The identification of serum tuftsin by reverse-phase high-performance liquid chromatography and mass spectrometry

Pharmacokinetics and bioavailability of tuftsin-derived T peptide, a promising antitumor agent, in beagles

Tuftsin, a natural phagocytosis-stimulating tetrapeptide, had aroused much interest in tumor immunotherapy, but the poor pharmacokinetics hampered its clinical developments, for that it was extremely susceptible to degradation by enzymolysis in vivo. T Peptide (TP) was a newly designed tuftsin derivative aimed to enhance stability and was proved to have significant antitumor activity. In this study, the pharmacokinetics and bioavailability of TP was first clarified in beagles with subcutaneous administration, by using a simple and robust competitive ELISA method. Dose-dependency and non-linear dynamics of TP after single-dose (2, 6 and 18 mg kg(-1), respectively) were found, and the half-time of TP was proved to reach 1.3-2.8 h. Multiple dosing of 6 mg kg(-1) once a day for 7 days resulted in a slight accumulation (accumulation index was 1.92 ± 0.43), indicating that the dosing interval in the following clinical trial needs to be extended. The absolute bioavailability of TP was 31.1 ± 6.2% after subcutaneous administration. These results first demonstrated the pharmacokinetics and bioavailability data of TP in vivo, which illustrated the potential druggability of TP and provided useful information for the dosage regimen design in the following clinical trials, as well as a simple and feasible analytical method for clinical sample analysis.

Splenic autotransplantation and oesophageal transection anastomosis in patients with portal hypertension (26 years clinical observation)

The surgical treatment methods for cirrhosis patients complicated with portal hypertension are complicated. In this study, we evaluated the effectiveness of a new treatment strategy: splenic auto-transplantation and oesophageal transection anastomosis on 274 patients from three aspects: clinical observation, splenic immunology and portal dynamics. From 1979 to 2005, 274 cirrhosis patients with portal hypertension who underwent the new treatment strategy were followed up to observe different clinical indexes, which were then compared with those of the traditional surgery treatment. From 1999 to 2002, a randomized control trial (RCT) was performed on 40 patients to compare their immune function after operation. From 1994 to 2004, another RCT was carried out on 28 patients to compare the portal dynamics through three-dimensional dynamic contrast enhanced MR angiography (3D DEC MRA) investigation after operation. Among 274 patients (mean age 41.8 years), the emergency operative mortality (4.4%), selective operative mortality (2.2%), complication rate (17.9%), morbidity of hepatic encephalopathy (<1%), bleeding rate of portal hypertension gastritis (PHG) (9.1%), and morbidity of hepatic carcinoma (8%) were similar to those under traditional operation; the spleen immunology function (Tuftsin, IgM) decreased among the groups 2 months after operation. Through 3D DCE MRA, the cross section area, the velocity and volume of blood flow of main portal vein decrease significantly after operation in both groups, the auto transplantation group was significantly lower in velocity and volume of blood flow than in the control group. Splenic auto transplantation and esophageal transection anastomosis are a safe, effective, and reasonable treatment strategy for portal hypertension with varicial bleeding. It can not only correct hypersplenism but also completely stanch blood, and auto transplanted spleen in the retroperitoneal space can preserve immune function and establish abroad collateral circulation.

Profiling histidine-containing dipeptides in rat tissues by liquid chromatography/electrospray ionization tandem mass spectrometry

