Biomedical subjects
Publications and source records attributed to C He.
The thiosemicarbazone molecule in C(10)H(12)N(6)S(2).2C(3)H(7)NO has -1 symmetry. The thiosemicarbazone moiety and the benzene ring are essentially coplanar, with mean and maximum deviations of 0.03 and 0. 11 A, respectively. The dimethylformamide molecules bridge the thiosemicarbazone moieties, forming two-dimensional sheets through N-H.O hydrogen bonds.
Data from four recent studies (S. H. Goh et al., J. Clin. Microbiol. 36:2164-2166, 1998; S. H. Goh et al., J. Clin. Microbiol. 34:818-823, 1996; S. H. Goh et al., J. Clin. Microbiol. 35:3116-3121, 1997; A. Y. C. Kwok et al., Int. J. Syst. Bacteriol. 49:1181-1192, 1999) suggest that an approximately 600-bp region of the chaperonin 60 (Cpn60) gene, amplified by PCR with a single pair of degenerate primers, has utility as a potentially universal target for bacterial identification (ID). This Cpn60 gene ID method correctly identified isolates representative of numerous staphylococcal species and Streptococcus iniae, a human and animal pathogen. We report herein that this method enabled us to distinguish clearly between 17 Enterococcus species (Enterococcus asini, Enterococcus rattus, Enterococcus dispar, Enterococcus gallinarum, Enterococcus hirae, Enterococcus durans, Enterococcus cecorum, Enterococcus faecalis, Enterococcus mundtii, Enterococcus casseliflavus, Enterococcus faecium, Enterococcus malodoratus, Enterococcus raffinosus, Enterococcus avium, Enterococcus pseudoavium, Enterococcus new sp. strain Facklam, and Enterococcus saccharolyticus), and Vagococcus fluvialis, Lactococcus lactis, and Lactococcus garvieae. From 123 blind-tested samples, only two discrepancies were observed between the Facklam and Collins phenotyping method (R. R. Facklam and M. D. Collins, J. Clin. Microbiol. 27:731-734, 1989) and the Cpn60 ID method. In each case, the discrepancies were resolved in favor of the Cpn60 ID method. The species distributions of the 123 blind-tested isolates were Enterococcus new sp. strain Facklam (ATCC 700913), 3; E. asini, 1; E. rattus, 4; E. dispar, 2; E. gallinarum, 20; E. hirae, 9; E. durans, 9; E. faecalis, 12; E. mundtii, 3; E. casseliflavus, 8; E. faecium, 25; E. malodoratus, 3; E. raffinosus, 8; E. avium, 4; E. pseudoavium, 1; an unknown Enterococcus clinical isolate, sp. strain R871; Vagococcus fluvialis, 4; Lactococcus garvieae, 3; Lactococcus lactis, 3; Leuconostoc sp., 1; and Pediococcus sp., 1. The Cpn60 gene ID method, coupled with reverse checkerboard hybridization, is an effective method for the identification of Enterococcus and related organisms.
16S rRNA sequence data have been used to provide a molecular basis for an accurate system for identification of members of the genus Mycobacterium. Previous studies have shown that Mycobacterium species demonstrate high levels (>94%) of 16S rRNA sequence similarity and that this method cannot differentiate between all species, i.e., M. gastri and M. kansasii. In the present study, we have used the recA gene as an alternative sequencing target in order to complement 16S rRNA sequence-based genetic identification. The recA genes of 30 Mycobacterium species were amplified by PCR, sequenced, and compared with the published recA sequences of M. tuberculosis, M. smegmatis, and M. leprae available from GenBank. By recA sequencing the species showed a lower degree of interspecies similarity than they did by 16S rRNA gene sequence analysis, ranging from 96.2% between M. gastri and M. kansasii to 75.7% between M. aurum and M. leprae. Exceptions to this were members of the M. tuberculosis complex, which were identical. Two strains of each of 27 species were tested, and the intraspecies similarity ranged from 98.7 to 100%. In addition, we identified new Mycobacterium species that contain a protein intron in their recA genes, similar to M. tuberculosis and M. leprae. We propose that recA gene sequencing offers a complementary method to 16S rRNA gene sequencing for the accurate identification of the Mycobacterium species.
