Release of iron from phagocytosed Escherichia coli and uptake by neutrophil lactoferrin

Escherichia coli were labeled with 59Fe and then either treated with myeloperoxidase, H2O2, and chloride or opsonized and mixed with human neutrophils. The myeloperoxidase system at pH 7.4 caused release of most of the bacterial 59Fe. A similar result has been obtained by Rosen and Klebanoff (J Biol Chem 257:13731, 1982) but at pH 5. Iron release at pH 7.4 did not require the presence of a chelator, and the majority passed through a 10,000 relative molecular mass cut-off ultrafiltration membrane. When iron-poor lactoferrin was present during incubation with myeloperoxidase, 88% of the released 59Fe was precipitated with anti-lactoferrin antiserum, indicating that it was lactoferrin-bound. When the bacteria were mixed with neutrophils in a 10:1 ratio, approximately 50% were phagocytosed. About 40% of the 59Fe was released from the ingested bacteria over a 40-minute period. Initially, most remained associated with the neutrophil phagosomes, but with time, there was gradual transfer of some of the iron to the medium. Using anti-lactoferrin antiserum, 50% to 60% of phagosomal iron and 64% to 71% of iron in the medium was shown to be bound to lactoferrin. Thus, iron is released from phagocytosed E coli. Most becomes bound to lactoferrin, and some of this is released into the surroundings of the neutrophils. This suggests that neutrophil lactoferrin may function to trap iron from ingested microorganisms, enabling its removal from sites of inflammation. This may prevent iron from catalyzing undesirable oxidative reactions, as well as making it unavailable for growth of microorganisms that survive the killing process.     

Increased expression of host iron-binding proteins precedes iron accumulation and calcification of primary lung lesions in experimental tuberculosis in the guinea pig

The growth and virulence of Mycobacterium tuberculosis depends on its ability to scavenge host iron, an essential and limited micronutrient in vivo. In this study, we show that ferric iron accumulates both intra- and extra-cellularly in the primary lung lesions of guinea pigs aerosol-infected with the H37Rv strain of M. tuberculosis. Iron accumulated within macrophages at the periphery of the primary granulomatous lesions while extra-cellular ferric iron was concentrated in areas of lesion necrosis. Accumulation of iron within primary lesions was preceded by an increase in expression of heavy chain (H) ferritin, lactoferrin and receptors for transferrin, primarily by macrophages and granulocytes. The increased expression of intra-cellular H ferritin and extra-cellular lactoferrin, more so than transferrin receptor, paralleled the development of necrosis within primary lesions. The deposition of extra-cellular ferric iron within necrotic foci coincided with the accumulation of calcium and phosphorus and other cations in the form of dystrophic calcification. Primary lung lesions from guinea pigs vaccinated with Mycobactrium bovis BCG prior to experimental infection, had reduced iron accumulation as well as H ferritin, lactoferrin and transferrin receptor expression. The amelioration of primary lesion necrosis and dystrophic calcification by BCG vaccination was coincident with the lack of extra-cellular ferric iron and lactoferrin accumulation. These data demonstrate that BCG vaccination ameliorates primary lesion necrosis, dystrophic mineralization and iron accumulation, in part by down-regulating the expression of macrophage H ferritin, lactoferrin and transferrin receptors, in vivo.     

Elevated non-transferrin bound iron in the lungs of patients with Pneumocystis carinii pneumonia

OBJECTIVE: The aim of the present work was to determine the concentrations of iron and iron-binding proteins in the lungs of patients suffering from Pneumocystis carinii (PCP), which is crucial for justifying the treatment with iron-chelating agents in this disease. PATIENTS AND METHODS: Bronchoalveolar lavage was performed in 10 HIV patients with PCP and five healthy controls. Total iron and iron-binding proteins (transferrin, ferritin and lactoferrin) were measured in acellular bronchoalveolar lavage fluid (BALF) in both groups. Iron was determined by atomic absorption spectrometry; transferrin and lactoferrin were measured using specific enzyme-linked immunosorbent assays (ELISA); and ferritin concentration was quantified by automated immunonephelometry. RESULTS: Our findings in patients with PCP demonstrated a six- to seven-fold increase of total iron levels and an eight-fold increase of ferritin in bronchoalveolar lavage fluid when compared with controls. No significant differences were found in transferrin or lactoferrin levels. Moreover, our results suggest that this iron is non-transferrin bound. CONCLUSION: Non-transferrin bound iron is increased in the lower respiratory tracts of PCP patients. This finding would lend experiment support to the use of iron-chelating agents in this disease.     

