The conformational properties of alamethicin in ethanol studied by NMR.

Alamethicin, a peptide consisted of 20 amino acid residues, has been known to function as an antibiotic. The peptides self-associate in biological membranes, form an ion channel, and then induce cell death by leaking intracellular contents through a transmembrane pore of an ion channel. We investigated conformation and its thermal stability of alamethicin-A6 and -U6 in ethanol using proton nuclear magnetic resonance (NMR) spectroscopy; alamethicin-A6 and -U6 have the amino acid sequences of UPUAUAQUVUGLUPVUUQQO and UPUAUUQUVUGLUPVUUQQO, respectively, where U and O represent α-aminoisobutyric acid and phenylalaninol, respectively. As indicated by the under bars in the sequences, only the residue 6 differs between the alamethicins. We show that the alamethicins in ethanol form helix conformation in the region of the residues 2-11 and a non-regular conformation in the regions of the N- and C-termini, and that the helices are maintained up to 66 °C at least. Conformations in the region of the residues 12-18 of the alamethicins, however, are not well identified due to the lack of NMR data. In addition, we demonstrate that the amide proton chemical shift temperature coefficients' method, which is known as an indicator for intramolecular hydrogen bonds in peptides and proteins in aqueous solutions, can be also applied to the alamethicins in ethanol. Further, we show that the conformation around the C-terminus of alamethicin-A6 is restrained by intramolecular hydrogen bonds, whereas that of alamethicin-U6 is either restrained or unrestrained by intramolecular hydrogen bonds; the alamethicin-U6 molecules having the restrained and unrestrained conformations coexist in ethanol. We discuss the two types of conformations using a model chain consisting of particles linked by rigid bonds called as the free jointed chain.

α-proton Chemical Shift Index and Amide Proton Chemical Shift Temperature Coefficient of Melittin in Methanol: Indicators for a Helix Structure and an Intra-Molecular Hydrogen Bond?

The methods of the α-proton chemical shift index (CSI) and the amide proton (NH) chemical shift temperature coefficient (Δδ/ΔT) were found experimentally by a number of studies on proton NMR chemical shifts of peptides and proteins in an aqueous solution, and have been widely accepted. They provide an insight into secondary structures and intra-molecular hydrogen bonds in peptides and proteins without complex calculation. Our question is whether the methods are applicable to helical peptides in methanol. Melittin, a peptide of 26 amino acid residues found in bee venom, has been known to consist of two helices (the residues 2-11 and 13-26) connected by a kink section (the residues 11-13). Employing the methods for melittin in methanol, we have shown that most of the CSI's for the residues 3-10 and 14-26 are - 1, and the Δδ/ΔT's for the residues 5-26 except 6 and 14 are more positive than - 6 ppb/℃. If the methods are applicable to melittin in methanol, these results indicate that helix structures are formed in the regions of the residues 3-10 and 14-26 and NH's in the residues 5-26 except 6 and 14 are involved in intra-molecular hydrogen bonds. The helical structure evaluated from the methods, hence, agrees nearly with the known helix structure. We also apply the methods to D-Pro14 melittin (synthetic melittin) and alamethicin (a peptide of 20 amino acid residues) in methanol, and show that they virtually work well.

Assessment of Delayed Large Local Reactions After the First Dose of the SARS-CoV-2 mRNA-1273 Vaccine in Japan.