The histidine-containing dipeptides carnosine (CAR) and structurally related anserine (ANS) and homocarnosine (HCAR), widely distributed in vertebrate organisms, have recently been proposed as endogenous quenchers for highly cytotoxic alpha,beta-unsaturated aldehydes generated by peroxidation. A sensitive, selective, specific and rapid liquid chromatographic/electrospray ionization tandem mass spectrometric assay was developed and validated for the simultaneous determination of these peptides in biological matrices in order to establish their plasma/tissue distribution. Samples (plasma or tissue homogenates from male rats) were prepared by protein precipitation with HClO(4) (1 : 1, v/v) containing H-Tyr-His-OH as internal standard. The supernatant was separated on a Phenomenex Sinergy polar-RP column with a mobile phase of water-acetonitrile-heptafluorobutyric acid (9 : 1 : 0.01, v/v/v) at a flow-rate of 0.2 ml min(-1), with a run time of 10 min. Detection was effected on an ion trap mass spectrometer equipped with an electrospray ionization interface operating in positive ionization mode. The acquisitions were in the multiple reaction monitoring mode using the following precursor --> product ion combinations: H-Tyr-His-OH (internal standard) m/z 319 --> 301; CAR m/z 227 --> 210 + 209; ANS m/z 241 --> 224 + 197 + 170; HCAR m/z 241 --> 156. The method was validated over the concentration range 15-1000 nmol g(-1) and the limit of quantification (LOQ) and limit of detection (LOD) were 12.5 and 4.2 pmol injected, respectively. The intra- and inter-day precisions were <10% (< or =17.47% at the LOQ) and the intra- and inter-assay accuracies were within +/-10% for all concentrations. The mapping profile in rat tissue gave the following results: the highest concentrations of CAR and ANS were found in skeletal muscles (soleus, gastrocnemius, tibialis), followed by the heart, cerebellum and brain (ANS below the LOQ). HCAR was found only in the brain and cerebellum. No histidine-containing dipeptides were detectable in plasma, liver, kidney and lung.

Tuftsin: on the 30-year anniversary of Victor Najjar's discovery

After a short description of the results of Victor Najjar's research on tuftsin and of the discoveries done by other authors in the early stage of tuftsin investigation, the current state of work on tuftsin is presented, based mainly on the literature published in the years 1984-1997. The presentation follows this order: the occurrence of tuftsin and retro-tuftsin sequences in proteins, their synthesis and biology, the antigenic properties of tuftsin, its influence on phagocytic cells, and other biologic activities of tuftsin, including antimicrobial, antiviral, antitumor and central effects, and the search for tuftsin superactive analogs.

Quantitative analysis of methionine enkephalin and beta-endorphin in the pituitary by liquid secondary ion mass spectrometry and tandem mass spectrometry

This manuscript reviews the use of an off-line combination of liquid chromatography (LC) and mass spectrometry (MS) to quantify endogenous neuropeptides in biological tissues and fluids, and tandem MS (MS/MS) to optimize the molecular specificity of the quantification of native peptides. Reversed-phase high-performance liquid chromatography (RP-HPLC) was used to purify selected endogenous neuropeptides from biological tissues and fluids. Liquid secondary ion MS (LSI-MS), also known as fast atom bombardment (FAB), is used to desorb and to ionize the peptide. The corresponding stable isotope-incorporated synthetic peptide of each peptide is used as the internal standard (I.S.) for quantification. The measurement of methionine enkephalin (ME) and of beta-endorphin1-31 (BE) in the human pituitary is described. This analytical method offers the highest molecular specificity for the measurement of a fully post-translationally modified peptide.

Mass spectrometric quantification of the mu opioid receptor agonist Tyr-D-Arg-Phe-Lys-NH2 (DALDA) in high-performance liquid chromatography-purified ovine plasma

The mu opioid receptor agonist Tyr-D-Arg-Phe-Lys-Amide (D-Arg2-Lys4-Dermorphin(1-4)amide=DALDA) was infused continuously for 2 h into sheep. The presence of DALDA in ovine plasma was determined by reversed-phase high-performance liquid chromatography (RP-HPLC) and mass spectrometry (MS) in plasma samples that were obtained at different times during and following that infusion. A stable isotope-incorporated internal standard, deuterated DALDA (d5-DALDA), was used for the MS quantification of DALDA via the protonated molecule ion, (M+H)+, of DALDA and of d5-DALDA. Time-course data (microg DALDA ml(-1) plasma vs. time) were obtained. Tandem MS (MS-MS) provided the product-ion spectrum of the (M+H)+ ion of DALDA in one of the samples to confirm the amino acid sequence of DALDA.

Sample preparation, high-performance liquid chromatographic separation and determination of substance P-related peptides

This review deals with the determination of low levels of substance P and peptide fragments derived from the undecapeptide, i.e. covers the whole amount of so-called substance P-like immunoreactivity (SPLI) in biological samples. First an overview of the most currently used sample pretreatment procedures is given, followed by a description of the most effective high-performance liquid chromatographic (HPLC) separation methods. Special attention is paid to the choice of the appropriate column and the possible pitfalls encountered in separation of fmol amounts of peptide material. Subsequently the most important techniques of detection are discussed. This section primarily focuses on the coupling of HPLC with radioimmunoassay (RIA), which is indispensable for detection of components in the fmol range at present. Finally, some aspects of preparation and chromatographic separation of radiolabelled antigens for use in RIA are discussed.

