[Comparison of mid-cheek tumors endoscopically assisted dissection between a single preauricular or transoral incision].

Objective: To summarize the preliminary experience of endoscopically assisted mid-cheek benign tumor resection using a single preauricular or transoral incision and to evaluate its indications, advantages, and disadvantages. Methods: Thirty-six patients with benign mid-cheek tumors were prospectively enrolled, including 11 males and 25 females, aged (37.2±15.9) years and ranged from 11 to 65 years old. The patients were randomly divided into two groups: endoscope-assisted tumor dissections through a single preauricular incision (19 cases) or transoral incision (17 cases). Their surgical approaches were introduced, and the tumor long-axis length, incision length, operative time, estimated intraoperative bleeding, postoperative drainage amount and time, aesthetic satisfaction, perioperative complications, and follow-up were recorded and analyzed. Results: The difference between the tumor long-axis lengths in the preauricular group [(2.2±0.9) cm] and the transoral group [(2.1±0.7) cm] was not statistically significant (t=0.46, P=0.687), and all surgical procedures were completed as planned. There was no significant difference in the incision size (t=1.57, P=0.100) or operative time (t=0.44, P=0.736). Compared with the preauricular group [(30.8±8.7) ml], transoral incision [(23.6±8.9) ml] reduced intraoperative blood loss (t=2.97, P=0.006) and improved aesthetic pleasure (t=3.44, P=0.015). Two cases of earlobe numbness and one case of temporary facial palsy were observed in the preauricular group; two cases of postoperative effusion were noted in the transoral group, and no signs of nerve injury were detected. No tumor recurrence was found during the 1-54-month of follow-up. perioperative complications. Conclusions: Endoscopic-assisted preauricular or transoral incision for dissecting mid-cheek benign tumors provides excellent aesthetic and minimally invasive results, reducing complications and obtaining satisfactory aesthetic results.

[A novel surgical technique for neck neoplasms: endoscope-assisted resection of benign tumors via a small concealed incision].

Objective: To introduce a new surgical procedure for the treatment of neck benign tumors by endoscopic techniques. Methods: Seventeen patients with neck benign tumor underwent surgery by endoscope through a concealed incision in Department of Oral and Maxillofacial Surgery, Qilu Hospital of Shandong University from January 2018 to August 2019 were analyzed, which included 3 cases of tumor in the submental area, 2 cases in submandibular region, 9 cases in lower pole region of parotid gland, 1 case in superior region of sternocleidomastoid muscle, 1 case in central region of sternocleidomastoid muscle, 1 case in inferior region of sternocleidomastoid muscle. All patients underwent routine preoperative examination and CT examination to evaluate tumor size, boundary, morphology and nature. According to the area where the tumor located, concealed incisions in different sites were designed. Lumps in the submental area and submandibular area were treated with oral vestibular sulcus incision. Benign tumors located in the lower pole region of parotid gland and the sternocleidomastoid muscle region were treated with approach of the short hidden postauricular incision. During the operation, the self-developed "maxillofacial suspension device" was used to provide the operating space. The tumors were completely removed with endoscope and all patients were followed up every 3 months. Results: All surgical procedures were performed as expected. Visual analogue scale (VAS) was 9.3 on average at 3 months after operation, all the patients were satisfied with the incision design and the cosmetic effect. No recurrences were found in patients with a follow-up period ranged from 1-15 months. Conclusions: These studies have shown that endoscope-assisted neck benign tumor resection is a surgical procedure with covert incision and good cosmetic results.

[Preliminary study on endoscope-assisted resection of superficial benign tumor of parotid gland].

Objective: To summarize the preliminary experience of endoscope -assisted resection of superficial parotid gland benign tumors, and to discuss the indications, advantages and disadvantages of the operation. Methods: The clinical data of 18 patients who underwent extracapsular resection of superficial parotid gland benign tumor in Department of Oral and Maxillofacial Surgery, Qilu Hospital of Shandong University from March 2018 to March 2019 were retrospectively analyzed, and the surgical methods were introduced. The indications, long axis length of tumor, incision design, operation time, intraoperative blood loss, postoperative drainage and drainage time, aesthetic satisfaction, postoperative complications and follow-up time were counted. Results: All procedures were completed as expected. The length of the long axis of the tumor was (2.3±0.6) cm, the incision in the tragus around the earlobe was short and concealed, the incision length was (5.1±1.3) cm, the operation duration was (2.0±0.4) h, intraoperative blood loss was (168.9±18.8) ml, postoperative drainage was (29.5±11.7) ml, drainage time was (3.6±0.5) d, 2 cases of temporary facial paralysis or earlobe numbness, three months after the operation, the results of the visual analogue scale of the incision design and the aesthetic effect were (9.6±0.1). Conclusions: Endoscope-assisted resection of superficial parotid gland benign tumor by inner tragus around earlobe approach is applicable and reliable, can reduce complications, shorten surgical incision to obtain satisfactory aesthetic effect, which is worth further expansion and improvement.