Pathological role of aminolevulinate in uremic patients

Previous reports have demonstrated that δ-aminolevulinate (ALA) can promote iron release from horse spleen ferritin under conditions of high serum ALA levels in uremia; therefore, we speculated that the accumulated ALA in uremic patients would stimulate iron release from ferritin, resulting in accelerated oxidative stress and uremic complications. We measured the plasma ALA of uremic patients and examined the ALA-induced iron release from human ferritin. The participants consisted of 30 hemodialysis patients and 14 healthy subjects. Plasma malondialdehyde was measured as a surrogate marker of lipid peroxidation. The plasma exchange effluent from two patients who had undergone plasma exchange (for the treatment of systemic lupus erythematosus and acute myeloblastic leukemia) was collected and treated to obtain the human ferritin-rich fraction. Iron release from ferritin was examined using bathophenanthroline sulfate. The influence of antioxidants and different pH levels on iron release were investigated. Plasma ALA and malondialdehyde concentration in the hemodialysis patient was significantly higher than that in healthy subjects. ALA was positively correlated with malondialdehyde. The abundance of iron release was dependent on the ALA concentration and incubation time. Iron release at the high pH of 7.6 was decreased compared with that at pH 7.4. Citrate increased iron release at pH 7.4, but citrate-stimulated iron release was totally abolished at pH 7.6. Our study suggests that ALA accumulation may have a role to play in certain complications in uremic patients, such as oxidative stress, by releasing iron from ferritin.     

Control of zinc transfer between thionein, metallothionein, and zinc proteins

Metallothionein (MT), despite its high metal binding constant (K_Zn = 3.2 × 10¹³ M⁻¹ at pH 7.4), can transfer zinc to the apoforms of zinc enzymes that have inherently lower stability constants. To gain insight into this paradox, we have studied zinc transfer between zinc enzymes and MT. Zinc can be transferred in both directions—i.e., from the enzymes to thionein (the apoform of MT) and from MT to the apoenzymes. Agents that mediate or enhance zinc transfer have been identified that provide kinetic pathways in either direction. MT does not transfer all of its seven zinc atoms to an apoenzyme, but apparently contains at least one that is more prone to transfer than the others. Modification of thiol ligands in MT zinc clusters increases the total number of zinc ions released and, hence, the extent of transfer. Aside from disulfide reagents, we show that selenium compounds are potential cellular enhancers of zinc transfer from MT to apoenzymes. Zinc transfer from zinc enzymes to thionein, on the other hand, is mediated by zinc-chelating agents such as Tris buffer, citrate, or glutathione. Redox agents are asymmetrically involved in both directions of zinc transfer. For example, reduced glutathione mediates zinc transfer from enzymes to thionein, whereas glutathione disulfide oxidizes MT with enhanced release of zinc and transfer of zinc to apoenzymes. Therefore, the cellular redox state as well as the concentration of other biological chelating agents might well determine the direction of zinc transfer and ultimately affect zinc distribution.     

The rise in the total iron-binding capacity after iron overdose

STUDY OBJECTIVES: To determine if and to what extent the total iron-binding capacity (TIBC) would increase following an iron overload, and to identify specific iron-binding proteins that might be responsible for the increased TIBC. DESIGN: A prospective laboratory investigation. SETTING: A certified regional poison control center. PARTICIPANTS: Six healthy adult male volunteers. MEASUREMENTS AND MAIN RESULTS: All volunteers ingested 20 mg/kg of elemental iron. Blood samples were drawn at hourly intervals for eight hours and analyzed for serum iron, TIBC, transferrin, ferritin, lactoferrin, glucose, bicarbonate, and WBC. Within two hours of ingestion, subjects developed symptoms of toxicity, including nausea, lightheadedness, vomiting, severe crampy abdominal pain, and voluminous diarrhea. The TIBC was statistically significantly increased at all points measured from one to six hours. Despite rising above 300 micrograms/dL in five of six subjects, the serum iron never exceeded the TIBC in any subject. Transferrin and ferritin did not increase to account for the increased TIBC. The lactoferrin levels did increase, but they did not correlate with significant increases in the TIBC. CONCLUSIONS: Twenty mg/kg of elemental iron caused clinical toxicity in this study, and after iron overload the colorimetric TIBC increased by unknown mechanisms.     

