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C Cheeseman

Publications and source records attributed to C Cheeseman.

13 recordsLinked to original sources
PubMed2005

Use of flue gas desulphurisation (FGD) waste and rejected fly ash in waste stabilization/solidification systems.

Stabilization/solidification (S/S) processes have been used as the final treatment step for hazardous wastes prior to land disposal. Fly ash is a by-product of coal-fired power generation; a significant proportion of this material is low-grade, reject material (rFA) that is unsuitable as a cement replacement due to its high carbon content and large particle size (>45 microm). Flue gas desulphurization (FGD) sludge is a by-product from the air pollution control systems used in coal-fired power plants. The objective of this work was to investigate the performance of S/S waste binder systems containing these two waste materials (rFA and FGD). Strength tests show that cement-based waste forms with rFA and FGD replacement were suitable for disposal in landfills. The addition of an appropriate quantity of Ca(OH)2 and FGD reduces the deleterious effect of heavy metals on strength development. Results of TCLP testing and the progressive TCLP test show that cement-rFA-Ca(OH)2 systems with a range of FGD additions can form an effective S/S binder. The Leachability Index indicates that cement-based waste forms with rFA replacement were effective in reducing the mobility of heavy metals.

Calcium Hydroxide↗
PubMed2002

Microbial influenced degradation of solidified waste binder.

Ordinary cement pastes with water/cement (w/c) ratios of 0.2, 0.4 and 0.5 were used to examine the chemical and physical effects of microbial influenced degradation (MID). Samples were exposed to an active culture of Thiobacillus thiooxidans or to sterile media containing sulphuric acid using an intermittent immersion technique. Acid consumption and Ca, Al and Fe releases are presented for an exposure period of 90 days. Exposed samples were also sectioned and analysed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). All cement paste samples were subject to significant degradation in either sterile acid media or the T. thiooxidans lixiviant. Corrosion depths observed from SEM examination of exposed samples were affected by the w/c ratio of the cement. The extent and rate of degradation were not apparent from the calculated rate of hydrogen ion consumption, or the leaching rates of Ca, Al and Fe. It was not possible to distinguish differences in corrosion due to the chemical and microbial influenced degradation from the results obtained to date and further work is focusing on modified procedures to address this.

Acidithiobacillus thiooxidans↗
PubMed2001

Control of infectious diseases of wildlife in Europe.

During the last 30 years, new epidemiological patterns have emerged as free-ranging wildlife have become progressively more involved in the epidemiology of both common and emerging infectious diseases of humans and domestic animals. This has been seen in rabies, bovine tuberculosis and more recently in wild-boar classical swine fever. Emerging diseases are of interest to veterinarians as well as public health officials but attempts to control these diseases have not always been successful as in wildlife populations control of either host or pathogen can present particular problems. Lessons should be learnt from previous experiences to help in the management of new emerging diseases in the future.

Animal Diseases↗
PubMed2001

Permeability of lime-activated pulverised fuel ash to metal-containing permeants.

Lime-activated pulverised fuel ash (PFA) has been leach tested under a range of pH conditions and the permeability of compacted samples determined using distilled water and aqueous solutions of Ca2+, Zn2+, Cd2+ and Mg2+. Although permeabilities were relatively high when tested with distilled water (> 1x10(-7) m/s), permeation with 0.05M metal solutions resulted in rapid reductions in permeability to less than 1x10(-10) m/s. Leachate and permeant solution analysis shows that metal ion release from samples is low. The reduction in permeability is believed to be due to pore sealing resulting primarily from metal hydroxide precipitation and results in a metal concentration gradient across the sample thickness. Lime-activated PFA therefore acts as both a chemical and physical barrier to metal ion migration and has the potential to form low permeability barriers.

Calcium Compounds↗
PubMed1994

Influence of vascular and luminal hexoses on rat intestinal basolateral glucose transport.

The influence of luminal and vascular hexoses in rats on glucose transport across the jejunal basolateral membrane (BLM) was measured using isolated membrane vesicles prepared from infused animals. In vivo vascular infusions of glucose produced an increase in glucose transport across BLM vesicles. Sucrose, mannose, galactose, and fructose had no significant effect. Plasma glucose concentrations were unaffected by galactose and sucrose vascular infusions, while mannose and fructose produced a modest rise, and glucose increased plasma glucose to 20 mM. Insulin release was significantly increased by vascular infusion of glucose and fructose, while mannose produced only a small sustained rise. Sucrose and galactose had no effect. Perfusion through the lumen of the rat jejunum in vivo, for up to 4 h, with glucose, fructose, sucrose, or lactate (100 or 25 mM) produced a significant increase in the maximal rate of glucose transport (up to 4- to 5-fold) across BLMs. Galactose and mannose had no effect. Luminal glucose perfusion produced a small nonsignificant increase in glucose inhibitable cytochalasin B binding to BLM vesicles, and no change was seen in the microsomal pool of binding sites. The abundance of GLUT2 in the jejunal BLM, as determined by Western blotting, was unaffected by luminal perfusion of 100 mM glucose for 4 h. Fructose almost completely inhibited the carrier-mediated uptake of glucose in control and upregulated jejunal BLM vesicles. These results are discussed in relation to the physiological role of the upregulation of GLUT2 activity by luminal and vascular hexoses.

