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Biomedical subjects

S L Wu

Publications and source records attributed to S L Wu.

At least 19 recordsLinked to original sources
PubMed2006

Surface characteristics, mechanical properties, and cytocompatibility of oxygen plasma-implanted porous nickel titanium shape memory alloy.

Good surface properties and biocompatibility are crucial to porous NiTi shape memory alloys (SMA) used in medical implants, as possible nickel release from porous NiTi may cause deleterious effects in the human body. In this work, oxygen plasma immersion ion implantation (O-PIII) was used to reduce the amount of nickel leached from porous NiTi alloys with a porosity of 42% prepared by capsule-free hot isostatic pressing. The mechanical properties, surface properties, and biocompatibility were studied by compression tests, X-ray photoelectron spectroscopy (XPS), and cell culturing. The O-PIII porous NiTi SMAs have good mechanical properties and excellent superelasticity, and the amount of nickel leached from the O-PIII porous NiTi is much less than that from the untreated samples. XPS results indicate that a nickel-depleted surface layer predominantly composed of TiO(2) is produced by O-PIII and acts as a barrier against out-diffusion of nickel. The cell culturing tests reveal that both the O-PIII and untreated porous NiTi alloys have good biocompatibility.

Alloys↗
PubMed2005

Immunosuppression by combined use of cyclosporine and resveratrol in a rat liver transplantation model.

INTRODUCTION: Despite continued progress in the development of immunosuppressive agents, allograft rejection remains an important cause of morbidity and mortality after liver transplantation. We examined the effect of intraperitoneal injection of cyclosporine (CsA) and resveratrol (Res) on allograft rejection after liver transplantation in rats. METHODS: Male Sprague-Dawley rats were selected as donors and male Wistar rats as recipients for a rejection model. The recipients were divided into three groups after orthotopic liver transplantation (OLTx): in the combination group both Res (100 mg/kg) and CsA (20 mg/kg) were given by intraperitoneal route once a day, whereas in the CsA group or control group CsA (20 mg/kg) or vehicle buffer was given. The survival period, serum chemistry, production of some cytokines, activation of transcription factor NF- kappaB, and histopathological findings were then compared among them. RESULTS: The mean survival period after OLTx in the combination group was significantly longer than that in the CsA group or control group (P < .05 and P < .01). On posttransplant day 7, the serum albumin level significantly improved, the serum total bile acid and alanine aminotransferase levels were significantly lower, the serum interleukin-2 and interferon-gamma levels were significantly lower, and the activation of transcription factor NF-kappaB in peripheral blood T lymphocytes was significantly suppressed in the combination group in comparison with those in the CsA group (all P < .05) or control group (all P < .01), and a histological examination revealed apparent difference in the severity of rejection between the combination group and CsA group (P < .05) or control group (P < .01). CONCLUSION: The combined use of CsA and Res has a stronger immunosuppressive effect on hepatocytes under allograft rejection in comparison with the sole use of CsA. Res might serve as a novel supplementary immunosuppressive agent for reducing the severity of hepatic allograft rejection in rats.

Animals↗
PubMed2004

Effects of alginate coated on PLGA microspheres for delivery tetracycline hydrochloride to periodontal pockets.

The effects of alginate coated on tetracycline (Tc) loaded poly (D, L-lactic-co-glycolic acid) (PLGA) microspheres fabricated by double emulsion solvent evaporation technique for local delivery to periodontal pocket were investigated. Alginate coated PLGA microspheres showed smoother surface but enlarged their particle sizes compared with those of uncoated ones. In addition, alginate coated microspheres enhanced Tc encapsulation efficiency (E.E.) from 11.5 +/- 0.5% of uncoated ones to 17.9 +/- 0.5%. Moreover, all of the coated PLGA microspheres even fabricated at different conditions could prolong Tc release from 9-12 days with 50% or higher in cumulative release of Tc compared with those of uncoated ones. The swelling ratios of PLGA microspheres for alginate coated or uncoated ones, one of the possible mechanisms for enhancing Tc release for the coated ones, were measured. The results showed that 20% or higher in swelling ratio for the coated microspheres at the earlier stage of hydration (e.g. < or = 24 h) could be an important factor to result in high Tc release compared to the uncoated ones. In conclusion, alginate coated Tc loaded PLGA microspheres could enhance Tc delivery to periodontal pocket by enhancing drug encapsulated efficiency, released quantities and sustained release period compared with uncoated ones.

