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Biomedical subjects

C Stanton

Publications and source records attributed to C Stanton.

At least 19 recordsLinked to original sources
PubMed2000

An assessment of DHS maternal mortality indicators.

This study presents an assessment of the quality of data relating to maternal mortality collected in 14 Demographic and Health Surveys (DHS) for 13 countries that included a complete sibling history. Four aspects of data quality are considered: completeness of the data for reported events, evidence of omission in the reporting of events, plausibility of the pattern of sibling deaths, and sampling errors of the maternal mortality estimates. Although the data relating to reported events are complete for most variables, comparisons of sibling-history-based estimates of adult mortality for both males and females with other independent estimates suggest that sibling estimates are more likely to be underestimates than overestimates. The downward bias is probably greater for female mortality than for male mortality. The sampling errors associated with maternal mortality ratios are substantially larger than those associated with other frequently used DHS indicators. This lack of precision precludes the use of these data for trend analysis and has led to the recommendation that this DHS module not be used more than once every ten years in the same country.

Adolescent↗
PubMed2000

Comparative survival rates of human-derived probiotic Lactobacillus paracasei and L. salivarius strains during heat treatment and spray drying.

Spray drying of skim milk was evaluated as a means of preserving Lactobacillus paracasei NFBC 338 and Lactobacillus salivarius UCC 118, which are human-derived strains with probiotic potential. Our initial experiments revealed that NFBC 338 is considerably more heat resistant in 20% (wt/vol) skim milk than UCC 118 is; the comparable decimal reduction times were 11.1 and 1.1 min, respectively, at 59 degrees C. An air outlet temperature of 80 to 85 degrees C was optimal for spray drying; these conditions resulted in powders with moisture contents of 4.1 to 4.2% and viable counts of 3.2 x 10(9) CFU/g for NFBC 338 and 5.2 x 10(7) CFU/g for UCC 118. Thus, L. paracasei NFBC 338 survived better than L. salivarius UCC 118 during spray drying; similar results were obtained when we used confocal scanning laser microscopy and LIVE/DEAD BacLight viability staining. In addition, confocal scanning laser microscopy revealed that the probiotic lactobacilli were located primarily in the powder particles. Although both spray-dried cultures appeared to be stressed, as shown by increased sensitivity to NaCl, bacteriocin production by UCC 118 was not affected by the process, nor was the activity of the bacteriocin peptide. The level of survival of NFBC 338 remained constant at approximately 1 x 10(9) CFU/g during 2 months of powder storage at 4 degrees C, while a decline in the level of survival of approximately 1 log (from 7.2 x 10(7) to 9.5 x 10(6) CFU/g) was observed for UCC 118 stored under the same conditions. However, survival of both Lactobacillus strains during powder storage was inversely related to the storage temperature. Our data demonstrate that spray drying may be a cost-effective way to produce large quantities of some probiotic cultures.

Bacteriocins↗
PubMed1999

The effect of conjugated linoleic acid on the antioxidant enzyme defense system in rat hepatocytes.

