Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 25
Filter
1.
J Shoulder Elbow Surg ; 32(8): 1673-1680, 2023 Aug.
Article in English | MEDLINE | ID: mdl-36871606

ABSTRACT

BACKGROUND: Few studies have retrospectively analyzed the relationship between joint range of motion (ROM) and muscle flexibility and shoulder and elbow throwing injuries in a large number of elementary school baseball players. The purpose of this study was to retrospectively identify the physical factors related to shoulder and elbow throwing injuries in younger baseball players. METHODS: A total of 2466 younger baseball players belonging to our Prefecture Rubber Baseball Federation who participated in medical check-ups from 2016 to 2019 were analyzed. Players completed a questionnaire and had a medical check-up that included a physical examination and ultrasonography. ROM (internal rotation [IR] angle and external rotation angle) of the shoulder and hip and the finger-to-floor distance and heel-to-buttock distance were measured. The straight leg raise was also performed. The results of two groups (normal group and injury group) were compared using the χ2 test, Mann-Whitney U test, and Student t test. Stepwise forward logistic regression models were developed to identify risk factors. RESULTS: On univariate analysis, nine of the 13 evaluated items showed significant decreases in ROM and muscle flexibility in the injury group. On multiple logistic regression analysis, grade, finger-to-floor distance, IR angle of the dominant side shoulder, and IR angle of the nondominant side hip were significantly associated with the occurrence of throwing injuries. Decreased total shoulder angle was observed not only on the dominant side but also on the nondominant side in the injury group. CONCLUSION: Decreased ROM and muscle flexibility were risk factors for baseball-related throwing injuries in elementary school baseball players. To prevent shoulder and elbow throwing injuries, players, coaches, medical staff, and parents need to be aware of these findings.


Subject(s)
Arm Injuries , Baseball , Shoulder Injuries , Shoulder Joint , Humans , Baseball/injuries , Retrospective Studies , Shoulder/physiology , Risk Factors , Range of Motion, Articular/physiology , Shoulder Joint/diagnostic imaging , Shoulder Joint/physiology , Shoulder Injuries/epidemiology
2.
J Orthop Surg Res ; 17(1): 553, 2022 Dec 20.
Article in English | MEDLINE | ID: mdl-36536379

ABSTRACT

BACKGROUND: Recently, cryotherapy has become a common practice for postoperative pain management. The current accepted practice in Japan is the use of cryotherapy at 5 °C after arthroscopic shoulder surgery. However, this therapy has been reported to be highly intense because the sustained low temperature causes discomfort for patients. The optimum temperature and duration of cooling required for comfortable and effective cryotherapy after arthroscopic shoulder surgery were investigated. METHODS: Because pain levels might differ depending on the condition, we selected 52 patients with rotator cuff injuries, which were the most common disorders indicated for arthroscopic shoulder surgery. Patients were treated with cryotherapy at 5 °C or 10 °C for 16 h or 24 h. The pain level was determined using the visual analogue scale, and deep shoulder joint temperatures were recorded at different time points for analysis. RESULTS: Pain after arthroscopic shoulder surgery was found to be related to the presence of a brachial plexus block using the interscalene approach during surgical anesthesia. To obtain effective analgesia with cryotherapy, the cooling temperature and duration of cryotherapy had to be changed based on the presence or absence of the brachial plexus block. Patients who received brachial plexus blocks had the lowest recorded pain scores after receiving cryotherapy at 5 °C for 24 h after surgery. Patients who did not receive the block had the lowest recorded pain scores when receiving cryotherapy at either 5 °C for 16 h or 10 °C for 24 h. CONCLUSIONS: Using universal cryotherapy intensity and duration settings regardless of the use of other interventions is likely to unintentionally increase postoperative pain levels. This study revealed that cryotherapy at 5 °C for 24 h was optimal for patients who received an anesthesia block and at 5 °C for 16 h or at 10 °C for 24 h for those who did not receive the anesthesia block. These results can be used as a reference for setting the temperature and duration of cryotherapy after arthroscopic shoulder surgery.


