Transferrin receptor expression by human bladder transitional cell carcinomas

Summary The expression of transferrin receptors (TFR) by normal and neoplastic urothelial cells was studied in control patients and in patients with transitional cell carcinoma of the bladder. These tumours were graded independently and consisted of 19 grade I, 30 grade II and 19 grade III lesions. TFRs were identified using a monoclonal antibody specific for TFR (OKT9) in an immunofluorescent or avidin/biotin-immunoperoxidase technique on fresh frozen sections. TFRs were not detected on normal urothelium. However, positive staining was found to increase with increasing pathological grade and stage of the tumours, ranging from 31.6% of grade I to 78.9% of grade III tumours and 51.2% of pTa (mucosa only lesions) to 87.5% of pT2/pT2+ (muscle invasion±deeper) primary urothelial malignancies.     

Transferrin gene frequencies in Cádiz (southern Spain)

Summary The genetic polymorphism of transferrin (Tf) was studied in a sample of 385 healthy unrelated subjects of both sexes resident in the province of Cádiz (southern Spain). Isoelectric focusing was carried out in polyacrylamide gels, followed by staining with Coomassie Blue R250. The gene frequencies obtained were as follows: Tf C1, 0.7922; Tf C2, 0.1883; Tf C3, 0.0195.     

献血员献血时间对血清铁蛋白、转铁蛋白的影响

目的：探讨献血员献血时间对血清铁蛋白（SF），转铁蛋白（TF）含量的影响，方法：分别应用放免法和免疫比浊法对138名献血员进行了SF和TF含量测定，并与345名正常人作对照，结果：女献血员SF含量低于正常（P＜0．05），而TF含量则高于正常（P＜0．05），献血时间越长，差异越显（P＜0．01），结论：测定SF和TF含量对女献血员的缺铁状态有一定的诊断价值。     

血清铜,锌,铁及其转运蛋白浓度在体外循环术中的急性时相变化

目的：观察血清铜、锌、铁浓度及其转运蛋白在体外循环术后的变化情况。方法：对体外循环的７名男性和４名女性在手术前后不同时间点抽取血清样品样进行铜、锌、铁及其转运蛋白浓度测定。结果：血清铜、锌、铁浓度在手术初期呈相似变化,即先增加再降低,而后各自呈现不同的应急反应。其中锌和铁的变化有显著性差异,而铜的变化在整个研究时期均无显著性差异（Ｐ〉０．０５）;三种转运蛋白均自手术开始时下降,其中白蛋白和转铁蛋白     

Coupling of Metal Containing Homing Devices to Liposomes via a Maleimide Linker: Use of TCEP to Stabilize Thiol-groups without Scavenging Metals

Liposomes for drug delivery are often prepared with maleimide groups on the distal end of PEG to enable coupling of homing devices, such as antibodies, or other proteins. EDTA is used to stabilize the thiol group in the homing device for attachment to the maleimide. However, when using a homing device that contains a metal, EDTA inactivates this by scavenging of the metal. Holo-transferrin (Tf) containing two iron atoms (Fe³⁺), has a much higher affinity for the Tf receptor than apo-Tf (which does not contain any Fe³⁺). To couple Tf to a liposome, the introduction of a thiol group is necessary. During this process, by using N-succinimidyl S-acetylthioacetate (SATA), followed by 2–3 h coupling to the liposomes, Fe³⁺ is scavenged by EDTA. This causes a decreased affinity of Tf for its receptor, resulting in a decreased targeting efficiency of the liposomes.

Tris(2-carboxyethyl)phosphine (TCEP) hydrochloride is a sulfhydryl reductant that is often used in protein biochemistry. We found that TCEP (0.01 mM) does not scavenge Fe³⁺ from Tf and is able to protect thiol groups for the coupling to maleimide. Furthermore, TCEP does not interfere with the maleimide coupling itself.

In this communication, we describe the preparation of liposomes, focussing on the coupling of Tf to the maleimide linker at the distal end of PEG, without loosing Fe³⁺ from Tf. This method can be applied to other metal-containing homing devices as well.     

Up-regulation of transferrin receptor 1 in chronic hepatitis C: Implication in excess hepatic iron accumulation.

BACKGROUND/AIMS:: To clarify the mechanism of excess hepatic iron accumulation in chronic hepatitis C, we investigated the expressions of transferrin receptor 1 and divalent metal transporter 1 in hepatocytes, both of which are involved in cellular iron uptake, in relation to the degree of hepatic iron accumulation and hepatic fibrosis by immunohistochemistrical study. METHODS:: Forty-six hepatic tissues with chronic hepatitis C and five normal hepatic tissues were examined. Chemical detection of hepatic iron accumulation was performed by Perl's Prussian blue stain. The immunohistochemistrical study was performed by avidin-biotin complex method with alkaline phosphatase. RESULTS:: In chronic hepatitis C: (1) Hepatic iron accumulation was significantly increased in relation to the advance of the fibrosis. (2) Divalent metal transporter 1 decreased significantly in relation to the advance of hepatic fibrosis. (3) Transferrin receptor 1 expression was always detected, although not in normal hepatic tissues; there was no relation between expression levels and the degree of hepatic fibrosis. CONCLUSIONS:: These data demonstrated that the transferrin receptor 1 expression was up-regulated irrespective of the degree of hepatic iron accumulation, suggesting that the up-regulation of transferrin receptor 1 might act as one of the key mechanisms implicated in the accumulation of hepatic iron in chronic hepatitis C.     

