Biomedical subjects

Jun Yu

Publications and source records attributed to Jun Yu.

188 records · Page 11Linked to original sources

PubMed2002

A complete sequence of the T. tengcongensis genome.

Thermoanaerobacter tengcongensis is a rod-shaped, gram-negative, anaerobic eubacterium that was isolated from a freshwater hot spring in Tengchong, China. Using a whole-genome-shotgun method, we sequenced its 2,689,445-bp genome from an isolate, MB4(T) (Genbank accession no. AE008691). The genome encodes 2588 predicted coding sequences (CDS). Among them, 1764 (68.2%) are classified according to homology to other documented proteins, and the rest, 824 CDS (31.8%), are functionally unknown. One of the interesting features of the T. tengcongensis genome is that 86.7% of its genes are encoded on the leading strand of DNA replication. Based on protein sequence similarity, the T. tengcongensis genome is most similar to that of Bacillus halodurans, a mesophilic eubacterium, among all fully sequenced prokaryotic genomes up to date. Computational analysis on genes involved in basic metabolic pathways supports the experimental discovery that T. tengcongensis metabolizes sugars as principal energy and carbon source and utilizes thiosulfate and element sulfur, but not sulfate, as electron acceptors. T. tengcongensis, as a gram-negative rod by empirical definitions (such as staining), shares many genes that are characteristics of gram-positive bacteria whereas it is missing molecular components unique to gram-negative bacteria. A strong correlation between the G + C content of tDNA and rDNA genes and the optimal growth temperature is found among the sequenced thermophiles. It is concluded that thermophiles are a biologically and phylogenetically divergent group of prokaryotes that have converged to sustain extreme environmental conditions over evolutionary timescale.

Bacillaceae↗

PubMed2002

Minimal introns are not "junk".

Intron-size distributions for most multicellular (and some unicellular) eukaryotes have a sharp peak at their "minimal intron" size. Across the human population, these minimal introns exhibit an abundance of insertion-deletion polymorphisms, the effect of which is to maintain their optimal size. We argue that minimal introns affect function by enhancing the rate at which mRNA is exported from the cell nucleus.

Active Transport, Cell Nucleus↗

PubMed2002

Management of cerebral ischemia due to Takayasu's arteritis.

OBJECTIVE: To explore the management of cerebral ischemia caused by Takayasu's arteritis. METHODS: Ninety-three cases treated from June 1984 to September 1999 at the General Post & Telecom Hospital, the Sir Run Run Shaw Hospital, the First Affiliated Hospital of Zhejiang University, the Second Medical College of Beijing University, Beijing An Zhen Hospital, and the Beijing Union Medical College Hospital, including 10 men and 83 women, were reviewed. Of the 93 cases, bypasses from the ascending aorta to the axillary or subclavian artery and from graft to the carotid artery were performed in 47 cases. Subclavian to carotid bypass was performed in six cases. Percutaneous transluminal angioplasty (PTA) was used in five cases and stenting in one. RESULTS: Marked improvement was achieved in 30.3%, fair in 34.9%, improvement in 21.2%, unchanged in 4.6%, and death in 9.0% before discharge; 30.6%, 38.8%, 16.3%, 4.1%, and 2.0% respectively during a mean follow-up of 48 months, and recurrence requiring revision in 8.2%. CONCLUSION: Patients with occlusive lesions of all four cervical arteries always have severe cerebral ischemia and their distal runoff is always unvisualised by angiography. However, we found by exploration that the internal carotid artery is patent in all but one patient. Therefore, an ascending aorta to carotid bypass is feasible in most instances, and this can and should be done when the cerebral perfusion is jeopardized at a time when the patient is in a stable or relatively stable condition. Unfortunately, the cerebral re-perfusion syndrome is still a serious and not completely solved problem.

Adolescent↗

PubMed2002

Expression of cyclin genes in human gastric cancer and in first degree relatives.

OBJECTIVE: To clarify the role of these cyclins in human gastric cancer. METHODS: 38 gastric cancer patients, 29 first degree relatives of gastric cancer patients, as well as 18 healthy subjects were included. The mRNA expression of cyclins D1, D2, D3 and E in gastric biopsies was evaluated by RT-PCR analysis using specific primers. Histomorphological features such as intestinal metaplasia, atrophy, H. pylori infection and severity of gastritis were determined by the updated Sydney System. RESULTS: Significant mRNA overexpression was found for cyclins D2, D3 and E compared with healthy normal specimen, but cyclin D1 expression was not different between tumor and normal tissues. In addition, cyclin D2 and D3 overexpression was significantly more frequent in first degree relatives than in healthy controls (P < 0.05). Among the various pathological findings, the overexpression of cyclins D2 and E was associated with intestinal metaplasia, and the overexpression of cyclin D3 was associated with intestinal metaplasia as well as atrophy. The overexpression of cyclins D2 and D3 was significantly correlated with H. pylori infection. No correlation was observed between the overexpression of cyclin D1 and any pathological variables. CONCLUSION: The overexpression of cyclins D2, D3 and E is a frequent event in patients with gastric cancer and their first degree relatives and may be an early event in gastric carcinogenesis.

Adult↗

PubMed2001

Iatrogenic Subclavian Steal Syndrome.