Alginates↗
PubMed2003

Expressions of Lewis antigens in human non-small cell pulmonary cancer and primary liver cancer with different pathological conditions.

The expressions of three X series Lewis antigens, including Lewis X (Le(x)), sialyl Lewis X (SLe(x)) and sialyl dimeric Lewis X (SDLe(x)) were studied with immuno-histochemical methods in human non-small cell pulmonary cancer (NSCPC) and primary liver cancer (PLC) with different pathological conditions. The Lewis antigens are mainly expressed on the cell surfaces, medially or slightly in the cytoplasm, but not in the cell nuclei of the cancer tissues. The regions adjacent to the cancer tissues do not express any Lewis antigens. The positive rates of these antigens in NSCPC were within the range of 75% to approximately 86%. There was no apparent difference in positive rates between the cases with different differentiation and the presence or absence of metastasis in peripheral lymph nodes, nor among the three antigens, except that the positive rate of SDLe(x) was lower (about 56%) in the cases with well/medium differentiation and without metastasis. However, the expression-intensities (SI indexes) of all three antigens were significantly higher in the samples of poor differentiation and with metastasis as compared to those with well/medium differentiation and without metastasis. The two sialyl Lewis antigens increased more significantly than non-sialylated Le(x). The expressions of these antigens were also observed in the peripheral lymph nodes with metastasis, but not in those without metastasis. The positive rates of Le(x), SLe(x) and SDLe(x) in human primary liver cancer were 83.3%, 88.9% and 77.8%, respectively. In the cases with cancer cell thrombosis (CCT) in portal vein (an index of metastasis), the expressions of all these three antigens were stronger than those in the cases without CCT. SLe(x) was the most abundant and most highly increased Lewis antigen on the surface of NSCPC and PLC, especially in the cases with poor differentiation and metastasis. In the study of the enzymatic basis of the increased Lewis antigens in PLC by using Northern blot, it was found that the level of alpha1,3 FucT-III/VI mRNA in PLC tissues was much higher than that in the adjacent regions, and more significantly higher in the cancer tissues from patients with CCT in portal vein. In contrast, the expression of alpha1,3 FucT-VII was rather low in cancer tissues and not different from the adjacent regions in spite of the presence or absence of CCT. These results reveal that the SLe(x) in PLC is mainly synthesized by alpha1,3 FucT-III/VI (especially VI) and is the most important Lewis antigen involved in the metastasis of PLC.

Carcinoma, Non-Small-Cell Lung↗
PubMed2001

Novel transmembrane GTPase of non-small cell lung cancer identified by mRNA differential display.

The technique of differential display was used previously to profile the gene expression patterns of non-small cell lung cancer, and several genes differentially expressed were thus identified. In this report, we demonstrate that a DNA fragment of 347-bp length, up-regulated in tumor tissues, showed 100% sequence similarity to human cDNA FLJ20693 for a 370-residue protein. The gene product of cDNA FLJ20693 was postulated to be a shorter isoform of transmembrane GTPase, termed TG370, based upon the results of searching for sequence homology. The nucleotide sequence alignment also indicated that the cDNA FLJ20693 and the cDNA for 741-residue human mitofusin 1 (TG741) possibly resulted from the event of alternative splicing from which a 127-bp region was retained in the latter. Analysis of the genome sequence confirmed the speculation that both cDNAs were mapped to the same chromosomal position composing of 18 exons, of which the 127-bp region of TG741 constituted exon 11. The alternative splicing in all lung cancer cell lines was also observed to occur nearly in all tissue specimens examined. The up-regulated expression of transmembrane GTPase was subsequently found in tumor tissues from at least five of seven non-small cell lung cancer patients. Also, a distinct PCR product was initially detected in cell line H520, and further sequence analysis identified the presence of the 86-bp region mapped to the genome sequence immediately followed by exon 10. To evaluate the retention of 86-bp region, it was found that, besides the predicted 486-bp product, an unexpected 332-bp product was concomitantly observed and identified as the result of exon 8 deletion. The expression and subcellular localization of the full-length TG741 and other shorter isoforms were detected by flow cytometry using three polyclonal antibodies. It was concluded that the full-length TG741 located at plasma membrane with its NH(2)-terminal domain exposed extracellularly and the shorter isoforms retained at cytosol. Finally, the up-regulation of transmembrane GTPase in tumor tissues was further illustrated using immunohistochemical staining.