Short-term effects of physiological concentrations of conjugated linoleic acid (CLA) on membrane integrity, metabolic function, cellular lipid composition, lipid peroxidation, and antioxidant enzymes were examined using rat hepatocyte suspension cultures. Incubation with CLA (5-20 ppm) for 3 h decreased the ability of hepatocyte plasma membranes to exclude trypan blue by approximately 25%, and caused leakage of cytosolic lactate dehydrogenase (LDH) into the medium. The significant decrease (P< 0.02) in hepatocyte viability as measured by LDH leakage during cell incubation with 10 and 20 ppm CLA was not associated with significant changes in cellular ATP content. Protein synthesis in hepatocytes was elevated (P < 0.05) in the presence of 5 and 10 ppm CLA, but at a higher concentration (20 ppm), protein synthesis was similar to that of control cells. Gluconeogenesis was maintained in cells incubated with lower concentrations of CLA (5 and 10 ppm) but was decreased (P < 0.02) at the higher concentration. Incubation with 20 ppm CLA for 3 h did not affect the specific activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme of cholesterol synthesis. Both cis-9,trans-11/trans-9,cis-11, and cis-10,trans-12/trans-10,cis-12 isomers of CLA were incorporated to a similar level into hepatocytes. Levels ranged from 3.9 to 4.1%, respectively, of total fatty acids in neutral lipids, and from 0.7 to 0.8%, respectively, of total fatty acids in phospholipids. Cellular lipid peroxidation remained unchanged in the presence of CLA (5-20 ppm), despite significant inhibition (P < 0.05) of superoxide dismutase. Catalase activity was maintained near control levels in the presence of 5 and 10 ppm CLA but was significantly decreased in the presence of 20 ppm CLA. Glutathione peroxidase activity was significantly decreased in the presence of 10 ppm CLA. The apparent sensitivity of the antioxidant enzyme defense system of liver cells to CLA, coupled with the lack of effect of CLA on lipid peroxidation in cells, suggests that cytotoxic effects of CLA as described by LDH leakage and decreased gluconeogenesis were not mediated by a prooxidant action in hepatocytes.

Adenosine Triphosphate↗
PubMed1999

Influence of a probiotic adjunct culture of Enterococcus faecium on the quality of cheddar cheese.

Cheddar cheese has previously been shown to be an effective vehicle for delivery of viable cells of a probiotic Enterococcus faecium strain to the gastrointestinal tract. The particular strain, E. faecium PR88, has proven efficacy in the treatment of irritable bowel syndrome, and in this study it was evaluated for suitability as a starter adjunct for Cheddar cheese manufacture. When added to cheesemilk at an inoculum of 2 x 10(7) cfu/mL, the enterococcal adjunct maintained viability in Cheddar cheese at levels of up to 3 x 10(8) cfu/g during 9 months of ripening. Increased proteolysis and higher levels of some odor-active volatile compounds were observed in Cheddar cheeses containing the PR88 adjunct compared with the control throughout the ripening period. In addition, the enterococcal adjunct strain did not affect cheese composition. Although sensory evaluation showed no significant difference in flavor/aroma and body/texture scores between control and experimental cheeses, repeated comments by the commercial grader consistently described the cheeses containing PR88 as 'more advanced than the control' and as having 'better flavor'. These findings indicate that the presence of the PR88 adjunct strain in Cheddar cheese at levels of >/=10(8) cfu/g may positively influence Cheddar flavor.

Cheese↗
PubMed1999

Alpha-tocopherol inhibits oxidative stress induced by cholestanetriol and 25-hydroxycholesterol in porcine ovarian granulosa cells.

The cytotoxicity of oxysterols including 7-ketocholesterol, alpha-epoxide, cholestanetriol and 25-hydroxycholesterol and the possible protecting effect of alpha-tocopherol on cholestanetriol and 25-hydroxycholesterol-induced cytotoxicity were investigated in primary cultures of porcine ovarian granulosa cells. Cell viability as determined by % trypan blue staining and mitochondrial function as determined using 3-[4,5-dimethylthiazol-2-yl]-2,5- diphenyltetrazolium bromide (MTT) reduction were decreased significantly after 24 h exposure to 2.5 microM alpha-epoxide, cholestanetriol and 25-hydroxycholesterol. 7-Ketocholesterol (2.5 microM) did not affect cell viability or mitochondrial function under the same culture conditions. The specific activities of catalase and superoxide dismutase, two antioxidant defense enzymes were increased significantly (p < 0.01) following 24 h exposure to 2.5 microM concentrations of cholestanetriol while only superoxide dismutase was increased in 25-hydroxycholesterol-treated cells (p < 0.001). Specific activity of glutathione peroxidase was unchanged relative to control cells. Levels of thiobarbituric acid reactive substances remained unchanged after exposure to 7-ketocholesterol, alpha-epoxide, cholestanetriol, 25-hydroxycholesterol and cholesterol. Administration of 1 microM alpha-tocopherol to the culture medium significantly improved cell viability and restored both superoxide dismutase and catalase activities to control levels in cholestanetriol -treated cells and only superoxide dismutase in 25-hydroxycholesterol-treated cells. These studies suggest that the cytotoxic nature of physiologically relevant concentrations of cholestanetriol and 25-hydroxycholesterol in granulosa cells is in part due to oxidative stress, but it may be reduced in the presence of alpha-tocopherol.

