N-confused double-decker porphyrins.
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Journal Article↗
Biomedical subjects
H Maeda
Publications and source records attributed to H Maeda.
Suppressor T cells regulate the nonanergic cell population that remains after peripheral tolerance is induced to the Mls-1 antigen in T cell receptor Vbeta 8.1 transgenic mice.
We have found suppressor T cells that inhibit the proliferative response of naive CD4(+) T cells in T cell receptor (TCR) Vbeta8.1 transgenic mice rendered tolerant in vivo by inoculation of Mls-1(a)-positive cells. This suppression was mediated by CD4(+) T cells but not by CD8(+) T cells or double-negative (DN) cells, and splenic CD4(+) T cells from tolerant mice displayed a greater suppression than lymph node CD4(+) T cells. Cell contact was required for efficient suppression, and known inhibitory cytokines such as IL-4, IL-10, and transforming growth factor beta were not involved. Suppressor T cells inhibited IL-2 production by naive CD4(+) T cells, and the addition of exogenous IL-2 diminished the suppressed activity while having little activity on tolerant T cells. Suppression was abolished by the elimination of CD25(+) T cells in the tolerant CD4(+) T cell subset. CD25(+)CD4(+) T cells suppressed the proliferative response of the residual fraction of the nonanergic population, namely, 6C10(+)CD4(+) T cells still present in the tolerant mice. However, 6C10(-)CD4(+) T cells still had reduced reactivity to Mls-1(a) even after CD25(+)CD4(+) T cells were removed and exogenous IL-2 was added. Suppressor cells appear to affect only residual nonanergic cells in situ, thereby facilitating the maintenance of the unresponsive state in vivo. These data provide a framework for understanding suppressor T cells and explain the difficulties and variables in defining their activity in other systems, because suppressor T cells apparently control only a small population of nonanergic cells in the periphery and may be viewed as a homeostatic mechanism.
Animals↗
Tyrosine nitration by peroxynitrite formed from nitric oxide and superoxide generated by xanthine oxidase.
Peroxynitrite (ONOO(-)) is a potent nitrating and oxidizing agent that is formed by a rapid reaction of nitric oxide (NO) with superoxide anion (O(2)). It appears to be involved in the pathophysiology of many inflammatory and neurodegenerative diseases. It has recently been reported (Pfeiffer, S., and Mayer, B. (1998) J. Biol. Chem. 273, 27280-27285) that ONOO(-) generated at neutral pH from NO and O(2) (NO/O(2)) was substantially less efficient than preformed ONOO(-) at nitrating tyrosine. Here we re-evaluated tyrosine nitration by NO/O(2) with a shorter incubation period and a more sensitive electrochemical detection system. Appreciable amounts of nitrotyrosine were produced by ONOO(-) formed in situ (2.9 micrometer for 5 min; 10 nm/s) by NO/O(2) flux obtained from propylamine NONOate (CH(3)N[N(O)NO](-) (CH(2))(3)NH(2)(+)CH(3)) and xanthine oxidase using pterin as a substrate in phosphate buffer (pH 7.0) containing 0.1 mm l-tyrosine. The yield of nitrotyrosine by this NO/O(2) flux was approximately 70% of that produced by the same flux of preformed ONOO(-) (2.9 micrometer/5 min). When hypoxanthine was used as a substrate, tyrosine nitration by NO/O(2) was largely eliminated because of the inhibitory effect of uric acid produced during the oxidation of hypoxanthine. Tyrosine nitration caused by NO/O(2) was inhibited by the ONOO(-) scavenger ebselen and was enhanced 2-fold by NaHCO(3), as would be expected, because CO(2) promotes tyrosine nitration. The profile of nitrotyrosine and dityrosine formation produced by NO/O(2) flux (2.9 micrometer/5 min) was consistent with that produced by preformed ONOO(-). Tyrosine nitration predominated compared with dityrosine formation caused by a low nanomolar flux of ONOO(-) at physiological concentrations of free tyrosine (<0.5 mm). In conclusion, our results show that NO generated with O(2) nitrates tyrosine with a reactivity and efficacy similar to those of chemically synthesized ONOO(-), indicating that ONOO(-) can be a significant source of tyrosine nitration in physiological and pathological events in vivo.