Expression of Kif5b protein is significantly associated with the progression, recurrence and prognosis of oral squamous cell carcinoma.

OBJECTIVE: Kinesin family member 5b (Kif5b), a conventional kinesin, mainly participates in lysosome and mitochondria transportation. Some studies have indicated that Kif5b may be associated with the development of a variety of tumors. However, the role Kif5b plays in oral squamous cell carcinoma (OSCC) has yet to be determined. Our study aimed at investigating the expression level of Kif5b in primary OSCC and discussing its clinical significance in patients' outcomes. PATIENTS AND METHODS: We measured Kif5b expression in 82 OSCC tissue samples with immunohistochemistry. The associations between the expression level of Kif5b and clinicopathological characteristics as well as patients' survival were statistically assessed. RESULTS: Kif5b level was significantly associated with tumor size (p=0.034), histological differentiation (p=0.028), disease recurrence (p=0.018), surrounding tissue invasion (p=0.045), recurrence time (p=0.036) and survival status (p=0.030). Kaplan-Meier cumulative survival analyses indicated that high expression of Kif5b was linked to worse overall survival (p=0.0112) and disease-free survival (p=0.0085). The univariate and multivariate Cox proportional hazard analysis further identified the expression status of Kif5b as an independent variable that correlated with patients' survival and recurrence. Furthermore, in 54 early-stage, clinically node negative OSCC patients, Kif5b expression were correlated with histological differentiation (p=0.034), disease recurrence (p=0.038) and surrounding tissue invasion (p=0.029). Univariate and multivariable logistic regression results showed that only Kif5b expression level could influence the probability of recurrence. CONCLUSIONS: Our results reveal that Kif5b expression is associated with poor clinical outcome in OSCC and even in early-stage, clinically node negative OSCC and may be a potential target for OSCC treatment.

Note: investigation on the influences of gripping methods on elastic modulus by a miniature tensile device and in situ verification.

In this paper, by gripping the specimen on various positions, including the gripping section, stress concentration transition section, and gauge length section, theoretical analysis on the influences of gripping methods on tensile elastic modulus calculation was investigated with a group of equations. Then, an image-based displacement measurement system was implemented, and the experimental verification via in situ tensile testing was carried out to verify the feasibility of the theoretical analysis by a miniature tensile device integrated with a metallographic microscope. The stress-strain curves of 2026 aluminum alloy were also obtained by gripping the specimens on various positions to illustrate the influences of gripping methods. The influence of gripping methods on elongation measurement was also investigated. This paper showed a modular calculation method of elastic modulus for the tensile testing of typical plate specimens.

Enhancing the hypotensive effect and diminishing the cytolytic activity of hornet mastoparan B by D-amino acid substitution.

Mastoparan B (MP-B) is a cationic tetradecapeptide (LKLKSIVSWAKKVL-CONH(2)) isolated from the venom of the Taiwan hornet Vespa basalis. Unlike other vespid mastoparans, the peptide is capable of inducing short-term hypotension and causes hemolysis in animals. This study was aimed to find out MP-B analogs that possess higher hypotensive potency with the least lytic action by D-amino acid substitution, especially at lysine (Lys) residues. The synthetic MP-B isomer in which Lys(2) was replaced by D-Lys showed a significant decrease in both hemolytic and hypotensive activities. Substitution of Lys(4) by D-Lys in MP-B also caused a marked reduction of hemolytic activity, but its hypotensive action was only slightly affected. However, when Lys(11,12) were replaced by D-Lys, the resulting isomer ([D-Lys(11,12)]MP-B) exhibited a higher hypotensive activity with negligible hemolytic activity as compared with the native peptide. The D-antipot of MP-B in which all amino acid residues were replaced by D-isomers showed the highest hypotensive activity with a hemolytic activity about 1/5 that of MP-B. The results reveal that D-Lys substitution at the N-terminus of MP-B (Lys(2,4)) causes decreases in both hypotensive and hemolytic activities, while D-Lys substitution at the C-terminus (Lys(11,12)) leads to a significant increase in hypotensive activity of MP-B with a remarkable decrease in hemolytic activity. The hypotensive effect of [D-Lys(11,12)]MP-B was more prominent on spontaneously hypertensive rats. At a proper dose (0.3mg/kg) the peptide could reduce the high blood pressure (approximately 180 mmHg) of the rat to a normal level (approximately 120 mmHg) for more than 3h. [D-Lys(11,12)]MP-B which possesses a potent hypotensive action with the least cytolytic side effect is the best MP-B analog for studying the mechanism of cardiovascular inhibition by MP-B and could be useful as a hypotensive agent in hypertension crisis.

