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Timothy J Peters

Publications and source records attributed to Timothy J Peters.

At least 19 recordsLinked to original sources
PubMed2006

Effect of areca nut on salivary copper concentration in chronic chewers.

The chewing of areca nut is associated with the development of oral submucous fibrosis (OSF), a condition predominantly encountered in Asians indulging in the habit. The pathogenesis of this condition is however, unclear, though several mechanisms have been proposed. Copper has previously been implicated as a possible aetiological factor. In this study, total copper concentration was measured via atomic absorption spectrophotometry in whole mouth saliva of 15 volunteers who were regular chewers, before and after their habitual chew. An aliquot of the latter was also analysed for copper. Six non-chewing volunteers acted as controls. Salivary copper concentrations were corrected for protein content. Over 50% of the subjects had basal salivary copper concentration higher than the range seen in normal controls. All but two subjects demonstrated an increase in the salivary [Cu] following their habitual chew. Marked changes were seen in those with low basal salivary concentrations. These data indicate that soluble copper found in areca nut is released into the oral environment of habitual chewers. Its buccal absorption may contribute to the oral fibrosis in Asians who regularly chew this nut.

Adolescent↗
PubMed2006

Iron and cadmium uptake by duodenum of hypotransferrinaemic mice.

Absorption from food is an important route for entry of the toxic metal, cadmium, into the body. Both cadmium and iron are believed to be taken up by duodenal enterocytes via the iron regulated, proton-coupled transporter, DMT1. This means that cadmium uptake could be enhanced in conditions where iron absorption is increased. We measured pH dependent uptake of (109)Cd and (59)Fe by duodenum from mice with an in vitro method. Mice with experimental (hypoxia, iron deficiency) or hereditary (hypotransferrinaemia) increased iron absorption were studied. All three groups of mice showed increased (59)Fe uptake (p<0.05) compared to their respective controls. Hypotransferrinaemic and iron deficient mice exhibited an increase in (109)Cd uptake (p<0.05). Cadmium uptake was not, however, increased by lowering the medium pH from 7.4 to 6. In contrast, (59)Fe uptake (from (59)FeNTA(2)) and ferric reductase activity was increased by lowering medium pH in control and iron deficient mice (p<0.05). The data show that duodenal cadmium uptake can be increased by hereditary iron overload conditions. The uptake is not, however, altered by lowering medium pH suggesting that DMT1-independent uptake pathways may operate.

Animals↗
PubMed2006

Diurnal excretion of urinary cortisol, cortisone, and cortisol metabolites in chronic fatigue syndrome.

OBJECTIVE: The aim of this study was to obtain comprehensive information on basal hypothalamic-pituitary-adrenal (HPA) axis activity in chronic fatigue syndrome (CFS) patients who were not affected by medication or comorbid psychiatric disorder likely to influence the HPA axis. METHOD: Steroid analysis of urine collections from 0600 to 2100 h at 3-h intervals in CFS patients and in controls. RESULTS: Urinary free cortisol and cortisone concentrations showed a significant normal diurnal rhythm, but levels were lower across the cycle in CFS. In contrast, while urinary cortisol metabolites also showed a normal diurnal rhythm, levels were not significantly different between the CFS and controls at any time. Derived metabolite ratios were similar in both groups. CONCLUSION: This study provides further evidence for reduced basal HPA axis function in patients with CFS, based on lower free cortisol and cortisone levels, but this is not corroborated by cortisol metabolite data. The difference between these measures cannot be explained by an altered timing of the diurnal rhythm.

Adult↗
PubMed2006

Circadian rhythm of urinary steroid metabolites.