Humans↗
Site-selective and stereoselective intramolecular (2pi + 2pi) photocycloaddition of arylalkenes to pyrene and its photocycloreversion
Irradiation of a benzene solution containing methyl p-(1-pyrenylmethoxymethyl)cinnamate (1a) with a high-pressure Hg lamp through Pyrex filter stereoselectively gave an intramolecular (2pi + 2pi) photocycloadduct (2a) in an 83% yield in a site-selective manner at the 4,5-position of the pyrene ring. Similar irradiation of an ortho-substituted derivative (3) afforded the corresponding (2pi + 2pi) cycloadduct (4) as a sole product at the 9,10-position of pyrene. The site-selective photocycloaddition can be reasonably explained by the intramolecular sandwich-type singlet exciplexes between the pyrene and phenyl rings.
Journal Article↗
Cutting edge: gab2 mediates an inhibitory phosphatidylinositol 3'-kinase pathway in T cell antigen receptor signaling.
Phosphatidylinositol 3'-kinase (PI3K) is a key component of multiple signaling pathways, where it typically promotes survival, proliferation, and/or adhesion. Here, we show that in TCR signaling, the scaffolding adapter Gab2 delivers an inhibitory signal via PI3K. Overexpression of Gab2 in T cell lines inhibits TCR-evoked activation of the IL-2 promoter, blocking NF-AT- and NF-kappaB-directed transcription. Inhibition is abrogated by mutating the Gab2 p85-binding sites, by treatment with PI3K inhibitors or by cotransfection of phosphatase homolog of tensin. Our findings provide the first evidence of a negative function for a scaffolding adapter in T cells and identify Gab2/PI3K-containing complexes as novel regulators of TCR signaling.
Adaptor Proteins, Signal Transducing↗
Anion antiport mechanism is involved in transport of lactic acid across intestinal epithelial brush-border membrane.
Intestinal epithelial membrane transport of L-lactic acid was characterized using rabbit jejunal brush-border membrane vesicles (BBMVs). The uptake of L-[(14)C]lactic acid by BBMVs showed an overshoot phenomenon in the presence of outward-directed bicarbonate and/or inward-directed proton gradients. Kinetic analysis of L-[(14)C]lactic acid uptake revealed the involvement of two saturable processes in the presence of both proton and bicarbonate gradients. An arginyl residue-modifying agent, phenylglyoxal, inhibited L-[(14)C]lactic acid transport by the proton cotransporter, but not by the anion antiporter. The initial uptakes of L-[(14)C]lactic acid which are driven by bicarbonate ion and proton gradients were inhibited commonly by monocarboxylic acids and selectively by anion exchange inhibitor 4, 4'-diisothiocyanostilbene-2,2'-disulfonic acid and protonophore carbonylcyanide p-trifluoromethoxyphenylhydrazone, respectively. These observations demonstrate that L-lactic acid is transported across the intestinal brush-border membrane by multiple mechanisms, including an anion antiporter and a previously known proton cotransporter.
Animals↗
Competition among seven Escherichia coli sigma subunits: relative binding affinities to the core RNA polymerase.
Seven different species of the RNA polymerase sigma subunit exist in Escherichia coli, each binding to a single species of the core enzyme and thereby directing transcription of a specific set of genes. To test the sigma competition model in the global regulation of gene transcription, all seven E.coli sigma subunits have been purified and compared for their binding affinities to the same core RNA polymerase (E). In the presence of a fixed amount of sigma(70), the principal sigma for growth-related genes, the level of Esigma(70) holoenzyme formation increased linearly with the increase in core enzyme level, giving an apparent K:(d) for the core enzyme of 0.26 nM. Mixed reconstitution experiments in the presence of a fixed amount of core enzyme and increasing amounts of an equimolar mixture of all seven sigma subunits indicated that sigma(70) is strongest in terms of core enzyme binding, followed by sigma(N), sigma(F), sigma(E)/sigma(FecI), sigma(H) and sigma(S) in decreasing order. The orders of core binding affinity between sigma(70) and sigma(N) and between sigma(70) and sigma(H) were confirmed by measuring the replacement of one core-associated sigma by another sigma subunit. Taken together with the intracellular sigma levels, we tried to estimate the number of each holoenzyme form in growing E. coli cells.
Binding, Competitive↗
Child and elderly victims in forensic autopsy during a recent 5 year period in the southern half of Osaka city and surrounding areas.