Application of artificial neural networks in multifactor optimization of an on-line microwave FIA system for catalytic kinetic determination of ruthenium (III).

A methodology based on the coupling of experimental design and artificial neural networks (ANNs) is proposed in the optimization of a flow injection system for the spectrophotometric determination of Ru (III) with m-acetylchlorophosphonazo (CPA-mA), which has been for the first time used for the optimization of high-performance capillary zone electrophoresis (J. Chromatogr. A 793 (1998) 317). And since it has been applied in many other regions like micellar electrokinetic chromatography, ion-interaction chromatography, HPLC, etc. (J. Chromatogr. A 850 (1999) 345; J. Chromatogr. A 799 (1998) 35; J. Chromatogr. A 799 (1998) 47). An orthogonal design is utilized to design the experimental protocol, in which five variables are varied simultaneously (Anal. Chim. Acta 360 (1998) 227). Feedforward-type neural networks with extended delta-bar-delta (EDBD) algorithm are applied to model the system, and the optimization of the experimental conditions is carried out in the neural network with 5-5-1 structure, which have been confirmed to be able to provide the maximum performance. In contrast to traditional methods, the use of this methodology has advantages in terms of a reduction in analysis time and an improvement in the ability of optimization. Under the optimum experimental conditions, Ru (III) can be determined in the range 0.040-0.60 mug ml(-1) with detection limit of 0.03 mug ml(-1) and the sampling frequency of 34 h(-1). The method has been applied to the determination of Ru (III) in refined ore as well as in secondary alloy and provided satisfactory results.

Electrophoretic behavior study and determination of some active components in Chinese medicinal preparations by capillary electrophoresis.

The determination of icariin (IC), rhein (RH), chrysophanol (CH), physcion (PHY), glycyrrhetic acid (GE), and glycyrrhizic acid (GI), in traditional Chinese preparations, Anshen Bunao oral liquid and Maren pill, has been investigated by micellar electrokinetic capillary electrophoresis. With borate buffer (10 mM), SDS (20 mM) and acetonitrile (10%) as background electrolyte (pH 9.55), 20 kV applied voltage and 254 nm UV detection, the six active compounds were completely separated within 10 min. The effects of buffer pH, concentration of borate, SDS and modifier on electrophoretic behavior and separation are discussed. Regression equations revealed linear relationships (correlation coefficients: 0.9960-0.9999) between the peak-area of each component and the content. In addition, the levels of the six active compounds in two kinds of traditional Chinese medicinal preparations were easily determined with recoveries of from 94.7% to 106.4%.

Direct solid-phase synthesis of octreotide conjugates: precursors for use as tumor-targeted radiopharmaceuticals.

Somatostatin analogues, such as octreotide, are useful for the visualization and treatment of tumors. Unfortunately, these compounds were produced synthetically using complex and inefficient procedures. Here, we describe a novel approach for the synthesis of octreotide and its analogues using p-carboxybenzaldehyde to anchor Fmoc-threoninol to solid phase resins. The reaction of the two hydroxyl groups of Fmoc-threoninol with p-carboxybenzaldehyde was catalyzed with p-toluenesulphonic acid in chloroform using a Dean-Stark apparatus to form Fmoc-threoninol p-carboxybenzacetal in 91% yield. The Fmoc-threoninol p-carboxybenzacetal acted as an Fmoc-amino acid derivative and the carboxyl group of Fmoc-threoninol p-carboxybenzacetal was coupled to an amine-resin via a DCC coupling reaction. The synthesis of protected octreotide and its conjugates were carried out in their entirety using a conventional Fmoc protocol and an autosynthesizer. The acetal was stable during the stepwise elongation of each Fmoc-amino acid as shown by the averaged coupling yield (> 95%). Octreotide (74 to 78% yield) and five conjugated derivatives were synthesized with high yields using this procedure, including three radiotherapy octreotides (62 to 75% yield) and two cellular markers (72 to 76% yield). This novel approach provides a strategy for the rapid and efficient large-scale synthesis of octreotide and its analogues for radiopharmaceutical and tagged conjugates.

