Reduced pain hypersensitivity and inflammation in mice lacking microsomal prostaglandin e synthase-1

We examined the in vivo role of membrane-bound prostaglandin E synthase (mPGES)-1, a terminal enzyme in the PGE2-biosynthetic pathway, using mPGES-1 knockout (KO) mice. Comparison of PGES activity in the membrane fraction of tissues from mPGES-1 KO and wild-type (WT) mice indicated that mPGES-1 accounted for the majority of lipopolysaccharide (LPS)-inducible PGES in WT mice. LPS-stimulated production of PGE2, but not other PGs, was impaired markedly in mPGES-1-null macrophages, although a low level of cyclooxygenase-2-dependent PGE2 production still remained. Pain nociception, as assessed by the acetic acid writhing response, was reduced significantly in KO mice relative to WT mice. This phenotype was particularly evident when these mice were primed with LPS, where the stretching behavior and the peritoneal PGE2 level of KO mice were far less than those of WT mice. Formation of inflammatory granulation tissue and attendant angiogenesis in the dorsum induced by subcutaneous implantation of a cotton thread were reduced significantly in KO mice compared with WT mice. Moreover, collagen antibody-induced arthritis, a model for human rheumatoid arthritis, was milder in KO mice than in WT mice. Collectively, our present results provide unequivocal evidence that mPGES-1 contributes to the formation of PGE2 involved in pain hypersensitivity and inflammation.     

The Observation of an Ultradian Rhythm of Heart Rate in Low Birth Weight Infants

The relationship between ultradian rhythm of heart rate and schedules of body contact or feeding was studied in five low birth weight infants of conceptional ages of 34-36 weeks. The differential contribution of body contact and feeding to the formation of the ultradian rhythm of heart rate was evaluated by applying two different schedules of two- and three-hour periods for feeding with a single schedule of three hours for body contact during an observation period of seven days. A chi-square periodogram was used to calculate the period of ultradian rhythm. As a result, a three-hour ultradian rhythm of heart rates was detected in all subjects, which seems to correspond to either schedule of body contact or of feeding. However, no clear changes in the ultradia n rhythm of heart rate were observed corresponding to changes in feeding schedules. The ultradian rhythm of heart rate seems to correspond more to body contact than to feeding.     

Relationship between antibody productivity by activated human lymph node lymphocytes from lung cancer patients and lymphocyte subsets

Regional lymph node lymphocytes from five patients with primary lung cancer were analyzed for subset composition, and exposed in vitro to the polyclonal human B cell mitogen Staphylococcus aureus Cowan I (SACI) or the murine B cell mitogen lipopolysaccharide (LPS) and then fused with mouse myeloma cells for investigation at the clonal level of their antibody (Ab) production and its statistical relation to the original subset composition. No correlation was found between the proportion of CD19+, CD23+, or CD3+ cells in the lymphocyte sample prior to its exposure to either SACI or LPS, and the Ab production efficiency, defined as the ratio of the number of Ab producing wells to the total number of proliferating wells. For lymphocytes exposed to LPS, however, a strong correlation (r = 0.931, p = 0.02) was observed between the Ab production efficiency and the ratio of CD8+ to CD3+ cells (CD8/CD3) in the original sample at least within the ranges studied (CD8/CD3 = 0.216–0.288). For those exposed to SACI, no correlation was found between the Ab production efficiency and the CD8/CD3 ratio (r = 0.881, p = 0.12) or the proportion of CD8+ cells (r = 0.808, p = 0.19) in the original sample. These results suggest that the repertoire of B cells responsive to LPS is different at least in part from the repertoire responsive to SACI and that the ratio CD8/CD3 could serve as a practical predictor for Ab production by human lymphocytes stimulated with LPS. This revised version was published online in July 2006 with corrections to the Cover Date.     

