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Biomedical subjects

B S Chen

Publications and source records attributed to B S Chen.

At least 19 recordsLinked to original sources
PubMed2001

A Gal4-sigma 54 hybrid protein that functions as a potent activator of RNA polymerase II transcription in yeast.

The bacterial final sigma(54) protein associates with core RNA polymerase to form a holoenzyme complex that renders cognate promoters enhancer-dependent. Although unusual in bacteria, enhancer-dependent transcription is the paradigm in eukaryotes. Here we report that a fragment of Escherichia coli final sigma(54) encompassing amino acid residues 29-177 functions as a potent transcriptional activator in yeast when fused to a Gal4 DNA binding domain. Activation by Gal4-final sigma(54) is TATA-dependent and requires the SAGA coactivator complex, suggesting that Gal4-final sigma(54) functions by a normal mechanism of transcriptional activation. Surprisingly, deletion of the AHC1 gene, which encodes a polypeptide unique to the ADA coactivator complex, stimulates Gal4-final sigma(54)-mediated activation and enhances the toxicity of Gal4-final sigma(54). Accordingly, the SAGA and ADA complexes, both of which include Gcn5 as their histone acetyltransferase subunit, exert opposite effects on transcriptional activation by Gal4-final sigma(54). Gal4-final sigma(54) activation and toxicity are also dependent upon specific final sigma(54) residues that are required for activator-responsive promoter melting by final sigma(54) in bacteria, implying that activation is a consequence of final sigma(54)-specific features rather than a structurally fortuitous polypeptide fragment. As such, Gal4-final sigma(54) represents a novel tool with the potential to provide insight into the mechanism by which natural activators function in eukaryotic cells.

Amino Acid Sequence↗
PubMed2001

The clinical use of small-dose tetracaine spinal anesthesia for transurethral prostatectomy.

UNLABELLED: In a double-blinded study, we compared conventional dose tetracaine (8 mg), small-dose tetracaine (4 mg) with added fentanyl and epinephrine, and small-dose tetracaine (4 mg) with added fentanyl subarachnoid anesthesia. Forty-five patients scheduled for transurethral resection of prostate (TURP) under subarachnoid anesthesia were randomly assigned to Group 1 (8 mg hyperbaric tetracaine), Group 2 (4 mg hyperbaric tetracaine, 10 microg fen-tanyl, and 0.2 mg epinephrine), and Group 3 (4 mg hyperbaric tetracaine, 10 microg fentanyl, and 0.2 mL saline). Evaluations were performed after spinal anesthesia. Subarachnoid block was successful in all patients except one in Group 1, who required general anesthesia by mask. The median peak sensory levels 10 min after the induction of spinal anesthesia in Group 1 was T8, which was significantly higher than Group 2 and Group 3 (P < 0.05). The time of sensory and motor recovery in Group 3 was less than in Groups 1 and 2 (P < 0.05). Hypotension was observed in four patients in Group 1 and none in Groups 2 and 3. We conclude that small-dose 4-mg hyperbaric tetracaine plus 10 microg fentanyl might provide adequate anesthesia and fewer side effects for TURP when compared with the conventional (8 mg) dose. IMPLICATIONS: Small-dose hyperbaric tetracaine (4 mg with 10 microg fentanyl added) may provide adequate anesthesia and fewer side effects for transurethral resection of the prostate.

Aged↗
PubMed2000

Transglutaminase-3, an esophageal cancer-related gene.

Transglutaminase-3 (TGase-3) is an enzyme with the ability to catalyze the irreversible cross-linking of peptide-bound glutamine residues either with peptide-bound lysines or with primary amines. It has been implicated in the formation and assembly of the cornified cell envelope of the epidermis, hair follicle and perhaps other stratified squamous epithelia. We show here the involvement of TGase-3 in human esophageal cancer. In an initial study, mRNA differential display was performed with 3 pairs of esophageal cancer tissues and matched normal adjacent mucosa by a 10-mer arbitrary primer and mixed anchored primers (GT15N, N = A, C and G). Four differentially expressed cDNA bands were consistently observed in all 3 normal tissues but barely detected in their tumor counterparts. One of them was identified to be the 3; end of TGase-3. Northern blot and dot blot analyses of 14 samples confirmed the down-regulation of TGase-3 in malignant tissues compared with normal epithelia. RT-PCR revealed that TGase-3 expression was lost in 3 esophageal carcinoma cell lines and decreased in 35/38 tumors compared with adjacent normal mucosa. Taken together, 49/52 (94.2%) esophageal tumors presented down-regulation of the gene. Our data suggest that alteration of TGase-3 expression is a common event in the development of human esophageal cancer.

Adenocarcinoma↗
PubMed2000

Novel human esophagus-specific gene c1orf10: cDNA cloning, gene structure, and frequent loss of expression in esophageal cancer.

