TRAG-3, a novel cancer/testis antigen, is overexpressed in the majority of melanoma cell lines and malignant melanoma

BACKGROUND

We have identified a novel cancer/testis antigen, TRAG-3, (Taxol Resistance Associated Gene-3) that was initially discovered in search for new genes involved in drug resistance by differential display. Early study of TRAG-3 revealed minimal to absent expression in various normal tissues and over-expression in many carcinoma cell lines including several melanoma lines.

MATERIALS AND METHODS

Northern and RT-PCR technologies were used to evaluate TRAG-3 expression in numerous cell lines and tumor tissue.

RESULTS

Analysis of a wider panel of normal tissues, 32 melanoma cell lines and 4 malignant melanomas demonstrates TRAG-3 expression in 25 of the 32 melanoma cell lines (78%) and four of four of the malignant melanoma tumors (100%). Of the additional eight normal tissues screened, expression was present in normal testis but absent in all other tissues. RT-PCR evaluation of TRAG-3 reveals two transcripts in many carcinoma cell lines with sequencing of these products demonstrating the 799 bp TRAG-3 transcript and a second alternatively spliced transcript, TRAG-3long TRAG-3 maps to band Xq28 within a MAGE gene complex, however sequence analysis demonstrates that TRAG-3 is not homologous to other known cancer/testis antigens.

CONCLUSION

TRAG-3 appears to be a novel cancer/testis antigen.

[Time course of TGF beta 1 and VEGF expression in experimental vein grafts]

OBJECTIVE

To investigate time course of TGF beta(1) and VEGF expression and their role in intimal hyperplasia.

METHODS

In situ hybridization and immunohistochemical technique were used to detect the time course of intimal hyperplasia, time course of TGF beta(1) mRNA and protein expression of TGF beta(1) and VEGF.

RESULTS

After autogenous vein replacement, the obvious neointima was seen at 2 weeks, and peaked at 8 weeks. The expression of TGF beta(1) mRNA peaked at 1 week and decreased gradually, but at 10 weeks, its positive cell percentage was still 10.1%. Both protein expression of TGF beta(1) and VEGF in VSMCs increased from 24 hours after grafting and peaked at 2 weeks. Their positive cell percentages were 40.6% and 36.6% respectively. After 4 weeks, their expression decreased at 8 weeks, the positive cell percentages were 8.9% and 13.8% respectively.

CONCLUSIONS

TGF beta(1) plays an important part in ECM accumulation by promoting ECM synthesis and decreasing ECM degradation. VEGF plays the key role in reendothelialization. They may affect each other and cooperated in the formation of intimal hyperplasia.

[Summary of 42 patients with acute aortic occlusion]

OBJECTIVE

To summarize the experience of diagnosis and treatment in 42 patients with acute aortic occlusion.

METHODS

Clinic data were analyzed. The emergency surgery of retrograde catheter thrombolectomy of transaortic thromboembolism were done, and the propathy and complications were treated simultaneously.

RESULTS

Normal blood flow were restored just after operation. Four patients died of myonephropathic metabolic syndrome and heart failure. 38 patients were followed up for 0.5 to 4 years. Among them, 36 were followed for more than 1 year. A better effectiveness was achieved in 28 patients. Two patients died of recurrence accompanied with heart failure.

CONCLUSION

Early diagnosis and treatment may increase the curative ratio and decrease the mortality in patients with acute aortic occlusion.

A logic for biological systems

This paper proposes a specification language, hybrid projection temporal logic of modelling, analyzing and verifying biological systems which can be considered, in general, to be hybrid systems consisting of a non-trivial mixture of discrete and continuous components. The syntax and semantics of the logic are presented, and some examples of hybrid systems are modelled to illustrate the formalism.

Observation of Coriolis Coupling between nu(2) + 4nu(4) and 7nu(4) in Acetylene &Xtilde;(1)Sigma(+)(g) by Stimulated Emission Pumping Spectroscopy

Stimulated emission pumping (SEP) spectroscopy has been used to examine a low energy region (E(vib) approximately 4400 cm(-1)) of &Xtilde;(1)Sigma(+)(g) acetylene at higher resolution than was possible in previous dispersed fluorescence studies. The expected bright state, nu(2) + 4nu(4), is observed to be coupled to the nearly degenerate 7nu(4) state by a Coriolis mechanism. A least-squares analysis yields values for zero-order vibrational energies, rotational constants, and a Coriolis-coupling coefficient that are all consistent with expectations. Calculated relative intensities of SEP transitions, accounting for interference due to axis-switching effects, are also consistent with observations. Implications of the observed Coriolis resonance with regard to global acetylene vibrational dynamics are also discussed. Copyright 2000 Academic Press.