Subject(s)
Brachial Plexus Block , Shoulder , Humans , Shoulder/surgery , Brachial Plexus Block/methods , Pain Management , Pain, Postoperative/etiology , Cryotherapy , Arthroscopy/methods , Anesthetics, Local
3.
Sci Total Environ ; 817: 152981, 2022 Apr 15.
Article in English | MEDLINE | ID: mdl-35026267

ABSTRACT

Microplastic (MP) pollution in the aquatic environment is a cause for increasing concern. However, analyzing MPs ingested by small organisms, such as zooplankton, is difficult because of the low content and small size of the ingested MPs. We attempted to determine the content of ingested MPs in individual zooplankton using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). To establish zooplankton model of MP ingestion, individual Daphnia magna were cultivated separately in microplate cells with polystyrene (PS) microspheres (10 µm in diameter, 245,000 particles, 135 µg) under different conditions. To prepare calibration curves for determining ingested PS content, approximately 100-150 µg of commercially available Daphnia-based powdered fish food, roughly corresponding to the weight of a single D. magna organism, was mixed with PS microspheres (0.005-26 µg) and analyzed using Py-GC-MS at 600 °C. In the resulting pyrograms, peaks of the styrene monomer and trimer from PS were detected, and linear relationships were obtained between the relative peak area and the amount of added PS. Finally, the cultivated zooplankton were individually subjected to Py-GC-MS analysis, and the ingested PS content in each zooplankton was successfully determined. Individual zooplankton cultured with PS in the absence of food ingested 2.3-7.9 µg of PS particles, whereas that in the presence of food (Chlorella vulgaris) ingested only 0.1-0.2 µg of PS particles. This result suggests that zooplankton might preferentially ingest ordinary food when both food and MPs are present, although further systematic studies are necessary to validate this observation.


Subject(s)
Chlorella vulgaris , Water Pollutants, Chemical , Animals , Daphnia , Gas Chromatography-Mass Spectrometry , Microspheres , Plastics , Polystyrenes/analysis , Pyrolysis , Water Pollutants, Chemical/analysis
4.
J Agric Food Chem ; 69(13): 3904-3911, 2021 Apr 07.
Article in English | MEDLINE | ID: mdl-33761247

ABSTRACT

Genipin was reacted with benzylamine and several amino acids to prepare gardenia blue (GB). The time-course of GB formation with benzylamine was monitored by high-performance liquid chromatography (HPLC), liquid chromatography time-of-flight mass spectrometry (LC-TOFMS), and 1H and 13C NMR measurements. In this experiment, we determined the molecular structures of some intermediates using accurate masses and additional NMR techniques such as heteronuclear multiple bond correlation (HMBC). GBs with amino acids (GB-AAs) were characterized by both liquid and solid-state NMR measurements. Interestingly, many significant peaks appeared in the solid-state NMR spectra, although the 13C NMR spectra from solution samples did not show any distinct peaks. Therefore, we determined that GB-AAs had an alternating copolymer structure composed of methyne and 5H-2-pyrindine, which was substituted by amino acids at N atom and linked with methyne at 5 and 7 positions. To confirm this molecular structure, the pyrolysis gas chromatography-mass spectrometry (GC-MS) measurement of GB-AAs was carried out, and 5H-2-pyrindine and its methyl derivatives were formed as main pyrolysis products from the polymer chains.


Subject(s)
Gardenia , Amino Acids , Benzylamines , Iridoids , Molecular Structure
5.
Sci Rep ; 8(1): 5763, 2018 04 10.
Article in English | MEDLINE | ID: mdl-29636486

ABSTRACT

Potential risks of supply shortages for critical metals including rare-earth elements and yttrium (REY) have spurred great interest in commercial mining of deep-sea mineral resources. Deep-sea mud containing over 5,000 ppm total REY content was discovered in the western North Pacific Ocean near Minamitorishima Island, Japan, in 2013. This REY-rich mud has great potential as a rare-earth metal resource because of the enormous amount available and its advantageous mineralogical features. Here, we estimated the resource amount in REY-rich mud with Geographical Information System software and established a mineral processing procedure to greatly enhance its economic value. The resource amount was estimated to be 1.2 Mt of rare-earth oxide for the most promising area (105 km2 × 0-10 mbsf), which accounts for 62, 47, 32, and 56 years of annual global demand for Y, Eu, Tb, and Dy, respectively. Moreover, using a hydrocyclone separator enabled us to recover selectively biogenic calcium phosphate grains, which have high REY content (up to 22,000 ppm) and constitute the coarser domain in the grain-size distribution. The enormous resource amount and the effectiveness of the mineral processing are strong indicators that this new REY resource could be exploited in the near future.

