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Biomedical subjects

J S Liu

Publications and source records attributed to J S Liu.

At least 73 records · Page 4Linked to original sources
PubMed1998

The use of 2 ipsilateral ureteral stents for relief of ureteral obstruction from extrinsic compression.

PURPOSE: We present our early experience with the novel approach of placing 2 parallel stents simultaneously in extrinsically obstructed ureters in which single stents had failed. The increased stiffness of 2 stents reduces kinking and luminal compression, and the potential space between the stents likely preserves flow around as well as through them. MATERIALS AND METHODS: Four patients recently presented with ureteral obstruction secondary to nonurinary tract malignancies. Previous stenting with a single 6F Double-J* stent had failed in all cases. Three patients experienced flank pain and 1 had persistent azotemia within 3 days of initial stent placement. All patients had significant residual sonographic hydronephrosis despite good stent position. In all cases cystoscopy/stent exchange was performed under local anesthesia with intravenous sedation. Parallel 4.7F Double-J stents were placed simultaneously over 2, 0.035 hydrophilic coated glide wires under fluoroscopic guidance after removal of the malfunctioning 6F stent. RESULTS: Stent placement was uneventful in all 4 patients with prompt drainage of contrast material seen after parallel ipsilateral stent placement. Patients tolerated the double 4.7F parallel stents with no discernible difference in irritative symptoms compared to single 6F stents. Flank pain and azotemia resolved in 3 patients, and hydronephrosis improved in all 4 after placement of parallel Double-J stents. All patients remain alive with a mean followup of 5.8 months (range 4 to 8). Except for 1 patient who later underwent ureterolysis, each has subsequently had the stent changed every 3 months. No patient has required proximal urinary diversion (that is percutaneous nephrostomy tube). CONCLUSIONS: Placement of 2 ipsilateral parallel ureteral stents simultaneously is an easy technique. It may obviate percutaneous nephrostomy tube placement in patients in whom drainage with a single stent failed, especially in cases of extrinsic ureteral compression.

Adult↗
PubMed1998

Bayesian adaptive sequence alignment algorithms.

The selection of a scoring matrix and gap penalty parameters continues to be an important problem in sequence alignment. We describe here an algorithm, the 'Bayes block aligner, which bypasses this requirement. Instead of requiring a fixed set of parameter settings, this algorithm returns the Bayesian posterior probability for the number of gaps and for the scoring matrices in any series of interest. Furthermore, instead of returning the single best alignment for the chosen parameter settings, this algorithm returns the posterior distribution of all alignments considering the full range of gapping and scoring matrices selected, weighing each in proportion to its probability based on the data. We compared the Bayes aligner with the popular Smith-Waterman algorithm with parameter settings from the literature which had been optimized for the identification of structural neighbors, and found that the Bayes aligner correctly identified more structural neighbors. In a detailed examination of the alignment of a pair of kinase and a pair of GTPase sequences, we illustrate the algorithm's potential to identify subsequences that are conserved to different degrees. In addition, this example shows that the Bayes aligner returns an alignment-free assessment of the distance between a pair of sequences.

Adenylate Kinase↗
PubMed1998

The carboxyl-terminal region of the human papillomavirus type 16 E1 protein determines E2 protein specificity during DNA replication.

The mechanism of DNA replication is conserved among papillomaviruses. The virus-encoded E1 and E2 proteins collaborate to target the origin and recruit host DNA replication proteins. Expression vectors of E1 and E2 proteins support homologous and heterologous papillomaviral origin replication in transiently transfected cells. Viral proteins from different genotypes can also collaborate, albeit with different efficiencies, indicating a certain degree of specificity in E1-E2 interactions. We report that, in the assays of our study, the human papillomavirus type 11 (HPV-11) E1 protein functioned with the HPV-16 E2 protein, whereas the HPV-16 E1 protein exhibited no detectable activity with the HPV-11 E2 protein. Taking advantage of this distinction, we used chimeric E1 proteins to delineate the E1 protein domains responsible for this specificity. Hybrids containing HPV-16 E1 amino-terminal residues up to residue 365 efficiently replicated either viral origin in the presence of either E2 protein. The reciprocal hybrids containing amino-terminal HPV-11 sequences exhibited a high activity with HPV-16 E2 but no activity with HPV-11 E2. Reciprocal hybrid proteins with the carboxyl-terminal 44 residues from either E1 had an intermediate property, but both collaborated more efficiently with HPV-16 E2 than with HPV-11 E2. In contrast, chimeras with a junction in the putative ATPase domain showed little or no activity with either E2 protein. We conclude that the E1 protein consists of distinct structural and functional domains, with the carboxyl-terminal 284 residues of the HPV-16 E1 protein being the primary determinant for E2 specificity during replication, and that chimeric exchanges in or bordering the ATPase domain inactivate the protein.

