Bianthraquinones from Cassia siamea

The isolation of two bianthraquinones, 1,1',3,8,8'-pentahydroxy-3',6-dimethyl[2,2'-bianthracene]-9,9',10,10'-tetrone and 7-chloro-1,1',6,8,8'-pentahydroxy-3,3'-dimethyl[2,2'-bianthracene]-9,9',10,10'-tetrone, from the root bark of Cassia siamea is reported. The structures were established by analysis of spectroscopic data and 7-chloro-1,1',6,8,8'-pentahydroxy-3,3'-dimethyl[2,2'-bianthracene]-9,9',10,10'-tetrone was determined on the direct comparison with synthetic compound.     

Retinoid signaling is required for chondrocyte maturation and endochondral bone formation during limb skeletogenesis

Retinoids have long been known to influence skeletogenesis but the specific roles played by these effectors and their nuclear receptors remain unclear. Thus, it is not known whether endogenous retinoids are present in developing skeletal elements, whether expression of the retinoic acid receptor (RAR) genes alpha, beta, and gamma changes during chondrocyte maturation, or how interference with retinoid signaling affects skeletogenesis. We found that immature chondrocytes present in stage 27 (Day 5.5) chick embryo humerus exhibited low and diffuse expression of RARalpha and gamma, while RARbeta expression was strong in perichondrium. Emergence of hypertrophic chondrocytes in Day 8-10 embryo limbs was accompanied by a marked and selective up-regulation of RARgamma gene expression. The RARgamma-rich type X collagen-expressing hypertrophic chondrocytes lay below metaphyseal prehypertrophic chondrocytes expressing Indian hedgehog (Ihh) and were followed by mineralizing chondrocytes undergoing endochondral ossification. Bioassays revealed that cartilaginous elements in Day 5.5, 8.5, and 10 chick embryo limbs all contained endogenous retinoids; strikingly, the perichondrial tissues surrounding the cartilages contained very large amounts of retinoids. Implantation of beads filled with retinoid antagonist Ro 41-5253 or AGN 193109 near the humeral anlagens in stage 21 (Day 3.5) or stage 27 chick embryos severely affected humerus development. In comparison to their normal counterparts, antagonist-treated humeri in Day 8.5-10 chick embryos were significantly shorter and abnormally bent; their diaphyseal chondrocytes had remained prehypertrophic Ihh-expressing cells, did not express RARgamma, and were not undergoing endochondral ossification. Interestingly, formation of an intramembranous bony collar around the diaphysis was not affected by antagonist treatment. Using chondrocyte cultures, we found that the antagonists effectively interfered with the ability of all-trans-retinoic acid to induce terminal cell maturation. The results provide clear evidence that retinoid-dependent and RAR-mediated mechanisms are required for completion of the chondrocyte maturation process and endochondral ossification in the developing limb. These mechanisms may be positively influenced by cooperative interactions between the chondrocytes and their retinoid-rich perichondrial tissues.     

Bleomycin stimulates lung fibroblasts to release neutrophil and monocyte chemotactic activity

We determined whether human lung fibroblasts might release chemotactic activity for neutrophils (NCA) and monocytes (MCA) in response to bleomycin. The human lung fibroblasts supernatant fluids were evaluated for chemotactic activity by a blind well chamber technique. Human lung fibroblasts released NCA and MCA in a dose- and time-dependent manner in response to bleomycin. Checkerboard analysis of supernatant fluids revealed that both NCA and MCA were chemotactic. Partial characterization revealed that NCA was partly heat labile, trypsin sensitive, and predominantly ethyl acetate extractable. In contrast, MCA was partly trypsin sensitive and ethyl acetate extractable. The release of chemotactic activity was inhibited by lipoxygenase inhibitors and cycloheximide. Molecular sieve column chromatography revealed that both NCA and MCA had multiple chemotactic peaks. NCA was inhibited by leukotriene B4 receptor antagonist and anti-IL-8 and G-CSF Abs. MCA was attenuated by leukotriene B4 receptor antagonist, and monocyte chemoattractant protein-1, GM-CSF, and TGF-beta Abs. Leukotriene B4 receptor antagonist and these Abs inhibited the corresponding m.w. chemotactic activity separated by column chromatography. The concentrations of IL-8, G-CSF, monocyte chemoattractant protein-1, GM-CSF, and TGF-beta in the supernatant fluids significantly increased in response to bleomycin. These data suggest that lung fibroblasts may modulate inflammatory cell recruitment into the lung by releasing NCA and MCA in response to bleomycin.     

A Clostridium perfringens hem gene cluster contains a cysG(B) homologue that is involved in cobalamin biosynthesis

The hem gene cluster, which consists of hemA, cysG(B), hemC, hemD, hemB, and hemL genes, and encodes enzymes involved in the biosynthetic pathway from glutamyl-tRNA to uroporphyrinogen III, has been identified by the cloning and sequencing of two overlapping DNA fragments from Clostridium perfringens NCTC8237. The deduced amino acid sequence of the N-terminal region of C. perfringens HemD is homologous to those reported for the C-terminal region of Salmonella typhimurium CysG and Clostridium josui HemD. C. perfringens CysG(B) is a predicted 220-residue protein which shows homology to the N-terminal region of S. typhimurium CysG. Disruption of the cysG(B) gene in C. perfringens strain 13 by homologous recombination reduced cobalamin (vitamin B12) levels by a factor of 200. When grown in vitamin B12-deficient medium, the mutant strain showed a four-fold increase in its doubling time compared with that of the wild-type strain, and this effect was counteracted by supplementing the medium with vitamin B12. These results suggest that C. perfringens CysG(B) is involved in the chelation of cobalt to precorrin II as suggested for the CysG(B) domain of S. typhimurium CysG, enabling the synthesis of cobalamin.     

