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PubMed1997

Superiority of carbohydrate-deficient transferrin to gamma-glutamyltransferase in detecting relapse in alcoholism.

OBJECTIVE: The usefulness of carbohydrate-deficient transferrin is widely accepted in screening (male) population samples for heavy alcohol consumption, but its role in relapse detection is not convincingly established. The authors therefore compared the diagnostic value of carbohydrate-deficient transferrin with the commonly used gamma-glutamyltransferase in identifying relapsed alcoholics during outpatient aftercare. METHOD: The patients were 101 male alcoholics who entered a 6-month rehabilitation program after hospital detoxification. Drinking status was assessed by means of self- and collateral reports obtained during regular contacts with the rehabilitation team; relapse was defined as consumption of any alcohol. Visits occurred weekly during month 1, biweekly during month 2, and every 4 weeks during months 3-6. At every visit a blood sample was taken for measurement of carbohydrate-deficient transferrin and gamma-glutamyltransferase. RESULTS: The proportion of men who reported relapse was 25.6% per scheduled contact on average. Positive predictive values indicated that relapse was identified with a 76.2% probability by carbohydrate-deficient transferrin values above the upper normal limit, in contrast to a 32.9% chance with gamma-glutamyltransferase. Carbohydrate-deficient transferrin was especially useful in detecting early relapses during the initial rehabilitation phase, when gamma-glutamyltransferase values had not normalized. Because of the longer half-life of gamma-glutamyltransferase, it had some value with a 4-week monitoring schedule in detecting new drinking episodes in alcoholics whose previous results had been normal. CONCLUSIONS: Carbohydrate-deficient transferrin proved to be superior to gamma-glutamyltransferase in relapse detection in an outpatient care setting for alcoholics.

Adult↗
PubMed1994

Beta 2-transferrin confirms perilymphatic fistula in children.

beta 2-Transferrin is a protein that is unique to the cerebrospinal fluid and aqueous humor. On the basis of this information and a recent study from our institution that demonstrated that beta 2-transferrin was also unique to human perilymph, a prospective, double-blind study to evaluate perilymphatic fistula in children was performed. Attending otolaryngologists at Children's Hospital of Pittsburgh evaluated and recommended surgery for 10 children (10 ears) who were suspected of having a congenital perilymphatic fistula. During the operation, the surgeon decided whether a perilymphatic fistula existed, on the basis of otomicroscopic findings, and then separate pieces of gelatin sponge were placed on the oval and round windows, respectively, and sent to the immunopathology laboratory where they were analyzed for beta 2-transferrin. Ten patients (10 ears) undergoing tympanoplasty or tympanomastoidectomy were used as controls and tested in a similar fashion. During the study, both the surgeons and patients were blinded from the results of the test. Of the 10 control patients, none was observed to have a perilymphatic fistula, and all were negative for beta 2-transferrin. Of the 10 patients undergoing exploratory tympanotomy for perilymphatic fistula, 1 ear was thought to be negative for perilymphatic fistula on microscopic visual examination, whereas 9 were considered to be positive for perilymphatic fistula. No beta 2-transferrin was identified from the ear that was considered not to have a perilymphatic fistula, whereas six of the nine ears that were thought to have perilymphatic fistula tested positive for beta 2-transferrin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Tumour necrosis factor-alpha upregulates transferrin receptors in K 562 cells.

The effects of tumour necrosis factor-alpha on transferrin receptor expression in a human chronic myelocytic leukaemia cell line, K 562 cells, were studied. Cytofluorometry studies showed that the numbers of transferrin receptors in exponentially growing K 562 cells were increased when the cells were incubated with tumour necrosis factor-alpha for 24 h. The induction of transferrin receptors by tumour necrosis factor-alpha may be mediated by a mechanism that is independent of growth since cell growth in treated cultures did not differ from that in the controls. The DNA contents of K 562 cells treated with tumour necrosis factor-alpha showed that after 24 h there were less cells in the G1 and S phases and more cells in the G2/M phase than in the control group. The phase of upregulation of transferrin receptors induced by tumour necrosis factor-alpha may be dependent on the cell cycle. This new evidence that tumour necrosis factor-alpha upregulates transferrin receptors suggests a cancer-anaemia cascade in which the cancer burden state activates macrophage release of tumour necrosis factor-alpha as a result of transferrin receptor expression.