Adenosine Triphosphatases↗
PubMed1998

Construction of an inducible nitric-oxide synthase gene transferring vector mediated by retrovirus.

AIM: To construct an inducible nitric-oxide synthase (iNOS) gene transferring vector mediated by retrovirus. METHODS: Recombinant DNA and polymerase chain reaction (PCR) amplification techniques were used. RESULTS: With 2 steps of molecular cloning, the full-length cDNA encoding macrophage iNOS was isolated from plasmid pKSiNOS and subcloned into intermediate vector pSP72, adjusting the restriction enzyme sites in both 5'- and 3'-flanking ends of insert fragment. The retroviral vector pLNCXiNOS which contains iNOS coding region, cytomegalovirus promoter and neomycin resistance (neor) gene was further constructed. The authenticity of insertion size and orientation of iNOS sequence was verified by restriction mapping and PCR analysis with iNOS gene-specific primers. CONCLUSION: Retroviral expression vector carrying iNOS fragment is obtained, which provides a material to establish a model of iNOS gene-modified neurons.

Cloning, Molecular↗
PubMed1997

Extracting protein alignment models from the sequence database.

Biologists often gain structural and functional insights into a protein sequence by constructing a multiple alignment model of the family. Here a program called Probe fully automates this process of model construction starting from a single sequence. Central to this program is a powerful new method to locate and align only those, often subtly, conserved patterns essential to the family as a whole. When applied to randomly chosen proteins, Probe found on average about four times as many relationships as a pairwise search and yielded many new discoveries. These include: an obscure subfamily of globins in the roundworm Caenorhabditis elegans ; two new superfamilies of metallohydrolases; a lipoyl/biotin swinging arm domain in bacterial membrane fusion proteins; and a DH domain in the yeast Bud3 and Fus2 proteins. By identifying distant relationships and merging families into superfamilies in this way, this analysis further confirms the notion that proteins evolved from relatively few ancient sequences. Moreover, this method automatically generates models of these ancient conserved regions for rapid and sensitive screening of sequences.

Algorithms↗
PubMed1997

Molecular evolution and phylogeny of satellite RNA associated with bamboo mosaic potexvirus.

Satellite RNA of bamboo mosaic potexvirus (satBaMV) is a linear RNA molecule which encodes a 20-kDa nonstructural protein. Sequences of seven different satBaMV isolates from bamboo hosts in three genera showed 0.7% to 7.5% base variation which spanned the whole RNA molecule. However, the putative 20-kDa open reading frame was all preserved in these isolates. The phylogenetic relationship based on the nucleotide sequence did not show particular grouping of satBaMV from the host in one genus; neither was the grouping of satBaMV evident by location of sampling. Putative secondary structures of the 3' untranslated regions showed a basic pattern with conserved hexanucleotides (ACCUAA) and polyadenylation signal (AAUAAA) located in the loop regions. Although the satBaMV-encoded 20-kDa protein is a nonstructural protein, its predicted secondary structure contains eight-stranded beta-sheets which may form "jelly-roll" structure similar to that found in capsid protein encoded by satellite virus of panicum mosaic virus.

Amino Acid Sequence↗
PubMed1997

3-Ketoglycoside-mediated metabolism of sucrose in E. coli as conferred by genes from Agrobacterium tumefaciens.

Escherichia coli strains that did not have the ability to use sucrose as a sole carbon source gained this ability after receiving a cloned fragment of DNA from Agrobacterium tumefaciens. No invertase was detected in the sucrose-metabolizing E. coli, but evidence for the activity of certain enzymes, known to be produced by biotype 1 strains of Agrobacterium, were found. Evidence was found for the presence of D-glucoside 3-dehydrogenase (G3DH) and alpha-3-ketoglucosidase. The activity of enzyme extracts on 3-ketosucrose also indicated that 3-ketoglucose reductase, or some enzyme that acts on 3-ketoglucose, was present in the Suc+ E. coli as well. The fragment was found to complement a G3DH mutant of A. tumefaciens and was also found to confer chemotaxis towards sucrose in E. coli.

Agrobacterium tumefaciens↗
PubMed1997

Bilateral cheiro-oral syndrome.

