Biomedical subjects

S J Schwartz

Publications and source records attributed to S J Schwartz.

At least 19 recordsLinked to original sources

PubMed2001

Analysis of lycopene geometrical isomers in biological microsamples by liquid chromatography with coulometric array detection.

Methods of analysis for determining low quantities of lycopene cis-trans isomers in biological tissues are needed. Development of two liquid chromatography (LC) methods based on the polymeric C30 stationary phase equipped with coulometric electrochemical array detection (ED) is described. Separation of 13 lycopene isomers including prolycopene, (a novel tetra-cis-lycopene found in Tangerine tomatoes) was accomplished with both isocratic and gradient methods using different proportions of methanol, methyl tert.-butyl ether, water and 1 M ammonium acetate buffer. Carotenoids were detected at potential settings between 200 and 620 mV. Differences in generated current-voltage curves aided in tentative identification of trans carotenoid species and select cis isomers of lycopene. These methods were successfully applied in the analysis of small quantities of plasma, buccal mucosal cells, prostate and cervical tissues. Limits of detection for trans-lycopene by ED were found to be 50 fmol representing a 10- to 100-fold increase over conventional UV-Vis absorbance methods.

Carotenoids↗

PubMed2001

The process of exploration in identity formation: the role of style and competence.

This study drew on two approaches to identity formation, each postulating differing but complementary exploration components (style and competence), in an effort to better understand the identity exploration process. The sample for this study (n=215) was socio-demographically diverse with respect to gender, age, ethnicity and setting, with participants drawn from two universities in two different settings (rural residential, and urban non-residential), with differing ethnicities (primarily non-Hispanic White vs. primarily Hispanic) and varying ages. Overall patterns of results revealed by hierarchical regression analyses were consistent with a process model of exploration and with the view that exploration is a multi-dimensional process comprized of multiple components. The findings also provide evidence for the utility of both of the critical constructivist and co-constructivist approaches to identity formation used in this study, and for the validity of the rich clinical/qualitative literature that gave rise to the construct of exploration.

Adolescent↗

PubMed2001

Polygalacturonase, pectinesterase, and lipoxygenase activities in high-pressure-processed diced tomatoes.

High-pressure processing (HPP) can inactivate pathogenic microorganisms and degradative enzymes without the use of heat, thereby minimizing the destruction of flavors, nutrients, and other quality attributes. Lipoxygenase plays a role in the off-flavor production of tomatoes, whereas pectinesterase and polygalacturonase impact tomato texture. The purpose of this study was to determine HPP's ability to inactivate lipoxygenase, pectinesterase, and polygalacturonase in diced tomatoes. Processing conditions used were 400, 600, and 800 MPa for 1, 3, and 5 min at 25 and 45 degrees C. The magnitude of applied pressure had a significant effect on inactivating lipoxygenase and polygalacturonase (p < 0.05), with complete loss of activity occurring at 800 MPa. Pectinesterase was very resistant to pressure treatment. Percent soluble solids, pH, titratable acidity, and color a/b values did not differ significantly among the high-pressure-processed samples as compared to the control, but color L values increased. This change in L values was not considered of practical importance. Apparent protein content decreased in the pressure-processed samples, due possibly to protein denaturation, loss of solubility, and/or a decrease in dye binding sites to assay protein content.

Carboxylic Ester Hydrolases↗

PubMed2001

Assessment of degradation and intestinal cell uptake of carotenoids and chlorophyll derivatives from spinach puree using an in vitro digestion and Caco-2 human cell model.