Cell Cycle↗
PubMed1990

Germ cell regulation of Sertoli cell transferrin mRNA levels.

Sertoli cells cultured in the presence of germ cells responded by increasing the level of transferrin mRNA 3-fold as determined by solution hybridization and Northern blot analysis. In contrast, the steady state levels of other mRNAs, including sulfated glycoprotein 1 (SGP-1), sulfated glycoprotein 2 (SGP-2), transferrin receptor, regulatory subunit of cAMP dependent protein kinase, and ferritin light chain, were not influenced by coculture with germ cells. The transferrin mRNA stimulatory activity was found in conditioned medium from germ cells but was not associated with germ cell membrane components. The activity was abolished by treatment of the medium with trypsin. Partial characterization and isolation of the protein(s) from conditioned medium indicated that it has an apparent mol wt between 10 and 30 K. Studies using inhibitors of protein and nucleic acid synthesis indicated that the stimulation of transferrin mRNA by germ cell conditioned medium required both transcription and translation. Sertoli cell enriched (germ cell depleted) testes were obtained from male offspring of pregnant females irradiated at the 19th day of gestation. Testicular transferrin mRNA levels from irradiated rats decreased in comparison to levels in the normal rat, whereas SGP-2 mRNA levels were unchanged. These studies demonstrate that germ cell secretions may interact with Sertoli cells to specifically increase the level of transferrin mRNA and that this interaction may be a mechanism by which germ cells regulate the flow of iron across the seminiferous epithelium.

Animals↗
PubMed2005

Production of catechol-siderophore and utilization of transferrin-bound iron in Bacillus cereus.

In the present study we attempted to ascertain whether Bacillus cereus was able to produce catechol-siderophore(s), and whether it was able to utilize transferrin-bound iron. The growth of B. cereus was stimulated in proportion to the iron-saturation level of the transferrin, and catechol-siderophores were produced in inverse proportion to this level. B. cereus was proved to uptake iron from partially iron-saturated transferrin or holotransferrin, without destroying the transferrin by its proteases. The catechol-siderophores from B. cereus were able to sustain and augment its growth on the transferrin-bound iron. These results indicate that B. cereus has the ability to produce catechol-siderophores, and to utilize transferrin-bound iron as an iron source for growth, via the siderophore-mediated iron-uptake system.

Bacillus cereus↗
PubMedDate not supplied

Elevated serum transferrin saturation and mortality.

BACKGROUND: A large proportion of US adults have elevated transferrin saturation, an indicator of a predisposition for iron overload. The purpose of this study was to evaluate the relationship between elevated serum transferrin saturation and mortality. METHODS: This cohort study was conducted using data from the First Health and Nutrition Examination Survey 1 (1971-1974) (NHANES I) merged with the NHANES I Epidemiologic Followup Study (1992) (N = 10,714). We used SUDAAN and appropriate weights to make population estimates for the adult US population (aged 25 to 74 years at baseline). All-cause mortality was evaluated in relation to serum transferrin saturation of greater than 45%, greater than 50%, greater than 55%, and greater than 60% using Cox proportional hazards regression. RESULTS: In a Cox proportional hazards model controlling for potential confounders, including comorbid diseases, smoking, and cholesterol, all-cause mortality is significantly greater for persons with a serum transferrin saturation of more than 55%, compared with those with saturations below this cutoff (hazards ratio [HR] = 1.60, 95% confidence interval [CI], 1.17-2.21). No one who died had hemochromatosis as any of the 20 listed causes of death. Many of the underlying causes of death for persons with serum transferrin saturation levels of more than 55% are common causes of death in the general population, although these persons were more likely to have died of cirrhosis and diabetes, a finding consistent with iron overload. CONCLUSIONS: In this nationally representative cohort of adults, those with elevated serum transferrin saturation, more than 2% of the adult US population, were at increased risk for all-cause mortality.

