Nerve agent metabolites, i.e., isopropyl methylphosphonic acid (IMPA) and pinacolyl methylphosphonic acid (PMPA), were derivatized by reacting them with 2,3,4,5,6-pentafluorobenzyl bromide (PFBBr) ...and were determined by mass spectrometry using an ultraviolet femtosecond laser emitting at 267 and 200 nm as the ionization source. The analytes of the derivatized compounds, i.e., IMPA-PFB and PMPA-PFB, contain a large side-chain, and molecular ions are very weak or absent in electron ionization mass spectrometry. The use of ultraviolet femtosecond laser ionization mass spectrometry, however, resulted in the formation of a molecular ion, even for compounds such as these that contain a highly bulky functional group. The signal intensity was larger at 200 nm due to resonance-enhanced two-photon ionization. In contrast, fragmentation was suppressed at 267 nm (nonresonant two-photon ionization) especially for PMPA-PFB, thus resulting in a lower background signal. This favorable result can be explained by the small excess energy in ionization at 267 nm and by the low-frequency vibrational mode of a bulky trimethylpropyl group in PMPA.
A simple method was proposed for on-site evaluation of the pulse width of an ultraviolet femtosecond laser coupled with a mass spectrometer. This technique was based on measurement of a two-photon ...ionization signal in mass spectrometry by translation of the prism in the pulse compressor of the femtosecond laser. The method was applied to optical pulses that were emitted at wavelengths of 267, 241, and 219 nm; the latter two pulses were generated by four-wave Raman mixing using the third harmonic emission of a Ti:sapphire laser (267 nm) in hydrogen gas. The measurement results show that this approach is useful for evaluation of the pulse width of the ultraviolet femtosecond laser used in mass spectrometry for trace analysis of organic compounds.
Multiphoton ionization processes were studied for three types of explosives using a line-tunable ultraviolet femtosecond laser. When peroxides such as triacetone triperoxide (TATP) and hexamethylene ...triperoxide diamine (HMTD) were ionized through a nonresonant two-photon process, a molecular ion was dominantly observed by reducing the excess energy remaining in the ion. However, an aromatic nitro compound such as 2,4,6-trinitrotoluene (TNT) produced large signals arising from molecular and fragment ions by resonant two-photon ionization. In addition, only fragment ions were produced from a nonaromatic nitro compound such as 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), even when a resonant two-photon ionization process was employed, suggesting that a further reduction in excess energy would be necessary if a molecular ion were to be observed.
Polychlorinated biphenyls (PCBs) in transformer and food oils were measured using gas chromatography combined with multiphoton ionization mass spectroscopy. An ultrashort laser pulse emitting in the ...far-ultraviolet region was utilized for efficient ionization of the analytes. Numerous signal peaks were clearly observed for a standard sample mixture of PCBs when the third and fourth harmonic emissions (267 and 200nm) of a femtosecond Ti:sapphire laser (800nm) were employed. The signal intensities were found to be greater when measured at 200nm compared with those measured at 267nm, providing lower detection limits especially for highly chlorinated PCBs at shorter wavelengths. After simple pretreatment using disposable columns, PCB congeners were measured and found to be present in the transformer oils used in Vietnam.
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•PCB congeners would be ionized by a process of two-photon ionization at 267 and 200nm.•The ionization energies were predicted to be 8.10–8.59eV for the PCB congeners.•PCBs were detected from the oil samples obtained in Vietnam.•A femtosecond laser emitting at 200nm was useful for sensitive detection of PCBs.
The laser pulse width was measured on-site the mass spectrometer by scanning a dispersion in the pulse compressor. A pulse width of 49 fs measured was close to 35 fs calculated from the spectrum.
Cells expressing interleukin-1β (IL-1β) mRNA were demonstrated by in situ hybridization in rat periapical lesions. A great number of osteoclasts with significant tartrate-resistant acid phosphatase ...activity were observed on the bone surfaces, and numerous IL-1β mRNA-expressing cells were widely distributed in the periodontal ligaments. IL-1β mRNA-expressing cells were mainly observed around the blood vessels in the vicinity of the bone resorption sites and occasionally found near the osteoblasts. Immunohistochemistry and enzyme histochemistry assays showed that IL-1β mRNA-expressing cells were not bone cells, but that they had the characteristic features of macrophages. These results suggested that macrophages may contribute to the production of IL-1β and play an important role in activation of osteoclastic bone resorption.
A Case Report of Generalized Juvenile Periodontitis HARA, Yoshitaka; AONO, Masao; CHINJU, Nobuhiro ...
Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology),
1984/06/28, Volume:
26, Issue:
2
Journal Article
Peer reviewed
Open access
A case of generalized juvenile periodontitis was observed. Then the patien's neutrophil function test and the immunohistopathological study with peroxidase-antiperoxidase (PAP) stain were conducted. ...1. The patient was a Japanese girl, 11 years and 7 months old, who was well-developed and well-nourished. The patient's chief complaint was the moving and the falling of permanent teeth. Her parents were first cousins. No history of similar illness in other members of her family could be obtained. There was a history of the falling of all deciduous teeth. In her oral findings, mobility of sixteen permanent teeth was M2-M3 and calculus deposit was slightly seen. Gram-negative anaerobic rod was demonstrated in her periodontal pocket. Based on above-described family history and clinical findings, the clinical diagnosis of Papillon-Lefévre syndrome might be suggested, but palmar-pluntar hyperkeratosis was not noted. 2. The chronological counts of white blood cells were always within normal limit. Serum IgG, IgA and IgM concentration were considerably increased. 3. The rate of phagocytosis and random migration of peripheral blood neutrophils (PBN) was within normal limit, but their chemotaxis stimulated with N-Formylmethionylleucylphenylalanine (FMLP) was significantly depressed. It was suspected that the neutrophil chemotaxis defect was due to a cell-associated defect. 4. The rate of superoxide (O2-) production of PBN stimulated with FMLP was slightly reduced in comparison with those of healthy human and adult periodontitis patients. 5. There was no difference in rate of superoxide production between gingival crevice neutrophils (GCN) and PBN stimulated with FMLP. On the other hand, stimulated with anaerobic organism, for example, Capnocytophaga or Actinobacillus actinomycetemcomitans, higher superoxide productions were seen in the case of GCN. 6. IgG-bearing cells which mostly consisted of plasma cells were predominant in patient's gingiva, IgA-bearing cells were few but more than IgM-bearing cells. The number of IgG-bearing cells was reduced at the side of pocket epithelium, while the numbers of IgA-and IgM-bearing cells made no difference at both sides of pocket and oral gingival epithelium. 7. S-100 protein-bearing cell, which was speculated as Langerhans cell, presented S-100 protein immunoreaction products in both nucleus and cytoplasm. Though among oral gingival epithelial cells some Langerhans cells were seen, they did not exist among pocket epithelial cells.
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