Although numerous studies have demonstrated the health benefits of chlorophyll derivatives, information regarding the digestion, absorption, and metabolism of these phytochemicals is quite limited. To better understand the digestion of these pigments, green vegetables including fresh spinach puree (FSP), heat- and acid-treated spinach puree (HASP), and ZnCl(2)-treated spinach puree (ZnSP) were subjected to an in vitro digestion method which simulates both the gastric and small intestinal phases of the process. Native chlorophylls were converted to Mg-free pheophytin derivatives during digestion. Conversely, Zn-pheophytins were completely stable during the digestive process. Transfer of lipophilic chlorophyll derivatives, as well as the carotenoids lutein and beta-carotene, into the aqueous micellar fraction from the food matrix was quantified. Micellarization of total chlorophyll derivatives differed significantly (p < 0.05) for FSP (37.6%), HASP (17.2%), and ZnSP (8.7%). Micellarization of chlorophyll a derivatives was determined to be significantly more efficient than chlorophyll b derivatives in FSP and HASP (p < 0.01), but not in ZnSP (p > 0.05). Intestinal cell uptake of micellarized pigments was investigated using HTB-37 (parent) and clonal TC7 lines of human Caco-2 cells. Medium containing the pigment-enriched fraction generated during digestion was added to the apical surface of fully differentiated monolayers for 4 h. Pigments were then extracted from cells and analyzed by C18 HPLC with photodiode array detection. Both Caco-2 HTB-37 and TC7 clone cells accumulated 20-40% and 5-10% of micellarized carotenoid and chlorophyll derivatives, respectively. These results are the first to demonstrate uptake of chlorophyll derivatives by human intestinal cells and to support the potential importance of chlorophylls as health-promoting phytochemicals.

Biological Availability↗

PubMed2001

Effects of lyophilized black raspberries on azoxymethane-induced colon cancer and 8-hydroxy-2'-deoxyguanosine levels in the Fischer 344 rat.

This study examined the effects of lyophilized black raspberries (BRB) on azoxymethane (AOM)-induced aberrant crypt foci (ACF), colon tumors, and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in male Fischer 344 rats. AOM was injected (15 mg/kg body wt i.p.) once per week for 2 wk. At 24 h after the final injection, AOM-treated rats began consuming diets containing 0%, 2.5%, 5%, or 10% (wt/wt) BRB. Vehicle controls received 5% BRB or diet only. Rats were sacrificed after 9 and 33 wk of BRB feeding for ACF enumeration and tumor analysis. ACF multiplicity decreased 36%, 24%, and 21% (P < 0.01 for all groups) in the 2.5%, 5%, and 10% BRB groups, respectively, relative to the AOM-only group. Total tumor multiplicity declined 42%, 45%, and 71% (P < 0.05 for all groups). Although not significant, a decrease in tumor burden (28%, 42%, and 75%) was observed in all BRB groups. Adenocarcinoma multiplicity decreased 28%, 35%, and 80% (P < 0.01) in the same treatment groups. Urinary 8-OHdG levels were reduced by 73%, 81%, and 83% (P < 0.01 for all groups). These results indicate that BRB inhibit several measures of AOM-induced colon carcinogenesis and modulate an important marker of oxidative stress in the Fischer 344 rat.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2000

Effects of ozone and oxygen on the degradation of carotenoids in an aqueous model system.

The effects of ozone and oxygen on the degradation of carotenoids in an aqueous model system were studied. All-trans beta-carotene, 9-cis beta-carotene, beta-cryptoxanthin, and lycopene were adsorbed onto a C(18) solid phase and exposed to a continuous flow of water saturated with oxygen or ozone at 30 degrees C. Carotenoids were analyzed using HPLC with a C(30) column and a photodiode array detector. Approximately 90% of all-trans beta-carotene, 9-cis beta-carotene, and beta-cryptoxanthin were lost after exposure to ozone for 7 h. A similar loss of lycopene occurred in only 1 h. When exposed to oxygen, all carotenoids, except beta-cryptoxanthin, degraded at lower rates. The degradation of all the carotenoids followed zero-order reaction kinetics with the following relative rates: lycopene > beta-cryptoxanthin > all-trans beta-carotene > 9-cis beta-carotene. The major degradation products of beta-carotene were tentatively identified on the basis of their elution on the HPLC column, UV-Vis spectra, and electrospray LC-MS. Predominant isomers of beta-carotene were 13-cis, 9-cis, and a di-cis isomer. Products resulting from cleavage of the molecule were beta-apo-13-carotenone and beta-apo-14'-carotenal, whereas epoxidation yielded beta-carotene 5,8-epoxide and beta-carotene 5, 8-endoperoxide.