Early fall of circulating iron and rapid rise of lactoferrin in septicemia and endotoxemia: an early defence mechanism

Total serum iron, plasma lactoferrin and circulating leukocytes were measured in piglets during the early phase of severe gram-negative septicemia and endotoxemia in 3 experimental settings: intravenous (i.v.) infusion of lipopolysaccharide (LPS) (n = 8), i.v. infusion of live Escherichia coli (n = 7) and intraperitoneal (i.p.) infusion of E. coli (n = 6). Iron dropped significantly during the first 30 min of LPS infusion from a median of 32 microM to 13.4 microM. A similar decrease in serum iron was demonstrated in the 2 other groups with minimum values at 120 min after the start of E. coli infusion. Plasma levels of lactoferrin increased significantly 120 min after the start of LPS infusion (median 6 mg/l) when compared to preinfusion values (0.25 mg/l). After i.v. infusion of E. coli a significant rise of plasma lactoferrin was demonstrated already 30 min after bacterial infusion (to 2.1 mg/l) compared to preseptic values (0.8 mg/l). This increase was accompanied with a significant drop of circulating leukocytes (to 7.3 x 10(9)/l) compared to before the infusion (17 x 10(9)/l) in the pigs given E. coli i.v. After i.p. E. coli infusion no significant change of plasma lactoferrin was observed. The rapid fall of total serum iron seen during endotoxemia and E. coli septicemia may in part be explained by the release of lactoferrin from granulocytes and the clearance of iron-bound lactoferrin in the blood or peritoneal cavity.     

Ferritin: a zinc detoxicant and a zinc ion donor.

Rats were injected with 1 mg of Zn2+ as zinc sulfate or 2 mg of Cd2+ as cadmium sulfate per kg of body weight on a daily basis. After seven injections, ferritin and metallothionein were isolated from the livers of the rats. Significant amounts of zinc were associated with ferritin. Incubation of such ferritin with apoenzymes of calf intestinal alkaline phosphatase, yeast phosphoglucomutase, and yeast aldolase restored their enzymic activity. The amount of zinc injected was insufficient to stimulate significant synthesis of metallothionein, but similar experiments with injection of cadmium did stimulate the synthesis of metallothionein. The amount of Zn2+ in ferritin of Cd-injected rats was greater than that in ferritin in Zn-injected rats, which was greater than that in ferritin of normal rats. Thus at comparable protein concentration ferritin from Cd-injected rats was a better Zn2+ donor than was ferritin from Zn-injected or normal animals. Ferritin is a normal constituent of several tissues, whereas metallothionein is synthesized under metabolic stress. Thus ferritin may function as a "metal storage and transferring agent" for iron and for zinc. It is suggested that ferritin probably serves as the initial chelator for Zn2+ and perhaps other metal ions as well and that under very high toxic levels of metal ions the synthesis of metallothionein is initiated as the second line of defense.     

Gastric digestion of pea ferritin and modulation of its iron bioavailability by ascorbic and phytic acids in caco-2 cells