BACKGROUND: Samples submitted for urinary steroid profile analysis are often untimed, but influence of collection time on interpretation is unknown. We report circadian rhythms of the major steroid metabolites and derived ratios in urine collected at 3-h intervals over 24 h, after first establishing that disturbance of sleep associated with collection does not alter rhythms on the succeeding day. METHODS: Assay of steroid metabolites (gas chromatography) and creatinine in urine collections made by 10 men and 10 women every 3 h starting at 2,100 for 24 h. Data were subjected to cosinor analysis. RESULTS: Summed cortisol and androgen metabolites exhibited significant circadian rhythms, as expected, but with a surprisingly long time-lag (maxima at around 1,400). Amplitudes were different, so that the ratio cortisol/androgen metabolites also showed a significant rhythm. The ratios 5alpha/5beta tetrahydrocortisol and 20-hydroxy/20-oxo cortisol metabolites showed significant rhythms which were not in phase with total cortisol metabolites, while 11-hydroxy/11-oxo cortisol metabolites showed no rhythm. There were no gender differences in time of maxima. Previously established gender differences in metabolite levels were confirmed. Creatinine levels showed no circadian rhythm. CONCLUSION: Circadian variation should be considered when interpreting results from urine steroid analysis. Calculation of steroid/steroid or steroid/creatinine ratios is not informative in untimed collections.

Adult↗
PubMed2005

Role of interleukin-6 in hypoxic regulation of intestinal iron absorption.

The regulation of intestinal iron absorption is not fully understood. Hepcidin, a liver-produced peptide, has recently been identified as a negative regulator of iron absorption in various conditions associated with altered iron metabolism (e.g. inflammation, anaemia, hypoxia). It is not clear whether these perturbants share a common signalling pathway. In this study, the importance of the cytokine interleukin-6 (IL-6) was investigated in the hypoxic mouse model. Hypoxia was associated with increased levels of circulating IL-6, decreased liver hepcidin mRNA and increased iron absorption (especially MT). A significant positive correlation existed between the total iron uptake and IL-6 levels in circulation. IL-6 per se, though inducing hepcidin mRNA, failed to affect basal iron absorption. The adaptive response to absorption following the hypoxic exposure was, however, more prominent if mice had been treated concurrently with IL-6. This enhancement in absorption occurred even though hepcidin mRNA was not significantly changed. Similar prominent responses were seen with both human and mouse IL-6. Anti-IL-6 antiserum normalised iron absorption in mice exposed to hypoxia, because of a reduction in the MT. These data indicate that IL-6 can influence iron absorption (especially MT) during the hypoxic exposure, but via a mechanism independent of hepcidin.

Animals↗
PubMed2004

Autonomic function and serum erythropoietin levels in chronic fatigue syndrome.

OBJECTIVE: Given previous findings, we wished to investigate whether there was evidence of autonomic dysfunction in patients with chronic fatigue syndrome, and whether this could be related to reduced erythropoietin levels and altered red blood cell indices. METHODS: We assessed autonomic function and analysed blood parameters (including erythropoietin) in 22 patients with chronic fatigue syndrome who were medication-free and without comorbid depression or anxiety. Results were compared to 23 iron-deficiency anaemia patients and 18 healthy individuals. RESULTS: Autonomic testing in patients with chronic fatigue syndrome yielded a significantly greater increase in heart rate together with a more pronounced systolic blood pressure fall on standing compared to healthy individuals. Heart rate beat-to-beat variation on deep breathing and responses to the Valsalva manoeuvre were normal. Two of 22 patients with chronic fatigue had mild normochromic normocytic anaemia with normal ferritin, vitamin B12 and folate levels. Serum erythropoietin levels were within reference range. CONCLUSION: Some autonomic dysfunction is present in chronic fatigue syndrome (CFS) patients; the explanation remains uncertain, but could relate to cardiovascular deconditioning. There were no major haematological, biochemical or immunological abnormalities in these patients.

Adult↗
PubMed2004

Duodenal ascorbate levels are changed in mice with altered iron metabolism.