To outline the recent features of child and elderly victims from the medico-legal perspective with special reference to abuse and neglect, a retrospective investigation of forensic autopsy cases over a 5 year period (1994-1998) in the southern half of Osaka city and surrounding areas (a population of 1.57 million) was undertaken. Among 646 autopsy cases, there were 53 child cases (under the age of 15 years, about 80% below 6) and 121 elderly cases (65 years old and above). Nearly half of the child deaths and more than half of the elderly deaths were described as accidental. Fire and traffic victims were much more frequent in the elderly. Child victims included those of neonaticide/infanticide (n=6), physical abuse (n=10), unintentional fatal infliction (n=2), neglect (n=2), mutual suicide (n=2), suicide (n=1) and murder (n=3). Child abuse and neglect were domestic maltreatment by the parents. In this series, there was a comparable number of fatalities due to maltreatment in the elderly (n=13) and in children, and non-domestic violence was more frequent in the elderly than domestic violence. Elderly females tended to be battered by their sons or grandsons in domestic violence cases, whereas males were predominantly attacked by younger males in non-domestic violence. The other elderly victims included those of self-neglect (n=2), murder (n=7) and suicide (n=9). Non-domestic homicide of the elderly occurred mainly in the center of the city, whereas domestic maltreatment of children and the elderly was sporadic, although somewhat more frequent in the peripheral zone of the city and the surrounding areas. The above profile of child and elderly abuse suggests a substantial influence of social and familial backgrounds.
Accidents↗
Automated determination of carboxyhemoglobin contents in autopsy materials using head-space gas chromatography/mass spectrometry.
To establish a method for the routine analysis of carboxyhemoglobin (COHb) in autopsy materials including those which have undergone postmortem changes, e.g. thermo-coagulation, putrifaction and contamination, an automated head-space gas chromatography/mass spectrometry (GC/MS) analysis was utilized. The procedure consisted of preparation of the sample in a vial and a carbon monoxide (CO) saturated sample, for estimation of hemoglobin content, in another vial, the addition of n-octanol, potassium ferricyanide and an internal standard (t-butanol), GC separation and determination of CO using a GC/MS system equipped with an automated head-space gas sampler. The method was practical not only with the blood and bone marrow aspirates to confirm the findings on the CO-oximeter system, but also with the thermo-coagulated and putrified blood.
Automation↗
Novel approach to quantitative reverse transcription PCR assay of mRNA component in autopsy material using the TaqMan fluorogenic detection system: dynamics of pulmonary surfactant apoprotein A.
A novel approach to quantitative reverse transcription (RT)-PCR assay of mRNA component using fluorescent TaqMan methodology and a new instrument (ABI Prism 7700 sequence detection system) was developed for autopsy materials. Pulmonary surfactant apoprotein A (SP-A) mRNA from a cadaveric lung was quantitated in real-time. The target SP-A gene and the endogenous reference of glyceraldehyde-3-phosphate (GAPDH) were amplified in the same tube, and an amount of the target was normalized to the reference. This assay had a high reproducibility and discrimination even in forensic autopsy materials up to 96 h postmortem. Elevated SP-A expressions were determined in some cases. This system without post-PCR sample handling would be a very useful tool in pathological diagnosis and DNA analysis.
Adolescent↗
Immunohistochemical distribution of C-reactive protein in the hepatic tissue in forensic autopsy.
Previously, we examined the expression of C-reactive protein (CRP) in hepatic tissues in fatal injuries (injury deaths) immunohistochemically, and classified the CRP distribution into three patterns: diffuse (D-) pattern, diffuse with strong positivity in the hepatic lobules; periportal (PP-) pattern, characterized by positive cells in the periportal region of some lobules; focal (F-) pattern, showing small islands of positive cells in some lobules. There was a relationship between the CRP distribution and the survival time. In this study, we further analyzed the deaths including those due to other than fatal injuries (non-injury deaths), and a study of a total of 314 deaths from various causes was performed. Generally, non-injury deaths showed findings similar to those in injury deaths. PP- and/or F-patterns were observed in 43.7% of cases having a short survival time (<6 h), but found in only 3% of those surviving longer (>6 h), showing that such findings are suggestive of a short survival time. D-pattern was found more frequently in non-acute deaths (60.4%), than in acute deaths (10.9%). In acute deaths, D-pattern was found in some cases showing extensive tissue injuries, such as burns and polytrauma, and inflammative predisposition. Immunohistochemical findings also showed some correlation with the serum CRP level. Our data suggest that hepatic CRP immunohistochemistry may be a useful tool for elucidating the dying process.
Acute Disease↗
Immunohistochemistry of pulmonary surfactant apoprotein A in forensic autopsy: reassessment in relation to the causes of death.