Importance: A delayed large local reaction (DLLR) is a delayed-onset adverse skin reaction that may occur after injection of the mRNA-1273 vaccine against SARS-CoV-2. Objective: To examine the associations between sex and age and susceptibility of DLLRs after mRNA-1273 vaccination. Design, Setting, and Participants: This retrospective cross-sectional study was conducted at the Self-Defense Forces large-scale vaccination center in Tokyo, Japan, from May 24 to November 30, 2021. Participants were recipients of the second dose of the mRNA-1273 vaccine who had received the first dose 4 to 6 weeks earlier. Five experienced dermatologists interviewed participants to assess whether they had experienced symptoms of DLLR after administration of the first dose of the vaccine. Exposure: Receipt of the first dose of the mRNA-1273 vaccine. Main Outcomes and Measures: The primary outcome was the incidence rate of DLLR stratified by sex and age group. Odds ratios (ORs) were calculated to evaluate the differences between groups. Outcomes were tested for significance using the Pearson χ2 test with 95% CIs. Results: Of 5893 participants in the study, 3318 (56.3%) were male (median age, 55 years [IQR, 38-68 years]) and 2575 (43.7%) were female (median age, 50 years [IQR, 34-67 years]). A total of 747 participants (12.7%) experienced DLLR symptoms after the first dose of the mRNA-1273 vaccine. Symptoms were mild and not considered as contraindications to the vaccine. The incidence rate was significantly higher among females (22.4% [577 participants]; OR, 5.30; 95% CI, 4.42-6.34) than among males (5.1% [170 participants]; reference). Moreover, the incidence rate was significantly higher among participants aged 30 to 39 years (14.3% [129 participants]; OR, 1.68; 95% CI, 1.25-2.26), 40 to 49 years (15.8% [136 participants]; OR, 1.89; 95% CI, 1.41-2.53), 50 to 59 years (14.9% [104 participants]; OR, 1.76; 95% CI, 1.29-2.40), and 60 to 69 years (12.6% [182 participants]; OR, 1.45; 95% CI, 1.10-1.91) than among participants aged 18 to 29 years (9.0% [81 participants]; reference). Conclusions and Relevance: In this cross-sectional study, the first dose of the SARS-CoV-2 mRNA-1273 vaccine was associated with a higher incidence of DLLR among females and among individuals aged 30 to 69 years. The findings suggest that DLLR may be a type IV allergic skin reaction.

A survey of the reactivity of in vitro diagnostic bilirubin reagents developed in Japan using artificially prepared bilirubin materials: A comparison of synthetic delta, unconjugated, and taurine-conjugated bilirubin.

BACKGROUND: In vitro diagnostic bilirubin reagents based on oxidation with bilirubin oxidase or vanadic acid for total and direct-reacting bilirubin are widely used in Japan; however, their reactivity to unconjugated and conjugated bilirubin and delta bilirubin has not been completely disclosed by manufacturers. We used artificially prepared bilirubin materials to investigate the reactivity with four in vitro diagnostic bilirubin reagents. METHODS: Porcine unconjugated bilirubin solution, chemically synthesized ditaurobilirubin solution, and chemically synthesized delta bilirubin solution were used as surrogates of naturally occurring unconjugated bilirubin, conjugated bilirubin, and delta bilirubin, respectively. The total bilirubin and direct-reacting bilirubin concentrations were measured by three bilirubin oxidase methods and one vanadic acid method, and the observed concentrations were compared with those obtained by the diazo-based reference measurement procedure. RESULTS: The unconjugated bilirubin and delta bilirubin concentrations were similar when any of the four in vitro diagnostic bilirubin reagents were used during total bilirubin measurement. This was consistent with reference measurement procedure and exhibited a converged inter-method variation. Compared with reference measurement procedure, significantly low ditaurobilirubin concentrations were observed by the in vitro diagnostic bilirubin reagents despite the converged inter-method variation. In delta bilirubin measurement, some reagents reacted doubtfully with unconjugated bilirubin, while showed lower ditaurobilirubin concentrations than its corresponding total bilirubin concentration. Reactivity with delta bilirubin was different for each method including reference measurement procedure. Some reagents were developed to react less with delta bilirubin and others to strongly react with delta bilirubin. CONCLUSIONS: We revealed the reactivity of IVD-TB and IVD-DB reagents to artificially prepared bilirubin materials, and their consistency with reference measurement procedure. The delta bilirubin data results vary depending on the reagents used.