Ascorbate has long been thought to play an important role in intestinal iron absorption. The recent identification of a possible ascorbate-dependent duodenal ferric reductase suggests a role for intracellular ascorbate in the control of iron absorption. We set out to determine whether duodenal ascorbate concentrations are altered by treatments known to alter the rate of iron absorption and whether ascorbate levels affect duodenal reductase activity. Duodenal ascorbate was extracted and assayed by HPLC and/or a chemical assay. Ferric reductase was assayed in vitro with ferric nitrilotriacetate or nitroblue tetrazolium as substrates. Duodenal ascorbate concentrations were increased by iron deficiency, genetic hypotransferrinemia, and hypoxia. Parenteral iron overload increased iron stores but did not affect duodenal ascorbate concentrations. Hemolytic anemia induced in mice by phenylhydrazine injection also did not affect duodenal ascorbate concentrations. In vitro studies with incubated duodenum showed that decreased tissue ascorbate was associated with decreased mucosal ferric reductase activity, whereas incubation with dehydroascorbate prevented both the decrease in ascorbate concentration and reductase activity. Mouse duodenum ascorbate concentrations changed in response to treatments that altered iron absorption rates; in particular, ascorbate levels generally increased when iron absorption was increased by iron deficiency, hypoxia, or genetic hypotransferrinemia. We conclude that changes in ascorbate levels are associated with changes in ferric reductase activity. These findings are consistent with the proposal that duodenal ascorbate plays a role in intestinal iron absorption.

Animals↗
PubMed2004

The effects of inhibition of haem biosynthesis by griseofulvin on intestinal iron absorption.

The relationship between haem biosynthesis and intestinal iron absorption in mice was investigated by ascertaining the effect of the haem synthesis inhibitor, griseofulvin, on duodenal iron absorption using both in vivo and in vitro measurements. Urinary 5-aminolaevulinic acid levels were increased within 24 hr of feeding mice with griseofulvin diet (2.5% w/w), with more marked increases seen after 3-7 days. Urinary porphobilinogen levels also showed a similar trend. In vivo intestinal iron absorption was significantly reduced (P<0.05) in experimental mice, mainly due to reduction in the transfer of 59Fe from the enterocytes to the portal circulation. In vitro studies using isolated duodenal fragments also exhibited marked decreases in both iron uptake and Fe (III) reduction. Changes in mucosal Divalent Metal Transporter 1 (DMT-1), Dcytb and Ireg1 (iron regulated protein 1) mRNA levels paralleled the changes in iron absorption. The reduction in iron absorption after griseofulvin treatment was normalised when mice were simultaneously injected with haem-arginate. These data support the hypothesis that intermediates in haem biosynthesis, particularly 5-aminolaevulinic acid, regulate intestinal iron absorption.

Administration, Oral↗
PubMed2004

Rhabdomyolysis in a patient with acute intermittent porphyria.

There are several conditions associated with rhabdomyolysis, such as direct muscle injury, viral infections, metabolic disorders and toxic effects from ingestion of drugs such as alcohol, opiates, cocaine or heroin. We report on a patient who was admitted to the accident and emergency unit with a clinical presentation of rhabdomyolysis and acute intermittent porphyria.

Adult↗
PubMed2003

Erythropoietin treatment in the neuropsychiatric porphyrias.

BACKGROUND: In a previous report, 31 patients with neuropsychiatric porphyria were studied and nine of these patients were anaemic in association with inappropriately low serum erythropoietin levels. We were also able to demonstrate that treatment with erythropoietin in non-porphyric patients (mainly diabetic patients with autonomic neuropathy) significantly reduced urinary delta-aminolaevulinic acid levels. METHODS: We treated six porphyric patients, five of whom were anaemic, with recombinant human erythropoietin (1000-2000 IU thrice weekly). They were all in clinical but not biochemical remission. Full blood count, including reticulocytes and platelets, urinary delta-aminolaevulinic acid, porphobilinogen and total porphyrins were measured monthly. Baseline serum ferritin, vitamin B(12), folate and C-reactive protein levels were all within the normal range and serum creatinine did not exceed 126 micromol/l. RESULTS: After 3 months of treatment, the average baseline haemoglobin increased significantly (p=0.01). When treatment was stopped, the haemoglobin decreased and after 3 months pre-treatment, haemoglobin levels were reached. Urinary delta-aminolaevulinic acid, porphobilinogen and porphyrin levels all tended to decrease during treatment with erythropoietin, but the difference between baseline and 3 months of erythropoietin was statistically significant only for porphobilinogen (p=0.03). The severity of porphyria attacks was reduced and the quality of life increased during treatment with erythropoietin. CONCLUSION: We conclude that in some porphyric patients treatment with erythropoietin reduces urinary delta-aminolaevulinic acid, porphobilinogen and porphyrin levels with an increase in well-being and a reduction in the severity of porphyria attacks.