Condensed chromatin and cell inactivation by single-hit kinetics

Mammalian cells are extremely sensitive to gamma rays at mitosis, the time at which their chromatin is maximally condensed. The radiation-induced killing of mitotic cells is well described by single-hit inactivation kinetics. To investigate if radiation hypersensitivity by single-hit inactivation correlated with chromatin condensation, Chinese hamster ovary (CHO) K1 (wild-type) and xrs-5 (radiosensitive mutant) cells were synchronized by mitotic shake-off procedures and the densities of their chromatin cross sections and their radiosensitivities were measured immediately and 2 h into G1 phase. The chromatin of G1-phase CHO K1 cells was dispersed uniformly throughout their nuclei, and its average density was at least three times less than in the chromosomes of mitotic CHO K1 cells. The alpha-inactivation co-efficient of mitotic CHO K1 cells was approximately 2.0 Gy(-1) and decreased approximately 10-fold when cells entered G1 phase. The density of chromatin in CHO xrs-5 cell chromosomes at mitosis was greater than in CHO K1 cell chromosomes, and the radiosensitivity of mitotic CHO xrs-5 cells was the greatest with alpha = 5.1 Gy(-1). In G1 phase, CHO xrs-5 cells were slightly more resistant to radiation than when in mitosis, but a significant proportion of their chromatin was found to remain in condensed form adjacent to the nuclear membrane. These studies indicate that in addition to their known defects in DNA repair and V(D)J recombination, CHO xrs-5 cells may also be defective in some process associated with the condensation and/or dispersion of chromatin at mitosis. Their radiation hypersensitivity could result, in part, from their DNA remaining in compacted form during interphase. The condensation status of DNA in other mammalian cells could define their intrinsic radiosensitivity by single-hit inactivation, the mechanism of cell killing which dominates at the dose fraction size (1.8-2.0 Gy) most commonly used in radiotherapy.     

An Electron Spin Resonance Study for Real-time Detection of Ascorbyl Free Radicals After Addition of Dimethyl Sulfoxide in Murine Hippocampus or Plasma During Kainic Acid-Induced Seizures

Electron spin resonance (ESR)-silent ascorbate solutions generate a detectable, likely concentration-dependent signal of ascorbyl free radicals (AFR) immediately upon addition of a molar excess of dimethyl sulfoxide (DMSO). We aimed to perform quantitative ESR analysis of AFR in real time after addition of DMSO (AFR/DMSO) to evaluate ascorbate concentrations in fresh hippocampus or plasma following systemic administration of kainate in mice. Use of a special tissue-type quartz cell allowed immediate detection of AFR/DMSO ESR spectra in fresh tissues from mice. AFR/DMSO content was increased significantly in fresh hippocampus or plasma obtained during kainate-induced seizures of mice, reaching maximum levels at 90 min after intraperitoneal administration of 50 mg/kg kainic acid. This suggests that oxidative injury of the hippocampus resulted from the accumulation of large amounts of ascorbic acid in the brain after kainic acid administration. AFR/DMSO content measured on an ESR spectrometer can be used for real-time evaluation of ascorbate content in fresh tissue. Due to the simplicity, good performance, low cost and real-time monitoring of ascorbate, this method may be applied to clinical research and treatment in the future.     

Synthesis and structure–activity relationships of cassiarin A as potential antimalarials with vasorelaxant activity

Cassiarin A 1, a tricyclic alkaloid, isolated from the leaves of Cassia siamea (Leguminosae), shows powerful antimalarial activity against Plasmodium falciparum in vitro as well as P. berghei in vivo, which may be valuable leads for novel antimalarials. Interactions of parasitized red blood cells (pRBCs) with endothelium in aorta are especially important in the processes contribute to the pathogenesis of severe malaria. Nitric oxide (NO) reduces endothelial expression of receptors/adhesion molecules used by pRBC to adhere to vascular endothelium, and reduces cytoadherence of pRBC to vascular endothelium. Cassiarin A 1 showed vasorelaxation activity against rat aortic ring, which may be related with NO production. A series of a hydroxyl and a nitrogen-substituted derivatives and a dehydroxy derivative of 1 have been synthesized as having potent antimalarials against P. falciparum with vasodilator activity, which may reduce cytoadherence of pRBC to vascular endothelium. Cassiarin A 1 exhibited a potent antimalarial activity and a high selectivity index in vitro, suggesting that the presence of a hydroxyl and a nitrogen atom without any substituents may be important to show antimalarial activity. Relative to cassiarin A, a methoxy derivative showed more potent vasorelaxant activity, although it did not show improvement for inhibition of P. falciparum in vitro. These cassiarin derivatives may be promising candidates as antimalarials with different mode of actions.     

