Biomedical subjects

M Zarrouk

Publications and source records attributed to M Zarrouk.

8 recordsLinked to original sources

PubMed2005

[Cadmium effects on mineral nutrition and lipid contents in tomato leaves].

The treatment of growing tomato (Lycopersicum esculentum) plants with CdCl2 (0, 1, 5, 10, 25 et 50 microM) on various plant physiological parameters and membrane lipids of primary and young leaves was studied. In leaves of tomato plants Cd produced a significant inhibition of growth, chlorophyll content and alteration of the nutrient status in both primary and young leaves. A decrease in lipid contents, specially galactolipids and phospholipids, was observed after Cd treatment.

Cadmium Chloride↗

PubMed2005

Ultrastructure and lipid alterations induced by cadmium in tomato (Lycopersicon esculentum) chloroplast membranes.

The effects of cadmium (Cd) uptake on ultrastructure and lipid composition of chloroplasts were investigated in 28-day-old tomato plants (Lycopersicon esculentum var. Ibiza F1) grown for 10 days in the presence of various concentrations of CdCl2. Different growth parameters, lipid and fatty acid composition, lipid peroxidation, and lipoxygenase activity were measured in the leaves in order to assess the involvement of this metal in the generation of oxidative stress. We first observed that the accumulation of Cd increased with external metal concentration, and was considerably higher in roots than in leaves. Cadmium induced a significant inhibition of growth in both plant organs, as well as a reduction in the chlorophyll and carotenoid contents in the leaves. Ultrastructural investigations revealed that cadmium induced disorganization in leaf structure, essentially marked by a lowered mesophyll cell size, reduced intercellular spaces, as well as severe alterations in chloroplast fine structure, which exhibits disturbed shape and dilation of thylakoid membranes. High cadmium concentrations also affect the main lipid classes, leading to strong changes in their composition and fatty acid content. Thus, the exposure of tomato plants to cadmium caused a concentration-related decrease in the fatty acid content and a shift in the composition of fatty acids, resulting in a lower degree of fatty acid unsaturation in chloroplast membranes. The level of lipid peroxides and the activity of lipoxygenase were also significantly enhanced at high Cd concentrations. These biochemical and ultrastructural changes suggest that cadmium, through its effects on membrane structure and composition, induces premature senescence of leaves.

Cadmium Chloride↗

PubMed2005

Usefulness of ligation-mediated PCR genotyping in tracking outbreak-associated Mycobacterium tuberculosis strains.

With the emergence of a multidrug resistant tuberculosis (MDR-TB) outbreak, the availability of a rapid typing method to carry out a nationwide prospective survey for the tracking of newly emerging MDR-TB foci became a priority. For this purpose, we have applied the IS6110 PCR-based genotyping assay, namely, LM-PCR (ligation-mediated PCR). The latter relies on ligation of a synthetic oligonucleotide priming site to a restriction site flanking IS6110. Sequences between the IS element and the restriction site are then amplified using an IS6110 specific outward primer and an oligonucleotide specific to the ligated priming site. Although it was found slightly less discriminative than the standard IS6110 restriction fragment length polymorphism analysis (IS6110 RFLP), LM-PCR allowed for the rapid and prospective identification of new outbreak-related cases within a large pool of circulating M. tuberculosis isolates. In comparison to IS6110 RFLP LM-PCR was found simple enough to justify its implementation in laboratories involved in MDR-TB surveillance at a nationwide scale.

Bacterial Typing Techniques↗

PubMed2000

Sodium chloride effects on lipase activity in germinating rape seeds.

Seeds of rape (Brassica napus L.) were germinated at various NaCl concentrations up to 200 mM. Germinating levels, seedling growth, triacylglycerol mobilization and lipase activity were investigated. High salt concentrations resulted in retardation of seed germination. Seedling growth as measured by radicle length was severely reduced by NaCl doses higher than 50 mM. Moreover, the mobilization of storage oil in control rapeseed seedlings, started about 24 h after imbibition. As for germination and growth, elevated salt concentrations are found to delay triacylglycerol degradation. Experiments using triolein as substrate indicated clearly that lipase activity was inhibited by salt treatment.

Brassica↗

PubMed2000

Effect of cadmium on lipid composition of pepper.