Adult↗
PubMed2003

Improved HPLC method for carbohydrate-deficient transferrin in serum.

BACKGROUND: There is need for a reference method for transferrin glycoforms in serum to which routine immunologic methods for the alcohol marker carbohydrate-deficient transferrin (CDT) can be traceable. We describe an improved HPLC method for transferrin glycoforms. METHODS: Transferrin was iron-saturated by mixing the serum with ferric nitrilotriacetic acid, and lipoproteins were precipitated with dextran sulfate and calcium chloride. Separation of glycoforms was performed on a SOURCE 15Q anion-exchange column using salt gradient elution. Quantification relied on selective absorbance of the iron-transferrin complex at 470 nm. The relative amount of each glycoform was calculated as a percentage of the area under the curve, using baseline integration. RESULTS: The HPLC system provided reproducible separation and quantification of the asialo-, monosialo-, disialo-, trisialo-, tetrasialo-, pentasialo-, and hexasialotransferrin glycoforms. Most importantly, disialo- and trisialotransferrin were almost baseline separated. The intra- and interassay CV for disialotransferrin were <5%. Serum and the pretreated samples were stable for at least 2 days at 22 or 4 degrees C. Sera from 132 healthy controls contained [mean (SD)] 1.16 (0.25)% disialotransferrin, 4.77 (1.36)% trisialotransferrin, 80.18 (2.01)% tetrasialotransferrin, and 13.88 (1.69)% pentasialo- + hexasialotransferrin. In some cases of a high (>6%) trisialotransferrin, monosialotransferrin was detected at <0.25%. Asialotransferrin was not detected in control sera, but was detected in 57% of chronic heavy drinkers and in 62% of sera with >/=2% disialotransferrin. CONCLUSIONS: The HPLC method fulfills the requirements of a preliminary reference method for CDT and should work for any combination of serum transferrin glycoforms. This method could also be useful for confirming positive CDT results by immunoassays in medico-legal cases.

Adult↗
PubMed1978

Analysis of the iron-binding sites of transferrin by isoelectric focussing.

1. Human transferrin was labelled with ferric nitrilotriacetate (FeNTA) at one of its two metal binding sites by variation of the pH. 2. Four transferrin forms, transferrin, transferrin(Fe) (A-site), transferrin(Fe) (B-site) and transferrin(2Fe) could be separated on flat bed gels by isoelectric focussing. 3. Incubation time, temperature and medium play an important role in the specificity of the binding of Fe. In NTA-pH-buffer, at 0.5 Fe-saturation, the A-site was preferentially labelled at pH 7--8, the B-site at a pH 8--9. 4. Under physiological conditions iron from the B-site has the tendency to move to the A-site.

Binding Sites↗
PubMed1986

Immunoturbidimetric measurement of transferrin.

This paper describes the development of an automated immunoturbidimetric assay for transferrin on a centrifugal analyser. Regression analysis of transferrin values measured immunoturbidimetrically demonstrates good agreement with data obtained by radial immunodiffusion (y = 0.997 + 0.024 g/l, r = 0.980, n = 50). The assay has a detection limit of 1.0 g/l and working range of approximately 1.0 to 6.0 g/l of transferrin. Day-to-day coefficient of variation is less than 3.5%. Immunoturbidimetric transferrin (g/l) and total iron binding capacity values (mumol/l) were compared using an established total iron binding capacity method (y = 0.050 X - 0.030 g/l, r = 0.967, n = 50). Minimal interference was found for lipaemic, haemolysed or icteric samples. Transferrin reference values with a mean of 3.05 g/l and 95% limits from 2.45 to 3.65 g/l were derived using serum from 300 apparently healthy subjects (150 males, 150 females). We conclude that the proposed transferrin method is more reliable and easier to perform than presently available total iron binding capacity methods.