[Morphological changes of muscle and capillary endothelial cells after aerobic exercise training under different temperature conditions].

The morphological changes of muscle cells and capillary endothelial cells of skeletal muscles were in wshigutet after long-term exercise training at various temperatures. One-hundred and forty rats were divided into seven groups and received a one-month exercise training at conditions of low (0 degree C), normal (26 degrees C) or high (42 degrees C) temperatures respectively. Muscle samples were obtained from extensor digitorum longus muscle (EDL) and soleus muscle (SOL) of each animal. These samples were used to observe the hitological differences by light microscope, and to observe the changes in the number of muscular mitochondria and capillary endothelial pinocytotic vesicles by electron microscope. We found that both low and high temperature groups had higher frequency of atrophy and necrosis in muscle fibers than the normal temperature group. Moreover, EDL muscle had significantly more mitochondria and pinocytotic vesicle than SOL muscle in the high and normal temperature groups. From these results, we suggested that changes of the environmental temperature cause histological malformations of muscle fibersabtw; in addition, these effects were more prominent in fast twitch muscles.

Comparison of three classes of snake neurotoxins by homology modeling and computer simulation graphics.

We present a systematic structure comparison of three major classes of postsynaptic snake toxins, which include short and long chain alpha-type neurotoxins plus one angusticeps-type toxin of black mamba snake family. Two novel alpha-type neurotoxins isolated from Taiwan cobra (Naja naja atra) possessing distinct primary sequences and different postsynaptic neurotoxicities were taken as exemplars for short and long chain neurotoxins and compared with the major lethal short-chain neurotoxin in the same venom, i.e., cobrotoxin, based on the derived three-dimensional structure of this toxin in solution by NMR spectroscopy. A structure comparison among these two alpha-neurotoxins and angusticeps-type toxin (denoted as FS2) was carried out by the secondary-structure prediction together with computer homology-modeling based on multiple sequence alignment of their primary sequences and established NMR structures of cobrotoxin and FS2. It is of interest to find that upon pairwise superpositions of these modeled three-dimensional polypeptide chains, distinct differences in the overall peptide flexibility and interior microenvironment between these toxins can be detected along the three constituting polypeptide loops, which may reflect some intrinsic differences in the surface hydrophobicity of several hydrophobic peptide segments present on the surface loops of these toxin molecules as revealed by hydropathy profiles. Construction of a phylogenetic tree for these structurally related and functionally distinct toxins corroborates that all long and short toxins present in diverse snake families are evolutionarily related to each other, supposedly derived from an ancestral polypeptide by gene duplication and subsequent mutational substitutions leading to divergence of multiple three-loop toxin peptides.

Controlled acid hydrolysis of colominic acid under microwave irradiation.

The hydrolysis of colominic acid under microwave irradiation was studied and compared with traditional heating methods. The microwave irradiation has several advantages over the heating method in the hydrolysis of colominic acid: (a) products with higher degrees of polymerization are obtained, (b) less lactone byproducts are observed, and (c) the hydrolytic rate is much faster. These advantages are probably due to the microwave effect. Oligosialic acids as the products of the acid hydrolysis of polysialic acid with conventional heating methods were fully lactonized, especially under the conditions of higher temperature and stronger acid.

Late development of renal arteriovenous fistula following gunshot trauma--a case report.

A 43-year-old man presenting with symptoms of congestive heart failure, cardiomegaly, and impaired left ventricular (LV) function was diagnosed as having a huge left renal arteriovenous (AV) fistula. The AV fistula might be attributed to a gunshot wound suffered during his military service twenty years ago. Percutaneous transcatheter arterial embolization utilizing multiple spring coils in conjunction with cyanoacrylic glue successfully occluded the fistula, with subsequent improvement of LV function and reduction of LV size on his serial echocardiographic follow-up.

The role of the N-terminal leucine residue in snake venom cardiotoxin II (Naja naja atra).