Nuclear magnetic resonance studies on conformation and stability of mastoparan in methanol.

Mastoparan is a small peptide composed of 14 amino acid residues found in wasp venom. It penetrates into cytoplasm through the cell membranes and then binds to a G protein to stimulate the release of histamine. Conformation and its thermal stability of mastoparan from Vespula lewisi (MP) in methanol are investigated by using proton nuclear magnetic resonance (NMR) spectroscopy. On the basis of data on NOESY cross peaks, spin-spin coupling constants between an amide proton (NH) and an α-proton, NH chemical shift analyses, and temperature dependence of integrated intensity of NH resonance lines, we found that MP forms the helix between the 5th and 12th residues at low temperatures and the helix segment is maintained even at 54°C. This conformation is similar to that of MP bound to detergent micelles, and hence, methanol is considered to be appropriate as a membrane mimetic for MP. In connection with the function of the venom peptide, significance of high stability of the helical conformation is discussed.

NMR studies on the conformation, stability and dynamics of alamethicin in methanol.

Alamethicin is an antibiotic peptide comprising 20 amino acid residues and functions as an ion channel in biological membranes. Natural alamethicins have a variety of amino acid sequences. Two of them, used as a mixed sample in this study, are: UPUAUAQUVUGLUPVUUQQO and UPUAUUQUVUGLUPVUUQQO, where U and O represent α-aminoisobutyric acid and phenylalaninol, respectively. As indicated, only the amino acid at position six differs, and the two alamethicins are referred to as alamethicin-A6 and -U6, respectively. The conformation and thermal stability of alamethicin-A6 and -U6 in methanol were examined using proton nuclear magnetic resonance (NMR) spectroscopy. Both alamethicins form an α-helix between the 2nd and 11th residues. The N-terminal, 19th and C-terminal residues take a non-helical conformation. The structure between the 12th and 18th residues has not been well determined due to the absence of cross peaks in the two-dimensional NMR data. The α-helices are maintained up to 54 °C at least. In contrast to these similarities, it has been found that the length of the α-helix of alamethicin-U6 is somewhat shorter than that of alamethicin-A6, the intra-molecular hydrogen bonds formed by the amide proton of the seventh residue is much more thermally stable for alamethicin-U6 than for alamethicin-A6, and the C-terminal residue of alamethicin-U6 has higher mobility than that of alamethicin-A6. The mobility of the N- and C-terminal residues is discussed on the basis of a model chain which consists of particles connected by rigid links, and the physiological significance of the mobility is emphasized.

NMR chemical shift analysis of the conformational transition between the monomer and tetramer of melittin in an aqueous solution.

It is known that melittin in an aqueous solution undergoes a conformational transition between the monomer and tetramer by variation in temperature. The transition correlates closely with isomers of the proline residue; monomeric melittin including a trans proline peptide bond (trans-monomer) is involved directly in the transition, whereas monomeric melittin having a cis proline peptide bond (cis-monomer) is virtually not. The transition has been explored by using nuclear magnetic resonance spectroscopy in order to clarify the stability of the tetrameric conformation and the cooperativity of the transition. In the light of temperature dependence of chemical shifts of resonances from the isomeric monomers, we qualitatively estimate the temperature-, salt-, and concentration-dependence of the relative equilibrium populations of the trans-monomer and tetramer, and show that the tetramer has a maximum conformational stability at 30-45 °C and that the transition cooperativity is very low.

Galectin-7 and actin are components of amyloid deposit of localized cutaneous amyloidosis.