Recovery of substance P and related C-terminal fragments on solid-phase extraction cartridges for subsequent high-performance liquid chromatographic separation and radioimmunoassay

The recoveries of substance P (SP) and five related peptides were evaluated on different types of solid-phase extraction sorbent. Best results were obtained by use of a C18 silica gel cartridge. Marked differences of extraction yields occurred for the different peptide fragments and, in general, recovery increased with increasing hydrophobicity of the peptide when reversed-phase materials like C18 and C8 cartridges were used. This observation is indicative of a sorption-desorption mechanism by prevailing solvophobic interactions. A similar trend was found when phenylpropyl silica gel (CPhenyl), generally known as a reversed-phase adsorbent of lower hydrophobicity, was used. It was concluded that a substantial participation of analyte-matrix pi-pi interactions has to be taken into account when extraction yields are compared with corresponding values obtained by use of a C8 cartridge. With CN silica gel cartridges, marked differences in extraction yields were obtained by use of acetonitrile or methanol as the organic modifier. As an attempt to explain this observation, conformational effects were assumed for the sorption-desorption behaviour of the peptides on the polar matrix.

The lack of antigenicity of tuftsin: a naturally occurring phagocytosis stimulating tetrapeptide

Tuftsin (Thr-Lys-Pro-Arg) is a naturally occurring tetrapeptide that stimulates all known functions of the polymorphonuclear leukocyte and macrophage cell lines. Tuftsin is located in the FC region of IgG between the 289 and 292 amino acid sequence of the CH2 domain. We describe unsuccessful attempts to generate antituftsin antibodies. In separate experiments tuftsin was chemically conjugated to methylated bovine serum albumin (CH3BSA), BSA, keyhole limpet hemocyanin (KLH) and purified protein derivative (PPD). Tuftsin was also polymerized with glutaraldehyde. Animals used for immunization were rabbits, roosters, and dogs. All experiments failed to produce antituftsin antibody. Probable reasons for the lack of antigenicity include: I) Lack of "foreignness" of tuftsin in mammal species. II) The small size of the tetrapeptide. III) Tuftsin may be exerting an adjuvant effect when coupled to foreign antigens and is therefore not recognized by the host immune system.

Optimizing recovery of peptides from an octadecylsilyl (ODS) cartridge

An analytical procedure has been studied in detail to optimize the recovery of the radiolabeled and unlabeled synthetic peptides substance P and methionine-enkephalin from a reversed phase octadecylsilyl disposable cartridge, which is one of the first steps to preferentially enrich peptides from a biologic matrix. Our previous research on biologic peptides indicated the need for the present study. The column flow-rate was found to be one of the most important experimental parameters; and its effect on the recovery of those two synthetic peptides was determined by the measurement of recovered radioactivity and by high performance liquid chromatography u.v. detection. The accuracy and reproducibility of the flow-rate affected recovery, and it was necessary to regulate the flow-rate with a syringe infusion pump. Recovery was optimum using a slow rate for both sample application and elution. Furthermore, a slow elution was more important than a slow rate of sample application. Such basic recovery studies on individual synthetic peptides are required before undertaking peptide extractions from biologic matrices.

Tuftsin: its chemistry, biology, and clinical potential

Tuftsin is a tetrapeptide, Thr-Lys-Pro-Arg, which resides in the Fc-domain of the heavy chain of immunoglobulin G. The peptide originates from a specific fraction of the parent protein through enzymatic processing. Tuftsin possesses a broad spectrum of activities related primarily to the immune system function and exerts on phagocytic cells, notably on macrophages. These include potentiation of various cell functions such as phagocytosis, motility, immunogenic response, and bactericidal and tumoricidal activities. The features of tuftsin, coupled with its low toxicity, make the peptide an attractive candidate for immunotherapy. Tuftsin's capacity to augment cellular activation is mediated by specific receptors that were identified, characterized, and recently isolated from rabbit peritoneal granulocytes. Tuftsin has been chemically synthesized by a variety of techniques, some of which are adequate for large-scale preparations. A multitude of analogs have also been synthesized and extensively studied for structure-function relationships.