Eight cases of pure bilateral cheiro-oral syndrome (COS) are reported. The location and etiology of lesion were well defined in six cases, including pontine infarct in three, and brainstem hemorrhage, unilateral thalamic infarct and bilateral subdural hematoma in one patient each respectively. Neuroimaging and neurophysiological studies were normal in another two patients. Taken together with the previous five reported cases of bilateral COS, pons is the most frequent site for presentation even in the absence of associated brainstem signs.

Adult↗
PubMed1997

Antiplatelet drugs induce apoptosis in cultured cancer cells.

In order to understand if antiplatelet drugs possess direct antineoplastic property, we tested the apoptotic effect of 5 popularly marketed antiplatelet drugs in Taiwan in 6 cultured cancer cell lines (Hep 3B hepatocarcinoma, U87-MG malignant glioma, PC-3 prostate adenocarcinoma, HeLa cervical adenocarcinoma, HL-60 preleukemia and K-562 chronic myelogenous leukemia). While acetylsalicylate and flunarizine exerted no effect on these cancer cells, pentoxifyline (PTX), dipyridamole (DYA) and ticlopidine hydrochloride (T. HCl) displayed a time and dose-dependent apoptotic effect on them except for HL-60 and K-562 cells. PTX induced apoptosis in U87-MG, Hep 3B and HeLa cells, DYA in HeLa cells, while T. HCl in U87-MG, Hep 3B, PC-3 and HeLa cells. Adriamycin also provoked apoptotic effect in all 6 cell lines but neither PTX, DYA nor T. HCl acted synergy with adriamycin to HeLa cells, implicating that they may share a similar pathway for inducing apoptosis. Therefore, our results show that the antiplatelet drugs do possess antineoplastic property in vitro. A co-administration of antiplatelet drugs is noteworthy for an alternative adjunctive therapy in cancer patients.

Antineoplastic Agents↗
PubMed1997

Prediction of total cholesterol: high-density-lipoprotein-cholesterol ratio in young adults.

Abnormal cholesterol fraction is an essential risk factor for atherosclerosis of large cerebral arteries in young Asians. In order to reduce the medical cost and social resource for cholesterol electrophoresis, especially in undeveloped and developing Asian countries, we evaluated the validity of Nanji's GUT score for predicting TC: HDLC ratio in this population. Results showed that GUT score only predicted 71% of them. We also tested the predictive power of CUT index, and predicting rate was 81%. Therefore, Nanji's GUT score is not an ideal surrogate for cholesterol electrophoresis. We recommend CUT index to screen for high-risk subjects till a new method can satisfy the economic pattern in Asian countries.

Adult↗
PubMed1996

Transient global amnesia and thalamic hemorrhage.

A left rostral thalamic hematoma was found in a 52-year-old hypertensive man who suffered from a 10-h episode of transient global amnesia (TGA). A neuropsychological study revealed no cognitive impairment in a follow-up period for 5 years. The left rostral part of the thalamus appears to be responsible for his TGA, due probably to an interference of the mamillothalamic tract, ventroamygdalofugal pathway or dorsal noradrenergic bundle.

Amnesia↗
PubMed1996

Arthrographic evaluation of developmental dysplasia of the hip. Outcome prediction.

Arthrograms of 35 hips in 33 children less than 2 years of age with typical development dysplasia of the hip were reviewed. After arthrograms were repeated for 11 hips 6 weeks following the initial test, results were classified into 6 types based on medial pooling ratio and morphology of the acetabular limbus. Using modified Severin's criteria for outcome evaluation, 7 of the 11 hips had been upgraded in type. All hips that were classified as Type I by arthrogram had Severin I results. The relation of arthrographic type and radiographic results was statistically significant. Immediate open reduction is recommended in hips classified as Type VI at first arthrogram or Type III and above at repeat arthrogram.

Arthrography↗
PubMed1996

The lipoprotein profile of young adults with cerebral atherosclerosis.