Adenocarcinoma↗
PubMed2001

New polyoxygenated briarane diterpenoids, briaexcavatolides O-R, from the gorgonian Briareum excavatum.

Four new polyoxygenated briarane-type diterpenoids, briaexcavatolides O-R (1-4), have been isolated from a gorgonian octocoral Briareum excavatum. Their structures were determined using spectroscopic and chemical methods. Metabolites 1-3 were found to contain oxygenated substituents at C-2, C-3, and C-4, and the relative configurations were assigned as 2R*,3R*,4R* at these three positions. Briaranes containing this type of stereochemistry are reported for the first time. The structures of metabolites 1 and 2 were further confirmed by single-crystal X-ray analyses. Compound 2 has been shown to exhibit significant cytotoxicity toward P-388 and HT-29 cancer cells.

Animals↗
PubMed2001

Inhibition of prostacyclin by indomethacin ameliorates the splanchnic hyposensitivity to glypressin in haemorrhage-transfused common bile duct-ligated rats.

Prostacyclin (PGI2) is an important contributor to the mediation of hyporeactivity to vasoconstrictors and the development of hyperdynamic circulation in portal hypertensive states. Inhibition of PGI2 synthesis in haemorrhage-transfused partially portal vein-ligated rats could ameliorate the splanchnic hyposensitivity to glypressin, a long-acting vasopressin analogue. This study investigated whether the hyposensitivity to glypressin also exists in rats with common bile duct ligation (BDL) and whether the inhibition of PGI2 synthesis by indomethacin could potentiate the portal-hypotensive effect of glypressin in bleeding BDL rats. Two series of BDL rats were used. Series 1 investigated the haemodynamic effects of low dose glypressin (0.07 mg kg-1) in BDL rats with or without bleeding by catheterization. In series 2, haemodynamic parameters were measured in stable or bleeding BDL rats that were receiving intravenously high dose glypressin (0.2 mg kg-1) or indomethacin (5 mg kg-1) followed by high dose glypressin. In rats with a hypotensive haemorrhage, 4.5 mL of blood was withdrawn and 50% of the withdrawn blood was reinfused before the administration of glypressin or indomethacin. Splanchnic hyposensitivity to glypressin was demonstrated in haemorrhage-transfused BDL rats receiving high, but not low, doses of glypressin. Indomethacin infusion did not cause significant systemic and portal haemodynamic changes in bleeding BDL rats (P > 0.05). The addition of indomethacin significantly enhanced the portal-hypotensive effects of glypressin (P < 0.05) and potentiated the increases in mean arterial pressure induced by glypressin infusion (P < 0.001) in bleeding BDL rats. Splanchnic hyposensitivity to glypressin observed in haemorrhage-transfused BDL rats could be ameliorated by the addition of indomethacin, suggesting a role of endogenous PGI2 in its pathophysiology.

Animals↗
PubMed2001

Detrimental effects of nitric oxide inhibition on hepatic encephalopathy in rats with thioacetamide-induced fulminant hepatic failure.

Hepatic encephalopathy is a complex neuropsychiatric syndrome seen secondary to acute liver failure, chronic parenchymal liver disease, or portal-systemic anastomosis. Vasodilatation induced by nitric oxide (NO) may be involved in the development of hepatic coma. However, there are no comprehensive data concerning the effects of NO inhibition on the severity of hepatic encephalopathy. Male Sprague-Dawley rats weighing 300-350 g were used. Fulminant hepatic failure was induced by intraperitoneal injection of thioacetamide (TAA, 350 mg kg-1 day-1) for 3 days. Rats were divided into two groups to receive either NG-nitro-L-arginine methyl ester (L-NAME, 20 mg kg-1 day-1 via intragastric gavage) or normal saline (N/S) from 2 days prior to TAA administration for 5 days. Severity of encephalopathy was assessed by counts of motor activity and neurobehaviour test scores. Plasma levels of endotoxin, tumour necrosis factor-alpha and nitrate/nitrite were determined by the chromogenic Limulus assay, enzyme-linked immunosorbent assay and colorimetric assay, respectively. Compared with N/S-treated rats, the mortality rate was significantly higher in rats receiving L-NAME (59% vs. 18%, P < 0.01). Inhibition of NO had detrimental effects on the counts of motor activities (P < 0.05) and neurobehaviour score (P < 0.01). Rats treated with L-NAME had significantly higher plasma levels of endotoxin (26.7 +/- 3.8 pg mL-1) and tumour necrosis factor-alpha (29.4 +/- 6.5 pg mL-1) compared with rats treated with N/S (13.2 +/- 2.7 pg mL-1 and 11.2 +/- 2.6 pg mL-1, respectively, P < 0.01). Plasma levels of endotoxin and tumour necrosis factor-alpha, but not of nitrate/nitrite, were significantly correlated with the severity of hepatic encephalopathy (P < 0.05). Chronic L-NAME administration had detrimental effects on the severity of encephalopathy in TAA-treated rats, suggesting a protective role of NO in the development of fulminant hepatic failure.