Cytokines IL-1beta, IL-2, IL-6, IL-8, MCP-1, GM-CSF and TNFalpha in patients with epithelial ovarian cancer and their relationship to treatment with paclitaxel

In vitro work suggests that cytokines may be important modulators of the cytotoxic effects of paclitaxel and subsequent drug resistance. This has been investigated in vivo in patients with ovarian cancer by ELISA. There was consistently elevated expression of IL-6 and IL-8 but not MCP-1, IL-1beta, IL-2, GM-CSF or TNFalpha. Peritoneal fluid concentrations of IL-6, IL-8 and MCP-1 were two to three logs greater than serum concentrations. Elevated concentrations of IL-6 correlated with a poor final outcome (P = 0.039), and increased IL-6 and IL-8 correlated with a poor initial response to chemotherapy (P = 0.041 and P = 0.041, respectively). There was a relatively clear pattern of change in all three cytokines. In serum, IL-6, IL-8 and MCP-1 decreased with the administration of steroids prior to paclitaxel, and increased in the 24 h after paclitaxel. Postoperative drainage fluid was relatively acellular, preventing flow-cytometric analysis of epithelial cells for apoptosis, but suggested activation of T cells by paclitaxel. IL-6 and IL-8 appear to be of prognostic importance in epithelial ovarian cancer. Treatment with paclitaxel is associated with an increase in expression of a limited number of cytokines in patients with ovarian cancer, notably IL-6, IL-8 and MCP-1.

Discovery of differentially expressed genes associated with paclitaxel resistance using cDNA array technology: analysis of interleukin (IL) 6, IL-8, and monocyte chemotactic protein 1 in the paclitaxel-resistant phenotype

In an attempt to define the molecular changes associated with the paclitaxel-resistant phenotype in human cancer, a paclitaxel-resistant ovarian cancer cell line, SKOV-3TR, was established through stepwise selection in increasing paclitaxel concentrations. SKOV-3TR was cross- resistant to doxorubicin and vincristine and overexpressed multidrug resistance gene 1 but not multidrug resistance associated protein. SKOV-3TR and the paclitaxel-sensitive SKOV-3 parent line were characterized using human cDNA array technology that examined expression of a wide variety of genes involved in cell growth, signal transduction, cell death, and immune function. cDNA probes from reverse transcribed mRNAs of both paclitaxel-resistant and parent cells were compared to identify genes differentially expressed in the paclitaxel-resistant cells. Of 588 different human cDNA transcripts compared, 6 genes were found to be markedly decreased, and 12 genes increased in the resistant subline. Northern analysis and/or reverse transcription-PCR confirmed that 12 of these 18 genes were over- or underexpressed in SKOV-3TR. In addition, at least eight of the genes were found differentially expressed in several other paclitaxel- and/or doxorubicin-resistant cell lines, both those with increased multidrug resistance expression and those without. Included in the set of overexpressed genes were the cytokines/chemokines interleukin 6, interleukin 8, and monocyte chemotactic protein 1. ELISA assays confirm that mRNA overexpression of these cytokine/chemokines was associated with the increased secretion of these molecules in the tissue culture supernatant. Evaluation of supernatants from an expanded collection of paclitaxel- and Adriamycin-resistant cell lines demonstrated that all of the resistant lines had significant overexpression of at least one cytokine/chemokine as compared with their drug-sensitive parent line. The overexpression of these cytokines seemed to be stable and associated with a drug-resistant phenotype with only a modest induction of cytokine expression in the parent line with short-term paclitaxel exposure. These findings suggest that the development of paclitaxel resistance is accompanied by multiple changes in gene expression including stable alterations in selective chemokine and cytokine expression. The role these associated genetic changes have in the drug-resistant phenotype is discussed.