Animals↗
PubMed1992

Role of intestinal basolateral membrane in absorption of nutrients.

Organic solutes leave the intestinal epithelium and enter the circulation via specific facilitated carriers located in the basolateral membrane. In the case of glucose it is a low-affinity, high-capacity transport system that can adapt to the carbohydrate content of the diet. Chronic diabetes also promotes the exit of glucose, and in both cases the effect results from an increased density of carriers in the basolateral membrane. In contrast, a rapid upregulation of this system that can be induced within 30 min by hyperglycemia does not involve large changes in the amount of transporter protein. Similarly, the absorptive capacity of the small intestine from some amino acids can be influenced by events occurring at the basolateral membrane. In the case of dibasic amino acid absorption, exit from the epithelium is the rate-limiting step. The activity of the basolateral carrier can be increased almost 10-fold within 60 s by the addition of micromolar concentrations of the neutral amino acid leucine to either the lumen or the plasma. This response does not involve the second messenger adenosine 3',5'-cyclic monophosphate and may represent an allosteric modulation of the carrier. These observations are discussed in relation to the role of the basolateral membrane as a locus for controlling intestinal absorption of organic nutrients.

Absorption↗
PubMed1990

Long-term effects of manipulations of dietary omega-3 fatty acids on clinical control and in vitro uptake of glucose and lipids in diabetic rats.

The intestinal absorption of nutrients is increased in diabetic rats fed chow, yet short-term (two week) studies have demonstrated reduced and near-normal intestinal nutrient absorption in diabetic rats fed a diet high in polyunsaturated fatty acids. In this study we undertook to establish the effect of 10 weeks' feeding of isocaloric semisynthetic diets with high or low ratios of saturated (S)-to-omega-3 polyunsaturated (P) fatty acids ("fish oil") when given to streptozotocin diabetic rats. The fasting plasma glucose concentration was approximately 10% lower in diabetic rats fed P as compared with S, although the oral and intravenous glucose tolerance tests and the time-course of the oral and intravenous glucose-stimulated immunoreactive insulin levels were similar in P and S, as also were the levels of the hemoglobin A1C. The fasting plasma triglyceride concentrations were similar in P and S, but the fasting plasma cholesterol concentrations were approximately 20% lower in diabetic rats fed P as compared with S. Feeding P to diabetic animals was associated with a heavier intestine, which was comprised of a greater proportion of mucosal than submucosal tissue. The enhanced jejunal uptake of fatty acids 18:0 (stearic) and 18:2 (linoleic) as well as cholesterol observed in diabetic as compared with non-diabetic animals fed S was not observed in those fed P. The enhanced uptake of glucose in diabetic rats was also influenced by diet, with a lower rate for jejunal and ileal uptake of glucose in diabetic rats fed P than in those fed S.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Use of polyunsaturated fatty acid diet to treat the enhanced intestinal uptake of lipids in streptozotocin diabetic rats.

Intestinal passive transport of lipids is enhanced in rats with streptozotocin-induced diabetes. The present study was undertaken to test the effect of semisynthetic isocaloric diets, varying in saturated (S) or polyunsaturated (P) fatty acid content, on intestinal lipid uptake when fed to rats previously rendered diabetic. In vitro uptake of fatty acids and cholesterol was higher in the jejunum and ileum of diabetic rats than in control rats fed rat chow. Feeding P prevented the enhanced jejunal and ileal uptake of 18:1 and 18:2, and feeding S prevented the enhanced jejunal uptake of 18:2 in diabetic rats fed rat chow. In diabetic rats, feeding P was associated with reduced jejunal uptake of 16:0 and 18:1 and reduced ileal uptake of 16:0, 18:0, and 18:2, as compared with diabetic rats fed S. Weight gain and blood glucose concentration was similar in diabetic animals fed chow, P or S. The percentage of the jejunal wall comprised of mucosa was greater in diabetic than in control rats fed chow or P but was similar in control and diabetic rats fed S. However, this diminution in uptake was not explained by these differences. The potential long-term role of feeding P in the diminution of the hyperlipidemia associated with human diabetes remains to be established.