Animals↗
PubMed2001

Inhibitory effect of anti-pyretic and anti-inflammatory herbs on herpes simplex virus replication.

The increasing clinical use of acyclovir, ganciclovir, and foscarnet against herpes simplex virus (HSV), varicella-zoster virus, and cytomegalovirus has been associated with the emergence of drug-resistant herpesvirus strains. To develop anti-HSV compounds from plants, 31 herbs used as antipyretic and anti-inflammatory agents in Chinese medicine were screened. Five different preparations (cold aqueous, hot aqueous, ethanolic, acid ethanolic, and methanolic) from 31 herbs were analyzed by plaque reduction assay, and 7 extracts. which showed significant antiviral activities, were further elucidated for their antiviral mechanisms. Our results showed that ethanolic extract of Rheum officinale and methanolic extract of Paeonia suffruticosa prevented the process of virus attachment and penetration. Aqueous extract of P. suffruticosa and ethanolic extract of Melia toosendan inhibited virus attachment to cell surface. Aqueous extract of Sophora flavescens and methanolic extract of M. toosendan showed no effect on virus attachment and penetration. These data indicated that these 4 herbs have a potential value as a source of new powerful anti-HSV compounds.

Alcohols↗
PubMed2001

Digoxin-like and digitoxin-like immunoreactive substances in elderly people. Impact on therapeutic drug monitoring of digoxin and digitoxin concentrations.

We compared digoxin-like (DLIS) and digitoxin-like (DTLIS) immunoreactive substance concentrations for 30 people older than 65 years with those for 25 people younger than 50. None received digoxin or had liver disease, uremia, or volume expansion. We found no DTLIS in any specimen, and only 1 specimen from an elderly person demonstrated a low DLIS concentration. In addition, for 22 non-volume expanded patients (8 younger than 50 years and 14 older than 65) receiving digoxin, the fluorescence polarization (FPIA) and the microparticle enzyme (MEIA) immunoassays revealed comparable serum digoxin concentrations, indicating an insufficient DLIS concentration to interfere with digoxin immunoassay results. Therefore, elderly people who are not volume expanded do not have elevated DLIS or DTLIS concentrations. Furthermore, for patients with liver disease or uremia (18 older than 65 years and 20 younger than 50), the DLIS and DTLIS concentrations were elevated. Finally, for 5 patients with liver disease who received digoxin, serum digoxin concentrations were lower by MEIA and higher by FPIA, indicating the patients had elevated DLIS levels that interfered with the assays. Elevated DLIS and DTLIS concentrations are associated with volume expansion and not age.

Aged↗
PubMed2001

Hepatic encephalopathy in rats with thioacetamide-induced fulminant hepatic failure: role of endotoxin and tumor necrosis factor-alpha.

BACKGROUND: Hepatic encephalopathy, a complex neuropsychiatric syndrome secondary to acute liver failure, chronic parenchymal liver disease or portal-systemic shunting, may possibly develop through mediators of endotoxin and tumor necrosis factor-alpha (TNF-alpha). However, there are no published data concerning the relationships between the severity of encephalopathy and the plasma levels of endotoxin and TNF-alpha. METHODS: Male Sprague-Dawley rats weighing about 300-350 g were used. Fulminant hepatic failure was induced by intraperitoneal injection ofthioacetamide (350 mg/kg/day) for 3 consecutive days. Severity of encephalopathy was assessed by measuring motor counts using an Opto-Varimex animal activity meter. Plasma levels of endotoxin and TNF-alpha were determined by chromogenic Limulus assay and ELISA method, respectively. RESULTS: Our study revealed that higher plasma levels of endotoxin (> 5.9 pg/ml) and TNF-alpha (> 18.8 pg/ml) were significantly associated with more blunted motor activities in rats with fulminant hepatic failure (p < 0.05). A significant correlation was observed between plasma concentrations of endotoxin and TNF-alpha (r = 0.59, p < 0.001). Plasma levels of endotoxin were weakly correlated with the total movements in an open field (r = -0.34, p = 0.032) and the counts of ambulatory (r = -0.38, p = 0.014) and vertical movements (r = -0.40, p = 0.010). There were no correlations between the motor counts and plasma levels of TNF-alpha (p > 0.05). CONCLUSIONS: In addition to endotoxin and TNF-alpha, other factors may participate in the pathogenesis of hepatic encephalopathy in rats with thioacetamide-induced fulminant hepatic failure.