Carotenoids↗

PubMed2000

Identity status formulae: generating continuous measures of the identity statuses from measures of exploration and commitment.

Mathematical formulae were devised for the purpose of generatin continuous measures of the four identity statuses from measures of exploration and com measures of exploration and commitment. The formulae were consistent with the conceptual definitions of the statuses. They were found to be effective both in terms of generating continuOUs measures of the statuses and in terms of deriving status assignments.

Achievement↗

PubMed1999

Carotenoid composition of marigold (Tagetes erecta) flower extract used as nutritional supplement.

Commercially prepared marigold flower (Tagetes erecta) extract was saponified and analyzed for carotenoid composition. HPLC analyses were performed on two normal-phase columns (beta-Cyclobond and silica) and on a C(30) reversed-phase column. The extract contained 93% utilizable pigments (detected at 450 nm), consisting of all-trans and cis isomers of zeaxanthin (5%), all-trans and cis isomers of lutein, and lutein esters (88%). All were identified by chromatographic retention, UV-visible spectra, and positive ion electrospray mass spectrometry in comparison to authentic standards. Contrary to previous findings, insignificant levels (<0.3%) of lutein oxidation products were detected in the saponified extract. This compositional determination is important for the application of marigold extract in nutritional supplements and increases its value as a poultry feed colorant because it contains more biologically useful lutein compounds than previously believed.

Animal Feed↗

PubMed1999

Paprika (Capsicum annuum) oleoresin extraction with supercritical carbon dioxide.

Paprika oleoresin was fractionated by extraction with supercritical carbon dioxide (SCF-CO(2)). Higher extraction volumes, increasing extraction pressures, and similarly, the use of cosolvents such as 1% ethanol or acetone resulted in higher pigment yields. Within the 2000-7000 psi range, total oleoresin yield always approached 100%. Pigments isolated at lower pressures consisted almost exclusively of beta-carotene, while pigments obtained at higher pressures contained a greater proportion of red carotenoids (capsorubin, capsanthin, zeaxanthin, beta-cryptoxanthin) and small amounts of beta-carotene. The varying solubility of oil and pigments in SCF-CO(2) was optimized to obtain enriched and concentrated oleoresins through a two-stage extraction at 2000 and 6000 psi. This technique removes the paprika oil and beta-carotene during the first extraction step, allowing for second-stage oleoresin extracts with a high pigment concentration (200% relative to the reference) and a red:yellow pigment ratio of 1.8 (as compared to 1.3 in the reference).

Capsicum↗

PubMed1998

Carotenoid determination in biological microsamples using liquid chromatography with a coulometric electrochemical array detector.

Numerous epidemiological studies have linked carotenoids to cancer preventive processes, thereby increasing interest in levels of these micronutrients in human tissue and serum. Conventional analyses of these biological tissues employ liquid chromatography (LC) with ultraviolet and visible absorbance (UV-VIS) detection. However, this type of carotenoid analysis does not provide adequate sensitivity for very small sample sizes, such as microscale biopsies, when only small quantities of tissue are available. Electrochemical detection (ECD) is a useful alternative to conventional UV-VIS detection methods for LC analysis of carotenoids in cases where high sensitivity is necessary. Both hydrocarbon (beta-carotene and alpha-carotene) and oxygenated carotenoids (lutein, zeaxanthin, and beta-cryptoxanthin) were detected at electrical potential settings between 220 and 520 mV. The generated electrochemical array data (hydrodynamic voltammograms) can be used to identify carotenoids as well as to differentiate between trans and cis configurations. Detection limits for beta-carotene by ECD were measured at 10 fmol representing approximately a 100- to 1000-fold increase over conventional LC-UV-VIS techniques. The developed methodology was applied successfully to microscale analysis of biological tissues.

Carotenoids↗

PubMed1998

Cervical tissue and plasma concentrations of alpha-carotene and beta-carotene in women are correlated.

