 5 and 9 was always higher in L. esculentum than in L. chmielewskii (151.7% higher). A higher proportion of photosynthates was directed into starch for L. esculentum than for L. chmielewskii. However, these characteristics did not improve the long-term photosynthetic efficiency of L. chmielewskii grown at high CO2 when compared with L. esculentum. The chloroplasts of tomato plants exposed to the higher CO2 concentration exhibited a marked accumulation of starch. The results reported here suggest that starch and/or sugar accumulation under high CO2 cannot entirely explain the loss of photosynthetic efficiency of high CO2-grown plants.

Homozygous familial hypercholesterolemia among French Canadians in Québec Province.

Abstract: Nineteen patients with homozygous familial hypercholesterolemia (FH) living at the time of the 1981 Canada census are the subject of this report. Their mean age at that time was 15, with a range of 1 to 26 years. All patients had extensive xanthomatosis but showed variable clinical manifestations of coronary heart disease (CHD); five (mean age, 21; range, 11 to 27 years) died from sudden death due to CHD. Plasma cholesterol levels varied more than twofold (557 to 1532 mg/dl). Variation in the concentrations of both plasma and low density lipoprotein cholesterol, as well as apolipoprotein B, were related neither to age at death from CHD nor to the clinical course of CHD. The mean high density lipoprotein cholesterol concentration (37 mg/dl) was lower than the mean value (49 mg/dl) in the control population (p less than 0.001). Both the clinical and biochemical features of this cohort are typical of homozygous FH. The prevalence of homozygotes among French Canadians in Quebec was approximately 1:275,000, and the minimum estimated frequency of heterozygotes was 1:270. In northeastern Quebec, the frequency of homozygotes was approximately 1:100,000, and the minimum estimated frequency of heterozygotes was 1:154. Only Afrikaaners in South Africa have correspondingly higher frequencies.