Biomedical subjects
Publications and source records attributed to Y Tang.
Three 2-alkenyl-4(1H)-quinolone compounds(I-III) were synthesized by two methods. III is a new compound from Evodia rutaecarpa and was synthesized through the reaction of the aldehyde intermediate(5) with Wittig reagent. The other two compounds were synthesized for the first time. These compounds showed vasodilating and antibacteria effects in pharmacological tests.
Upstream of the human epsilon-globin gene is the Locus Control Region (LCR) of the human beta-globin cluster, which consists of four DNase-I hypersensitive sites(HS1-HS4). It has been reported in transgenic experiments that HS3 preferentially regulates epsilon-globin gene expression. In order to elucidate the regulatory function of HS3 in the expression of globin gene, nuclear extracts from mouse hematopoietic tissues at several developmental stages were prepared and the binding of the nuclear factors to HS3 was analysed by using electrophoresis mobility shift assay(EMSA). Our results showed that the binding patterns of HS3 with nuclear extracts of mouse hematopoietic tissues at day 13 and day 18 of gestation were completely different; furthermore, by Southwestern Blot, the distinction between both stages was also demonstrated. It has been known that GATA and CACCC binding motifs are contained within HS3 core region. Using competitive gel-retardation assay, we found that no shift bands could be competed by using CACCC motif as a competitor. However one shift band at day 13 and day 18 of gestation could be competed respectively by using GATA motif as a competitor. We suggested that the shift bands, which could not be competed by both motifs, might be novel and stage-specific factors. In addition, by using Western Blot, we demonstrated that the two shift bands at day 13 and day 18 of gestation, competed by GATA motif, were GATA-2 and GATA-1 respectively: GATA-1 was expressed in mouse hematopoietic tissues at day 18 of gestation and not expressed at day 13 of gestation; however, GATA-2 was only expressed in mouse hematopoietic tissues at day 13 of gestation. According to these results, we speculated that HS3 might play an important role in regulation of stage-specific expression of globin genes through interaction between stage-specific nuclear factors and HS3.
We investigated 11 families with hereditary multiple exostoses (EXT) by linkage analysis using 8 short-tandem-repeat (CA)n polymorphic markers on chromosomes 8, 11 and 19. The Lod score in four families indicated that the gene responsible for EXT is located in the pericentromeric region of chromosome 11.
The composition of No. II medium obtained with shaking cultivation contained three factors: nitrogen source, carbon source, and inorganic salts. The relationship between component factors (x(i)) of the media and spore numbers (y) of Bacillus thuringiensis (Bt) was demonstrated by the orthogonal-rotation-combination test. A response surface equation was formed as follows: y = 384 - 7.245x1 + 11.705x2 + 15.475x3 + 14.039x1(2) + 41.831x2(2) - 79.49x3(2) - 35.375x1x2 - 3.375x1x3 - 106.625x2x3. The results showed that this method is simple, practical, and rapid enough for selecting fermentation media for Bt. In addition, the whole course of batch fermentation was also investigated.
The SPECT ligand AM 281, a less lipophilic analog of the cannabinoid receptor antagonist SR 141716A, robustly potentiated electrically-evoked release of acetylcholine from superfused hippocampal slices and prevented the inhibition of acetylcholine release by the cannabimimetic drug WIN 55212-2. These results, similar to earlier observations with SR 141716A, indicate that AM 281 is either a cannabinoid receptor antagonist or inverse agonist. Despite showing lower affinity than SR 141716A in hippocampal membrane binding experiments, AM 281 had slightly greater potency than SR 141716A in the hippocampal slice experiments, perhaps because of reduced drug absorption to slice membranes and to the apparatus.
Stimulus recognition in monkeys is severely impaired by destruction or dysfunction of the perirhinal cortex and also by systemic administration of the cholinergic-muscarinic receptor blocker, scopolamine. These two effects are shown here to be linked: Stimulus recognition was found to be significantly impaired after bilateral microinjection of scopolamine directly into the perirhinal cortex, but not after equivalent injections into the laterally adjacent visual area TE or into the dentate gyrus of the overlying hippocampal formation. The results suggest that the formation of stimulus memories depends critically on cholinergic-muscarinic activation of the perirhinal area, providing a new clue to how stimulus representations are stored.