New complications are resulting from percutaneous transluminal angioplasty (PTA) and stent deployment. A 43-year-old female, admitted with weakness in the right arm, was diagnosed with right subclavian stenosis. Following PTA and a Palmaz stent deployment, her condition worsened, and symptoms spread. A corrective surgical procedure found the Palmaz stent to be almost completely compressed. The stent and plaques were carefully extracted. The etiology of compressed stent was probably due to an insufficient radial force or Hoop strength of stent. If an occlusion of the subclavian artery occurs at the segment proximal to the orifices of vertebral artery and internal mammary artery, a vertebral-subclavian steal syndrome may occur. This can be diagnosed in patients manifesting symptoms that include vertebral-basilar arterial insufficiency and a difference in brachial systolic blood pressure of at least 30 mm Hg between the two arms, with a bruit at the base of the neck or in the supraclavicular area. </hea

Journal Article↗

PubMed2001

Characterization of the Streptococcus pneumoniae NADH oxidase that is required for infection.

Streptococcus pneumoniae is an important human pathogen capable of causing serious infections. NADH oxidase, a factor necessary for infection, was previously identified as part of a signature-tagged mutagenesis screen of a S. pneumoniae clinical isolate, 0100993. The mutant, with a plasmid insertion disrupting the nox gene, was attenuated for virulence in a murine respiratory tract infection model. A complete refined nox deletion mutant was generated by allelic-replacement mutagenesis and found to be attenuated for virulence 10(5)-fold in the murine respiratory tract infection model and at least 10(4)-fold in a Mongolian gerbil otitis media infection model, confirming the importance of the NADH oxidase for both types of S. pneumoniae infection. NADH oxidase converts O(2) to H(2)O. If O(2) is not fully reduced, it can form superoxide anion (O2(-)) and hydrogen peroxide (H(2)O(2)), both of which can be toxic to cells. Bacterial cell extracts from the allelic-replacement mutant were found to lack NADH oxidase activity and the mutant was unable to grow exponentially under conditions of vigorous aeration. In contrast, the mutant displayed normal growth characteristics under conditions of limited aeration. The S. pneumoniae nox gene was cloned and expressed in E. coli. The purified His-tagged NADH oxidase was shown to oxidize NADH with a K:(m) of 32 microM, but was unable to oxidize NADPH. Oxidation of NADH was independent of exogenous FAD or FMN.

Alleles↗

PubMedDate not supplied

Proteome analysis of gastric cancer metastasis by two-dimensional gel electrophoresis and matrix assisted laser desorption/ionization-mass spectrometry for identification of metastasis-related proteins.

A well-described animal model was used to understand the molecular mechanisms of carcinogenesis and metastasis of gastric cancer at the protein level. Gastric cancer was induced in 12 Wistar rats by oral administration of N-methyl-N'-Nitro-N-Nitrosoguanidine (MNNG). The protein expression patterns of normal gastric tissue, gastric cancer, and corresponding metastases were analyzed by proteomics in matched tissues of 3 rats. Proteins in the region of molecular masses of 15-75 kDa and an isoelectric point of 3-7 were separated by two-dimensional electrophoresis (2-DE) and identified by peptide fingerprinting with matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS). Twenty-seven spots corresponding to 25 different proteins served as landmarks for comparison between tissues. The identified proteins included cytoskeletal proteins, stress associated proteins, proteins involved in signal transduction, cell proliferation and differentiation, and metabolism. Eleven proteins were up-regulated and 2 proteins were down-regulated in tumor tissue when compared with normal tissue. Twelve proteins were up-regulated and 8 proteins were down-regulated in the metastases when compared with the primary tumor. The overexpression of HSP27 in gastric cancer was confirmed by immunohistochemical analysis of human gastric cancer specimens. Combining well-defined animal models with proteome analysis will improve our understanding of the fundamental changes that contribute to the process of carcinogenesis and the formation of metastases in gastric cancer.

Adenocarcinoma↗

PubMedDate not supplied

Noninvasive monitoring of pneumococcal meningitis and evaluation of treatment efficacy in an experimental mouse model.

Noninvasive real-time in vivo bioluminescent imaging was used to assess the spread of Streptococcus pneumoniae throughout the spinal cord and brain during the acute stages of bacterial meningitis. A mouse model was established by lumbar (LP) or intracisternal (IC) injection of bioluminescent S. pneumoniae into the subarachnoid space. Bacteria replicated initially at the site of inoculation and spread progressively from the spinal cord to the brain or from the brain down to the cervical part of the spinal column and to the lower vertebral levels. After 24 hr, animals showed strong bioluminescent signals throughout the spinal canal, indicating acute meningitis of the intracranial and intraspinal meninges. A decline in bacterial cell viability, as judged by a reduction in the bioluminescent signal, was observed over time in animals treated with ceftriaxone, but not in untreated groups. Mice treated with the antibiotic survived infection, whereas all mice in untreated groups became moribund, first in the IC group then in the LP group. No untreated animal survived beyond 48 hr after induction of infection. Colony counts of infected cerebrospinal fluid (CSF) correlated positively with bioluminescent signals. This methodology is especially appealing because it allows detecting infected mice as early as 3 hr after inoculation, provide temporal, sequential, and spatial distribution of bacteria within the brain and spinal cord throughout the entire disease process and the rapid monitoring of treatment efficacy in a nondestructive manner. Moreover, it avoids the need to sacrifice the animals for CSF sampling and the potential manipulative damage that can occur with other conventional methods.

Animals↗