AIM： To understand the digestive stability and mechanism of release and intestinal uptake of pea ferritin iron in caco-2 cell line model.
METHODS： Pea seed ferritin was purified using salt fractionation followed by gel filtration chromatography.The bioavailability of ferritin iron was assessed using coupled in vitro digestion/Caco-2 cell model in the presence or absence of ascorbic acid and phytic acid.Caco-2 cell ferritin formation was used as a surrogate marker of iron uptake. Structural changes of pea ferritin under simulated gastric pH were characterized using electrophoresis, gel filtration and circular dichroism spectroscopy.
RESULTS： The caco-2 cell ferritin formation was significantly increased （P 〈 0.001） with FeSO4 （19.3±9.8 ng/mg protein） and pea ferritin （13.9 ± 6.19 ng/mg protein） compared to the blank digest （3.7 ± 1.8 ng/mg protein）. Ascorbic acid enhanced while phytic acid decreased the pea ferritin iron bioavailability. However,either in the presence or absence of ascorbic acid, the ferritin content of caco-2 cells was significantly less with pea ferritin than with FeSO4. At gastric pH, no band corresponding to ferritin was observed in the presence of pepsin either on native PAGE or SDS-PAGE. Gel filtration chromatography and circular dichroism spectroscopy revealed a pH dependent loss of quaternary and secondary structure.
CONCLUSION： Under gastric conditions, the iron core of pea ferritin is released into the digestive medium due to acid induced structural alterations and dissociation of protein. The released iron interacts with dietary factors leading to modulation of pea ferritin iron bioavailability,resembling the typical characteristics of non-heme iron.     

Increased lower respiratory tract iron concentrations in alkaloidal ("crack") cocaine users

Study objective: We hypothesized that the use of inhaled alkaloidal ("crack") cocaine could increase lung content of iron, either by inducing alveolar hemorrhage or by other mechanisms. Intrapulmonary accumulation of iron could promote chronic lung diseases in crack users. The goal of this study was to determine whether iron and ferritin content of alveolar macrophages or fluid recovered by BAL was increased in subjects using crack, compared with nonsmokers. METHODS: BAL was performed in 31 volunteer subjects, including healthy nonsmokers (n = 7), subjects smoking crack alone (n = 7), as well as subjects smoking both crack and cigarettes (n = 7) or cigarettes alone (n = 10). Iron content of alveolar macrophages and BAL fluid was determined by a colorimetric method and ferritin content of alveolar macrophages, and BAL fluid was measured by a two-sided immunoradiometric method. RESULTS: Alveolar macrophages recovered from crack users contained more iron than did alveolar macrophages from nonsmokers (25.4 +/- 2.9 nmol/10(6) vs 5.5 +/- 0.6 nmol/10(6) [mean +/- SE]; p < 0.01). There were similar increases in alveolar macrophage ferritin as well as BAL fluid iron and ferritin in crack users, compared with nonsmokers. BAL fluid ferritin concentrations in subjects smoking both crack and cigarettes were increased, compared with subjects smoking crack alone or cigarettes alone (p < 0.05). CONCLUSIONS: Use of crack increases intrapulmonary concentrations of iron and ferritin. Effects of crack on extracellular ferritin concentrations may be additive with effects of cigarette smoking. Although the mechanism(s) causing pulmonary iron accumulation were not identified by this study, it may be a result of occult alveolar hemorrhage or increased vascular permeability. The increase in lung iron burden in habitual crack users could promote chronic lung diseases in these subjects.     

Iron status in Danish women, 1984-1994: a cohort comparison of changes in iron stores and the prevalence of iron deficiency and iron overload

BACKGROUND AND OBJECTIVES: From 1954 to 1986, flour in Denmark was fortified with 30 mg carbonyl iron per kilogram. This mandatory enrichment of cereal products was abolished in 1987. The aim was to evaluate iron status in the Danish female population before and after abolishment of iron fortification. METHODS: Iron status, serum ferritin and haemoglobin, was assessed in population surveys in 1983-1984 comprising 1221 Caucasian women (1089 non-blood-donors, 130 donors) and in 1993-1994 comprising 1261 women (1155 non-blood-donors, 104 donors) equally distributed in age cohorts of 40, 50, 60 and 70 yr. RESULTS: In the 1984 survey, median ferritin values in the four age cohorts in non-blood-donors were 44, 57, 84 and 80 microg/L, and in the 1994 survey 40, 67, 97 and 95 microg/L, respectively. In 1984, premenopausal women had median ferritin of 43 microg/L and in 1994 of 39 microg/L (NS). In 1984, postmenopausal women had median ferritin of 75 microg/L and in 1994 of 93 microg/L (P < 0.0001). The prevalence of depleted iron stores (ferritin < 16 microg/L) was not significantly different in 1984 and 1994 either in premenopausal or in postmenopausal women. The prevalence of small + depleted iron stores (ferritin 300 microg/L) was unchanged in premenopausal women and had increased from 2.4% to 5.5% in postmenopausal women (P = 0.003). During the study period there was an increase in body mass index both in premenopausal and postmenopausal women (P = 0.06 and P = 0.008). Postmenopausal women displayed an increase in alcohol consumption (P < 0.0001) and a decrease in tobacco smoking (P < 0.001). In premenopausal women, there was a marked increase in the use of non-steroid anti-inflammatory drugs (P < 0.0001) in the study period, while this was unchanged in postmenopausal women. In premenopausal blood donors, median ferritin decreased from 1984 to 1994 (36 microg/L vs. 24 microg/L, P < 0.06). In postmenopausal blood donors, ferritin was not significantly different from 1984 to 1994 (50 microg/L vs. 41 microg/L, P = 0.15). CONCLUSION: Abolition of iron fortification reduced the median dietary iron intake in Danish women from 12 to 9 mg/d. Despite the absence of food iron fortification, from 1984 to 1994, body iron stores were unchanged in premenopausal women, whereas iron stores and the prevalence of iron overload in postmenopausal women had increased significantly. The reason appears to be the changes in dietary habits with a lower consumption of dairy products and eggs, which inhibit iron absorption, and a higher consumption of alcohol, meat and poultry, containing heme iron and enhancing iron absorption.     