In order to elucidate the relationship between the lipoprotein profile and large cerebral artery atherosclerosis in the young adults living in developing Asian countries, the serum lipoprotein profile and the luminal diameter of large cerebral arteries (internal carotid, middle/anterior cerebral and vertebrobasilar arteries) were measured and correlated in 67 young Taiwanese with non-embolic cerebral infarct (CI). Totally 23 (21.9%) patients had atherosclerotic stenosis. A significant elevation of the serum total cholesterol (TC), triglyceride, total lipids, beta-lipoprotein (beta-LP) and pre-beta-LP level was found in atherosclerotic CI patients. But multiple regression analysis showed only the serum beta-LP (p = 0.0041) and TC (p = 0.0324) level to be the independent risk factors for atherosclerosis. Secondary dyslipoproteinemia is the main cause for hyperlipoproteinemia in our atherosclerotic patients. Therefore, an abnormal lipoprotein profile is linked to large cerebral artery atherosclerosis in young Asians regardless of ethnic group. A tailored program is recommended to modify the life style and dietary habit, as well as to gain access to secondary control for large cerebral atherosclerosis prevention in developing countries.

Adult↗
PubMed1995

The functions of human papillomavirus type 11 E1, E2, and E2C proteins in cell-free DNA replication.

We examined the functions of human papillomavirus type 11 (HPV-11) E1 and E2 proteins purified from Sf9 cells infected with recombinant baculoviruses in cell-free HPV-11 origin (ori) replication. The E1 protein binds specifically to a wild type but not to a mutated sequence in the ori spanning nucleotide position 1. It also has a relatively strong affinity for nonspecific DNA. A neutralizing antiserum directed against the amino-terminal one-third of the E1 protein totally abolishes initiation and elongation, suggesting that it functions as an initiator and a helicase at the replication fork. An antiserum against the carboxyl-terminal portion of E1 protein abolished replication only when added prior to initiation. Thus this portion of E1 is hidden in the replication complexes. The HPV-11 E2 protein appears not to be essential for elongation, but it must be present in the preinitiation complex for the E1 protein to recruit host DNA replication machinery to the ori. E2 antiserum added after preincubation in the absence of the cell extracts totally abolished replication. An identical conclusion is also reached for the bovine papillomavirus type 1 E2 protein. Finally, the HPV-11 E2C protein lacking the transacting domain of the full-length E2 protein partially inhibits E2-dependent ori replication.

Animals↗
PubMed1995

Gibbs motif sampling: detection of bacterial outer membrane protein repeats.

The detection and alignment of locally conserved regions (motifs) in multiple sequences can provide insight into protein structure, function, and evolution. A new Gibbs sampling algorithm is described that detects motif-encoding regions in sequences and optimally partitions them into distinct motif models; this is illustrated using a set of immunoglobulin fold proteins. When applied to sequences sharing a single motif, the sampler can be used to classify motif regions into related submodels, as is illustrated using helix-turn-helix DNA-binding proteins. Other statistically based procedures are described for searching a database for sequences matching motifs found by the sampler. When applied to a set of 32 very distantly related bacterial integral outer membrane proteins, the sampler revealed that they share a subtle, repetitive motif. Although BLAST (Altschul SF et al., 1990, J Mol Biol 215:403-410) fails to detect significant pairwise similarity between any of the sequences, the repeats present in these outer membrane proteins, taken as a whole, are highly significant (based on a generally applicable statistical test for motifs described here). Analysis of bacterial porins with known trimeric beta-barrel structure and related proteins reveals a similar repetitive motif corresponding to alternating membrane-spanning beta-strands. These beta-strands occur on the membrane interface (as opposed to the trimeric interface) of the beta-barrel. The broad conservation and structural location of these repeats suggests that they play important functional roles.

Algorithms↗
PubMed1995

Bilateral cheiro-oral syndrome and traumatic subdural hematoma.

Typical bilateral cheiro-oral syndrome was encountered in a 74-year-old man who had bilateral subdural hematoma after a minor head injury. The delayed grave neurologic deficits occurred 1 month later without expansion of the hematoma. Removal of the lesions reversed both cheiro-oral syndrome and his late-onset neurological disabilities.

Aged↗
PubMed1995

Amphotericin B-induced leukoencephalopathy in a patient with cryptococcal meningitis.

A 43-year-old male was diagnosed as having cryptococcal meningitis based on his clinical condition, cerebrospinal fluid (CSF) profile and high titer CSF cryptococcal antigen. The patient received intravenous amphotericin B at a total dose of 91 mg over 5 days. The therapy was then abandoned due to acute hepatorenal failure. The patient's neurologic status remained stable for 2 months, after which he began experiencing somnolence, confusion and a personality change. Cranial computed tomography revealed multifocal white matter lesions, and a brain biopsy showed a demyelination change with concurrent IgM and C1q deposition. A clinical diagnosis of amphotericin B-induced leukoencephalopathy was made. The patient's clinical condition was partially reversed after low-dose steroid therapy.

Adult↗