Animals↗
PubMed1999

Evaluation of cheddar cheese as a food carrier for delivery of a probiotic strain to the gastrointestinal tract.

Cheddar cheese was evaluated as a food carrier for the delivery of viable microorganisms of Enterococcus faecium (Fargo 688; Quest Int., Naarden, The Netherlands) to the gastrointestinal tract. This strain had previously been shown to possess properties required of a probiotic microorganism including the ability to relieve irritable bowel syndrome. The strain was found to survive to high numbers in Cheddar cheese during ripening at 8 degrees C for 15 mo (4 x 10(8) cfu/g) and in yogurt during storage at 4 degrees C for 21 d (4 x 10(7) cfu/g). In an in vitro model system, Cheddar cheese was found to have a greater protective effect than yogurt upon exposure of the probiotic culture to porcine gastric juice at pH 2. Subsequently, a feeding trial involving 8 pigs per group was performed in which a rifampicin-resistant variant of the probiotic strain was fed for 21 d at a mean daily intake of 1.3 x 10(10) cfu/d from Cheddar cheese or 3.7 x 10(9) cfu/d from yogurt. During the feeding period, Cheddar cheese yielded a significantly higher mean fecal probiotic count (2 x 10(6) cfu/g of feces) than did yogurt (5.2 x 10(5) cfu/g of feces). These data indicate that mature Cheddar cheese compares very favorably with fresh yogurt as a delivery system for viable probiotic microorganisms to the gastrointestinal tract.

Animal Feed↗
PubMed1998

Development of a probiotic cheddar cheese containing human-derived Lactobacillus paracasei strains.

Cheddar cheese was manufactured with either Lactobacillus salivarius NFBC 310, NFBC 321, or NFBC 348 or L. paracasei NFBC 338 or NFBC 364 as the dairy starter adjunct. These five strains had previously been isolated from the human small intestine and have been characterized extensively with respect to their probiotic potential. Enumeration of these strains in mature Cheddar cheese, however, was complicated by the presence of high numbers (>10(7) CFU/g of cheese) of nonstarter lactic acid bacteria, principally composed of lactobacilli which proliferate as the cheese ripens. Attempts to differentiate the adjunct lactobacilli from the nonstarter lactobacilli based on bile tolerance and growth temperature were unsuccessful. In contrast, the randomly amplified polymorphic DNA method allowed the generation of discrete DNA fingerprints for each strain which were clearly distinguishable from those generated from the natural flora of the cheeses. Using this approach, it was found that both L. paracasei strains grew and sustained high viability in cheese during ripening, while each of the L. salivarius species declined over the ripening period. These data demonstrate that Cheddar cheese can be an effective vehicle for delivery of some probiotic organisms to the consumer.

Amino Acids↗
PubMed1998

Elevation of conjugated cis-9, trans-11-octadecadienoic acid in bovine milk because of dietary supplementation.

Cows on pasture were fed full fat soybeans (toasted, flaked, and pelleted) or ground full fat rapeseeds to investigate effects on cis-9, trans-11-octadecadienoic acid in milk. Three herds of 16 cows each that were on pasture were fed 3.1 kg/d of unmolassed beet pulp (control), 3.0 kg/d of rapeseed concentrate, or 3.1 kg/d of a soybean supplement. The concentration of cis-9, trans-11-octadecadienoic acid in the milk of cows fed the rapeseed and soybean supplements was significantly higher than in the milk of cows fed the control diet during the feeding trial. Over the trial, the cis-9, trans-11-octadecadienoic acid concentration in the milk of individual cows varied from 6.8 to 25.7 mg/g of fat in the control herd, from 10.6 to 33.5 mg/g of fat in the herd fed the rapeseed concentrate, and from 8.8 to 30.5 mg/g of fat in the herd fed the soybean supplement. The concentration of cis-9, cis-12-octadecadienoic acid, the substrate for cis-9, trans-11-octadecadienoic acid synthesis in the rumen, was 4.9 g/100 g of fatty acid methyl esters in the milk fat of cows fed the soybean supplement, 2.5 g/100 g of fatty acid methyl esters in the milk fat of cows fed the rapeseed concentrate, and 2.3 g/100 g of fatty acid methyl esters in the milk fat of the control cows. Milk yield and milk constituent yields were not affected by supplementation of either full fat soybeans or rapeseeds compared with controls, but milk protein concentration was significantly reduced by both oilseed supplements.