6.
BMC Musculoskelet Disord ; 18(1): 511, 2017 Dec 04.
Article in English | MEDLINE | ID: mdl-29202746

ABSTRACT

BACKGROUND: Although a loss of rotator cuff integrity leads to the superior migration of the humeral head, the parameters that characterize the anterolateral migration of the humeral head have not been established. The purpose of this study was to investigate the correlation between the translation of the humeral head scale (T-scale) and clinical outcomes of rotator cuff repair, as well as the correlation between the T-scale and radiologic parameters. METHODS: One hundred thirty-five consecutive patients with full-thickness rotator cuff tears underwent primary rotator cuff repair. The T-scale, which indicates the distance from the center of the humeral head to the lateral coracoacromial arch, was measured on axial computed tomography scans, and the acromiohumeral interval (AHI) was measured radiographically. The correlation of the two parameters with the clinical scores of the Japanese Orthopaedic Association and University of California-Los Angeles scores and active forward elevation (FE) were evaluated at the preoperative and postoperative stages, respectively. RESULTS: The postoperative T-scale and AHI correlated well with the postoperative FE and clinical scores in the patients with large-massive tears but not in those patients with small-medium tears and preoperative large-massive tears. A significant correlation was observed between the postoperative T-scale and AHI. The T-scale was subject to cuff repair integrity. CONCLUSIONS: We demonstrated that the postoperative T-scale was well correlated with the clinical results and postoperative AHI after rotator cuff repair for large-massive tears, indicating that poor outcomes are associated with combined superior and anterolateral migration of the humeral head following retears.


Subject(s)
Humeral Head/diagnostic imaging , Humeral Head/surgery , Rotator Cuff Injuries/diagnostic imaging , Rotator Cuff Injuries/surgery , Rotator Cuff/diagnostic imaging , Rotator Cuff/surgery , Adult , Aged , Aged, 80 and over , Female , Follow-Up Studies , Humans , Male , Middle Aged
7.
J Chromatogr A ; 1471: 186-191, 2016 Nov 04.
Article in English | MEDLINE | ID: mdl-27769532

ABSTRACT

Thermally assisted hydrolysis and methylation-gas chromatography (THM-GC) in the presence of an organic alkali was validated for the compositional analysis of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] accumulated in whole bacterial cells. Recombinant Cupriavidus necator Re2058/pCB113 was grown in a batch fermentation with different concentration of palm oil and fructose in order to control the molar fraction of 3HHx in P(3HB-co-3HHx) produced in the cells. Trace amounts (30µg) of freeze-dried cells were directly subjected to THM-GC in the presence of tetramethylammonium hydroxide (TMAH) at 400°C. The obtained chromatograms clearly showed nine characteristic peaks, attributed to the THM products from 3HB and 3HHx units in the polymer chains, without any appreciable interference by the bacterial matrix components. Based on these peak intensities, the copolymer compositions were determined rapidly without using any cumbersome and lengthy sample pretreatment as in conventional GC method. Moreover, the compositions thus obtained were strongly correlated with those by NMR and conventional GC involving solvent extraction.