Occult celiac disease prevents penetrance of hemochromatosis

AIM:To report a patient with C282Y homozygocity,depleted body iron and intestinal atrophy caused by celiac disease (CD) who experienced resolution of the enteropathy with subsequent normalization of iron metabolism upon gluten free diet. METHODS:To obtain information on the tissue distribution and quantitative expression of proteins involved in duodenal iron trafficking,we determined the expression of divalent-metal transporter 1 (DMT1),ferroportin 1 (FP1) and transferrin receptor (TfR1) by means of immunohist-ochemistry and real-time PCR in duodenal biopsies of this patient. RESULTS:Whereas in hereditary hemochromatosis patients without CD, DMT1 expression was up-regulated leading to excessive uptake of iron, we identified a significant reduction in protein ana mRNA expression of DMT1 as a compensatory mechanism in this patient with HH and CD. CONCLUSION:Occult CD may compensate for increased DMT1 expression in a specific subset of individuals with homozygous C282Y mutations in the hemochromatosis (HFE) gene,thus contributing to the low penetrance of HH.     

Preoperative evaluation of chronic alcoholics assessed for surgery of the upper digestive tract

BACKGROUND: Alcoholics are at risk of developing major complications in the postoperative period. Adequate prophylactic treatment, as well as preoperative abstinence, can significantly decrease the rate of complications. However, the preoperative diagnosis of alcoholism is difficult to establish. The purpose of this study was to assess whether three preoperative visits, an alcohol-related questionnaire (CAGE), and the laboratory markers carbohydrate-deficient transferrin (CDT) and gamma-glutamyltransferase (GGT) would increase the rate of detection of chronic alcoholics. METHODS: The study included the Departments of ENT, Facial and Maxillofacial Surgery, and General Surgery of a university hospital; 705 male patients were assessed for tumor surgery of the upper digestive tract and were allocated to 5 different groups. All patients were seen three times, and five different strategies were used to detect chronic alcoholics. The gold standard was the diagnosis of alcohol misuse made by an experienced (blinded) investigator according to the DSM-III-R. The main outcome measurements were the detection rates of the different test strategies. RESULTS: By clinical routine alone, only 16% were detected during the first visit and 34% after three visits. If the CAGE questionnaire was added, sensitivity increased to 64%. The further addition of GGT or CDT led to 80 and 85% detections, respectively. A combination of all tests had a sensitivity of 91%. CONCLUSIONS: To detect more alcoholic patients at risk for major complications, patients should be seen more often, and additional diagnostic tools such as the CAGE, CDT, and GGT should be used before surgery.     

早期糖尿病肾病预测指标及危险因素研究

目的探讨糖耐量减低（IGT）患者早期糖尿病肾病的预测指标、患病率及影响因素。方法262例受试者中正常糖耐量（NGT）103人、IGT98人、糖尿病（DM）61人，全部进行即刻尿转铁蛋白／肌酐（UTRF／Cr）和尿白蛋白／肌酐（UAlb／Cr）的检测及临床观察指标的测定。结果（1）UTRF／Cr与UAlb／Cr呈显著正相关，r=0．618，P＜0.001。（2）IGT组的UAlb／Cr（中位数，极差）、UTRF／Cr（中位数，极差）高于NGT组（0．015，0．44mg／mg比0.012，0．58mg／mg，t=-1.981，P=0．049；0.064，4.96mg／mg比0.034，7.30mg／mg，t=-2．249，P=0．026）。（3）各组UTRF／Cr比值的阳性率明显高于白蛋白尿的阳性率（41．6％比29．7％，P（0．01）。（4）Logistic回归分析显示白蛋白尿的主要危险因素是DBP，OR=1．064，2hPGOR=1．109，P＜0.01；非糖尿病组的主要危险因素是DBP，OR=1．064，P＜0.01。结论在IGT阶段已存在早期糖尿病肾脏损害，高血压是其重要的危险因素。尿转铁蛋白／肌酐比值的检测较白蛋白尿／肌酐比值更灵敏，但仍需进一步综合比较二者的敏感性和特异性。     

Carbohydrate Deficient Transferrin in Abstaining Patients With End-Stage Liver Disease

BACKGROUND: Carbohydrate deficient transferrin (CDT), a biochemical marker of chronic alcohol consumption, is used by researchers and clinicians alike in a variety of populations. Levels of CDT may be affected by certain types of medical illnesses and conditions. Thus the interpretation of CDT results may need to be carefully examined in these populations. Because CDT is synthesized, glycosylated, and secreted by the liver, the use of CDT values in patients with liver disease has been an area of focused interest. METHODS: We evaluated the CDT values of 79 abstaining patients with end-stage liver disease. These patients were recruited from a liver transplant clinic while they were listed and waiting for transplantation. Patients were determined to be abstaining both by interview and by random blood alcohol levels in those with a diagnosis of alcoholic liver disease. The severity of the liver disease was categorized by the Child-Pugh score. Correlations were determined between CDT values and liver enzymes, and Child-Pugh scores and liver diagnosis. RESULTS: Nearly 50% of the patients had a CDT value of 2.6% or above, indicating a clinically positive value. There were strong correlations between CDT and a number of biochemical and physical variables, most importantly the Child-Pugh score (r = 0.52, p = 0.000). Specific liver diseases were not associated with absolute CDT values. However, patients with hepatitis C (HCV) had a significantly higher chance of having a clinically positive CDT compared with patients with other types of liver diseases. CONCLUSIONS: These results suggest that an elevated CDT value may not accurately represent alcohol consumption in patients with advanced liver disease. In fact, in such patients, the CDT may become a marker for the degree of liver impairment in alcoholic and nonalcoholic liver disease. CDT values should be viewed with caution in any patient with liver disease especially when the degree of cirrhosis reaches a Child-Pugh score of C (total score of 10 or above).