Animals↗
PubMed1996

Processing and expression of rat and human clotting factor-X-encoding cDNAs.

The cDNA encoding clotting factor X, which participates in the middle stage of the blood coagulation cascade was cloned from a rat liver cDNA library. Sequencing of the rat factor-X-encoding cDNA revealed that this vitamin-K-dependent protein has a dibasic Arg-Arg sequence at the propeptide cleavage site, as occurs in other vitamin-K-dependent proteins. Although the human and rat deduced amino acid sequences are remarkably similar (76% identical), they do significantly differ in that human factor-X contains a unique Thr-Arg sequence at the propeptide cleavage site [Fung et al., Proc. Natl. Acad. Sci. USA 82 (1985) 3591-3595], where a dibasic sequence would normally be expected. This specific site is the recognition motif for the endoprotease, furin, which is located in the Golgi apparatus. Both rat and human cDNAs expressed in Cos-1 cells resulted in secretion of a mixture of single- and two-chain forms of factor X. The two-chain forms were devoid of the propeptide and were produced at similar rates by the transfected cells. The efficient processing of human factor X, when compared to rat factor X, may indicate that an additional protease(s), which recognizes the Thr-Arg motif, may be involved in proteolytic processing of the human enzyme.

Amino Acid Sequence↗
PubMed1996

Maternal mortality.

A new approach to measuring maternal mortality indicates that there are some 585,000 maternal deaths, 99% of them in developing countries. This is around 80,000 deaths more than earlier estimates have suggested and indicates a substantial underestimation of maternal mortality in the past. There is a greater disparity in levels of maternal mortality between industrialized and developing countries than in any other public health indicator. While significant progress has been made in reducing infant mortality, the same is not true for maternal mortality. Although the actions needed to reduce maternal mortality have long been known, 1 woman in 50 is still dying as a result of pregnancy-related complications and the figure rises to 1 in 10 in many parts of Africa. By contrast, the figure for developed countries can be as low as 1 in 8,000.

Cause of Death↗
PubMed1995

Evidence for competition between vitamin K-dependent clotting factors for intracellular processing by the vitamin K-dependent gamma-carboxylase.

This study demonstrates an apparent competition between newly synthesized precursors of prothrombin and factor X for binding to and processing by the gamma-carboxylase in the ER membrane of hepatocytes. The precursor of factor X appears to exhibit a strong affinity for the carboxylase than the prothrombin precursor. This conclusion is supported by the findings that 1) in normal hepatocytes, the factor X precursor prevents increased prothrombin precursor binding to the ER membrane, 2) increased prothrombin binding to the ER membrane was measured in H4-II-E-C3 Reuber H-35 cells where factor X synthesis is suppressed. The variations in the concentrations of the prothrombin and the factor X precursors that were as associated with the ER membrane correlated with the available prothrombin and factor X substrate pools for the gamma-carboxylase.

Animals↗
PubMed1995

Langerhans cell histiocytosis involving the corpus callosum and cerebellum: gadolinium-enhanced MRI.

Langerhans cell histiocytosis is a systemic disorder consisting of abnormal histiocyte proliferation, in the form of focal deposits. Central nervous system involvement is most common in the hypothalamus, although other sites have been described, such as the cerebellum and the meninges. We present a case with presumed involvement of the corpus callosum and cerebellum, demonstrating gadolinium enhancement on MRI.

Adolescent↗