Adult↗
PubMed1998

Evaluation of the iron status of the newborn by soluble transferrin receptors in serum.

The concentration of soluble transferrin receptors in serum has proven to be a reliable predictor of iron status in adults. Its high sensitivity for iron deficiency combined with a small sample size (10 microliters) makes it an interesting parameter for the assessment of iron stores in newborn infants. In the present study we investigated the usefulness of the concentration of soluble transferrin receptors in serum in the assessment of iron metabolism in the newborn. Infants born after an uncomplicated labour were compared to infants in the intensive care unit. The concentration of soluble transferrin receptors in serum was found to be elevated compared to normal adults and independently of iron metabolism. The concentration of soluble transferrin receptors did not correlate with serum iron and ferritin concentrations. In contrast to what was found in other studies, no relationship could be demonstrated between soluble transferrin receptors and birth weight or gestational age. The results of this study have shown that care has to be taken in the interpretation of the concentration of soluble transferrin receptors in serum in newborn infants. It seems to be a parameter which is independent of iron metabolism at least during the first days of life.

Adult↗
PubMed2000

Assessment of iron status with a new fully automated assay for transferrin receptor in human serum.

Serum transferrin receptor is considered as a reliable marker of iron status particularly when iron deficiency is associated with chronic disorders such as inflammation, infection or malignancy. The present study aims to illustrate the performances of a new fully automated assay using immunonephelometry. The intra and between-assay precision was found to be very good (CVs < 4%). In healthy subjects there was no statistically significant difference between men and women. With a cut-off of 1.76 mg/l for diagnosing iron deficiency either alone or combined with anemia of chronic diseases, the sensitivity and specificity were respectively 82% and 96.8%. Unlike conventional biochemical and hematological tests, soluble transferrin receptor was unaffected by confounding pathologies. In genetic hemochromatosis the concentration of soluble transferrin receptor was mostly decreased due to the regulatory effect of iron intracellular level. Our study confirms the reliability of soluble transferrin receptor for the assessment of iron status. It is now possible to assay soluble transferrin receptor, ferritin and transferrin on the same apparatus within 15 minutes.

Chronic Disease↗
PubMed2003

The analysis of carbohydrate-deficient transferrin, marker of chronic alcoholism, using capillary electrophoresis.

Carbohydrate-deficient transferrin (CDT) is currently considered to be the best available marker for the diagnosis of chronic alcoholism. A large variety of methods have been developed, demonstrating the need for standardisation. Commercially available anion-exchange chromatographic-based assays are easy to use and require no specialised, expensive instruments. However, these methods cannot identify genetic transferrin variants or the carbohydrate-deficient glycoprotein syndrome. In 1989, a capillary isoelectric focusing method was developed for quantitative measurement of CDT. Despite the optimal resolution, this method is not easily applied in a clinical routine environment due to the complexity of analysis. Capillary electrophoresis in a polymer network using coated capillaries allowed full resolution of the sialoforms of human transferrin. The drawbacks due to an expensive and time-consuming sample preparation were eliminated when a method in neat serum was developed. Capillary zone electrophoresis allowed full resolution of the transferrin isoforms with a high analytical performance in a short analysis time thanks to a strong electroosmotic flow. Genetic transferrin variants were easily detected, avoiding false-positive results. Also, using capillary zone electrophoresis, it was shown that CDT is a suitable marker of chronic alcohol abuse detection in transferrin CD (common/cathodal) variants.

Alcoholism↗
PubMed2004

N-glycans of human amniotic fluid transferrin stimulate progesterone production in human first trimester trophoblast cells in vitro.