Structural analysis and mapping of DNase I hypersensitivity of HS5 of the beta-globin locus control region

The beta-globin locus control region (LCR) is a cis regulatory element that is located in the 5' part of the locus and confers high-level erythroid lineage-specific and position-independent expression of the globin genes. The LCR is composed of five DNase I hypersensitive sites (HSs), four of which are formed in erythroid cells. The function of the 5'-most site, HS5, remains unknown. To gain insights into its function, mouse HS5 was cloned and sequenced. Comparison of the HS5 sequences of mouse, human, and galago revealed two extensively conserved regions, designated HS5A and HS5B. DNase I hypersensitivity mapping revealed that two hypersensitive sites are located within the HS5A region (designated HS5A(major) and HS5A(minor)), and two are located within the HS5B region (HS5B(major), HS5B(minor)). The positions of each of these HSs colocalize with either GATA-1 or Ap1/NF-E2 motifs, suggesting that these protein binding sites are implicated in the formation of HS5. Gel retardation assays indicated that the Ap1/NF-E2 motifs identified in murine HS5A and HS5B interact with NF-E2 or similar proteins. Studies of primary murine cells showed that HS5 is formed in all hemopoietic tissues tested (fetal liver, adult thymus, and spleen), indicating that this HS is not erythroid lineage specific. HS5 was detected in murine brain but not in murine kidney or adult liver, suggesting that this site is not ubiquitous. The presence of GATA-1 and NF-E2 motifs (which are common features of the DNase I hypersensitive sites of the LCR) suggests that the HS5 is organized in a manner similar to that of the other HSs. Taken together, our results suggest that HS5 is an inherent component of the beta-globin locus control region.

Structure-based ligand design by dynamically assembling molecular building blocks at binding site

A structure-based ligand design method is proposed and tested. The method is based on stochastic dynamics simulation of multiple copies of molecular building blocks in the presence of a receptor molecule. The molecular building blocks are assembled into candidate compounds "on the fly" at given intervals during the simulation. In the algorithm, a special effort is made to explore different possible combinations of building blocks and to select an optimum combination. By repeating the cycle of deconstruction and reconstruction in a single simulation, a set of candidate compounds that can be built from the building blocks evolves and is dynamically optimized. The method was tested by breaking two known flexible human immunodeficiency virus type 1 protease inhibitors into building blocks and reassembling them in the active site of the enzyme. For the inhibitor L700417, a set of conformations was generated by the calculation. Among these, the original compound was recovered with the lowest energy at the experimentally observed binding site and in the correct conformation. For pepstatin, the experimentally observed binding mode of the backbone of the inhibitor was reproduced by a calculation in which the building blocks corresponding to the side-chain groups were omitted. Proteins 1999;36:462-470.

TRAG-3, a novel gene, isolated from a taxol-resistant ovarian carcinoma cell line

The mechanisms responsible for the development of the taxol resistance phenotype are unclear, and are likely explained by multiple mechanisms. To understand the molecular changes associated with drug resistance more fully, a taxol-resistant subline, derived from the human ovarian cancer cell line SKOV-3, was established through selection by culture in incrementally increasing taxol concentrations. Comparison of SKOV-3 to SKOV-3TR by differential display identifies a new gene, TRAG-3 (Taxol Resistance Associated Gene- 3). In comparison to the parental line, SKOV-3, TRAG-3 mRNA is overexpressed in the taxol-resistant cell line SKOV-3TR. The nucleotide sequence of the TRAG-3 cDNA contains an open reading frame of 333bp that predicts for a protein product of 110 amino acids. A GenBank search identifies a cosmid clone containing a genomic sequence corresponding to that of TRAG-3. DNA and protein analysis reveals that TRAG-3 has no homology to any known cDNAs or proteins. Northern analysis demonstrates that TRAG-3 is overexpressed in the taxol-resistant breast cancer cell line MDA 435TR as well as the doxorubicin-resistant multiple myeloma cell lines 8226/DOX40 and 8226/MDR10V. A survey of normal tissue shows minimal or absent TRAG-3 mRNA expression. Screening of a wide variety of cancer cell lines demonstrates TRAG-3 expression in many cell lines derived from different tissue types. In summary, TRAG-3 is a novel gene whose expression is associated with the chemotherapy-resistant and neoplastic phenotype.

[Effects of inflammatory infiltration on the formation of abdominal aortic aneurysm]

OBJECTIVE

To explore inflammatory infiltration and its effects on the formation of abdominal aortic aneurysm (AAA).

METHODS

Immunohistochemical technique was used to detect lymphocyte (CD45 positive) and macrophage (CD68 positive) infiltration while in situ hybridization was applied to investigate the mRNA expression of Matrix Metalloproteinase-9 (MMP-9) in 20 cases of human AAA and 4 cases of normal human abdominal aortas.