Adult↗
PubMed2003

Alcoholic muscle disease and biomembrane perturbations (review).

Excessive alcohol ingestion is damaging and gives rise to a number of pathologies that influence nutritional status. Most organs of the body are affected such as the liver and gastrointestinal tract. However, skeletal muscle appears to be particularly susceptible, giving rise to the disease entity alcoholic myopathy. Alcoholic myopathy is far more common than overt liver disease such as cirrhosis or gastrointestinal tract pathologies. Alcohol myopathy is characterised by selective atrophy of Type II (anaerobic, white glycolic) muscle fibres: Type I (aerobic, red oxidative) muscle fibres are relatively protected. Affected patients have marked reductions in muscle mass and impaired muscle strength with subjective symptoms of cramps, myalgia and difficulty in gait. This affects 40-60% of chronic alcoholics (in contrast to cirrhosis, which only affects 15-20% of chronic alcohol misuers).Many, if not all, of these features of alcoholic myopathy can be reproduced in experimental animals, which are used to elucidate the pathological mechanisms responsible for the disease. However, membrane changes within these muscles are difficult to discern even under the normal light and electron microscope. Instead attention has focused on biochemical and other functional studies. In this review, we provide evidence from these models to show that alcohol-induced defects in the membrane occur, including the formation of acetaldehyde protein adducts and increases in sarcoplasmic-endoplasmic reticulum Ca(2+)-ATPase (protein and enzyme activity). Concomitant increases in cholesterol hydroperoxides and oxysterol also arise, possibly reflecting free radical-mediated damage to the membrane. Overall, changes within muscle membranes may reflect, contribute to, or initiate the disturbances in muscle function or reductions in muscle mass seen in alcoholic myopathy. Present evidence suggest that the changes in alcoholic muscle disease are not due to dietary deficiencies but rather the direct effect of ethanol or its ensuing metabolites.

Acetaldehyde↗
PubMed2003

The importance of alcohol-induced muscle disease.

Alcohol-induced muscle disease (AIMD) is a composite term to describe any muscle pathology (molecular, biochemical, structural or physiological) resulting from either acute or chronic alcohol ingestion or a combination thereof. The chronic form of AIMD is arguably the most prevalent skeletal muscle disorder in the Western Hemisphere affecting more than 2000 subjects per 100,000 population and is thus much more common than hereditary disorders such as Becker or Duchenne muscular dystrophy. Paradoxically, most texts on skeletal myopathies or scientific meetings covering muscle disease have generally ignored chronic alcoholic myopathy. The chronic form of AIMDs affects 40-60% of alcoholics and is more common than other alcohol-induced diseases, for example, cirrhosis (15-20% of chronic alcoholics), peripheral neuropathy (15-20%), intestinal disease (30-50%) or cardiomyopathy (15-35%). In this article, we summarise the pathological features of alcoholic muscle disease, particularly biochemical changes related to protein metabolism and some of the putative underlying mechanisms. However, the intervening steps between the exposure of muscle to ethanol and the initiation of the cascade of responses leading to muscle weakness and loss of muscle bulk remain essentially unknown. We argue that alcoholic myopathy represents: (a) a model system in which both the causal agent and the target organ is known; (b) a myopathy involving free-radical mediated pathology to the whole body which may also target skeletal muscle and (c) a reversible myopathy, unlike many hereditary muscle diseases. A clearer understanding of the mechanisms responsible for alcoholic myopathy is important since some of the underlying pathways may be common to other myopathies.