OBJECTIVE: To explore the change of serum melatonin (MT) and its diagnosis value in hepatic encephalopathy (HE). METHODS: The change of MT in serum in cirrhotic patients with HE and without HE was determined by ELISA, and normal serum served as control. The change of serum MT during exacerbation and remission stage of HE was also determined. RESULTS: The level of MT in patients with HE was higher than that without (P<0.01). Both groups were higher than normal group (312.7 +/- 77.4) ng/L, (149.8 +/- 38.4) ng/L, and (77.3 +/- 28.4)ng/L, respectively, P<0.01. The level of serum MT was higher in exacerbation stage than remission stage, (308.5 +/- 59.1) ng/L and (147.8 +/- 23.3) ng/L, respectively, P<0.01. CONCLUSION: The elevation of MT in serum may be one of pathogenic factors for HE. Dynamic measurement of MT in serum is conducive to the diagnosis of HE.
The cDNA encoding glial cell derived neurotrophic factor (GDNF) was cloned into the Pichia expression vector pPIC9K and then transformed into his4 mutant yeast GS115 by electroporation. Multicopy transformants were screened by various G418 concentrations and induced by methanol. The human GDNF gene was cloned into the baculovirus transfer vector pBacPAK8. The recombinant transfer vector pBacPAK-GDNF was coinfected with linear Bm-BacPAK6 DNA into BmN cells. The recombinant virus was screened and plaque-purified. The silkworm larvae were infected with the recombinant virus and collected 5 days later. SDS-PAGE and Western blot confirmed that GDNF was expressed in Pichia culture medium and silkworm larvae hemolymph. The GDNF protein expressed in Pichia and silkworm larvae could significantly promote the survival and neurite outgrowth of dopaminergic neurons.
OBJECTIVE: To report the surgical technique and clinical application of extended resection of Vater's papilla (ERVP). METHODS: ERVP was performed in 12 selected patients with tumors of ampulla of Vater according to the following criteria: (1) no signs of distant mestastasis before operation; (2) no hepatic and peritoneal mestastasis during exploration, frozen section of peripancreas-duodenal lymph nodes being negative; (3) tumor less than 2 cm in diameter, pathologic examination of tumor being adenocarcinoma or adenoma; (4) pathologic examination of edge of resection being negative. RESULTS: There was no operative death nor complications in 12 cases treated by ERVP. The average time of operation was 2.3 hours, the average amount of blood infused was 433 ml, and the average time of hospitalization was 15.8 days. In 5 of 10 cases of Vater's ampullary adenocarcinoma, the mean survival time was 42 months (36-62 months). The remaining 5 cases are still alive at 20-64 months. Two patients with Vater's ampullary adenoma still survive at 32 and 46 months, respectively. CONCLUSION: ERVP is easy to perform with comparatively less surgical trauma and complication, but redical excision of tumor is not easy. It may be particulary indicated for older and high-risk patients, or patients with cancer less than 2 cm in diameter.
Hippocampal neurons cultured from 7 to 9 d in vitro were used to observe the effect of glutamate. Treatment of glutamate for 24 h greatly decreased neuronal survival and pretreatment with pituitary adenylate cyclase activating polypeptide (PACAP) significantly attenuated hippocampal neuron death induced by glutamate. Moreover, glutamate dose-dependently increased the intracellular calcium concentration in cultured hippocampal neurons, while PACAP inhibited the increase of intracellular calcium concentration induced by glutamate. PACAP 6-38, a specific PACAP type I receptor antagonist, completely inhibited the amelioration of glutamate induced death and the decrease of intracellular calcium concentration induced by PACAP in cultured hippocampal neurons. The data suggest that PACAP has a neuroprotective effect on the hippocampal neuronal damage induced by glutamate, which is related to an inhibition of glutamate-induced increase of intracellular calcium concentration and mediated by PACAP type I receptor.
The aim of the study was to investigate the effect of exogenous glial cell line derived neurotrophic factor (GDNF) on spinal cord neurons after sciatic nerve axotomy. Upon silicone tubulization of transected sciatic nerve in the adult rat, either 0.9% saline or GDNF solution was injected into the silicone chamber. It was observed by Nissl and enzyme histochemistry staining that exogenous GDNF decreased lesion induced motor neuron death in lateral nucleus of spinal anterior horn and the changes in activity of cholinesterase and acid phosphatase in spinal cord and sensory ganglions. These results suggest that exogenous GDNF is capable of protecting motor neurons from death induced by peripheral nerve injury.