RESULTS

Inflammatory infiltration occurred in every case of AAA with various degree, and there was a parallel tendency between the degree of injury of abdominal aortic elastin and that of inflammatory infiltration in AAA. Inflammatory infiltration was not found in normal aortas. MMP-9 mRNA was detected in macrophages and lymphocytes in all 20 cases, in smooth muscle cells in 13, and not in normal abdominal aortas.

CONCLUSIONS

Inflammatory infiltration attended and enhanced the formation of AAA through a complex of sequence of biochemical, cellular and immune events.

[Relationship between PDGF-A, bFGF and proliferation of smooth muscle cells in vein grafts]

OBJECTIVE

To detect the relationship between platelet-derived growth factor-A (PDGF-A), basic fibroblast growth factor (bFGF), and proliferation of smooth muscle cells in vein grafts.

METHODS

An animal model of autogenous vein graft was established by transplanting internal branch of the jugular vein to the common iliac artery by end-to-end anastomosis. 25 rats were used. The grafted veins were harvested at 6 h, 2 d, 1 w, 2 w and 4 w respectively after the operation. The expression of PDGF-A and bFGF in different stages after grafting procedure was observed immunohistochemically.

RESULTS

The expression of PDGF-A peaked at 1 w, paralleled with proliferation of SMC, and was significantly higher than that at 6 h (P < 0.01). The expression of PDGF-A diminished gradually. At 4 w, it was significantly lower than that at 1 w (P < 0.01). bFGF demonstrated bimodal pattern of the expression: the first peak of expression occurred by 2 d and the second peak by 2 w. The difference was significantly compared with other stages.

CONCLUSIONS

The expression of PDGF-A 1 contributed to migration and proliferation of SMC. Except for contributing to proliferation of SMC, bFGF perhaps took part in endothelization.

[The relation-ship between apoptosis, apoptosis related-gene expression and proliferative activity in smooth muscle cell after autogenous vein grafting]

OBJECTIVE

To study the mechanism of graft vein stenosis.

METHODS

A rat experimental model of autogenous vein graft was established by transplanting the right external jungular vein into the infrarenal abdominal aorta in 100 Wister rats. Electric microscope, TUNEL and immunohistochemical S-P technique were used to detect the apoptosis, the expression of apoptosis related-gene bcl-2 and bax and proliferation cell nuclear antigen (PCNA) of smooth muscle cells(SMCs) in vein graft.

RESULTS

From 1 to 8 weeks after replacement, the expression of apoptosis and PCNA of SMCs was continuously higher than the control group (P < 0.01). From 1 to 2 weeks, the expression of TUNEL and PCNA showed peak value. From 1 to 2 weeks, the positive rate of apoptosis was lower than that of PCNA, but from 4 to 8 weeks, the positive rate of TUNEL was higher than that of PCNA. There was obvious positive correlation between the expression of TUNEL and PCNA (r = 0.813 P < 0.05). One to 2 weeks after vein grafting, bcl-2 positive rate increased and was more different than the control group and the group of 4 to 8 weeks after vein grafting (P < 0.010).

CONCLUSIONS

The imbalance of proliferation and apoptosis may be related to the vessel remodeling and vein graft stenosis, and bcl-2 and bax protein may involve in the regulation of apoptosis of VSMC. Adopting the mixed strategy to regulate the balance between proliferation and apoptosis may be useful to prevent vein graft stenosis.

[Reconstruction of esophagus by microsurgical technique in forty-five cases]

Reconstruction and repair of atresia or defect of the upper portion of esophagus is difficult. From November 1980 to December 1997, forth-five cases, consisting 35 males and 10 females, were treated with microsurgical technique. The 45 patients fell into the following groups as esophageal atresia of various causes in 21 cases, anastomotic fistula or stenosis following reconstruction of esophagus in 7 cases and late carcinoma of esophagus in 17 cases. The types of reconstruction consisted of transfer of free jejunum with its lower portion carrying a vascular pedicle in 24 cases, free transfer of jejunal graft in 15 cases, free vascularized jejunal graft in 2 cases and free vascularized tubular skin graft in 4 cases. After a follow-up of 6-19 months besides eight cases died from late esophageal carcinoma, thirty-seven cases were survived and could take food by mouth. All of the benign cases could return to work. In patients having late esophageal carcinoma, the operative procedure could improve the life quality and facilitate chemotherapy and radiotherapy.