Subject(s)
Caproates/analysis , Chemistry Techniques, Analytical/methods , Chromatography, Gas , Cupriavidus necator/chemistry , Hot Temperature , 3-Hydroxybutyric Acid/chemistry , Caproates/chemistry , Chemistry Techniques, Analytical/instrumentation , Fermentation , Hydrolysis , Magnetic Resonance Spectroscopy , Methylation , Palm Oil , Plant Oils/metabolism , Polymers
8.
Knee ; 23(3): 554-8, 2016 Jun.
Article in English | MEDLINE | ID: mdl-26869506

ABSTRACT

BACKGROUND: To the best of our knowledge, there has been no detailed study on bone-patellar tendon-bone (BTB) grafts for remnant-preserving, selective-bundle anterior cruciate ligament (ACL) augmentation. Therefore, we aimed to develop such a technique using a BTB graft. METHOD: A total of five patients underwent surgery using the presented procedure. These patients were young, male, and with high body mass index, and hence required very high durability of reconstructed ACL. A femoral bone tunnel was created using the inside-out technique via an accessory far-medial portal, protecting the remnant using a probe, regardless of the presence of an anteromedial (AM) or posterolateral (PL) tunnel. A single tibial tunnel was drilled at the center of the AM or PL attachment and two transverse skin incisions were made in the ipsilateral knee. The central third of the patellar tendon attached to a patellar and tibial bone plug autograft with a width of seven millimeters was harvested by subcutaneous tunneling. The femoral side was fixed using a cortical fixation device for BTB and the tibial bone plug was fixed using an interference screw with the knee at an angle of 20° of flexion by applying maximal manual traction. RESULTS: Bone tunnel enlargement, which was measured by computed digital radiography, was not observed in all cases. A BTB autograft for remnant-preserving, selective-bundle ACL augmentation offers reduced risk of tunnel enlargement. CONCLUSION: The presented procedure might be considered one of the potentially available options for patients with ACL partial tear who require very high durability of reconstructed ACL. LEVEL OF EVIDENCE: 5.


Subject(s)
Anterior Cruciate Ligament Injuries/surgery , Anterior Cruciate Ligament Reconstruction/methods , Anterior Cruciate Ligament/surgery , Bone-Patellar Tendon-Bone Grafting/methods , Knee Joint/surgery , Adolescent , Adult , Arthroscopy , Athletic Injuries/surgery , Autografts , Femur/surgery , Humans , Male , Patellar Ligament/transplantation , Tibia/surgery , Transplantation, Autologous , Young Adult
9.
Food Sci Biotechnol ; 25(3): 875-882, 2016.
Article in English | MEDLINE | ID: mdl-30263348

ABSTRACT

Acorn (Quercus acutissima CARR.) is a nut from the Fagaceae family that has been used in traditional medicine for many years. However, shells from acorns are regarded as a by-product and are mostly discarded. Anti-adipogenic activities of acorn shells were investigated using 3T3-L1 cells and methanol shell extracts (AE-M). AE-M demonstrated Cu2+-chelation activities and anti-oxidant activities via reduction of oxidative stress levels induced using AAPH. Six days after adipocyte differentiation, 50 and 100 µg/mL AE-M completely suppressed 3T3-L1 adipogenesis and the anti-adipogenic effect was stronger than for the positive control 50 µM quercetin. Treatment with AE-M in 3T3-L1 cells reduced mRNA expression levels of adipogenic genes. AE-M-inhibition was found in pre-adipogenic, early, and intermediate stages of adipogenesis in 3T3-L1 cells. The Wnt/ß-catenin signaling pathway is required for AE-M-inhibition of 3T3-L1 adipogenesis.

10.
Food Sci Biotechnol ; 25(4): 1169-1174, 2016.
Article in English | MEDLINE | ID: mdl-30263390

ABSTRACT

The antioxidant and anti-adipogenic activities of chestnut byproducts were evaluated. At 100 µg/mL, the methanol extract (ME) scavenged 34.2% of DPPH and 78.8% of ABTS radicals. The DPPH and ABTS radical scavenging activity of the water extract (WE) was found to be low (13.7 and 33.1%, respectively) compared with controls. WE and ME dose-dependently inhibited lipid accumulation of 3T3-L1 adipocytes. WE and ME at 100 µg/mL suppressed 3T3-L1 adipogenesis by 71.0 and 96.5%, respectively, when compared with mature adipocytes. The results indicated that WE and ME inhibited adipocyte differentiation by down-regulating the mRNA expression levels of CCAAT/enhancer binding protein (C/EBP)-ß, C/EBPα, and peroxisome proliferator-activated receptor (PPAR)-γ in 3T3-L1 cells. Our study also revealed that WE and ME inhibited pre- and early stage adipogenesis in 3T3-L1 cells. The results suggest that chestnut byproducts are a promising source of antioxidant and antiobesity molecules.

