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Biomedical subjects

D Topping

Publications and source records attributed to D Topping.

12 recordsLinked to original sources
PubMed2005

Population and virulence factor dynamics in fecal Escherichia coli from healthy adults consuming weight control diets.

Individual susceptibility to gastrointestinal infection is seen commonly in food poisoning outbreaks, but factors (such as diet) which may modulate this variability are understood poorly. Similarly, factors altering the population dynamics of enteric non-pathogenic Escherichia coli or of pathogenic E. coli containing toxin-signature DNA sequences in the colonic flora of healthy individuals are largely unknown. Feces were collected 4 times over a 12 week period from 41 healthy volunteer adults on a weight control diet (high or low in fiber). E. coli strains were examined by conventional culture followed by PCR for virulence genes stx1, stx2, eae and hlyA, and polymorphic beta-glucuronidase. Total E. coli counts ranged from undetectable to 8.75 log10 CFU/g feces and were unaffected by dietary fiber consumption or gender. Total E. coli counts were correlated positively with age (r = 0.401, P < 0.05). Fifty-eight percent (n = 24) of study individuals harboured more than 1 morph of beta-glucuronidase, indicating the presence of more than 1 strain of E. coli. Virulence genes were detected in 12 of 41 adults, comprising 10 stx1, 3 stx2, 3 eae, and 0 hlyA, but occurrence was not associated with diet, gender, or age. Factors influencing strain mobility over time did not appear to include diet or gender, while the positive relationship between total E. coli numbers and increasing age suggests that some older individuals are "more permissive" to mobile E. coli, including those with toxin genes.

Adhesins, Bacterial↗
PubMed2004

The impact of involvement of biomedical scientists in specimen dissection and selection of blocks for histopathology: a study of time benefits and specimen handling quality in Ayrshire and Arran area laboratory.

AIMS: To assess possible time benefits of specimen dissection by biomedical scientists (BMSs) and the quality of specimen handling by BMSs, in a department where BMSs trim those specimens requiring simple descriptions, from which standard blocks are taken. METHODS: Specimen handling by BMSs and consultant pathologists was compared. Time taken for each specimen trimmed was recorded prospectively. To determine specimen handling quality, adherence to dissection standard operating procedures (SOPs) was assessed by recording retrospectively whether or not each action in the SOP had been performed. Information on subsequently required extra levels or blocks was recorded. RESULTS: Analysis of data from 672 specimens trimmed by consultants showed that any given action in the SOPs was performed on average on 60.2% of applicable/assessable specimens; for 660 similar specimens trimmed by BMSs, each action was performed on average on 80.1% of specimens. Of the specimens where data on extra blocks were recorded, extra blocks were required in 3% of those trimmed by pathologists and in 4% of those trimmed by BMSs. Extra levels were required in 12% of those trimmed by pathologists and in 16% of those trimmed by BMSs. BMS trimming saves 16 hours of consultant time each month. The difference between pathologists and BMSs in time for each specimen trimmed is negligible. CONCLUSIONS: The advantages of increased adherence to trimming SOPs and saving consultant time outweigh the relatively small number of extra blocks and levels required when BMSs trim. There is no reduction in quality of dissection.

Allied Health Personnel↗
PubMed2001

Insulin stimulation of hepatic triacylglycerol secretion and the etiology of insulin resistance.

The recent observations that insulin can either stimulate or inhibit triacylglycerol secretion by the liver, depending on prior metabolic (possibly insulinemic) state, have rationalized the many apparently contradictory observations, obtained over the past three decades, on the effects of the hormone on this aspect of hepatic metabolism. Extrapolation to the situation in vivo suggests that frequent stimulation of insulin secretion may result in a chronic stimulation of VLDL secretion, and increased delivery of acyl moieties to muscle, where they induce insulin resistance if provided in excess of the oxidative needs (mostly due to exercise) of the tissue. High fructose/sucrose diets, which also stimulate hepatic VLDL secretion, will have the same effect, especially if consumed frequently during the diurnal cycle. Due to the quantitative importance of muscle as a site for insulin-sensitive glucose metabolism, these effects may initiate the metabolic vicious cycle that results in the development of the metabolic syndrome, well in advance of overt obesity or the diagnosis of type-2 diabetes.