We have identified a novel human gene, designated C1orf10, using modified differential display PCR. The C1orf10 gene, which spans 5 kb in length, is composed of three exons. The deduced protein contains 495 amino acids with one transmembrane domain. The amino acid sequence of C1orf10 is characterized by the presence of a calcium-binding motif of about 90 amino acids at its N-terminal and a conserved consecutive repeat sequence of 60 amino acids that was identified previously only in bacterial ice nucleation proteins. In normal adult tissues, C1orf10 is highly expressed only in the esophagus and was undetectable in a total of 15 other tissues examined, suggesting its important role in esophageal cells. The expression of C1orf10 is either dramatically reduced or absent in esophageal cancer cell lines (3/3) as well as primary esophageal cancer tissues (35/37) compared with the corresponding normal esophageal mucosa. Using a radiation hybrid panel, C1orf10 was found to be located on chromosome 1q21. These findings suggest that expression of C1orf10 is unique to esophageal cells and that loss of its expression may play a role in the development of esophageal cancer.

Adult↗
PubMed2000

Decreased expression of SPRR3 in Chinese human oesophageal cancer.

cDNA fragments that were differentially expressed between human oesophageal carcinomas and matched normal adjacent mucosa were isolated using an improved mRNA differential display technique. One of them was identified as the 3'-untranslated region of SPRR3 and was homologous to the esophagin cDNA. Northern blot, dot blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses revealed that SPRR3 expression was lost in three cell lines of oesophageal carcinoma and was dramatically decreased in 54 out of 57 primary oesophageal carcinomas compared with adjacent normal mucosa. Esophagin has been shown to be down-regulated in western oesophageal carcinomas. The data suggest that esophagin is probably the protein product of the gene SPRR3 and that altered mRNA expression of SPRR3/esophagin is a frequent event in the development of Chinese oesophageal cancer.

3' Untranslated Regions↗
PubMed2000

Home-based patient-controlled epidural analgesia with bupivacaine for patients with intractable herpetic neuralgia.

This clinical report is based on retrospective observation of the outcome and effects of patient-controlled epidural analgesia (PCEA) with bupivacaine infusion administered at home to five patients with intractable herpetic neuralgia. All patients had severe pain (9 or 10 visual analogue scale [VAS]points) confined to the affected dermatomes, which was refractory to medication. The interval between zoster onset and PCEA application ranged from 27 to 60 days (mean, 37.2 d). The average daily amount of bupivacaine used was 36.5 to 91.2 mg (mean +/- standard deviation, 62.4 +/- 19.7 mg). The duration of PCEA therapy ranged from 10 to 28 days (18.4 +/- 7.6 d). One patient developed drug tolerance. All treatments resulted in effective and satisfactory pain relief (VAS, 0-3), with increase in physical activities to normal levels and easing of sleep and appetite impairment. No deleterious effects were found during PCEA therapy. After discontinuation of PCEA, two patients did not complain of pain but still had slight paresthesia, one of them required low-dose antidepressant for 17 days; three patients continued to have occasional sharp pain (VAS, 2-3) and required low-dose antidepressant and analgesic as-needed for one to six months. These results suggest that PCEA with bupivacaine infusion provides effective pain relief in patients with intractable herpetic neuralgia and is a feasible and effective home treatment modality with limited side effects.

Adult↗
PubMed1999

Mutational analysis of yeast TFIIB. A functional relationship between Ssu72 and Sub1/Tsp1 defined by allele-specific interactions with TFIIB.

TFIIB is an essential component of the RNA polymerase II core transcriptional machinery. Previous studies have defined TFIIB domains required for interaction with other transcription factors and for basal transcription in vitro. In the study reported here we investigated the TFIIB structural requirements for transcription initiation in vivo. A library of sua7 mutations encoding altered forms of yeast TFIIB was generated by error-prone polymerase chain reaction and screened for conditional growth defects. Twenty-two single amino acid replacements in TFIIB were defined and characterized. These replacements are distributed throughout the protein and occur primarily at phylogenetically conserved positions. Most replacements have little or no effect on the steady-state protein levels, implying that each affects TFIIB function rather than synthesis or stability. In contrast to the initial sua7 mutants, all replacements, with one exception, have no effect on start site selection, indicating that specific TFIIB structural defects affect transcriptional accuracy. This collection of sua7 alleles, including the initial sua7 alleles, was used to investigate the allele specificity of interactions between ssu72 and sub1, both of which were initially identified as either suppressors (SUB1 2mu) or enhancers (sub1Delta, ssu72-1) of sua7 mutations. We show that the interactions of ssu72-1 and sub1Delta with sua7 are allele specific; that the allele specificities of ssu72 and sub1 overlap; and that each of the sua7 alleles that interacts with ssu72 and sub1 affects the accuracy of transcription start site selection. These results demonstrate functional interactions among TFIIB, Ssu72, and Sub1 and suggest that these interactions play a role in the mechanism of start site selection by RNA polymerase II.