11.
Food Sci Biotechnol ; 25(4): 1183-1187, 2016.
Article in English | MEDLINE | ID: mdl-30263392

ABSTRACT

Antioxidant and anti-adipogenic activities of water extract (WE) and methanol extract (ME) of acorn shells (AS), from Quercus acutissima Carruth. grown in Korea, were investigated. At a concentration of 50 µg/mL, the WE had a scavenging activity of 53.84% for the DPPH and 76.09% for the ABTS radical, while the ME had corresponding scavenging activities of 29.09 and 48.43%. Total phenolic contents of WE and ME were 375.96 and 288.01 mg gallic acid equivalents/g of extracts, respectively. Both extracts significantly inhibited 3T3-L1 adipogenesis in a dose-dependent manner, and concomitantly decreased the size and number of intracellular lipid droplets. Furthermore, the antiadipogenic activities of WE and ME are largely limited in the pre- and early stages of adipogenesis. The results suggest that AS may be a promising source of antioxidants and anti-obesity compounds.

12.
Anal Sci ; 31(2): 79-83, 2015.
Article in English | MEDLINE | ID: mdl-25746804

ABSTRACT

Thermally assisted hydrolysis and methylation-gas chromatography (THM-GC) in the presence of an organic alkali was applied to the direct analysis of copolymer composition for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] accumulated in whole bacterial cells. Cupriavidus necator was grown on a liquid medium with different molar ratios of valeric acid (V) to glucose (G) in order to control the compositions of P(3HB-co-3HV) produced in the cells. Trace amounts (0.03 mg) of dried Cupriavidus necator cells were directly subjected to THM-GC in the presence of tetramethylammonium hydroxide (TMAH) at 400°C. The obtained chromatograms clearly showed nine characteristic peaks, attributed to the THM products from 3HB and 3HV units in the polymer chains, without any appreciable interference by the bacterial matrix components. Based on these peak intensities, the copolymer compositions were determined rapidly without using any cumbersome sample pretreatment. Moreover, the compositions thus obtained were in good agreement with those obtained by the conventional technique.


Subject(s)
3-Hydroxybutyric Acid/chemistry , Chromatography, Gas/methods , Cupriavidus necator/cytology , Pentanoic Acids/chemistry , Polymers/chemistry , Temperature , Hydrolysis , Methylation , Time Factors
13.
Knee Surg Sports Traumatol Arthrosc ; 23(5): 1549-51, 2015 May.
Article in English | MEDLINE | ID: mdl-24667941

ABSTRACT

A case of pseudoaneurysm that is a rare complication of shoulder arthroscopy is reported. A 73-year-old man with rotator cuff tear underwent arthroscopic rotator cuff repair. On post-operative day 3, a pulsating mass (diameter 5 mm) was detected near the anterior portal. Then, the mass gradually enlarged, which was diagnosed as pseudoaneurysm. After the consultation with vascular surgeons, the mass was surgically excised following ligation of feeding artery 6 weeks after the arthroscopic surgery. Thus far, no recurrence has been observed. Level of evidence V.


Subject(s)
Aneurysm, False/etiology , Arm Injuries/surgery , Arthroscopy/adverse effects , Postoperative Complications , Rotator Cuff Injuries , Shoulder Injuries , Thoracic Arteries , Aged , Aneurysm, False/diagnosis , Humans , Magnetic Resonance Imaging , Male , Rotator Cuff/surgery , Ultrasonography, Doppler, Color
14.
J Agric Food Chem ; 60(17): 4222-6, 2012 May 02.
Article in English | MEDLINE | ID: mdl-22458968