To reassess the immunohistochemical distribution of pulmonary surfactant apoprotein A (SP-A) in relation to the causes of death, 282 forensic autopsy cases were reviewed. The most intense and dense granular immunostaining of intra-alveolar SP-A was observed in the hyaline membrane syndrome from various traumas, protracted death from drowning, and perinatal aspiration of amniotic fluid. Similar granular staining pattern was found in fatal poisoning by a muscle relaxant and organophosphate pesticides. An evident increase of intra-alveolar granular staining was noted in most fatalities from mechanical asphyxia and drowning, and some cases of fire death. SP-A staining was usually very weak or sparse in alcohol intoxication, poisoning by hypnotics and also carbon monoxide poisoning. These findings suggest that the amount of intra-alveolar granular SP-A staining may be a possible indicator of severity and duration of respiratory distress (agony) from peripheral (non-central nervous system) origin and alveolar damage.
Asphyxia↗
Methamphetamine-related fatalities in forensic autopsy during 5 years in the southern half of Osaka city and surrounding areas.
To outline the recent features of methamphetamine-related fatalities from the medico-legal point of view, a retrospective investigation of forensic autopsy cases involving methamphetamine during a 5-year period (1994-1998) in the southern half of Osaka city and surrounding areas (about 1.57 million population) was undertaken. Among 646 autopsy cases, methamphetamine was detected in 15 victims (nine males, six females; 16-71 years of age; most frequently in males in their thirties). Primary scenes of fatal events were concentrated in the middle of the city. About half of them were transferred from emergency medical centers (survival time, up to 30 h). The cause and manner of death were: methamphetamine poisoning (n=4), homicide (n=4), accidental falls and aspiration from drug abuse (n=4), fire death (n=1), myocardial infarction (n=1), and cerebral hemorrhage (n=1) under drug influence. Usually injection scars and fresh puncture sites were found. Blood methamphetamine concentrations were 2.29-17.05 micromol/dl in the fatal poisoning, 0. 44-3.80 micromol/dl in deaths from other extrinsic causes (trauma), and 1.35-2.17 micromol/dl in cardio- and cerebrovascular strokes. Common complications were cardiomyopathy, cerebral perivasculitis and liver cirrhosis/interstitial hepatitis. Fatal and nonfatal methamphetamine poisonings are separately dealt with by the administrative medical examiner's office and in emergency medical centers. Tightly cooperative approaches of clinical and medico-legal experts are required for the effective social and medical management of drug abuse.
Adolescent↗
Imidoylation of acidic hydrocarbons with selenium and isocyanides: A new synthetic method for preparation of selenoimidates
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Journal Article↗
Prostatic laceration associated with blunt pelvic trauma.
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Abdominal Injuries↗
Formation of abasic sites in DNA by t-butyl peroxyl radicals: implication for potent genotoxicity of lipid peroxyl radicals.
We investigated abasic site formation in calf thymus DNA after exposure to a model compound of lipid-derived peroxyl radical that was generated by the reaction of tert-butyl hydroperoxide (t-BuOOH) with hemoglobin. Abasic site density in DNA was quantified by use of an enzyme-linked immunosorvent assay-like assay. In the presence of 10 mM t-BuOOH and 12.5 or 25 microM hemoglobin, 0.6-1.0 abasic sites/10(4) nucleotides were formed. However, abasic sites were not detected after replacing hemoglobin with nonheme iron, e.g. EDTA/Fe(2+), which initiates the production of alkyl and alkoxyl radicals. Therefore, the present results suggest that lipid peroxyl radicals may have a genotoxic potential through unique reactions, including depurination and depyrimidination, which lead to DNA strand breakage.
DNA↗
Stability and structure of doubly N-confused porphyrins.
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Drug Stability↗
Isolation and characterization of a novel zinc finger gene, ZNF219, and mapping to the human chromosome 14q11 region.
We have isolated and characterized a novel zinc finger gene by screening a human testis cDNA library. The isolated cDNA, termed ZNF219, contains an open reading frame of 2169 nucleotides encoding 723 amino acids. Sequence analysis revealed 9 sets of Kruppel-related zinc finger structures and proline-rich regions in several parts. ZNF219 exhibited ubiquitous expression in all fetal and adult tissues examined. The transcript size was 5.5 kb in adult tissues, while the main transcript size in the embryo stage was 3.5 kb. The transcript size is developmentally regulated. When the plasmid cloned with green fluorescent protein (GFP)-tagged ZNF219 was expressed in HeLa and COS7 cells, strong fluorescence intensities were observed only in the nucleus of both cells by fluorescence confocal microscopy. These data suggest that ZNF219 may be related to the regulation of transcription and developmental regulation. Genomic structure analysis mapped ZNF219 to chromosome 14q11 between markers D14S72 and D14S990, because a sequence tagged site mapped to the locus was found in the intron region of the ZNF219 gene.
Adult↗