Umbilical cord trace elements and minerals and risk of early childhood wheezing and eczema.

It has been suggested that foetal nutrition might influence the inception of wheezing and atopic disorders in childhood but specific nutrients have not been implicated. In the Avon Longitudinal Study of Parents and Children umbilical cord samples were assayed for trace elements and minerals, and mothers were asked about wheezing and eczema in their children. Associations of cord concentrations of selenium, zinc, copper, manganese, magnesium, iron, lead and mercury with wheezing at 30-42 months, with wheezing patterns defined by the presence or absence of transient infant, later onset or persistent wheezing at 0-6 months and 30-42 months, respectively (n=2,044), and with eczema at 18-30 months (n=2,173), were analysed. Cord selenium was negatively associated with persistent wheeze (adjusted odds ratio (OR) per doubling concentration: 0.67). Cord iron was negatively associated with later onset wheeze (OR: 0.86) and with eczema (OR: 0.90). Children with high cord concentrations of selenium and iron were less likely than those with low concentrations to wheeze transiently in infancy. The level of foetal exposure to selenium and iron may possibly influence the risk of wheezing and eczema in early childhood although, in view of the multiple analyses carried out, it is possible that the main findings occurred by chance.     

Orally active α-ketohydroxy pyridine iron chelators intended for clinical use: in vivo studies in rabbits

Increased daily iron excretion from iron overloaded, 59Fe lactoferrin labelled rabbits was observed following the intragastric administration of 1,2-dimethyl-3-hydroxy pyrid-4-one (L1) or 1-ethyl-2-methyl-3-hydroxy pyrid-4-one (L1-NEt) at doses of 200 mg/kg. 59Fe excretion induced by these drugs was predominantly faecal and was comparable to that caused by similar doses of subcutaneous or intramuscular desferrioxamine. The effectiveness of the two alpha-ketohydroxy pyridine chelators was confirmed by repeated administration, intragastrically or by subcutaneous or intramuscular injection, to the same or other rabbits. Examination of the urine during the administration of the chelators revealed their high specificity for iron but not for copper, zinc, calcium or magnesium.     

Iron, mycobacteria and tuberculosis

The role of iron in the growth and metabolism of M. tuberculosis and other mycobacteria is discussed in relation to the acquisiton of iron from host sources, such as transferrin, lactoferrin and ferritin, and its subsequent assimilation and utilization by the bacteria. Key components involved in the acquisition of iron (as ferric ion) and its initial transport into the mycobacterial cell are extracellular iron binding agents (siderophores) which, in pathogenic mycobacteria, are the carboxymycobactins and, in saprophytic mycobacteria, are the exochelins. In both cases, iron may be transferred to an intra-envelope, short-term storage molecule, mycobactin. For transport across the cell membrane, a reductase is used which converts FeIII-mycobactin to the FeII form. The ferrous ion, possibly complexed with salicylic acid, is then shuttled across the membrane either for direct incorporation into various porphyrins and apoproteins or, for storage of iron within the bacterial cytoplasm, bacterioferritin. The overall process of iron acquisition and its utilization is under very genetic tight control. The importance of iron in the virulence of mycobacteria is discussed in relationship to the development of tuberculosis. The management of dietary iron can therefore be influential in aiding the outcome of this disease. The role of the old anti-TB compound, p-aminosalicylate (PAS), is discussed in its action as an inhibitor of iron assimilation, together with the prospects of being able to synthesize further selective inhibitors of iron metabolism that may be useful as future chemotherapeutic agents.     