The SiO2-TiO2 composite powders with various Si/Ti ratios were prepared by the sol-gel processing, using tetraisopropylorthotitane (Ti(OPri)4) and tetraethoxysilane (Si(OEt)4) as starting materials. The effect of the powder's heat history on the electrorheological (ER) activity of the resulting suspensions, which were prepared by dispersing the powders into silicon oil, was investigated. The infrared spectra, scanning electron microscopy, X-ray diffraction, and zeta potential were used to characterize the structural evolution of the as-prepared gel powders upon heating. The results show a remarkable reduction in gelation time, relative to the single-component systems, due to the combined effects of a higher reactivity of Ti(OPri)4 over Si(OEt)4 and a nucleophilic attack of the Ti atom by the as-hydrolyzed species of Si precursor to form an environment similar to alkali catalysis. It was found that gel powders would gradually eliminate the -OH groups and become denser in structure upon heating, leading to a decrease of ER activity of the resulting suspensions. However, the initial Si/Ti composite compositions have little effect on ER activity behavior. Copyright 1997 Academic Press. Copyright 1997Academic Press
The mechanism of inhibition of peptidyl inhibitors with thrombin was studied using molecular modeling, molecular mechanics, and CoMFA statistical analysis. A new procedure for the elucidation of binding conformations, BCSPL, is described and was employed to obtain the binding conformers of a series of 18 tripeptidyl thrombin inhibitors. Energetic studies and QSAR analysis of the BCSPL-derived conformers indicated a modest correlation between the calculated binding energies of the title compounds and their inhibitory activities to human alpha-thrombin. CoMFA analysis of the BCSPL alignment resulted in a satisfactory model of the thrombin active site.
A practically unbiased stereological method to obtain estimates of the volume and total length of nerve fibers in brain white matter is described. The sampling scheme is designed so that the majority of brain white matter is left intact, thus providing the possibility for resampling and further analysis. Uniform sampling of one complete hemispherical white matter is performed. The volume fraction of nerve fibers in white matter is estimated by point counting. The total length of nerve fibers was estimated from the product of the volume of white matter, obtained with the Cavalieri principle, and the fiber length density, obtained from the isotropic, uniform random sections which were ensured by the isector. The size of nerve fibers was derived by measuring the profile diameter perpendicular to its longest axis. The influence of the postmortem fixation delay on nerve fiber parameters was investigated in one dog and one pig. The criteria for identification of nerve fiber profiles at light microscopy were evaluated using electron microscopy.
The purpose of this study was to examine whether rCGRP has effects on TNF-alpha produced by mouse resident peritoneal macrophages. Macrophages were obtained from the peritoneal exudate of male Balb/c mouse. The cells were plated on culture dishes at a density of 2.5x10(5) cells per well and allowed to adhere for 2 hr. Pretreatment with rCGRP (10 nM-1 microM) for 24 hr, the macrophages were cultured with LPS 1 microg/ml for another 24 h. The medium was harvested for measuring TNF-alpha by ELISA kits. The results showed that rCGRP had no direct effects on TNF-alpha production, but it inhibited LPS-induced TNF-alpha production in a concentration-dependent manner. When rCGRP was at a concentration of 1 microM, the LPS-induced TNF-alpha production was inhibited by 39%. The effect of rCGRP was reversed by hCGRP(8-37) (10 microM), an antagonist of CGRP1 receptor. The LPS-induced TNF-alpha production from macrophages was also inhibited by forskolin 3 microM, an activator of adenylate cyclase. Furthermore, pretreatment with H-89 1 microM or Rp-cAMPS 100 microM, the inhibitors of cAMP-dependent protein kinase, the effect of rCGRP was abolished. These data suggest that the LPS-induced TNF-alpha production is inhibited by rCGRP via activation of cAMP responses in mouse resident peritoneal macrophages.