Since endotheliocyte strains of guinea-pig and inbred strains of guinea-pig are not easily obtained, it is impossible to ensure the consistence of antigenicity between endotheliocytes and donor organs when endotheliocytes are used as an inductor in the research of immunological tolerance. So it is necessary to establish the guinea-pig endotheliocyte-donor model. One side of common carotid arteries was removed and reversed. After collagenase digestion, culture of endotheliocytes was performed. And the survival time of guinea-pig was observed. Cultured cells were confirmed as endotheliocytes by the study of morphology, immunohistochemistry and electron microscopy. The two-month-survival of guinea-pigs was 92% (103/112). The establishment of guinea-pig endotheliocyte-donor model can provide the foundation for the research of guinea-pig endotheliocyte and immunological tolerance.
We established mouse lines containing either full-length wild-type p53 or nuclear localization signal-I (NLS-I) deleted p53 to study the role of NLS-I in p53 translocation and function. Induction of apoptosis in response to DNA damage, a primary function of p53, was tested in these cell lines. After exposure to gamma-ionizing radiation or hydrogen peroxide, DNA ladders and labeling of nucelosomal fragments were detected in cells with wild-type p53 gene, but not in p53 null cells or NLS-I deleted cells, suggesting that the NLS-I of p53 protein is necessary for apoptosis. Analysis of p53 protein from subcellular fractions indicated that NLS-I deprived p53 remained in the cytoplasmic fraction, which may explain why NLS-I deleted p53 failed to induce apoptosis.
A chemiluminescence reaction detector was developed for the detection of polyphenols separated by HPLC based on the inhibition of chemiluminescence from the luminol-potassium hexacyanoferrate(III) reaction by polyphenols. The separation was carried out on a RP-C18 column at 37 degrees C by using stepwise gradient elutions. The detection limits are in the range of 6.8 x 10(-7)-2.0 x 10(-9) g/ml for catechol, protocatechuic acid, chlorogenic acid, rutin, resorcinol, hydroquinone and p-tert.butylpyrocatechol. The method is sensitive, selective, fast and simple. It has been successfully applied to the determination of chlorogenic acid and rutin in real tobacco samples.
Histone acetylation is important in chromatin remodelling and gene activation. Nearly all known histone-acetyltransferase (HAT)-associated transcriptional co-activators contain bromodomains, which are approximately 110-amino-acid modules found in many chromatin-associated proteins. Despite the wide occurrence of these bromodomains, their three-dimensional structure and binding partners remain unknown. Here we report the solution structure of the bromodomain of the HAT co-activator P/CAF (p300/CBP-associated factor). The structure reveals an unusual left-handed up-and-down four-helix bundle. In addition, we show by a combination of structural and site-directed mutagenesis studies that bromodomains can interact specifically with acetylated lysine, making them the first known protein modules to do so. The nature of the recognition of acetyl-lysine by the P/CAF bromodomain is similar to that of acetyl-CoA by histone acetyltransferase. Thus, the bromodomain is functionally linked to the HAT activity of co-activators in the regulation of gene transcription.
Activation of heterotrimeric GTP-binding (G) proteins by their coupled receptors, causes dissociation of the G protein alpha and betagamma subunits. Gbetagamma subunits interact directly with G protein-gated inwardly rectifying K+ (GIRK) channels to stimulate their activity. In addition, free Gbetagamma subunits, resulting from agonist-independent dissociation of G protein subunits, can account for a major component of the basal channel activity. Using a series of chimeric constructs between GIRK4 and a Gbetagamma-insensitive K+ channel, IRK1, we have identified a critical site of interaction of GIRK with Gbetagamma. Mutation of Leu339 to Glu within this site impaired agonist-induced sensitivity and decreased binding to Gbetagamma, without removing the Gbetagamma contribution to basal currents. Mutation of the corresponding residue in GIRK1 (Leu333) resulted in a similar phenotype. Both the GIRK1 and GIRK4 subunits contributed equally to the agonist-induced sensitivity of the heteromultimeric channel. Thus, we have identified a channel site that interacts specifically with Gbetagamma subunits released through receptor stimulation.
We have reinvestigated a large kindred identified over 25 years ago segregating for a form of pure autosomal dominant hereditary spastic paraplegia (HSP). We have examined additional relatives in order to refine the clinical and genetic characteristics of this disorder, and performed an analysis to determine if anticipation is present in this family. Analysis of onset ages in parent-to-child transmissions of HSP is consistent with anticipation. These results provide support for dynamic mutation as the underlying mechanism of this form of HSP, and suggest a trinucleotide repeat instability occurring primarily in the female germ line.