Results from epidemiologic studies suggest that a carotenoid-rich diet may reduce risk for cervical cancer, possibly by inhibiting the progression of cervical intraepithelial neoplasia, a preneoplastic lesion of the cervical tissue. Laboratory studies suggest that the mechanism may be linked to the metabolism of carotenoids to retinoic acid or retinoic acid-like compounds, which has been hypothesized to occur in the cervical tissue. The purpose of this study was to demonstrate the presence of provitamin A carotenoids in biopsied samples of this peripheral tissue in human subjects and to examine the relationship between baseline concentrations of these carotenoids in plasma and normal cervical tissue in subjects who were being evaluated for possible participation in a diet intervention trial. Subjects were 13 women aged 19-41 y. With the use of HPLC methodology, plasma concentrations of alpha-carotene, beta-carotene and beta-cryptoxanthin were determined with UV/visible light detection for plasma and electrochemical detection for cervical tissue. Relationships between plasma and cervical tissue were evaluated with Pearson correlation analysis. Adjusted for plasma cholesterol concentration, plasma alpha-carotene and beta-carotene were correlated with cervical tissue concentrations (r = 0.91, P < 0.001; r = 0.90, P < 0.001; respectively). Adjusted for plasma cholesterol concentration, plasma beta-cryptoxanthin tended to be correlated with cervical tissue concentrations (r = 0.62, P = 0.058). These findings suggest that plasma concentrations of alpha-carotene and beta-carotene are good predictors of cervical tissue concentrations of these compounds in human subjects and describe a first step toward demonstrating a biological link between provitamin A carotenoids and cervical cancer in vivo.

Adult↗

PubMed1998

Bioavailability of beta-carotene is lower in raw than in processed carrots and spinach in women.

Populations at risk of vitamin A deficiency usually rely on dietary provitamin A carotenoids to meet vitamin A needs, yet bioavailability of these compounds is influenced by several factors as follows: location in the plant source, the presence of other influencing dietary components, and type and extent of processing. The purpose of this study was to examine the plasma beta-carotene response to raw vs. processed carrots and spinach. Subjects were eight healthy females aged 23-36 y who consumed approximately 9.3 mg beta-carotene daily from either raw or thermally processed and pureed vegetables in two 4-wk treatment periods in a crossover study. Plasma concentrations of total, all-trans-, and cis-beta-carotene and alpha-carotene were measured at base line and the end of each treatment period by using HPLC assays. Total and all-trans (but not cis) plasma beta-carotene concentrations were significantly greater than base-line concentrations in the processed feeding period (P < 0. 04) and tended to be greater in the raw feeding period (P = 0.08). Daily consumption of processed carrots and spinach over a 4-wk period produced an increase in plasma beta-carotene concentration that averaged three times that associated with consumption of the same amount of beta-carotene from these vegetables in the raw form (P = 0.09). Increased cis isomers provided in the processed vegetables did not result in significantly greater plasma cis-beta-carotene isomer concentrations. These results suggest that isomerization of beta-carotene by heat treatment does not negate the enhanced beta-carotene uptake associated with consuming commercially processed vegetables compared with raw vegetables.

Adult↗

PubMed1998

Lycopene stability during food processing.

Accumulating epidemiological evidence continues to show that lycopene, found in tomatoes, grapefruits and watermelons, is associated with a reduced risk of developing certain chronic diseases and cancers. With respect to lycopene in tomato products, the effect of thermal processing on its stability has not yet been rigorously addressed. This paper assesses the effect of several different heat treatments on lycopene's isomeric distribution in a variety of tomato products, as well as in organic solvent mixtures containing all-trans lycopene. Experimental results indicate that in contrast to beta-carotene, lycopene remained relatively resistant to heat-induced geometrical conversion during typical food processing of tomatoes and related products. The presence of fat, the change in percentage of solids, and the severity of heat treatment were not contributing factors in the formation of lycopene isomers in tomato products, except at extreme conditions not regularly employed in the food industry or during food preparation. However, lycopene in organic solvent isomerized readily as a function of time even in the absence of light and the presence of antioxidants. These findings suggest that while lycopene is stable in the tomato matrix, sample handling techniques should be carefully evaluated to minimize the formation of lycopene cis isomers in organic solutions.