Animals↗
PubMed2001

An evaluative study of the effects of the implementation of UBSG on nurses' perceptions of professional governance.

Health care reform has been a major economic and political challenge in Taiwan. Successful implementation of change in hospitals requires managers to learn new skills. Unit-based shared governance (UBSG) is one innovation used to restructure health care organizations to promote the performance of professionals and to achieve goals for organizations. This research, conducted in a 150-bed community hospital, was a quasi-experimental study designed to evaluate the effectiveness of implementing UBSG. This article describes and compares the degree of nurses' perceptions of professional governance between a UBSG group (n = 29) and a control group (n = 24). The findings of this study indicate that the majority of UBSG respondents scored at a high level of participation in decision-making and professional practice (p < .05). Nurses in the UBSG group shared more in professional governance activities (p < .05). It is suggested that decentralized UBSG within a division of nursing can empower nurses. The study provides an empirical basis for implementing UBSG.

Adult↗
PubMed2001

[The effectiveness of implementing an unit-based shared governance model].

The purpose of the nonequivalent control group study was to establish a regional unit-based shared governance model. Fifty-three subjects distributing to experimental (n = 29) and control (n = 24) groups-age, working years, and education were matched statistically-were selected by "purposeful sampling" of Index of Professional Nurse Governance pretest mean scores from six units at a nursing department. Based on Martin's "systematic" evaluation model for shared governance, the study collected: (1) manager's and staff's perception of existing governance using open-ended questions, (2) measure of organizational efficiency using the IPNG and the Index of Working Satisfaction, and (3) the research team's assessment of the unit's willingness to continue this model in the future. The reliability and validity of the questionnaires were established. Intervention of the model was approximately four months, including: preparatory and evaluating phase: data was collected; educative phase: empowering managers and staff were educated in the shared governance concepts; implementing phase: shared governance team was built up. Two-tailed t and chi 2 tests were used to detect differences between the two groups. Results showed, after establishing the unit-based model, (1) an increase in the nursing professional governance and work satisfaction among nurses; (2) an enhanced partnership between managers and nurses; (3) staff nurses perceived increased autonomy, authority, and more frequently expressed their opinions to managers; (4) managers perceived their staff to have more potential competence, then task pushed effectively. The findings suggest that managers and nurses need to refine their professional roles based on the organizational mission, as well as to expand nurses' representation and participation in current organization-wide committees by trust and full delegation from their managers.

Female↗
PubMed2000

A novel adapter protein employs a phosphotyrosine binding domain and exceptionally basic N-terminal domains to capture and localize an atypical protein kinase C: characterization of Caenorhabditis elegans C kinase adapter 1, a protein that avidly binds protein kinase C3.

Atypical protein kinase C isoforms (aPKCs) transmit regulatory signals to effector proteins located in the cytoplasm, nucleus, cytoskeleton, and membranes. Mechanisms by which aPKCs encounter and control effector proteins in various microenvironments are poorly understood. By using a protein interaction screen, we discovered two novel proteins that adapt a Caenorhabditis elegans aPKC (PKC3) for specialized (localized) functions; protein kinase C adapter 1 (CKA1, 593 amino acids) and CKA1S (549 amino acids) are derived from a unique mRNA by alternative utilization of two translation initiation codons. CKA1S and CKA1 are routed to the cell periphery by exceptionally basic N-terminal regions that include classical phosphorylation site domains (PSDs). Tethering of PKC3 is mediated by a segment of CKA1 that constitutes a phosphotyrosine binding (PTB) domain. Two aromatic amino acids (Phe(175) and Phe(221)) are indispensable for creation of a PKC3-binding surface and/or stabilization of CKA1.aPKC complexes. Patterns of CKA1 gene promoter activity and CKA1/CKA1S protein localization in vivo overlap with patterns established for PKC3 expression and distribution. Transfection experiments demonstrated that CKA1/CKA1S sequesters PKC3 in intact cells. Structural information in CKA1/CKA1S enables delivery of adapters to the lateral plasma membrane surface (near tight junctions) in polarized epithelial cells. Thus, a PTB domain and PSDs collaborate in a novel fashion in CKA1/CKA1S to enable tethering and targeting of PKC3. Avid ligation of a PKC isoform is a previously unappreciated function for a PTB module.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Structural properties and mechanisms that govern association of C kinase adapter 1 with protein kinase C3 and the cell periphery.