Animals↗
PubMed1987

Is leucine an allosteric modulator of the lysine transporter in the intestinal basolateral membrane?

The transport of the dibasic amino acid L-lysine was investigated using basolateral membrane vesicles prepared from rat jejunal mucosal scrapings. The majority of the carrier-mediated transport was unaffected by the presence of sodium in the incubation medium, but voltage clamping of the vesicles did increase lysine uptake, indicating an associated movement of charge. Kinetic analysis of lysine influx and efflux showed the system to be symmetrical, but although the Vmax was comparable to other amino acid transport systems in this membrane, the dissociation constant for the overall reaction (KT) was an order of magnitude larger. This low affinity for lysine would explain the relatively slow rate of transport of this amino acid across the basolateral membrane. Competition experiments indicated that this system has a relatively narrow specificity carrying only lysine, arginine, ornithine, and histidine. In contrast the presence of L-leucine caused a marked stimulation of lysine efflux and influx across the vesicles. This effect was observed with leucine concentrations as low as 0.1 microM. It is concluded that although the lysine transport system in the basolateral membrane is slow in its basal state it can be rapidly turned on by the presence of L-leucine. The remarkably low concentrations required to do this suggest a possible allosteric interaction between the transporter and this neutral amino acid.

Allosteric Regulation↗
PubMed1986

Effect of external abdominal irradiation on intestinal morphology and brush border membrane enzyme and lipid composition.

Previous studies have shown that external abdominal irradiation is associated with alterations in intestinal morphology and function. The activity of the jejunal brush border membrane (BBM) enzyme markers sucrase (S) and alkaline phosphate (AP) were not altered by 600 rad irradiation in the rat. In contrast, ileal BBM, AP, and AP/S were increased 3, 7/8, and 28 days postirradiation. The total lipid composition of the jejunal BBM was lower than in control animals only at 3 days postirradiation; this was due to a decrease in the total free fatty acid content. In addition to a lower total free fatty acid content, the ileal BBM contained an increased amount of total phospholipid (PL) which resulted in an increased phospholipid/cholesterol ratio at 3 days following irradiation. Variations in the BBM phospholipid composition occurred in both jejunum and ileum. In the jejunal BBM, the phospholipid composition changes did not alter the choline or amine phospholipid content; therefore, the choline/amine phospholipid ratio was unaffected by irradiation at 600 rad. In the ileal BBM, the phosphatidyl ethanolamine was increased at 3, 7/8, 14, and 28 days following irradiation. The choline/amine phospholipid ratio was not altered in the ileal BBM due to concomitant increases in lecithin content. Jejunal villus height, villus surface area, and the number of cells per villus were decreased at 3 days postirradiation, but increased by day 7/8 and 14 postirradiation to levels much higher than observed in control jejunal villi. The mucosal surface area was decreased at 3 and 7/8 days following irradiation but returned to control values by Day 14. Jejunal microvillus morphology was unaffected by irradiation. Few significant changes were observed in ileal villus morphology following irradiation at 600 rad. Ileal villus height, villus surface area, and mucosal surface area did not change, but the number of cells per villus initially decreased at 3 days and then increased beyond control values at 7/8 and 14 days postirradiation. Ileal microvillus height was significantly decreased only at 7 days postirradiation, while the number of microvilli per micron was increased only at 3 days postirradiation. This study suggests that changes in intestinal morphology and brush border composition may contribute to the altered passive permeation toward lipids which has been reported following abdominal radiation.

Abdomen↗
PubMed1985

Intestinal uptake of hexoses and fatty acids in tumor-bearing rats.

An in vitro technique was used to examine the rate of uptake of varying concentrations of glucose, galactose, and a homologous series of saturated fatty acids into the jejunum of control rats and Noble rats bearing prostatic tumor variants of primary human prostatic adenocarcinoma 52. Both groups of animals were healthy, eating and gaining weight normally. The uptake of acetic and butyric acid was reduced in tumor-bearing rats, but the uptake of four medium chain-length fatty acids was unchanged. The similar value of the incremental change in free energy in the control and tumor-bearing animals indicates similar passive permeability properties of the jejunum in the two groups. The uptake of varying concentrations of glucose and galactose was similar in the control and in the tumor-bearing animals. It is concluded that there are only subtle changes in nutrient uptake in tumor-bearing rats that are eating and gaining weight normally. It is suggested that any alteration in nutrient absorption which might occur in the cachectic tumor-bearing animal is probably due to alterations in food intake or body weight, rather than due to a direct effect of the tumor on the intestine.

Adenocarcinoma↗
PubMedDate not supplied

Mountain excitement.

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Emergencies↗