Advanced glycation end products (AGEs) have been implicated as causal factors in the vascular complications of diabetes and it is known that these products interact with cells through specific receptors. The AGE-receptor complex, originally described as p60 and p90, has been characterised in hemopoietic cells and the component proteins identified and designated AGE-R1, -R2 and -R3. In the current study we have characterised this receptor in human umbilical vein endothelial cells (HUVECs) and elucidated several important biological properties which may impact on AGE mediated vascular disease. 125I-AGE-BSA binding to HUVEC monolayers was determined with and without various cold competitors. The synthetic AGE, 2-(2-furoyl)-4(5)-furanyl-1H-imidazole (FFI)-BSA, failed to compete with AGE-BSA binding unlike observations already reported in hemopoietic cells. The ability of 125I-AGE-BSA to bind to separated HUVEC plasma membrane (PM) proteins was also examined and the binding at specific bands inhibited by antibodies to each component of the AGE-receptor complex. Western blotting of whole cell and PM fractions, before and after exposure to AGE-BSA, revealed that AGE-R1, -R2 and -R3 are subject to upregulation upon exposure to their ligand, a phenomenon which was also demonstrated by immunofluorescence of non-permeabilised cells. mRNA expression of each AGE-receptor component was apparent in HUVECs, with the AGE-R2 and -R3 gene expression being upregulated upon exposure to AGEs in a time-dependent manner. A phosporylation assay in combination with AGE-R2 immunoprecipitation demonstrated that this component of the receptor complex is phosphorylated by acute exposure to AGE-BSA. These results indicate the presence of a conserved AGE-receptor complex in vascular endothelium which demonstrates subtle differences to other cell-types. In response to AGE-modified molecules, this complex is subject to upregulation, while the AGE-R2 component also displays increased phosphorylation possibly leading to enhanced signal transduction.
There are four different variants of the kalilo "family" of linear mitochondrial plasmids. This family is found in several heterothallic species and one pseudohomothallic species of Neurospora, as well as in one homothallic species of Gelasinospora. The mode of dispersal of these plasmids is not known. Horizontal transmission has proved difficult to demonstrate. Another possibility is transfer by introgression, and this is modelled in the present paper. We have used introgression and subsequent heterokaryosis to successfully transfer the LA-kalilo plasmid from a Haitian strain of Neurospora crassa to the standard Oak Ridge N. crassa background, the LA-kalilo plasmid from the pseudohomothallic Neurospora tetrasperma to N. crassa, and the kalilo plasmid from N. crassa to N. tetrasperma. Thus, introgression is shown to be a possible avenue of dispersal between species. The recipient strains were all senescent but the mechanism of this senescence is not known. It could be caused by the plasmids, but if so the mechanism is novel since plasmid/mtDNA junction fragments of the type found in the standard mode of mtDNA insertion could not be detected. However, mtDNA changes were observed in the senescent recipients.
Crry is a potent complement regulator that inhibits classical and alternative pathway C3 convertases in rodents. We have produced transgenic animals expressing Crry as a recombinant soluble protein driven by the broadly active metallothionein-I promoter. These animals have high serum and urinary levels of rsCrry leading to inhibition of complement activity. In nephrotoxic serum nephritis (NSN), injected antibodies bind to glomeruli, leading to complement activation and subsequent glomerular injury and albuminuria. We have shown that rsCrry can block such injury and reduce albuminuria by as much as 75%. Corresponding to the reduction in albuminuria was the complete absence of C3 staining in glomeruli by immunofluorescence microscopy in 17/20 transgene positive animals. Support for a local source of protective rsCrry in this model is provided by the demonstration of Crry transgene mRNA in the glomerulus and a very high fractional excretion of rsCrry in the urine. Therefore, rsCrry expression markedly ameliorates an antibody-induced disease model in vivo. In addition, local synthesis of Crry in other organs that are targets of immune injury has been found. For example, Crry transgene mRNA is present throughout the central nervous system and in pancreatic islets. Thus, continuous complement inhibition at the C3 convertase step appears to be feasible and is effective in complement-mediated injury states. A number of disease models affecting these target organs can be tested using these mice.
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