Alcohol Drinking↗
PubMed2003

Chronic alpha-tocopherol supplementation in rats does not ameliorate either chronic or acute alcohol-induced changes in muscle protein metabolism.

Chronic alcohol muscle disease is characterized by reduced skeletal muscle mass precipitated by acute reduction in protein synthesis. The pathogenic mechanisms remain obscure, but several lines of evidence suggest that increased oxidative stress occurs in muscle in response to alcohol and this may be associated with impaired alpha-tocopherol status. Potentially, this implies a therapeutic role for alpha-tocopherol, especially as we have shown that supplemental alpha-tocopherol may increase the rate of protein synthesis in normal rats [Reilly, Patel, Peters and Preedy (2000) J. Nutr. 130, 3045-3049]. We investigated the therapeutic effect of alpha-tocopherol on plantaris muscle protein synthesis in rats treated either acutely, chronically or chronically+acutely with ethanol. Protein synthesis rates were measured with a flooding dose of L-[4-(3)H]phenylalanine. Protein, RNA and DNA contents were determined by standard laboratory methods. Ethanol caused defined metabolic changes in muscle, including decreased protein, RNA and DNA contents in chronically treated rats. In acute or chronic+acute studies, ethanol suppressed fractional rates of protein synthesis. alpha-Tocopherol supplementation did not ameliorate the effects of either acute, chronic or chronic+acute alcohol on plantaris muscle protein content or rates of protein synthesis. In control animals (not treated with alcohol), alpha-tocopherol supplementation decreased muscle protein content owing to increases in protein turnover (both synthesis and degradation). alpha-Tocopherol supplementation is not protective against the deleterious effects of alcohol on protein metabolism in skeletal muscle.

Animals↗
PubMed2003

Effect of Tin-mesoporphyrin, an inhibitor of haem catabolism, on intestinal iron absorption.

Haem biosynthesis is the most important destination for absorbed iron, hence it can be hypothesized that iron absorption regulation should be integrated with haem metabolism. As an initial step to test this hypothesis, the effect on iron absorption of Tin-mesoporphyrin (SnMP), inhibitor of haem oxygenase, altering haem and its biosynthetic intermediates, was studied. Mice injected with SnMP (5-25 micro mol/kg daily for up to 3 d) showed dose-dependent increases in intestinal iron absorption measured in vivo and in vitro. In order to investigate the effects of SnMP, enzymes and intermediates of haem metabolism were measured. Hepatic 5-amino-laevulinate (ALA) synthase activity (pmol/min/mg protein) was significantly reduced in SnMP-treated mice (10 and 25 micro mol/kg daily for 3 d) (mean +/- standard deviation, control 11.2 +/- 2.6; treated 6.3 +/- 1.7; P < 0.01). Hepatic ALA dehydratase activity (pmol porphobilinogen/mg protein/min) showed significant reductions following SnMP treatment (control 180 +/- 60, treated 130 +/- 50; P < 0.05). The effect of SnMP on iron absorption was reversible, with absorption returning to normal after 3 d. Furthermore, the effect of SnMP on duodenal iron absorption was abolished by the simultaneous injection of ALA (6 micro mol/l). ALA alone had no effect on iron absorption. In-vitro studies using duodenal fragments isolated from mice treated with SnMP (10 micro mol/kg daily for 3 d), showed significant increases (P < 0.05) in both mucosal iron uptake and Fe(III) reducing activity. We conclude that intermediates in haem metabolism, in particular levels of ALA, may play a role in duodenal iron absorption.

5-Aminolevulinate Synthetase↗
PubMed2003

Skeletal muscle and jejunal protein synthesis in normal and ethanol-treated rats: the effect of the nitric oxide synthase inhibitors, L-omega-nitro-L-arginine methyl ester and N(G)-nitro-L-arginine in vivo.