AIMS: During pregnancy, the placenta produces a variety of steroid hormones and proteins. Several of these substances have been shown to exert immunomodulatory effects. Progesterone is thought to mediate some of these effects by regulating uterine responsiveness. The aim of this study was to clarify the effect of amniotic fluid transferrin and its N-glycans on the release of progesterone by first trimester trophoblast cells in vitro. METHODS: Cytotrophoblast cells were prepared from human first trimester placentae by trypsin-DNAse dispersion of villous tissue followed by a percoll gradient centrifugation and depletion of CD45 positive cells by magnetic cell sorting. Trophoblasts were incubated with varying concentrations (50-300 microg/ml) of transferrin from human amniotic fluid and serum as well as with N-glycans obtained from amniotic fluid transferrin. Culture supernatants were assayed for progesterone by enzyme-immunometric methods. RESULTS: The release of progesterone increased in amniotic fluid transferrin- and N-glycan-treated trophoblast cell cultures compared to untreated trophoblast cells. There was no stimulating effect of serum transferrin on the progesterone production of trophoblast cells. CONCLUSIONS: The results suggest that amnion-transferrin and especially its N-glycans modulate the endocrine function of trophoblasts in culture by up regulating progesterone secretion.

Amniotic Fluid↗
PubMed1979

Effects of obesity, total fasting and re-alimentation on L-thyroxine (T4), 3,5,3'-L-triiodothyronine (T3), 3,3',5'-L-triiodothyronine (rT3), thyroxine binding globulin (TBG), cortisol, thyrotrophin, cortisol binding globulin (CBG), transferrin, alpha 2-haptoglobin and complement C'3 in serum.

UNLABELLED: The effects of total fasting for 31 +/- 10 days followed by re-alimentation with an 800 calorie diet on thyroid function, i.e. T4,T3,rT3,RT3U (resin T3 uptake), and TSH, and on TBG levels in serum were studied sequentially in obese hospitalized patients (N=18). Additionally, cortisol, growth hormone, prolactin, parathyrin and free fatty acids were followed as hormonal and metabolic parameters, respectively. Further, CBG, transferrin, alpha 2-haptoglobin and complement C'3 were measured as representatives of other serum proteins. Results before fasting: T4, T3, TBG, cortisol, CBG, alpha 2-haptoglobin and complement C'3 of the obese patients were elevated when compared with healthy normal weight controls, whereas rT3, T4/TBG ratio, T3/TBG ratio, TSH, coritsol/cbg ratio, growth hormone, prolactin, parathyrin and transferrin of the obese group were normal. RT3U and fT4 index were decreased in the obese patients. Results during fasting: Significant decreases were observed during fasting for the following parameters -- T3, TBG, T3/TBG ratio, transferrin, alpha 2-haptoglobin complement C'3. rT3, T4/TBG ratio, RT3U, fT4 index and FFA increased. T4, tsh response to TRH stimulation, cortisol, CBG, cortisol/cbg ratio, parathyrin, growth hormone and prolactin did not change. Results during re-alimentation: T3, TBG, T3/TBG ratio, TSH response to TRH, transferrin, alpha 2-haptoglobin and complement C'3 increased. Conversely, fT3, RT3U, FFA, cortisol and cortisol/cbg ratio decreased whereas the other parameters did not change. CONCLUSIONS: 1) There is no evidence for primary hypothyroidism in obese patients during prolonged fasting and re-alimentation. 2) The rapid decrease of T3 and increase of RT3U after initiation of fasting are not fully explained by the observed slower decreases in TBG. 3) The alterations of T3, rT3 and RT3U resemble in their kinetics the changes in FFA levels. 4) Fasting reduced the levels of only certain serum proteins, interestingly TBG, transferrin, alpha 2-haptoglobin and complement C'3, all of which, except transferrin, are elevated in obesity. 5) The magnitude of the observed decreases does not suggest any clinically relevant deficiencies in serum proteins. 6) Re-alimentation reverses rapidly all observed changes.

Adult↗
PubMed1982

Transferrin and iron movements in the rat conceptus during gestation.