New analogue of arenastatin A, a potent cytotoxic spongean depsipeptide, with anti-tumor activity

Two analogues possessing steric hindered substituents on C-15 of arenastatin A (1), a potent cytotoxic spongean depsipeptide, were synthesized and shown to enhance stability in mouse serum. Notably, 15-tert-butylanalogue (6) with higher cytotoxicity exhibited in vivo anti-tumor activity through iv administration different from 1. Additionally, conformation analysis among the two analogues and arenastatin A (1) indicated that the torsion angle from C-14 to C-20 is a conclusive factor for the potent cytotoxicity of 1.     

Serine protease inhibitors modulate chemotactic cytokine production by human lung fibroblasts in vitro

Chemotactic chemokines can be released from lung fibroblasts in response to interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha. An imbalance between proteases and antiproteases has been observed at inflammatory sites, and, therefore, protease inhibitors might modulate fibroblast release of chemotactic cytokines. To test this hypothesis, serine protease inhibitors (FK-706, alpha(1)-antitrypsin, or N(alpha)-p-tosyl-L-lysine chloromethyl ketone) were evaluated for their capacity to attenuate the release of neutrophil chemotactic activity (NCA) or monocyte chemotactic activity (MCA) from human fetal lung fibroblasts (HFL-1). Similarly, the release of the chemoattractants IL-8, granulocyte colony-stimulating factor, monocyte chemoattractant protein-1, macrophage colony-stimulating factor, and granulocyte/macrophage colony-stimulating factor, from HFL-1, were evaluated in response to IL-1beta and TNF-alpha. NCA, MCA, and chemotactic cytokines were attenuated by FK-706. However, matrix metalloproteinase inhibitors were without effect, and cysteine protease inhibitors only slightly attenuated chemotactic or cytokine release. These data suggest that IL-1beta and TNF-alpha may stimulate lung fibroblasts to release NCA and MCA by a protease-dependent mechanism and that serine protease inhibitors may attenuate the release.     

Spermine induces cataract and 43-kDa protein that binds spermine possibly participates in the cataract formation

Among polyamines (putrescine, spermidine, and spermine), spermine specifically induces cataract in an organ cultured lens. Spermine uptake nearly paralleled the cataract formation. When polyamines were added to lens soluble proteins, spermine specifically induced turbidity. When lens soluble proteins were separated by gel chromatography, heavy-molecular-weight protein (HMW, high molecular form of alpha-crystallin) and proteins between betaH- and betaL-crystallin fractions reacted with spermine and aggregated. SDS-polyacrylamide gel electrophoresis of the aggregated proteins showed that 43-kDa lens protein was commonly observed in both aggregates. Spermine-affinity chromatography of the total soluble proteins showed the binding of HMW protein to the gel and the chromatogram of the second turbidity peak in the gel chromatography showed the binding of 43-kDa protein. These results indicated that 43-kDa protein, which is present as a subunit in HMW and also in free form, binds spermine and induces turbidity of lens soluble proteins and produces cataract in a cultured lens.     

Purification and characterization of the recombinant Thermus sp. strain T2 alpha-galactosidase expressed in Escherichia coli

The nucleotide sequence of the Thermus sp. strain T2 DNA coding for a thermostable alpha-galactosidase was determined. The deduced amino acid sequence of the enzyme predicts a polypeptide of 474 amino acids (M(r), 53,514). The observed homology between the deduced amino acid sequences of the enzyme and alpha-galactosidase from Thermus brockianus was over 70%. Thermus sp. strain T2 alpha-galactosidase was expressed in its active form in Escherichia coli and purified. Native polyacrylamide gel electrophoresis and gel filtration chromatography data suggest that the enzyme is octameric. The enzyme was most active at 75 degrees C for p-nitrophenyl-alpha-D-galactopyranoside hydrolysis, and it retained 50% of its initial activity after 1 h of incubation at 70 degrees C. The enzyme was extremely stable over a broad range of pH (pH 6 to 13) after treatment at 40 degrees C for 1 h. The enzyme acted on the terminal alpha-galactosyl residue, not on the side chain residue, of the galactomanno-oligosaccharides as well as those of yeasts and Mortierella vinacea alpha-galactosidase I. The enzyme has only one Cys residue in the molecule. para-Chloromercuribenzoic acid completely inhibited the enzyme but did not affect the mutant enzyme which contained Ala instead of Cys, indicating that this Cys residue is not responsible for its catalytic function.     

Behavioral compensations in a positional learning and memory task by aged monkeys

The present experiment assessed learning and memory of a positional task by evaluating behavioral strategies as well as accuracy of a task in four young and four aged monkeys. They were tested in a delayed response (DR) task that has been widely used to study animal models of aging. The task consisted of two phases; an acquisition of the task and a positional memory test with five delay times (1-30 s). There was no clear difference between age groups in the number of trials needed for acquisition of the task. However, an analysis of behavior revealed differences in behavioral characteristics displayed during testing. The young monkeys showed various irrelevant behaviors during the execution of the task. In contrast, the aged monkeys consistently concentrated on the task exhibiting no behaviors irrelevant to the task. These results showed than the aged monkeys' performance was supported by a different behavioral strategy from the young monkeys. The results of the memory test were similar to those of the acquisition on the accuracy and the behavior. The aged monkeys depended on behavioral cues to preserve their positional memory, especially during the task. The present study suggests that cognitive impairments in aged monkeys can be compensated for by employing behavioral strategies.