The nitric oxide synthase (NOS) inhibitors, L-omega-nitro-L-arginine methyl ester (L-NAME; 25 mg/kg and 100 mg/kg) and N(G)-nitro-L-arginine (L-NNA; 100 mg/kg) were used to investigate the role of NO on in vivo skeletal muscle and jejunal (mucosa and seromuscular layer) protein synthesis rates in normal (ie, untreated) and ethanol-dosed (75 mmol/kg body weight) rats. Fractional rates of protein synthesis, ie, percentage of protein pool renewed each day, k(s), %/d) were measured with a flooding dose of L-[(3)H-4]phenylalanine. In response to both doses of L-NAME and L-NNA, k(s) in skeletal muscle of normal rats decreased by 9% to 31% (P between <.05 and <.001). In the mucosa, k(s) was significantly reduced only by the higher dose of L-NAME (-49%, P <.001). In the seromuscular layer, k(s) was reduced by 15% to 57% (P between <.05 and <.001) in response to both doses of L-NAME and L-NNA. Ethanol dosage reduced k(s) in skeletal muscle (-35%, P <.001), and small reductions also occurred in the jejunal mucosal and seromuscular layers (-14% P <.05 and -12% P <.05, respectively). However, in the presence of L-NAME, ethanol reduced k(s) in jejunal mucosal and seromuscular layers by -35% (P <.01) and -30% (P <.01), respectively, compared with controls. This exacerbating effect of L-NAME predosage in ethanol-treated rats was not demonstrable in skeletal muscle. The data thus suggest that (1) endogenous NO facilitates constitutive skeletal muscle and jejunal protein synthesis in control animals in vivo; (2) the sensitivity of jejunal (but not skeletal muscle) protein synthesis to acute ethanol is increased when inhibitors of NOS are used. This tentatively implies that, in response to ethanol, overproduction of NO is not involved in the ethanol-induced reduction of protein synthesis in skeletal muscle or the jejunum.

Algorithms↗
PubMed2003

Nutritional intake of hazardous drinkers and dependent alcoholics in the UK.

There are no recent assessments of nutritional intake in alcohol misusers in the United Kingdom. The purpose of this study was to measure nutritional intake in alcoholics attending an Alcohol Misuse outpatient clinic in an inner city general hospital in the United Kingdom and relating this to various measures of alcohol dependence. All patients (n = 30; 27 male, 3 female) consumed at least 100 g ethanol per day (mean 162 g/day) for at least 5 years and completed questionnaires on socio-demographics, alcohol dependency and psychosocial problems and had assays of biochemical and haematological indices. The data were analysed first with respect to the entire patient population and then according to the degree of alcohol dependency (mild, moderate or severe). The results showed that with respect to the entire patient group, one-third were below normal body weights, but one-quarter was overweight. The total energy intake (kJ/day) including alcohol was apparently adequate with respect to recommended levels in most patients. On average, approx. 60% of energy intake came from alcohol. The whole patient population had a low intake of one or more macro- and micro-nutrient compared to the dietary reference requirements. All patients had intakes of vitamin E and folate below UK recommended standards, while 85 - 95% of patients had low intakes of selenium and Vitamin D. Between 50 and 85% of all patents had intakes below UK recommended standards in calcium and zinc and Vitamins A, B(1), B(2), B(6) and C. There were significant correlations between calorie intake (when alcohol was excluded) and vitamins B(1), B(2), B(6) and C, and Ca, Mg, Fe and Zn intake. There were no correlations between alcohol intake with any of the nutritional and anthropometric variables or between the three subgroups with respect to daily energy, micro- and macro-nutrient intakes. In conclusion, malnutrition was common in this patient group: all subjects had intakes below UK recommended standards in one or more micro- or macro-nutrient. However, there was no difference in the degree of malnutrition between the harmful drinkers (mild dependency) and heavily dependent subgroups.

Adult↗