Posttetanic potentiation (PTP) is an essential aspect of synaptic transmission that arises from a persistent presynaptic [Ca2+]i following tetanic stimulation. At crayfish neuromuscular junctions, several inhibitors of mitochondrial Ca2+ uptake and release (tetraphenylphosphonium or TPP+, carbonyl cyanide m-chlorophenylhydrazone or CCCP, and ruthenium red) blocked PTP and the persistence of presynaptic residual [Ca2+]i, while endoplasmic reticulum (ER) Ca2+ pump inhibitors and release channel activators (thapsigargin, 2,5-di-(tert-butyl)-1,4-benzohydroquinone or BHQ, and caffeine) had no effects. PTP apparently results from the slow efflux of tetanically accumulated mitochondrial Ca2+.
Previous pathological reports have indicated that swollen and vacuolated motoneuron cell bodies are the most predominant feature characterising Wobbler mouse motoneuron disease, but there has been little supportive evidence using area measurements. The present study focuses on the possible role of changes in neuronal nuclear and perikaryal volumes in the cervical spinal cord ventral horn, using new and traditional stereological probes which provide unbiased estimates of volume. Semithin sections from the ventral horn of Wobbler mice and age and sex-matched phenotypically normal littermates were examined at 2 ages (young and old). The young Wobbler group had significantly larger volume weighted mean perikaryal volumes compared with age-matched controls, reflecting the presence of large swollen cells characteristic of this group; this situation was reversed in the control group. Number-weighted perikaryal volume estimates in the old Wobbler group were smaller than in age-matched controls. The variation in perikaryal volume was greatest in the young Wobbler group in which the coefficient of variation was 127%. The mean number weighted and volume weighted mean nuclear volumes were significantly smaller in the old Wobbler group compared with age-matched controls and young Wobbler groups. The application of new stereological probes has enabled us to document more precisely these changes in neuronal structure in the Wobbler mutant mouse.
A new species of the sandfly subgenus Paraphlebotomus Theodor from Kenya is described and named Phlebotomus mireillae. The type locality is Utut Reserve, near Gilgil, Nakuru District. The description is based on 10 males and 10 females reared from individual egg batches of wild-caught females. Males of the new species differ from nine other species of the subgenus by the shape of the aedeagus, which is straight, not curved or hooked. They are separated from the remaining three species by other differences in the aedeagus, and in the style and coxite process. Female P. mireillae have backwardly pointing spines inside the distal quarter of the spermathecal ducts, a character not previously described for phlebotomine sandflies. Additional characters which distinguish females of the new species from others of the subgenus are differences in the pharyngeal armature and spermathecae and the lengths of the third antennal segment and labium.
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Hydrated water molecules of pyrimidine/purine/pyrimidine DNA hairpin triplex was studied by a comparison of triplex (CC.AG6) formed by a host oligodeoxypyrimidine of 5'-d(TC)3T4(CT)3(CC) with a target hexadeoxypurine 5'-d(AG)3(AG6) strand and by triplexes (MM.AG6, MC.AG6, and CM.AG6) formed by oligonucleotides with the exact sequences as above except 5-methylcytosine replaced all (MM), 5' end half (MC), and 3' end half (CM) cytosine bases in CC via FT-IR spectroscopy in hydrated film. Results revealed that: (i) all these triplexes have a similar hydration pattern, in which water molecules probably bound in the N7 sites of adenines and guanines in the Crick-Hoogsteen groove, and to the methyl group of thymidines in the Watson-Hoogsteen groove. There are also some bound water molecules found at the O2 sites of thymines in both Watson-Crick and Crick-Hoogsteen grooves. (ii) In the CC.AG6 triplex the S-type sugars are always dominant in all hydrated states, whereas in MM.AG6 triplex the relative population of the N-type sugars is very close to that of the S-type between 86% and 66% of humidity. Furthermore, the sugar conformation in two partially modified triplexes (CM.AG6, and MC.AG6) are dominant by the N-type at lower humidity. This phenomenon might reflect that the degree of bound water varies among the binding sites of bases. (iii) The effect of introducing a methyl group on cytosine is to generate a spine of hydrophobic region in MM (MC and MC). The enlarging hydrophobic area not only increase the stability in solution, and also the stability in sodium hydrated films of the pyrimidine/purine/pyrimidine hairpin triplexes.