Animals↗
PubMed2000

Modulation of the acute phase response by altered expression of the IL-1 type 1 receptor or IL-1ra.

A complete understanding of the role for endogenously produced interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), and IL-1 receptor antagonist (IL-1ra) in the acute phase response to inflammation remains unknown. In the present studies, knockout mice lacking either a functional IL-1 type I receptor (IL-1RI(-/-)), a TNF type I receptor (TNFR-I(-/-)), or both IL-1 type I and TNF type I receptors (IL-1RI(-/-)/TNFR-I(-/-)) received a turpentine abscess. Additional mice deficient in IL-1ra protein (IL-1ra(-/-)) or overexpressing IL-1ra protein (IL-1ra(tg)) were similarly treated. After a turpentine abscess, IL-1 receptor knockout mice exhibited an attenuated inflammatory response compared with wild-type or animals lacking a functional TNFR-I. Mice overexpressing IL-1ra also had an attenuated hepatic acute phase protein response, whereas IL-1ra knockout mice had a significantly greater hepatic acute phase response. We conclude that the inflammatory response to a turpentine abscess is the result of a balance between IL-1ra expression and IL-1 binding to its type I receptor. Endogenously produced IL-1ra plays a central role in mitigating the magnitude of the IL-1-mediated inflammatory response and, ultimately, the outcome to a turpentine abscess.

Abscess↗
PubMed1999

Aleurone flour is a rich source of bioavailable folate in humans.

With the use of novel milling technology, it has become commercially viable to isolate the aleurone layer of cells from wheat grain and to prepare a novel flour from this fraction that has a natural folate concentration of approximately 500 microgram/100 g. The aim of this study was to determine the relative bioavailability of natural folate from aleurone flour when ingested as a cereal. Using a series of randomized, short-term intervention trials with a cross-over involving eight men and eight women aged between 29 and 50 y, we compared the increment of plasma folate following ingestion of 1) 100 g wheat bran cereal (low folate control), 2) 100 g aleurone cereal, and 3) a tablet containing 500 microgram folic acid taken together with 100 g wheat bran cereal (high folate control). Folate absorption was measured by estimating the area under the plasma folate concentration versus time curve. The extent of increase in plasma folate over the 7-hour period following ingestion of aleurone cereal was more than fourfold greater than that observed following the wheat bran cereal (P < 0.0001) and not different from that observed following the 500 microgram folic acid tablet taken with wheat bran cereal. Differences were significant when data for males and females were analyzed separately (P < 0.001). This study has shown that cereal made from wheat aleurone flour is a good source of bioavailable, natural folate.

Absorption↗
PubMed1994

Hydroxypropylmethylcellulose, viscosity, and plasma cholesterol control.

The mechanism for the lowering of plasma cholesterol by water-soluble nonstarch polysaccharides (NSP) could involve alteration of intestinal viscosity leading to attenuated fat and steroid digestion and absorption. Alternatively, there may be direct inhibition of hepatic cholesterol synthesis by short-chain fatty acids produced by large bowel bacterial fermentation. A synthetic NSP, hydroxypropylmethylcellulose (HPMC), has been shown to lower plasma low-density lipoprotein (LDL) cholesterol in humans. This polysaccharide is not fermented by the large bowel microflora and has been shown to lower the plasma and liver cholesterol in hamsters, with no change noted in hepatic sterol synthesis. In further studies with hamsters, a linear relationship has been identified between plasma cholesterol and the logarithm of hydroxymethylcellulose viscosity. Only a relatively small increment in viscosity was necessary to achieve a maximal effect, suggesting that intestinal digestion may be quite sensitive to increased NSP intake.

Animals↗
PubMed1993

Dietary fatty acids and protection against experimental cardiac arrhythmias in rats.

Sudden cardiac death accounts for about 50% of total coronary disease mortality in westernized industrial countries. The lack of early symptoms for this disorder makes prevention the preferred strategy. In a rat model of cardiac ischemia, dietary n-6 (sunflower seed oil) and n-3 (fish-oil) polyunsaturated fatty acids were shown to protect against arrhythmia compared with saturated fat, with greatest protection observed with fish oil. The frequency of arrhythmia was similar with monounsaturated fat from olive oil and saturated fat.