The N-terminal leucine residue of snake venom cardiotoxin II (CTX II) (Naja naja atra) was systematically replaced with D-leucine (CTXII-L1-D-L), glycine (CTXII-L1G) or deleted [CTXII-(2-60)] to study the role of leucine residue in CTX II molecule. CTX II, CTXL1-D-L, CTXL1G and CTX(2-60) were produced by chemical synthesis method and purified by high performance liquid chromatography. Owing to folding problem in CTXII-(2-60), only CTX II, CTXII-L1-D-L and CTXII-L1G were produced in a pure form and characterized by amino acid analysis, mass spectrometry and peptide mapping. In the structural aspect, changing the Leu-1 by D-Leu or Gly causes a drastic alteration in the whole CTX II structure as detected by circular dichroism, 1-anilino-naphthalene-8-sulfonate (ANS) fluorescence assay. In the functional aspect, both CTXII-L1-D-L and CTXII-L1G are still retained substantial biological activity of CTX II. Therefore, the results indicate that both the chirality and the side-chain of the N-terminal leucine residue of CTX II are important elements in maintaining the whole CTX II structure. In addition, this study is the first report in elucidating the reason why the first N-terminal residue of most CTXs (90.3%) is leucine residue.

Kinetic studies of the inhibitory effects of propeptides subtilisin BPN' and Carlsberg to bacterial serine proteases.

The propeptides of bacterial subtilisin BPN' and Carlsberg were synthesized to investigate their inhibitory function on the enzymes. Kinetically, pro-BPN' inhibits the proteolytic activities of subtilisin BPN' and Carlsberg separately in a slow binding mode. Pro-Carlsberg behaves as a typical rapid equilibrium competitive inhibitor for these two proteases. Functionally, pro-Carlsberg inhibits the subtilisins with moderate selectivity. The inhibition constant Ki of pro-BPN' to subtilisin BPN' is 5.0 nM, and 6.1 nM to subtilisin Carlsberg. The on-rate of pro-BPN' to subtilisin BPN' is 5.8 x 10(5) M(-1)s(-1), and the off-rate 2.9 x 10(-3) s(-1). Similarly, the on-rate of pro-BPN' to subtilisin Carlsberg is 2.2 x 10(5) M(-1)s(-1), and the off-rate 1.3 x 10(-3) s(-1). On the other hand, the Ki of pro-Carlsberg to subtilisin BPN' gives 1.3 x 10(2) nM, and 88 nM to subtilisin Carlsberg. Based on the key features of the interactions between pro-BPN' and subtilisin from X-ray crystallographic results (Gallagher et al., 1995), the correlation between the sequence of subtilisin propeptides and their inhibition abilities on the proteases are compared and discussed.

Protein engineering of venom toxins by synthetic approach and NMR dynamic simulation: status of basic amino acid residues in waglerin I.

The tertiary structure of waglerin I has been determined by NMR and dynamic simulated annealing [Chuang et al., Biochim. Biophys. Acta 1292, 145-155 (1996)]. It is believed that the peptide basicity of waglerin may play an important role for its activity due to its high content of basic amino acids. In order to investigate the active site of the toxin, seven analogues of waglerin, [Ala3]-waglerin, [Ala7]-waglerin, [Ala10]-waglerin, [Ala14]-waglerin, [Ala18]-waglerin, [Ala20]-waglerin and [Ala22]-waglerin have been synthesized chemically by single replacement of basic amino acid residues one by one with Ala. By correlation of structures for each analogue with LD50 toxicity bioassays, it is found that the [Ala10]-waglerin exhibits no toxicity and the active site of the native toxin seems to reside in the proximity of the disulfide loop, which is spatially close to His10. Furthermore, the closer is the disulfide loop to the basic amino acid in waglerin, the more influential is the basic amino acid on the toxicity of waglerin. Based on the tertiary structure of waglerin, the structures of all synthetic analogues were derived based on computer-simulated modelling. By the pair-wise structural comparison, the disulfide loop in [Ala10]-waglerin analogue is found to be twisted as compared to the native form, in agreement with the lack of toxicity for this synthetic analogue.

Structural characterization of the metal binding site in the cysteine-rich region of HIV-1 Tat protein.

Human immunodeficiency virus type-1 Tat protein transactivates the gene expression of retrovirus. The unique cysteine-rich region of Tat protein is biologically essential. This study characterizes the structural features of a synthetic Tat21-38 peptide covering the cysteine-rich region with Zn binding property. UV titrations confirm Tat peptide binds with two Zn2+ cations maximally per monomer, as previously reported(1). Only monomer is observed from the electrospray mass spectrum. Interestingly, a modified Ellman reaction (2) can differentiate a metal chelated thiolate of cysteine residue from a free one. Three disulfide bonds are formed in apo-Tat21-38 peptide. One Tat21-38 molecule utilize four Cys residues in coordination with the first incorporated Zn2+ cation. Five out of seven Cys residues are coordinating with two Zn cations of the complex Zn-Tat21-38 (2:1). A model of the coordination arrangement of Zn binding sites at different states is proposed.