[Management of true extremity aneurysms: experience in 23 patients]

OBJECTIVE

To explore the etiologic feature and specificity of diagnosis and treatment in true aneurysms of the extremities.

METHOD

23 patients with true aneurysms of the extremities from January 1984 to September 1997 were retrospectively reviewed.

RESULT

Of 30 true aneurysms of the extremities, multiple aneurysms were found in 7 patients (30.4%). The multiple aneurysms were diagnosed in the same time or in different time. 21 patients were treated by exclusion of aneurysm and replacement with autogenous saphenous vein or graft.

CONCLUSION

Early diagnosis and treatment are recommended to prevent complications which can cause limb loss, and multiple aneurysms must be taken into account. Importance of arteriography should be stressed in the diagnosis of multiple aneurysms. Exclusion of aneurysm and autogenous saphenous vein reconstruction is the first choice of treatment, circulation of the operated extremities should be noticed and close follow-up is imperative to pay attention to the development of new aneurysms.

[Surgical treatment of extracranial carotid artery aneurysm]

OBJECTIVE

To study the experience in the treatment of extracranial carotid aneurysm.

METHODS

67 cases of extracranial carotid artery aneurysm(ECAA) were treated surgically from January 1986 to June 1997.

RESULTS

There were a mortality rate of 1.5% and a hemiparalysis rate of 4.5%.

CONCLUSION

Clinical examinations are important for diagnosis of ECAA. Angiography plays a significant role in understanding the morphology, function, pathophysiology of ECAA. To decrease postoperative cerebral ischemia, collateral circulation of cerebral vessels should be evaluated and matas test done. Correct operative method is a key factor for successfull treatment.

[Ultrasonic angiography in therapeutic decision-making in peripheral occlusive vascular diseases]

OBJECTIVE

To study quickscan (QS) in different therapeutic decision-making in 55 patients with peripheral occlusive vascular diseases.

METHODS

Based on QS results, 30 patients were treated conservatively. The disease progress and therapeutic effects were assessed by QS in every three months. Percutaneous transluminal angioplasty was performed successfully in 5 patients without prior diagnostic angiography. 20 patients were scheduled for surgery. Operation of eleven patients was guided by information obtained from QS findings only, which was confirmed during operation. Angiography was necessary in 9 patients except one to formulate a therapeutic strategy.

RESULTS

The accuracy of QS was 92%(23/25).

CONCLUSION

QS is of value in deciding the access route of angiography and PTA, and can replace preoperative angiography, Quickscan is time-saving, inexpensive, objective and accurate. It can be used in therapeutic decision making in peripheral occlusive vascular diseases and bypass grafting.

The accuracy of color Doppler flow imaging for the detection of symptomatic deep venous thrombosis in Chinese patients

To evaluate the ability of color Doppler flow imaging (CDFI) to detect deep venous thrombosis (DVT), which is difficult to diagnose clinically, 67 limbs of 60 patients who presented with clinical signs strongly indicative of DVT during the period between June 1988 and June 1992, were examined. The iliac, common femoral, and superficial femoral veins were assessed with the patient in the supine position, and the popliteal vein was examined with the patient prone. Gentle but firm compression with the transducer probe was used to test for the presence of DVT. Ascending contrast venograms were also obtained within 24 h after the ultrasound procedure, with venography being used as the standard for comparison with CDFI. DVT was identified in 63 limbs by contrast venography and in 62 limbs by CDFI. The sensitivity and specificity of CDFI were 98.4% and 100%, respectively, while the positive and negative predictive values were 100% and 80%, respectively. The thromboses were classified into three patterns: the filling type, the local type, and mural thrombus, detected in 63%, 27%, and 10%, of the limbs respectively, with the filling type being the most common in this series. The results of our study illustrated that CDFI is highly sensitive and specific for detecting symptomatic DVT and that it should be gradually substituted for venography in such patients.

Experience in prevention of serious complications of laparoscopic cholecystectomy

OBJECTIVE

To study the causes and prevention of the complications of laparoscopic cholecystectomy (LC).