ABSTRACT

Thermally assisted hydrolysis and methylation-gas chromatography (THM-GC) in the presence of trimethylsulfonium hydroxide, using a vertical microfurnace pyrolyzer, was validated for the compositional analysis of fatty acid components in microalgae. The chromatograms of a microalga, Pavlova lutheri , obtained under optimized THM conditions clearly showed a series of fatty acid methyl esters including thermally labile polyunsaturated fatty acid components. On the basis of these peak areas, their chemical compositions were rapidly determined without using any tedious sample pretreatment with a precision of <8% relative standard deviation. Moreover, the compositions thus obtained were in good agreement with those obtained by the conventional technique involving solvent extraction. Finally, the THM-GC technique was applied for the compositional analysis of fatty acid components in a newly found microalga, Coccomyxa gloeobotrydiformis . The obtained data showed a high abundance (24 mol %) of α-linolenic acid components, suggesting its potential usefulness as feed sources and/or functional foods.


Subject(s)
Chromatography, Gas/methods , Fatty Acids/analysis , Haptophyta/chemistry , Hot Temperature , Functional Food , Hydrolysis , Methylation , alpha-Linolenic Acid/analysis
15.
Anal Sci ; 27(10): 1053-6, 2011.
Article in English | MEDLINE | ID: mdl-21985932

ABSTRACT

Thermochemolysis-gas chromatography in the presence of tetramethylammonium acetate was applied to the direct determination of terephthalic acid (TPA) contained in solid decomposition products obtained from the hydrothermal recycling process of poly(ethylene terephthalate) (PET). On the chromatograms of the hydrothermal decomposition products of PET, a sharp peak of the TPA component was clearly observed as its corresponding dimethyl ester formed through the thermochemolysis reaction. Based on the peak intensities, the contents of TPA in the decomposition products were determined precisely and rapidly without using any cumbersome sample pretreatments.


Subject(s)
Hot Temperature , Phthalic Acids/analysis , Polyethylene Glycols/chemistry , Quaternary Ammonium Compounds/chemistry , Chromatography, Gas , Polyethylene Terephthalates
16.
J Chromatogr A ; 1216(15): 3296-9, 2009 Apr 10.
Article in English | MEDLINE | ID: mdl-19223033

ABSTRACT

Reaction efficiencies of two organic alkalis, tetramethylammonium hydroxide (TMAH) and trimethylsulfonium hydroxide (TMSH), with lipids during thermally assisted hydrolysis and methylation (THM) were examined focusing on (1) the types of lipids and (2) degree of unsaturation of fatty acid moieties. Different types of lipids such as triglycerides, phospholipids, free fatty acids and cholesteryl esters containing saturated, monounsaturated or polyunsaturated fatty acid (PUFA) residues were subjected to THM-gas chromatography (GC) in the presence of TMAH or TMSH. The obtained results revealed that the THM reaction using TMAH allowed almost quantitative methylation of saturated and monounsaturated fatty acid components independently of the classes of lipids. However, strong alkalinity of TMAH brought about isomerization and/or degradation of PUFA components. In contrast, the use of TMSH was effective to highly sensitive detection of PUFA as well as saturated and monounsaturated fatty acid components contained in triglycerides, phospholipids (phosphatidylcholines) and free fatty acids. On the other hand, TMSH was proved to react hardly with any kind of fatty acid residues in cholesteryl esters due to their steric hindrance.


Subject(s)
Alkalies/metabolism , Lipid Metabolism , Quaternary Ammonium Compounds/metabolism , Sulfonium Compounds/metabolism , Temperature , Chromatography, Gas/methods , Fatty Acids, Unsaturated/metabolism , Hydrolysis , Methylation , Sensitivity and Specificity
17.
Anal Sci ; 22(11): 1403-7, 2006 Nov.
Article in English | MEDLINE | ID: mdl-17099270