Antioxidants↗

PubMed1996

Isolation and structural elucidation of the predominant geometrical isomers of alpha-carotene.

The recent development and application of a polymeric C30 stationary phase have given unique separations of cis-trans carotenoid isomers in reversed-phase (RP) liquid chromatography (LC) owing to the exceptional shape selectivity of this stationary phase. In the present research, several geometrical isomers of alpha-carotene were at least partially resolved from a photo-isomerized mixture when chromatographed on a 3-microns polymeric C30 column. Double bond configurations of the five predominant alpha-carotene peaks, as isolated on a semi-preparative C30 column, were unambiguously assigned using 1H nuclear magnetic resonance (NMR) spectroscopy, giving the following order of elution: 13-cis, 13'-cis, all-trans, 9-cis, and 9'-cis geometrical forms. Electronic absorption spectra for these isomers were in agreement with the identification of peaks. The alpha-carotene isomers separated and identified herein had not been previously resolved in RPLC. Confirmation of the structures of geometrical alpha-carotene isomers will aid further studies on the possible physiological roles of these compounds in biological tissues.

Carotenoids↗

PubMed1996

Statistical methods in rehabilitation literature: a survey of recent publications.

OBJECTIVE: To document the use of statistical methods in the recent rehabilitation research literature. DESIGN: Descriptive survey study. METHODS: All 1,039 articles published between January 1990 and December 1993 in the American Journal of Physical Medicine and Rehabilitation and the Archives of Physical Medicine and Rehabilitation were reviewed for the use of statistical methods. RESULTS: There were 682 (66%) research articles in the sample that included systematic data collection and analysis. The most frequently encountered analytic tests and techniques included: (1) analysis of variance, (2) t tests, (3) correlation analysis, (4) contingency table analysis, (5) regression, and (6) nonparametric tests. Results were compared with results of a review of the 1982 rehabilitation literature by Wainapel and Kayne. Our study showed an increased sophistication in statistical methodology as well as a more intense use of such methods. In addition, there was a large number of relatively obscure and poorly documented tests encountered in the more recent literature. There was also a lack of adherence to a standardized format for describing statistical methods. CONCLUSIONS: The following recommendations are made: (1) Training curricula for rehabilitation professionals should provide instruction in the most commonly-encountered statistical methods and should be revised as needed to reflect changes in statistical method usage. (2) When less common statistical tests are applied, the responsibility of the authors to fully describe and justify their methods should be recognized. (3) Critical assessment of the literature is facilitated when statistical methods are reported in a standardized format.

Periodicals as Topic↗

PubMed1996

cis-trans lycopene isomers, carotenoids, and retinol in the human prostate.