Animals↗
PubMed1992

Oat bran lowers plasma cholesterol levels in mildly hypercholesterolemic men.

The effects of oat bran and wheat bran on plasma lipid concentrations were compared in a crossover study. Each bran (123 g oat bran or 54 g wheat bran) added nearly 18 g of nonstarch polysaccharide to a background diet containing about 10 g nonstarch polysaccharide. Twenty-three men (average plasma cholesterol level = 5.84 mmol/L, and low-density-lipoprotein (LDL) cholesterol level = 4.11 mmol/L) were randomly assigned to either the oat or wheat bran diet for 4 weeks and then changed to the alternate bran diet for a similar period. The oat bran diet produced significantly lower levels of plasma total cholesterol and LDL cholesterol: 5.65 +/- 0.16 and 3.88 +/- 0.15 mmol/L (mean +/- standard error) for oat bran vs 5.89 +/- 0.16 and 4.11 +/- 0.16 mmol/L for wheat bran. Food intake diaries showed that average consumption of total fat and saturated fat was identical during the two test periods, which excluded displacement of fat as an explanation for lowering of plasma cholesterol by oat bran. Our results indicate that in mildly hypercholesterolemic men, a diet high in soluble oat fiber can significantly lower plasma total cholesterol and LDL cholesterol and thus potentially lower the risk of coronary heart disease.

Adult↗
PubMedDate not supplied

Arginine-enhanced enteral nutrition augments the growth of a nitric oxide-producing tumor.

BACKGROUND: Arginine-enhanced diets have been shown to be beneficial in tumor-bearing hosts, but no data exist regarding their effects in hosts bearing nitric oxide (NO)-producting tumors. OBJECTIVE: To examine the effect of arginine supplementation on the growth of a NO-producing murine breast cancer cell line. METHODS: EMT-6 cells were grown in various concentrations of arginine in the presence or absence of the inducible nitric oxide synthase (iNOS) inhibitor, aminoguanidine (1 mmol/L). Forty-eight hours later, nitrite accumulation and viable cell number were assessed. BALB/c mice were then pair-fed basal purified diets (n = 10), 4% casein diets (isonitrogenous control, n = 5), or 4% arginine-enhanced diets (n = 10). One week later, 10(5) EMT-6 cells were implanted subcutaneously into the dorsal flank. After tumor implantation, five mice fed basal purified diets and five mice fed arginine-enhanced diets also received aminoguanidine (100 mg/kg subcutaneously twice daily). Two weeks after tumor cell implantation, tumor size (mean diameter), animal weight, serum and tumor nitrite and nitrate levels were measured. RESULTS: There was minimal nitrite accumulation in arginine-free media, while increasing the arginine concentration increased nitrite levels. Viable cell number did not increase in arginine-free media, but increased nearly twofold in 100 and 1000 mumol/L arginine. In 5000 and 10,000 mumol/L arginine, the difference in viable cell number was not statistically different than that seen in arginine-free media, whereas the addition of aminoguanidine blocked nitrite accumulation and increased viable cell number at these arginine concentrations. Arginine-enhanced diets stimulated tumor growth in vivo more than twofold over tumor growth in mice fed isonitrogenous control or basal purified enteral diets. Mice fed arginine-enhanced diets also had increased serum nitrite and nitrate levels over mice fed basal purified enteral diets, whereas tumors from mice fed arginine-enhanced diets had nitrite and nitrate levels similar to mice fed basal purified enteral diets. Aminoguanidine blocked the increase in serum nitrite and nitrate, but failed to block the increased tumor growth in mice receiving the arginine-supplemented diets. CONCLUSIONS: Arginine concentration influences the growth of EMT-6 tumor cells in vitro and dietary arginine supplementation augments tumor growth in vivo. The mechanism of the growth modulation in vitro is NO-dependent whereas the enhanced tumor growth in vivo is NO-independent.

Animals↗