Transferrin binding by the placenta increased progressively from Day 14 to Day 21 of gestation. Qualitatively similar changes in the rate of iron transfer to the fetus were also seen. These results suggest that the increase in iron transfer to the fetus occurs as a result of an increase in the number of transferrin receptors on the maternal surface of the placenta rather than being due to a change in the affinity or turnover rate of the existing receptors, although disproportionate change in the number of receptors and maternal placental surface area suggests that there may be a reduction of the density of transferrin receptors. The ratios of fetal and total (fetal plus placental) iron to transferrin showed that maturation of the mechanism of iron release from transferrin and the intra-placental iron transport system occurred during development. In contrast to that in the chorioallantoic placenta, iron and transferrin incorporation into the yolk sac decreased during gestation, indicating that the yolk sac does not have a physiological role in the transport of iron from the mother to the fetus in the last part of pregnancy. For at least 28 h after fetectomy, the placenta continued to accumulate iron at the same rate as the controls. The iron thus accumulated was stored mainly as insoluble haemosiderin, and was not refluxed into the maternal circulation. These results indicate that iron transport by placental cells is 'preprogrammed' and is not subject to feedback control by the fetus or the placenta itself.

Animals↗
PubMed1988

Seminal fluid transferrin as an index of gonadal function in men.

Seminal fluid transferrin concentrations of proven fertile donors and normozoospermic patients were significantly higher (P less than 0.001) than those in other groups examined. There were no significant differences in the transferrin values among vasectomized, azoospermic and very severe oligozoospermic subjects. Values were also similar in patients affected by secretory or excretory azoospermia. Regression analysis showed a positive correlation (P less than 0.001, r = 0.72) between seminal fluid transferrin concentrations and sperm density. A negative correlation (P less than 0.02, r = 0.28) existed between circulating FSH and seminal fluid transferrin concentrations. There were no significant differences between seminal fluid transferrin and the percentages of abnormal sperm cells or immature seminal line elements. These results indicate that the nature of seminiferous tubule dysfunction can be precisely defined by examining seminal fluid transferrin in combination with other biological values usually used to explore testicular function.

Follicle Stimulating Hormone↗
PubMed1992

Subcellular localization of transferrin and pyrophosphate in liver cells after perfusion in situ or incubation in vitro.

Rat livers were perfused in situ with [125I]-transferrin, FITC-dextran and [32P]-inorganic pyrophosphate (PP). In a parallel set of experiments rat liver homogenates was incubated with [125I]-transferrin and [32P]-PPi. In both sets of experiments cellular organelles were prepared by density gradient centrifugation in metrizamide. In the perfusion experiments [125I]-transferrin and FITC-dextran accumulated in fractions rich in plasma membrane enzymes, whereas in the homogenate experiments [125I]-transferrin remained in soluble fractions. [32P]-PPi remained in soluble fractions in both sets of experiments, i.e. PPi did not co-localize with transferrin taken up by intact cells. In another set of experiments fractions rich in endosomes were tested for their ability to synthesize PPi from ATP. No PPi was found. The results argue against a role for PPi in transferrin-iron release within endosomes.

Adenosine Triphosphate↗
PubMed1993

The transferrin receptor: its diagnostic value and its potential as therapeutic target.

Transferrin receptors are present on almost all mammalian cells. The receptor participates in the cellular acquisition of iron from transferrin by receptor-mediated endocytosis. Receptor abundancy is generally regulated by two factors: i) cellular iron status and ii) cell growth. These two factors form the basis for the utilization of transferrin receptor determination as a diagnostic tool. In the assessment of body iron status and erythropoietic activity the measurement of circulating transferrin receptor has proved to be of value as a measure of mild tissue iron deficiency, to distinguish iron deficiency anemia from the anemias of chronic disease, and as a sensitive index of iron deficiency during pregnancy. Histochemical analysis of the presence and abundancy of the transferrin receptor will continue to serve as an additional tool in special cases to distinguish between malignant and normal cell growth, and to provide additional information about the biological behaviour of tumor cells. Finally, the transferrin receptor holds a potential as a target for direct and indirect drug delivery in the therapy of malignant cell growth.

Drug Carriers↗