[The effect of blood AST, ALT and lactate after short and middle distance exercise training].

Twenty-four nursing college students aged 16 and 17 years were selected as research subjects and divided into two groups. Group A comprised 12 individuals who were trained for short distance running (5km/day) over a four-week period, while group B was trained for middle distance running (7km/day) during the same period. Blood AST (aspartate aminotransferase), ALT (alanine aminotransferase) and lactate were performed at rest (before training) and after exercise every week. After both short and middle distance exercise training, the lactate values after 1-3 week(s) training period were persistently higher than those before training and the differences between then are significant. However, the lactate value after 4 weeks training period is lower than that after the third week training. There are significant differences between the AST values after 1-4 week(s) training period and those before exercise in short distance exercise training. There are no significant differences between the AST values after training and those before exercise in middle distance exercise training. The ALT values after 1-4 week(s) training period were lower than those before exercise in short and middle distance exercise training. In conclusion, after 4 weeks training, the lactate and AST values can't reduce to those before training in middle distance exercise training, and the lactate value in short distance exercise training is the same as former. Further investigation is needed.

Structural requirements for the edema-inducing and hemolytic activities of mastoparan B isolated from the hornet (Vespa basalis) venom.

Mastoparan B (MP-B) is a cationic tetradecapeptide isolated from the black-bellied hornet (Vespa basalis) venom. It has a primary structure (LKLKSIVSWAKKVL-CONH2) distinct from other vespine mastoparans. The peptide caused a dose-dependent swelling in rat hind paw and showed a potent hemolytic activity in guinea pig red blood cells. Studies on the structure activity relationship of the peptide showed that replacing lysine at position 2 (Lys2) by asparagine (Asn) in the MP-B sequence caused about 40% decrease in its edema-inducing activity at 50 micrograms/paw and 90% decrease in hemolytic activity at 30 microM of the peptide, while the same substitution at Lys4 did not cause a significant change in either activity. Replacing either Lys11 or Lys12 by leucine (Leu) caused little or no decrease in the edema-inducing and hemolytic activities. Decreases in both activities were observed when both Lys11 and Lys12 were replaced by Leu. On the other hand, replacing tryptophan at position 9 (Trp9) by tyrosine or phenylalanine in MP-B sequence almost abolished its hemolytic activity, while the edema-inducing activity was only partially inhibited. Circular dichroism spectra of the peptides measured in 20% trifluoro-ethanol revealed that substitution of Lys and Trp did not cause a significant change in the conformation of MP-B. it appears that Lys2 is crucial for both hemolytic and edema-inducing activities of MP-B, while Trp9 is of special importance to the hemolytic activity of MP-B. Lys11 and Lys12 in MP-B probably play a lesser role in both activities.

Structural analysis of a biologically active echistatin analogue des(46-49)-[Ala8,37]-echistatin gamma with three disulfide bonds by 2D-NMR and computer graphics.

An echistatin analogue, designated as des(46-49)-[Ala8,37]-echistatin gamma, was synthesized chemically by solid-phase peptide synthesis. The analogue was made by replacing Cys8 and Cys37 residues with two alanines and the deletion of C-terminal peptide 46-49 of echistatin gamma, resulting in an artificial polypeptide of 45 amino acids with three disulfide bonds. In the platelet aggregation assay, the analogue exhibits almost the same activity as echistatin gamma, indicating that the linear sequence of des(46-49)-[Ala8,37]-echistatin gamma contains all of the primary-structure information that is required for proper folding of this synthetic polypeptide. The tertiary structure of the analogue, as determined from high-resolution nuclear magnetic resonance (NMR) coupled with dynamic simulated annealing, is very similar to that of echistatin alpha1 which differs from echistatin gamma by 8 residues. In particular the two important sites of the Arg-Gly-Asp (RGD) loop and the C-terminal Lys45, both of which show some degree of disorder, are maintained in similar spatial orientation and proximity as those in echistatin alpha 1 even without the constraint provided by the disulfide bond of the (Cys8-Cys37) pair. These results provide new insights in further defining distinct structural features of echistatin gamma, which are involved in supporting the active polypeptide conformation to achieve biological activity in the absence of one pair of disulfide bonds.