Interaction of lactoferrin and lipopolysaccharide (LPS): effects on the antioxidant property of lactoferrin and the ability of LPS to prime human neutrophils for enhanced superoxide formation.

Lactoferrin is a 77-kDa iron-binding protein to which a wide variety of divergent biologic functions have been ascribed. It has recently been reported that lactoferrin interacts with bacterial lipopolysaccharide (LPS) in such a fashion as to affect the binding of lactoferrin to myeloid cells. Two other potential interactions of LPS and lactoferrin were explored. Lactoferrin prevents hydroxyl radical formation by binding iron, even at low pH. Lactoferrin inhibited iron-catalyzed formation of hydroxyl radical in the presence of LPS at pH 7.4 and 4.5. Low concentrations of LPS can be used to "prime" neutrophils toward enhanced function, such as formation of stimulated superoxide anion. Lactoferrin inhibited LPS priming of neutrophils if LPS contamination of the protein (provided by commercial suppliers) was first reduced. Inhibition of LPS priming was observed whether apolactoferrin or iron-saturated lactoferrin was used. Similar inhibition of LPS priming was observed when neutrophils were incubated with other serum proteins (e.g., albumin, apotransferrin, or iron-saturated transferrin). These results show that LPS should not be expected to affect the free radical biology of lactoferrin, which is a crucial physiologic function of this protein. However, lactoferrin inhibits LPS priming, and this effect requires consideration in experimental models of inflammation.     

Inadequate calcium,folic acid,vitamin E,zinc, and selenium intake in rheumatoid arthritis patients: results of a dietary survey

Objectives:To determine the adequacy of calcium, folic acid, vitamin E, zinc, and selenium intake in patients with rheumatoid arthritis (RA).Methods:We conducted an observational study on 48 patients (13 men, 35women; mean age, 64.5 years) with RA attending a specialty clinic in New Zealand comparing their dietary intake as measured by a 5-day dietary survey with recommended dietary intake (RDI) guidelines. Information on disease activity, functional ability, and drug therapy also was obtained.Results:The percentage of patients who achieved the RDI was 23% for calcium,46% for folic acid, 29% for vitamin E, 10% for zinc, and only 6% for selenium. Patients on methotrexate had a significantly reduced intake of folic acid as a percentage of RDI (P < .05) compared with those on other therapies. In contrast, dietary intake of iron and protein was largely adequate and unrelated to anemia.Conclusions:Patients with RA should receive dietary education or supplementationto bring their intake of calcium, folic acid, vitamin E, zinc, and selenium up to the RDI.     

Effect of transferrin, lactoferrin and chelated iron on human T-lymphocytes.

The effect of different forms of iron and iron-binding proteins on the proliferative response of human lymphocytes to phytohaemagglutinin (PHA) has been studied. Transferrin enhanced proliferation, the effect being proportional to the degree of iron saturation up to 100%, but decreased if additional iron was present. The lipophilic complex ferric pyridoxal isonicotinoyl hydrazone (FePIH) also enhanced proliferation, but the hydrophilic complex ferric nitrilotriacetate (FeNTA) was inhibitory. Fe-lactoferrin could not substitute for Fe-transferrin, although iron-free (apo) lactoferrin abrogated the inhibitory effect seen when iron levels exceed the binding capacity of transferrin. Lymphocyte ferritin levels increased 4-fold as the iron saturation of transferrin increased from 0 to 90% but no further increase was seen at higher iron levels, suggesting that lymphocytes are poorly equipped to detoxify excess iron through stimulation of ferritin synthesis. The effect of iron on the CD4:CD8 ratio after 72 h culture with PHA was also examined. The ratio was approximately 2:1 for cells cultured with transferrin at iron saturations between 0 and 75%, with FePIH, or without either, but decreased to 1.1:1 when cells were cultured in the presence of FeNTA, regardless of whether or not saturated Fe-transferrin was present. These results show that iron can affect lymphocyte proliferation and subset ratios in different ways according to the form and amount present, and may help to explain some of the immunological disturbances associated with iron overload.     