Induction of Cytoplasmic Streaming and Movement of Chloroplast Induced by L-Histidine and its Derivatives in Leaves of Egeria densa

Rotational cytoplasmic streaming in leaves of Egeria densa wasinduced by light as well as by L-histidine (L-His). During bothtreatement with light and with L-His chloroplasts on the periclinalface were dislodged and moved to the anticlinal face where rotationalcytoplasmic streaming occurred. The effective concentrationof L-His was about 0.01 mM and the effect was almost saturatedat 0.1 mM. A derivative of L-His, 3-methyl-L-histidine, wasslightly less effective than L-His. By contrast, 1-methyl-L-histidinewas almost ineffective for induction of streaming, not onlyin Egeria but also in Vallisneria. Our resutlts are in markedcontrast to Fitting's result (1936) that 1-M-L-His is more effectivethan L-His. In Egeria, 1-methyl-L-His counteracted the stimulativeeffect of L-His. 1-Methyl-L-His penetrated into leaf cells ofEgeria to the same extent as 3-methyl-L-His and to a greaterextent than L-His. This observation excludes the possibilitythat the impermeability of leaves to 1-M-L-His might be responsiblefor its ineffectiveness. 1-M-L-His did not interfere with photodinesis.Differences in the mechanism of induction of rotational streamingby L-His and by light are discussed. ⁴ Present address: Fukui Institute of Technology, Gakuen, Fukui,910 Japan (Received July 16, 1990; Accepted December 20, 1990)     

Fine structure and 18S rDNA phylogeny of a marine araphid pennate diatom Plagiostriata goreensis gen. et sp. nov. (Bacillariophyta)

A marine araphid pennate diatom Plagiostriata goreensis is described from the sand grains of Goree Island, Dakar, Republic of Senegal, based on observations of fine structure of its frustule. The most striking feature of the species is its striation, which is angled at approximately 60° across the robust sternum. The other defining features of the species are its one highly reduced rimoportula and apical pores located at both ends of the valve margin. In the 18S rDNA phylogeny, the species appears as a member of a ‘small‐celled clade’ of araphid pennate diatoms that consist of Nanofrustulum, Opephora and Staurosira. The results of the phylogenetic analyses suggest that the distinct characters of the diatom; namely, oblique striae and apical pores, may have been acquired independently. However, it remains unclear whether the rimoportula of P. goreensis is a reduced state or P. goreensis acquired its morphologically curious rimoportula independently after the loss of an ancient rimoportula at the root of the small‐celled clade.     

Endothelin regulates neural crest deployment and fate to form great vessels through Dlx5/Dlx6-independent mechanisms

Endothelin-1 (Edn1), originally identified as a vasoconstrictor peptide, is involved in the development of cranial/cardiac neural crest-derived tissues and organs. In craniofacial development, Edn1 binds to Endothelin type-A receptor (Ednra) to induce homeobox genes Dlx5/Dlx6 and determines the mandibular identity in the first pharyngeal arch. However, it remains unsolved whether this pathway is also critical for pharyngeal arch artery development to form thoracic arteries. Here, we show that the Edn1/Ednra signaling is involved in pharyngeal artery development by controlling the fate of neural crest cells through a Dlx5/Dlx6-independent mechanism. Edn1 and Ednra knock-out mice demonstrate abnormalities in pharyngeal arch artery patterning, which include persistent first and second pharyngeal arteries, resulting in additional branches from common carotid arteries. Neural crest cell labeling with Wnt1-Cre transgene and immunostaining for smooth muscle cell markers revealed that neural crest cells abnormally differentiate into smooth muscle cells at the first and second pharyngeal arteries of Ednra knock-out embryos. By contrast, Dlx5/Dlx6 knockout little affect the development of pharyngeal arch arteries and coronary arteries, the latter of which is also contributed by neural crest cells through an Edn-dependent mechanism. These findings indicate that the Edn1/Ednra signaling regulates neural crest differentiation to ensure the proper patterning of pharyngeal arch arteries, which is independent of the regional identification of the pharyngeal arches along the dorsoventral axis mediated by Dlx5/Dlx6.