Seedlings (2 weeks old) of pepper (Capsicum annum) were grown in nutrient solution with added CdCl(2) (10 or 50 microM) for 7 days. In Cd-treated plants, changes in acyl lipids and fatty acid composition were investigated. Cd particularly lowered the amount of monogalactosyldiacylglycerol (MGDG) and enhanced accumulation of phospholipids [phosphatidylcholine (PC), phosphatidylethanolamine and phosphatidylglycerol] in leaves. In contrast, content of PC and galactolipids (MGDG and digalactosyldiacylglycerol) decreased in roots. Fatty acid composition of leaves was also changed by Cd addition to external medium, but no important changes occurred in roots. Levels of leaf polyunsaturated fatty acids, especially 18:3 and 16:3, were reduced. Lipid and fatty acid composition changes in roots are discussed in relation to Cd tolerance in pepper.

Cadmium Chloride↗

PubMed2000

Do extraction procedures affect olive oil quality and stability?

Quality and stability of olive oil extracted using discontinuous (pressing) or continuous (centrifuging) procedures were studied. Virgin olive oils extracted from two olive varieties were stored for 17 months. Analytical parameters of oil quality (acidity, peroxide value, polyphenol content, chlorophyll amount, fatty acid composition and triacylglycerol molecular species) were followed at different time intervals. Our results showed that no differences exist between the two types of tested mill, since the studied parameters were unchanged or varied slightly in the same range during the time of oil conservation. Changes depend on olive varieties rather than extraction systems used. Moreover, oils produced by the continuous system contain comparatively higher levels of polyphenols, which may confer to them greater resistance against oxidation for long-term storage.

Fatty Acids↗

PubMed1997

Cadmium- and copper-induced changes in tomato membrane lipids.

Cadmium and copper uptake and distribution, as well as their effects on growth and lipid composition were investigated in 17-day-old tomato seedlings (Lycopersicon esculentum Mill. cv. 63/5 F1) grown in culture solution supplied with two concentrations of Cd or Cu (0, 5 and 50 microM). The accumulation of Cd and Cu increased with external metal concentrations, and was considerably higher in roots than in primary leaves. Biomass production of the growing roots and primary leaves was strongly depressed at high metal levels. Also, significant decreases in the content of lipid classes and changes of fatty acid composition were recorded in heavy metal-stressed plants in comparison with controls. Glycolipid contents were decreased more in leaves than in roots by Cd-treatment, but copper decreased both to similar extents in both organs. Likewise, both metals reduced the phospholipid and neutral lipid contents more in roots than in leaves. In almost all lipid classes the proportion of palmitic acid (16:0) increased, and that of linoleic (18:2) or linolenic (18:3) acid decreased, suggesting that heavy metal treatment induced an alteration in the fatty acid desaturation processes. Furthermore, the accumulation of palmitate (16:0) rather than stearate (18:0) indicated an alteration in the ratio of products from the fatty acid synthase. Copper was found to be the most unfavourable for plant growth and lipid metabolism. The possible mechanisms by which heavy metals, especially Cu, induce a strong lipid shift are discussed.

Cadmium↗

PubMed1995

Social and leisure activities and risk of dementia: a prospective longitudinal study.

OBJECTIVE: To study the relationship between social and leisure activities and risk of subsequent dementia in older community residents. SETTING: A cohort study of people aged 65 and older were followed-up 1 and 3 years after a baseline screening (the Paquid study). PARTICIPANTS: 2040 older subjects living at home in Gironde (France) were randomly selected and followed for at least 3 years. DATA COLLECTION: Information about social and leisure activities was collected during the baseline screening with an interview by a psychologist. Incident cases of dementia were detected during the first and third year follow-up screenings according to the DSM-III-R criteria. MAIN RESULTS: All but one of the social and leisure activities noted were significantly associated with a lower risk of dementia. Only golden club participation was not significantly associated with this risk. After adjustment for age and cognitive performance measured by the Mini-Mental State Exam, visual memory test, and verbal fluency test, only traveling (Relative risk (RR) = .48,95% Confidence Interval (95% CI) = .24-.94), odd jobs or knitting (RR = .46,95% CI = .26-.85), and gardening (RR = .53, 95% CI = .28-.99) remained significant. CONCLUSIONS: Regular participation in social or leisure activities such as traveling, odd jobs, knitting, or gardening were associated with a lower risk of subsequent dementia.

Aged↗