Effect of zinc supplementation on trace elements and intestinal metallothionein concentrations in experimental colitis in the rat

BACKGROUND AND AIM: Zinc enhances cell protection against infection and injury and the healing processes themselves. We evaluated the effect of zinc supplementation at different doses on a model of experimental colitis in the rat. METHODS: Colitis, induced by intra-rectal instillation of dinitrobenzen-sulphonic acid, was assessed at 1 week by examining: general outcome and macroscopic damage, myeloperoxidase activity, mucosal zinc, iron and metallothionein concentrations. Rats received zinc sulphate, 2 mg/kg or 30 mg/kg, twice a day by gavage for 9 days, starting 3 days before the induction of colitis, or intrarectal instillation of zinc (20 mg/kg) once daily starting 8 hours after the induction of colitis and for 6 days thereafter RESULTS: Zinc-treated rats had less diarrhoea, higher body weight and lower colonic weight than untreated rats but no effect was observed on macroscopic inflammation, adhesions, colonic distension and neutrophil infiltration of the colonic mucosa. Zinc supplementation did not affect mucosal iron and zinc concentrations or plasma zinc levels in colitic rats. Metallothionein synthesis was induced in control rats and to a lesser extent in colitic rats. CONCLUSION: Zinc administration induces metallothionein synthesis but has little effect on the short-term course of experimental colitis.     

The study of trace elements in the hair of patients with esophageal carcinomain high risk area

AIM To study the change of trace elements in the hair of patients with esophageal carcinoma and the role oftrace elements in its development and progress.METHODS The hair of 60 normal people and 126 patients was collected and was divided into groupsaccording to the patients' pathologic changes. The atomic absorption method and fluorescence method wereused to measure the trace elements of copper, zinc, iron, calcium and selenium.RESULTS Zinc in the hair of various patients: a remarkable difference was found between normal people(182mg· kg 1)and the patients (103- 81.6mg·kg 1) (t = 3.79, P<0.01 Duncan' new multiple rangemethod). There was a certain difference between simple hyperplasia and cancer (t = 3.21, P<0.01 ). As forcopper, a great difference existed between normal people (12.01mg· kg-l) and patients with dysphagia (15.16mg·kg-1) and cancer (17.02-17.15mg·kg-1) (t=2.43, P<0.05). No change of zinc and copperwas observed in cancer patients (t = 1.61, P >0.05). The ratio of zinc to copper increased with thedevelopment of pathologic change. The selenium levels in patients (0.46-0.67mg·kg-1) was below that ofnormal people (l.03mg·kg-1), while iron and calcium levels in the patients decreased with the developmentof pathologic process.CONCLUSION Both zinc and copper play an important role in the pathologic change of esophagealcarcinoma. Zinc and copper in the hair changed with development of the pathologic process. Zinc revealedpositive correlation ( r = -0. 889, P < 0.01 while copper showed negative correlation ( r = 0.921, P < 0.01 ).The ratio of copper to zinc in the hair is of great diagnostic value.     

Iron-binding proteins and free iron in synovial fluids of rheumatoid arthritis patients

Summary Iron-binding proteins (lactoferrin, transferrin and ferritin) and free iron were measured in synovial fluid (SF) from 30 patients with rheumatoid arthritis (RA) and 20 osteoarthritis (OA) patients. The iron-binding proteins except transferrin were significantly increased in RA SF as compared with OA SF. Similarly, free iron was also significantly higher in RA SF than in OA SF, whereas the ferritin saturation index, transferrin saturation index and bound iron were more significantly decreased in RA SF than in OA SF. These results suggest that RA SF contains sufficient micromolar amounts of free iron to allow hydroxyl radical formation. Also the capacity of iron-binding proteins to bind free iron is inadequate in the presence of a large amount of iron-binding proteins which are present in RA SF.