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Biomedical subjects

S Kasim-Karakas

Publications and source records attributed to S Kasim-Karakas.

4 recordsLinked to original sources
PubMed2001

LC/ES-MS detection of hydroxycinnamates in human plasma and urine.

Hydroxycinnamates are components of many fruits and vegetables, being present in particularly high concentrations in prunes. An abundance of phenolic compounds in the diet has been associated with reduced heart disease mortality. However, little is known about the absorption and metabolism of these metabolites after normal foods are consumed. An LC--electrospray--MS method was developed to measure the concentration of caffeic acid in human plasma and urine, but it can also be applied to ferulic acid and chlorogenic acid. The limit of detection was found to be 10.0 nmol/L for caffeic acid and 12.5 nmol/L for ferulic and chlorogenic acids. The method was tested on samples of plasma and urine collected from volunteers who consumed a single dose of 100 g of prunes and increased levels were observed, demonstrating that the method is capable of detecting changes in hydroxycinnamate levels induced by dietary consumption.

Absorption↗
PubMed1999

Catechin is present as metabolites in human plasma after consumption of red wine.

Flavonoids are components of fruits, vegetables and wines. An abundance of flavonoids in the diet is correlated with reduced heart disease mortality, suggesting that they act as protective nutrients. However, little is known about the absorption and metabolism of flavonoids after normal foods are consumed. This study measured the levels of one abundant flavonoid, (+)-catechin, and its metabolites in plasma after five male and four female volunteers consumed 120 mL of red wine (RW) one day and de-alcoholized red wine (DRW) on a separate day. Each wine sample contained 35 +/- 1 mg catechin (mean +/- SEM). Plasma levels of catechin and its metabolite 3'-O-methylcatechin (3'MC) were determined by gas chromatography-mass spectrometry (GC-MS) of the trimethylsilylated (TMS) derivatives. Glucuronide and sulfate conjugates were determined after enzymatic hydrolysis. Before RW or DRW consumption, plasma levels of catechin, 3'MC and all conjugates were <2 nmol/L. After 1 h, average levels of catechin, 3'MC and all conjugates increased to 91 +/- 14 nmol/L (RW) and 81 +/- 11 nmol/L (DRW). At 1 h, 21 +/- 1% of the metabolites were methylated and <2% of catechin and 3'MC were unconjugated. Catechin was present as both a sulfate conjugate and a conjugate containing both glucuronide and sulfate residues. 3'MC was present primarily as a glucuronide conjugate. At every time point, catechin was present almost exclusively as metabolites, and these levels were independent of ethanol. Therefore, if flavonoids are protective nutrients, the active forms are likely to be metabolites, which are far more abundant in plasma than the forms that exist in foods.

Adult↗
PubMed1996

Relationship of plasma leptin to plasma insulin and adiposity in normal weight and overweight women: effects of dietary fat content and sustained weight loss.

Leptin, the product of the human homologue of the ob gene, which is defective in the obese (ob/ob) mouse, may be a humoral regulator of human adiposity. Plasma leptin concentrations were measured by RIA in 19 normal weight [body mass index (BMI) = 24.5 +/- 0.6 kg/m2] and 19 overweight to obese (BMI = 34.7 +/- 1.2 kg/m2) nondiabetic postmenopausal women on sequential controlled weight-maintaining diets containing 31%, 23%, and 14% of energy as fat, each for 4-6 weeks. Thereafter, the subjects ate a very low fat diet (< 15%) ad libitum; plasma leptin and insulin concentrations, BMI, percent body fat (%BF), and resting energy expenditure were determined after 6 and 8 months. Absolute and adiposity-corrected plasma leptin levels were higher in overweight/obese women (37.7 +/- 3.5 ng/mL; 1.01 +/- 0.07 ng.mL-1.%BF-1) than in normal weight women (16.9 +/- 2.2 ng/mL; 0.57 +/- 0.06 ng.mL-1.%BF-1, both P < 0.005 vs. obese), but were not different between the 31%, 23%, and 14% fat diets when body weight was stable. Plasma leptin was highly correlated with BMI (r = 0.81, P < 0.0001), %BF (r = 0.80, P < 0.0001), and fasting plasma insulin (r = 0.61, P < 0.0001). After 8 months on the ad libitum low fat diet, the women had lost an average of 6.9 +/- 1.0% of body mass (-2.0 +/- 0.3 kg/m2, P < 0.0001). In 15 subjects who lost more than 7% of body mass (-12.3 +/- 1.0%), plasma leptin concentrations decreased (-9.6 +/- 1.9 ng/mL, P < 0.0005), and the decrease of plasma leptin per change of adiposity (delta leptin/delta %BF) was greater in overweight/obese women (3.6 +/- 0.5) than in normal weight women (0.9 +/- 0.4, P < 0.01 vs. obese). In 18 other subjects who lost less than 7% of body mass (-2.7 +/- 0.6%), plasma leptin was unchanged (+1.4 +/- 1.4 ng/mL). Overall, the change of plasma leptin was significantly correlated with change of BMI (r = 0.43, P < 0.02), the change of %BF (r = 0.49, P < 0.005), the change of resting energy expenditure (r = 0.40, P < 0.02), and with the change of plasma insulin independently of changes of body adiposity (r = 0.45, P < 0.01). We conclude that plasma leptin concentrations are: 1) not affected by dietary fat content per se; 2) highly correlated with BMI, %BF, and plasma insulin in both overweight/obese and normal weight women; 3) decreased in parallel with plasma insulin after sustained weight loss; and 4) decreased more in overweight/obese than in normal weight women.

Adipose Tissue↗