The precursor protein of localized cutaneous amyloidosis (LCA) is believed to be cytokeratins on the basis of previous immunohistochemical studies. To identify the candidate amyloid protein biochemically, amyloid proteins were extracted with distilled water from lesional skin of LCA associated with Bowen's disease. The proteins were resolved on one- or two-dimensional polyacrylamide gel electrophoresis followed by characterization with immunoblot analysis. The proteins with multiple molecular weights of 50-67 kDa and two proteins with 25 and 35 kDa were identified as keratins, serum amyloid P component and apolipoprotein E, respectively. The unknown 14-kDa (pI = 7.0) and 42-kDa (pI = 5.4) proteins reacted with the antibody against galectin-7 and actin, respectively. The protein with the molecular weight of 14 kDa was identified as galectin-7 by MALDI-TOF mass spectrometer. Their electrophoretic mobilities were identical with normal counterparts extracted from cultured normal human keratinocytes. Galectin-7 and actin were detected by immunoblot assay in the water-soluble fractions prepared from the lesional skins of two patients with primary LCA. Immunohistochemical studies of tumor-associated (n = 9) and primary (n = 10) LCA revealed various degrees of positive immunoreactivities with the antibodies for galectin-7 and F-actin. Galectin-7 and actin, which contain considerable amount of ß-sheet structure, may be candidate amyloidogenic proteins of primary and secondary LCA.

The hematological and clinical effects of X-ray contrast medium contaminating autologous blood for transfusion purposes.

Little information is available regarding the influence of non-ionic low-osmolar iodinated contrast medium (CM) in stored blood on the quality of blood components. We sought to evaluate the quality of such CM-contaminated blood in terms of the degree of hemolysis, production of microaggregates, level of iodine concentration, and RBC shape, and to identify the pros and cons of autologous blood donation immediately after X-ray examination using CM. In conclusion, contamination by such CM in blood collected around 2h after the completion of X-ray examination appears unlikely to induce deleterious effects on blood components.

NMR studies on the monomer-tetramer transition of melittin in an aqueous solution at high and low temperatures.

Melittin, a peptide of 26 amino acid residues, has been used as a model peptide for protein folding and unfolding, and extensive research has been done into its structure and conformational stability. Circular dichroism (CD) studies have demonstrated that melittin in an aqueous solution undergoes a transition from a helical tetramer to a random coil monomer not only by heating but also by cooling from room temperature (i.e., heat- and cold-denaturation, respectively). The heat-denaturation has been also examined by nuclear magnetic resonance (NMR) experiments, however, no NMR data have been presented on the cold-denaturation. In this paper, using proton ((1)H) NMR spectroscopy, we show that melittin undergoes conformational transitions from the monomer to the tetramer to the monomer by elevating temperature from 2 to 70 °C. Only melittin including a trans proline peptide bond participates in the transitions, whereas melittin including a cis proline one does not. The tetramer has maximum conformation stability at around 20 °C, and cooperativity of the heat-denaturation is extremely low.

NMR studies on thermal stability of α-helix conformation of melittin in pure ethanol and ethanol-water mixture solvents.

Thermal stability of the α-helix conformation of melittin in pure ethanol and ethanol-water mixture solvents has been investigated by using NMR spectroscopy. With increase in water concentration of the mixture solvents (from 0 wt% to ~71.5 wt%) as well as temperature (from room temperature to 60 °C), the intramolecular hydrogen bonds formed in melittin are destabilized and the α-helix is partially uncoiled. Further, the hydrogen bonds are found to be more thermally stable in pure ethanol than in pure methanol, suggesting that their stability is enhanced with increase in the size of the alkyl groups of alcohol molecules.

Helix conformation of a small peptide melittin in a methanol-water mixed solvent studied by NMR.

Temperature dependence of the α-helix conformation of bee venom melittin in methanol-water mixed solvents has been examined by NMR, in order to elucidate conformation stability and a phase diagram. At high methanol concentration of 100 - ca. 80 wt.%, melittin forms a full α-helix conformation in the temperature range from 25 °C to 60 °C. At intermediate methanol concentration of ca. 80 - ca. 25 wt.%, it undergoes a thermal transformation from a full α-helix to a partial α-helix. In solutions of low methanol concentrations of ca. 25 - 0 wt.%, partial α-helix monomers and their self-aggregated conformers coexist at low temperatures, and the relative number of the monomers increases with increase in temperature. The monomers turn to a random coil state at high temperatures only below ca. 10 wt. % methanol concentrations. The thermal transitions are discussed from the viewpoint of stability of intra-molecular hydrogen bonds and inter-molecular hydrophobic interactions.