Association of an atypical protein kinase C (aPKC) with an adapter protein can affect the location, activity, substrate specificity, and physiological role of the phosphotransferase. Knowledge of mechanisms that govern formation and intracellular targeting of aPKC.adapter protein complexes is limited. Caenorhabditis elegans protein kinase C adapter proteins (CKA1 and CKA1S) bind and target aPKCs and provide prototypes for mechanistic analysis. CKA1 binds an aPKC (PKC3) via a phosphotyrosine binding (PTB) domain. A distinct, Arg/Lys-rich N-terminal region targets CKA1 to the cell periphery. We discovered that a short segment ((212)GGIDNGAFHEHEI(224)) of the V(2) (linker) region of PKC3 creates a binding surface that interacts with the PTB domain of CKA1/CKA1S. The docking domain of PKC3 differs from classical PTB ligands by the absence of Tyr and Pro. Substitution of Ile(214), Asn(216), or Phe(219) with Ala abrogates binding of PKC3 with CKA1; these residues cooperatively configure a docking site that complements an apolar surface of the CKA1 PTB domain. Phosphorylation site domains (PSD1, residues 11-25; PSD2, residues 61-77) in CKA1 route the adapter (and tethered PKC3) to the cell periphery. Phosphorylation of Ser(17) and Ser(65) in PSDs 1 and 2 elicits translocation of CKA1 from the cell surface to cytoplasm. Activities of DAG-stimulated PKCs and opposing protein Ser/Thr phosphatases can dynamically regulate the distribution of adapter protein between the cell periphery and cytoplasm.

Adaptor Proteins, Signal Transducing↗
PubMed2000

The formation and mechanism of multimerization in a freeze-dried peptide.

Atrial natriuretic peptide (ANP) is a peptide with 25 amino acid residues (hANP 4-28) and one intra-chain disulfide bond. We used the size-exclusion chromatography (SEC), sodium dodecyl sulfate in polyacrylamide gel electrophoresis (SDS-PAGE), and reversed-phase liquid chromatography with electrospray mass spectrometry (LC-MS) methods to examine the freeze-dried products of ANP to determine the types, sizes, and amounts of the multimer formation in different stability protocols (by varying the conditions with lyophilization cycles, excipients, storage temperatures, and times). Under the non-annealing lyophilization cycle or lyophilization with high concentration of bulking agent (mannitol), multimer formation increased with increasing storage times. Two kinds of multimers were observed; the major portion is reducible and the minor portion is non-reducible. The reducible multimers are disulfide-linked multimers as determined by LC-MS. The non-reducible multimer was mainly a dimer, possibly linked by a covalent bond between the side chain of tyrosine in one molecule and the dehydroalanine intermediate in another molecule, based on the evidences of the mass of the non-reducible dimer along with the elution position in SEC, and the change of the UV spectrum in the aromatic region. The analysis of degradants suggests that the mechanism start from an beta-elimination of disulfide linkage to form a free thiolate ion (HS-) and a dehydroalanine-type peptide intermediate. The HS- then catalyzed ANP to form the disulfide-linked multimers. The dehydroalanine-type ANP intermediate then reacted with another ANP molecule to form a non-disulfide-linked dimer through reaction with the side chain of tyrosine. These results suggest that the source of multimer formation be initiated by phase transition (from amorphous to crystalline phase) either in the freeze-dried process or during storage. That phase change may induce a drastic change in pH and moisture to damage the peptide. The detailed mechanism and the kinetics of ANP multimerization are discussed. The formation of the multimers was diminished by using the thermal treatment (the annealing step) with a proper ratio of mannitol to ANP peptide in the lyophilization, and/or increase of the acetate buffer concentration in the formulation.

Amino Acid Sequence↗