ABSTRACT

The cross-linking structure of the ultra violet (UV)-cured resin prepared from dipentaerithritol hexacrylate (DPHA) was characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with supercritical methanolysis. The MALDI-mass spectrum of the decomposition products obtained by supercritical methanolysis contained a series of peaks of sodium-cationized methyl acrylate (MA) oligomers up to around m/z = 4000 formed through selective cleavage and methylation occurred at ester linkages in UV-cured DPHA. Furthermore, in order to observe widely distributed sequence lengths in the cross-linking junctions, the decomposed products of the cured resin were then fractionated using size exclusion chromatography followed by the MALDI-MS measurements of the individual fractions. The MALDI-mass spectra of the lower molar mass fractions mainly consisted of a series of peaks of MA oligomers around m/z values of several thousands, whereas those of higher molecular weight showed a broad peak up to m/z ca. 180000. The observed distributions of the supercritical methanolysis products suggested that the network junctions in the given UV-cured resin were composed of up to around 2000 acrylate units.


Subject(s)
Acrylic Resins/chemistry , Acrylic Resins/radiation effects , Cross-Linking Reagents/chemistry , Acrylates/chemistry , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Ultraviolet Rays
18.
Rapid Commun Mass Spectrom ; 20(8): 1345-50, 2006.
Article in English | MEDLINE | ID: mdl-16555367

ABSTRACT

A small amount of an oligomeric hindered amine light stabilizer (HALS) (Adekastab LA-68LD) in polypropylene (PP) materials was directly determined by solid sampling matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) using an internal standard method. First the matrix reagent (dithranol), 20 mg, and the empirically selected internal standard, angiotensin I (MW = 1296.5), 5 microg, were premixed in the solid state. The matrix mixture was then co-ground with the PP sample containing the HALS in liquid nitrogen using a freezer mill. The powdered sample mixture was spotted on the sample plate, suspended in ion-exchanged water, dried to adhere on the plate, and subjected to MALDI-MS. Three series of the HALS components accompanied by the oxidized species were clearly observed as their molecular ions (M*+)) along with that of the internal standard in the mass spectra. A fairly good linear relationship (R2 = 0.9991) with a relative standard deviation of ca. 11% was observed between the relative peak intensities of the HALS components and the HALS contents ranging from 0.1-2.5 wt%, which could be used as the calibration line to determine the HALS content in PP composites directly by MALDI-MS. The UV-exposed PP composite samples were evaluated by this method to interpret the photostabilizing action of HALS in the PP materials based on the observed change in the relative abundances of the original and oxidized HALS components as a function of UV-exposure time.

19.
Appl Environ Microbiol ; 71(11): 7539-41, 2005 Nov.
Article in English | MEDLINE | ID: mdl-16269798

ABSTRACT

On-probe sample pretreatment using trifluoroacetic acid as an additional reagent enabled the direct detection of phospholipids in whole bacteria by means of matrix-assisted laser desorption ionization mass spectrometry for not only gram-negative organisms but also gram-positive ones with a thicker peptidoglycan layer.


Subject(s)
Gram-Positive Bacteria/chemistry , Phospholipids/analysis , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Bacillus subtilis/chemistry , Bacillus subtilis/cytology , Bacteriological Techniques , Gram-Positive Bacteria/cytology , Trifluoroacetic Acid/pharmacology
20.
Rapid Commun Mass Spectrom ; 19(5): 706-10, 2005.
Article in English | MEDLINE | ID: mdl-15702488

ABSTRACT

A novel method for the direct analysis of condensed tannin components in bark was developed on the basis of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with a simple solid sampling technique. The MALDI mass spectra obtained from the wood (bark) powder sample clearly showed a series of peaks corresponding to the sodium ion adducts of condensed tannin oligomers up to around m/z 3000. The results indicate that the condensed tannins in the bark sample used in this work mostly consist of combinations of flavan-3-ol units such as profisetinidin (PF), prorobinetinidin (PR) and prodelphinidin (PD), at least up to 10-mers (m/z approximately 3000).


Subject(s)
Acacia/metabolism , Plant Bark/metabolism , Specimen Handling/methods , Spectrometry, Mass, Electrospray Ionization/methods , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Tannins/analysis , Tannins/chemistry , Wood , Plant Extracts/analysis , Plant Extracts/chemistry
SELECTION OF CITATIONS
SEARCH DETAIL
...