DNA-Binding Proteins↗
PubMed1997

[Clinical application study of intraoral high-level mandibular neurotomy: Reported of 19 cases]

Trigeminal neuralgia is a common disease in clinical practice. The recurrence rate after avulsion is relatively high. In order to reduce the recurrence rate, the author developed a new method and operated on 19 cases with intraoral high level trigeminal neurotomy based on 21 cases of adult human skull anatomy. The method is simple, safe and in good condition. The author emphasized that the proper management of the buccal branch during operation may have a close relation with the post-operative recurrence rate.

Journal Article↗
PubMed1996

Determination of the food specific IgE antibodies: comparison of MAST-CLA and CAP systems.

BACKGROUND: This study was carried out to compare two techniques used to determine the food specific IgE antibody. METHODS: Thirty-four allergic patients were evaluated for most common food IgE antibodies by multiple allergosorbent chemiluminescent assay (MAST-CLA). IgE antibodies to eight of these food allergens were also measured by Pharmacia CAP (CAP) test. RESULTS: The food specific IgE showed good agreement between MAST-CLA and CAP (kappa = 0.3-0.77). The sensitivity of MAST-CLA assay for food specific IgE antibody was variable comparing with that of CAP system. The accuracy ranged from 0.76 to 0.97. The agreement between the results of MAST-CLA and skin test was variable (kappa = 0.03-0.58). The agreement was poor in wheat, peanut and soybean (kappa = 0.03-0.12). Similar result between CAP and skin test was also obtained (kappa = 0.06-0.82). The agreement was poor in wheat (kappa = 0.06) and milk (kappa = 0.15). CONCLUSIONS: Different results might be related to quality of the extract, how they are performed in vitro test and difference of correspondent allergens employed in the tests.

Adolescent↗
PubMed1994

Transport of 2-aminoisobutyric acid in cultured endothelial cells.

Conflicting reports exist concerning the presence of a Na(+)-coupled amino acid transport system in cultured endothelial cells. We have employed a non-metabolizable analog, 2-aminoisobutyric acid (AIB), to investigate the activity of Na(+)-dependent amino acid transport in cultured human umbilical vein endothelial cells (HUVEC). We found a pronounced saturable, Na(+)-dependent component of AIB uptake in 'fresh' (non-starved) HUVEC. The Na(+)-dependent component accounted for 78% of total AIB uptake with a high sensitivity to external Na+. The accumulation of AIB was inhibited by ouabain preincubation, consistent with the energetics of Na(+)-coupled transport. Amiloride, an epithelial Na+ channel blocker, also inhibited AIB transport at high concentration. The results strongly support the presence of a Na(+)-coupled transport system of amino acid in HUVEC.

Amiloride↗
PubMed1994

[An experimental study on the HA-coated zirconia ceramic material for an endosseous implant]

HA layer is sintered onto the surface of zirconia ceramic material.These column-like composite implants and titanium implants were inserted into the femurs of the dogs.The speciments were taken at the third month after operation,and the shear strengths between the implants and bone were measured.The undecalcified bone section containing the composite ceramic implant were cut for light microscopy,scanning electron microscopy and elemental analyses of C,P and Zr.Mechanical testing results revealed that the attachment strength of HA-coated zirconia samples is more stronger,as companied with the titanium samples.Histologic evaluations of the undecalcified specimens showed that extremely close juxlaposition of bone to HA-coated zirconia ceramic implants was seen.

Journal Article↗
PubMed1994

[A biomechanical investigation of Ha-coated ceramic implant]

Two samples of Ha-coated ceramic implants of which sintering temperatures were 850 degrees centigrade,1050 degrees centigrade respectively,were prepared.Pure titanium implant of the same size was accomplished using a transcortical implant model in adult Mongrel dogs.Follow-up periods were 1,3 and 6 months.The results in vivo were evaluated using push-out tests and scanning electron microscope.There were significant differences in push-coated ceramic implants and pure titanium implants,especially for the 1 and 3 months follow-up period.SEM investigation of the interface after push-out test showed for the HA-coated ceramic implants to be fractured in the coating layer and for the Ti-implant to be fractured at the implant-bone interface.

Journal Article↗
PubMed1994

[Three-dimensional computed tomography in the diagnosis of diseases of jaw bone(report of 22 cases).].

3DCT reconstruction,as a new roentnogenographic technique,has not been yet used so much in Oral Maxillofacial Surgery in our country.Scine early 1993,22 cases of 3DCT reconstruction have been performed on a Siemens Plus-s CT scanner for the diagnosis and surgical planning of jaw bone disease and injuries.It demonstrated that 3DCT reconstruction is a useful technique for the diagnosis and surgical planning of jaw bone disease.

English Abstract↗