PATIENTS AND METHODS

Based on experience with 2 428 cases, the following should be paid attention to when dissecting and separating adhesions around the gallbladder and of the Calot's triangle. The best method for the prevention of mistaking the common bile duct (CBD) for the cystic duct is to find the junction of the cystic infundibulum and duct, separate the gallbladder wall along the infundibulum, and transect the cystic duct at the junction with the infundibulum. If dense adhesions around the gallbladder or of the Calot's triangle are met with, LC should be abandoned and open the cholecystectomy (OC) should be used instead. In separating the Calot's triangle, blunt dissection should be used to avoid burning the extrahepatic bile duct (EHBD), and blind hemostasis should be avoided. If the cystic artery lies in the upper part and the back of the cystic duct, the cystic duct should be dissected out, clipped and cut first, then the cystic artery be dealt with. If the cystic artery is in the front part of the pedicle of the gallbladder, the artery should be separated, clipped and cut first. Injury to the adjacent organs may be avoided by using electric coagulating hook correctly and avoiding accidental damage to the viscera, and keeping from viscera injury due to current chemotaxis in the closed cavity of the body.

RESULTS

A total of 2427 patients were cured. One patient died of frequent episodes of supraventricular tachycardia and pneumonia on the 21st day after LC.

CONCLUSION

If LC surgeons follow the above said principles of LC technique. LC is very safe for patients with benign diseases of the gallbladder.

[Ultrasonic angiography in diagnosis of peripheral vascular disease]

The ability of Quickscan (QS) was studied to assess haemodynamically significant lesions in the iliac and femoro-popliteal arteries. Quickscan was prospectively and independently compared to digital subtraction angiography (DSA) of the iliac and femoro-poplited arteries. In 155 patients, 631 arterial segments were evaluated. A QS frequency ratio of greater than 1:3 had a sensitivity of 93% and a specificity of 85% in detecting stenosis > 50% diameter (75% area) reduction in the iliac artery as shown on DSA. The sensitivity and specificity for stenosis in the femoral and popliteal arteries were 85%, 96%, 82%, 98% respectively. In the detection of occlusion, QS had a sensitivity of 84% and a specifity of 98% in the iliac artery; 94%, 97%, in the femoral; and 94%, 85% in the popliteal arteries respectively. There was a significant correlation between the area reduction found by QS and the calf/brachial pressure index (CBI) (r = -0.77 P < 0.01). 35 patients underwent successfully angioplasty based on QS findings. We conclude that quickscan can provide an inexpensive, quick and noninvasive screening technique for the routine initial assessment of peripheral vascular disease.

A two-year experience with laparoscopic cholecystectomy--a report of 1475 cases from Kunming, China

Over a 2-year period, from 12 September 1991 to 11 September 1993, laparoscopic cholecystectomy was performed on 1475 patients with benign gallbladder disease in Kunming General Hospital, Yunnan, China. Of these, 28 cases (1.9%) were converted to open surgery. Various complications were documented in 27 instances including extrahepatic bile duct injury in 4 cases (0.3%), postoperative haemorrhage requiring laparotomy in 3 cases (0.2%) and bile leak from cystic duct stump in 1 case (0.07%). There was 1 (0.07%) death in the series. The junction between the gallbladder infundibulum and the cystic duct is an important landmark which laparoscopic surgeons must identify in the course of the procedure. Because the junction remains a comparatively constant landmark, in difficult laparoscopic cholecystectomy, excessive dissection of the bile duct would be unnecessary. During dissection of the hepatic hilus, blund dissection is recommended and the blind use of cautery and haemostasis should be avoided.

Purification and characterization of hedgehog liver metallothioneins

Two forms of liver metallothioneins (MTs) were purified from hedgehog exposed to zinc, using gel filtration on Sephacryl S-100 and DEAE Sepharose Fast Flow chromatography. The peptide chain weight of both MT-1 and MT-2 was found to be about 10,000, as determined by high performance liquid chromatography. This value was higher than that calculated from amino acid analysis. The amino acid composition of hedgehog liver MT-1 and MT-2 resembles that of liver to MTs from rabbit and other species. Their distinctive features include an extremely high cysteine content, about 33% of all the amino acid residues, and an absence of aromatic amino acids and histidine. In addition, a rapid method for the determination of MTs during animal tissue purification has been established. The samples were directly added in an ammoniacal solution of a Co(II) salt for recording linear sweep polarograms. By comparison with the commonly used metal determination method, our method is direct, rapid, credible and suitable for all the MTs or MT-like samples.