All steroid receptors possess a bipartite nuclear localization signal sequence (NLS) that localizes within the second zinc finger of their DNA-binding domain. Fine-structure mapping of the rat glucocorticoid receptor (rGS) NLS identified a composite signal composed of three distinct proto-NLSs that function effectively when present in unique pairs. At least one of the rGR proto-NLSs appears to influence receptor trafficking within the nucleus, as revealed by a unique nuclear staining pattern of receptors possessing a point mutation (i.e., arginine at position 496; R496), at proto-NLS, pNLS-2. Specifically, carboxyl-terminal-truncated rGRs possessing various point mutations at R496 localized within a limited number of large foci in nuclei of transiently transfected COS-1 cells. R496 mutations did not affect subnuclear targeting when present in full-length rGR, reflecting a protective effect of the receptor's ligand-binding domain that can be exerted in cis and in trans. The effects of rGR R496 mutations on subnuclear targeting were not autonomous because we also observed a coincident localization of hsp70, the 70-kDa heat shock protein, within nuclear foci that include r496 mutant receptors. The elimination of R496 mistargeting by overexpression of an hsp70 partner (i.e., the DnaJ homologue, HDJ-2/HSDJ) suggests that the hsp70/DnaJ chaperone system is mobilized to specific sites within the nucleus in response to inappropriate targeting or folding of specific mutant receptors. HDJ-2/HSDJ overexpression also corrects defective transactivation and transrepression activity of R496 mutant GRs. Thus, molecular chaperones, such as members of the hsp70 and DnaJ families, may survey the nucleus for misfolded proteins and actively participate in their refolding into biologically active conformational states.
The membrane lipids of free living and bacteroid forms of Bradyrhizobium japonicum, obtained from nodules occupied by both typed and untyped bacteria, were isolated and characterized by a combination of NMR spectroscopy, mass spectrometry, and other chemical and physical methods. These studies indicated that both the free living and bacteroid forms of this organism contain glycolipids almost exclusively of the type found in plant cells. In the bacteroid forms, there was a dramatic shift towards the synthesis of digalactosyl diacylglycerol as the major lipid. This glycolipid has rarely been found outside of the plant kingdom and photosynthetic bacteria, and its occurrence in the bacteroid form of a plant symbiont is therefore remarkable. The presence of plant cell and organelle contaminants in the bacteroid preparations was ruled out by scanning electron microscopy, Southern blot analyses for plant DNA using specific gene probes, and chemical analyses for plant marker steroids, steroid glycosides, and cerebrosides. Digalactosyl diacylglycerol is not found in the plasma membrane of plant cells (of which the peribacteroid membrane is an extension) but is thought to be restricted to plastids. This result follows our earlier finding that the other predominant plant glycolipid, sulfoquinivosyl diacylglycerol, is a membrane component of fast growing Rhizobia and is found even when cells are cultivated in free culture where there is no question of plant contamination. The near absence of these lipids in the membranes of bacteria outside of this special group of organisms and photosynthetic bacteria suggests that the trait could have been passed on through gene transfer from plants to the bacteria at some point during the development of their symbiotic relationship. In the case of digalactosyl diacylglycerol, there is also the possibility that some common biosynthetic intermediates are used by both the plant and the bacteria. This is a striking parallel with some host-pathogen interactions.
BACKGROUND: Cross-leg free flaps have been described for reconstruction of leg defects in cases of trauma with no suitable recipient vessels in the vicinity of the defect. The pitfalls, however, have not been well documented in the literature. The technique of transfer and the length of time required before pedicle division depend on the nature of the flap and the contact surface. METHODS: Eight cross-leg free flap reconstructions were performed on seven patients between 1986 and 1993. These included three latissimus dorsi muscle flaps, three fibula osteomyocutaneous flaps, one tensor fascia lata myocutaneous flap, and one posterolateral thigh flap. The important technical considerations are outlined. RESULTS: One latissimus dorsi flap failed, whereas the rest of the flaps completely survived. The morbidity of the recipient and donor sites are listed. CONCLUSION: We conclude that the technique offers the possibility of salvaging limbs that are, otherwise, nonreconstructable. It is useful for young patients. When the flap is long, it can function as a nutrient flap for the distal limb even though the pedicle has been divided. It is a backup procedure in an urgent situation of re-exploration in which reestablishment of circulation should take place as soon as possible.