Surgical indications for combined partial rectosigmoidectomy in ovarian cancer.

AIM: To evaluate surgical indications for combined partial rectosigmoidectomy in ovarian cancer with direct invasion of the rectum and sigmoid colon or dissemination into the pouch of Douglas. METHODS: Subjects comprised 25 patients with ovarian cancer who underwent primary surgery and rectosigmoidectomy between 1990 and 2002 at our hospital. Federation of Obstetrics and Gynecology staging of tumors was II (n = 6), III (n = 17) or IV (n = 2). The histologic type was serous adenocarcinoma (n = 18), clear cell adenocarcinoma (n = 4), and others (n = 3). Bowel resection was performed during primary surgery in 18 patients, and after neoadjuvant chemotherapy (NAC) in seven patients. Cumulative survival rate was compared between NAC and non-NAC groups. Patients were divided into three groups based on extent of surgical resection to compare survival rates: no residual tumor (n = 19); maximum residual tumor diameter <1 cm (n = 5); and maximum residual tumor diameter > or =1 cm (n = 1). RESULTS: Cumulative 5-year survival was 41.3% for all patients. Cumulative 5-year survival in the 18 patients who underwent bowel resection during primary surgery was 62.2%, compared to 13.9% in the seven patients who underwent bowel resection after NAC. Cumulative 5-year survival based on extent of surgical resection was: no residual tumor, 60.8%; residual <1 cm, 0%; and residual > or =1 cm, 0%. Cumulative 5-year survival for patients with complete tumor resection (no residual tumor), excluding clear cell adenocarcinoma, was 79.5%. CONCLUSION: In ovarian cancer with direct invasion of the rectum or sigmoid colon or dissemination into the pouch of Douglas, complete tumor resection with rectosigmoidectomy during primary surgery is associated with good clinical outcomes.

Synthesis and Diels-Alder reactions of 1,2-dimethylene[2.n]metacyclophanes.

The Diels-Alder reaction of 1,2-dimethylene[2.n]MCPs (MCP = metacyclophane) with suitable dienophiles followed by aromatization and photoinduced or FeCl(3)-induced transannular cyclization afforded phenanthrene-anellated polycyclic aromatic hydrocarbons, which were found to adopt helical chirality in the solid state.

Immunohistochemical study of chronological and photo-induced aging skins using the antibody raised against D-aspartyl residue-containing peptide.

BACKGROUND: Biologically uncommon D-aspartyl residues have been reported in the elderly tissues such as tooth, eye lens, aorta, and brain. We have previously prepared the antibody against D-aspartyl residue-containing peptide and found that it reacted with elastotic material of actinic elastosis. METHODS: Immunoreactivity of the normal skins obtained from sun-exposed and sun-protected skins of varied ages with this antibody was studied. RESULTS: In the sun-exposed skins, the antibody showed negative reaction with the skin specimens of young donors, whereas it reacted with elastotic materials of actinic elastosis of the elderly. In the sun-protected skins, the antibody recognized elastic fiber-like structures and inner layer of vessels found from the mid to lower dermis of old donors but showed no positive reaction to skin specimens of young donors. CONCLUSIONS: The results suggest that the antibody is a potent marker for chronological and ultraviolet (UV)-induced skin aging. Unusual eosinophilic bodies seen in the superficial dermis in the sun-exposed area of the elderly skins were also immunoreactive with the antibody, suggesting that the eosinophilic bodies resulted from UV-induced skin damage.