An evaluation of the Health Professionals Follow-Up Study has detected a lower prostate cancer risk associated with the greater consumption of tomatoes and related food products. Tomatoes are the primary dietary source of lycopene, a non-provitamin A carotenoid with potent antioxidant activity. Our goal was to define the concentrations of lycopene, other carotenoids, and retinol in paired benign and malignant prostate tissue from 25 men, ages 53 to 74, undergoing prostatectomy for localized prostate cancer. The concentrations of specific carotenoids in the benign and malignant prostate tissue from the same subject are highly correlated. Lycopene and all-trans beta-carotene are the predominant carotenoids observed, with means +/- SE of 0.80 +/- 0.08 nmol/g and 0.54 +/- 0.09, respectively. Lycopene concentrations range from 0 to 2.58 nmol/g, and all-trans beta-carotene concentrations range from 0.09 to 1.70 nmol/g. The 9-cis beta-carotene isomer, alpha-carotene, lutein, alpha-cryptoxanthin, zeaxanthin, and beta-cryptoxanthin are consistently detectable in prostate tissue. No significant correlations between the concentration of lycopene and the concentrations of any other carotenoid are observed. In contrast, strong correlations between prostate beta-carotene and alpha-carotene are noted (correlation coefficient, 0.88; P < 0.0001), as are correlations between several other carotenoid pairs, which reflects their similar dietary origins. Mean vitamin A concentration in the prostate is 1.52 nmol/g, with a range of 0.71 to 3.30 nmol/g. We further evaluated tomato-based food products, serum, and prostate tissue for the presence of geometric lycopene isomers using high-performance liquid chromatography with a polymeric C30 reversed phase column. All-trans lycopene accounts for 79 to 91% and cis lycopene isomers for 9 to 21% of total lycopene in tomatoes, tomato paste, and tomato soup. Lycopene concentrations in the serum of men range between 0.60 and 1.9 nmol/ml, with 27 to 42% all-trans lycopene and 58 to 73% cis-isomers distributed among 12 to 13 peaks, depending upon their chromatographic resolution. In striking contrast with foods, all-trans lycopene accounts for only 12 to 21% and cis isomers for 79 to 88% of total lycopene in benign or malignant prostate tissues. cis Isomers of lycopene within the prostate are distributed among 14 to 18 peaks. We conclude that a diverse array of carotenoids are found in the human prostate with significant intra-individual variation. The presence of lycopene in the prostate at concentrations that are biologically active in laboratory studies supports the hypothesis that lycopene may have direct effects within the prostate and contribute to the reduced prostate cancer risk associated with the reduced prostate cancer risk associated with the consumption of tomato-based foods. The future identification and characterization of geometric lycopene isomers may lead to the development of novel agents for chemoprevention studies.

Aged↗

PubMed1995

High-performance liquid chromatography with light-scattering detection and desorption chemical-ionization tandem mass spectrometry of milk fat triacylglycerols.

The utility of reverse-phase high-performance liquid chromatography (HPLC), desorption chemical-ionization mass spectrometry (DCI-MS) and tandem mass spectrometry (MS/MS) for the characterization of triacylglycerols in complex mixtures has been further explored. Triacylglycerols of anhydrous bovine milk fat were separated by using two reverse-phase C18 HPLC columns, and eluents were monitored with an evaporative light-scattering detector. Fifty-eight fractions were resolved and analyzed by positive ion isobutane DCI-MS. The formation of protonated molecules and of major fragments corresponding to the random loss of any one of the constituent fatty acids readily identified acyl carbon numbers and the number of double bonds within each fatty acid. MS/MS was only required when the original mass spectra indicated the presence of more than one triacylglycerol or of impurities in a fraction. Protonated molecules produced by DCI were fragmented using high energy collisional activation, and the resulting ions were detected by MS/MS. Odd-chain triacylglycerols were also readily distinguished using this methodology. The positive ion DCI and MS/MS techniques described here demonstrate the usefulness of this approach for the characterization of triacylglycerols in complex mixtures.

Animals↗

PubMed1992

Chromatographic analysis of cis/trans carotenoid isomers.

Cis/trans configurations of carotenoids are known to effect the biochemistry of carotenoids in certain situations. Methodology for separating carotenoid cis/trans isomers is of importance to nutritionists and food scientists because cis isomers of provitamin A carotenoids have lower provitamin A activities than the all-trans form. Traditional food processing and preservation methods, especially thermal treatments, induce the formation of cis isomeric forms. However, many challenges, are apparent for identifying and analyzing cis/trans isomers present in foods and other biological tissues. The development of current chromatographic methods for the separation of carotenoid cis/trans isomers is reviewed. For the separation of beta-carotene isomers, most procedures employ either Ca(OH)2 or Vydac C18 columns. In general, polymeric C18 columns allow for the detection of cis carotenes, while monomeric C18 columns provide for some separation of certain xanthophylls. The main cis isomers detected in foods are the 13-cis and 9-cis forms, although other forms have also been found (mainly 15-cis and various di-cis isomers). More studies involving the metabolism and physiological consequences of cis/trans isomers in the diet are needed. However, due to limitations in current techniques, further method development in the area of separation, detection and quantitation of cis/trans carotenoid isomers will be required.

Carotenoids↗