Biomedical subjects

L S Chang

Publications and source records attributed to L S Chang.

At least 37 records · Page 2Linked to original sources

PubMed2000

Genetic organization of A chain and B chain of beta-bungarotoxin from Taiwan banded krait (Bungarus multicinctus). A chain genes and B chain genes do not share a common origin.

beta-Bungarotoxin, the main presynaptic neurotoxin purified from the venom of Bungarus multicinctus, consists of two dissimilar polypeptide chains, the A chain and the B chain, cross-linked by an interchain disulfide bond. In this study, A and B chain genes isolated from the liver of B. multicinctus encoded the A and B chain precursors, respectively. Analyses of the coding regions of the A and B chain genes revealed that both consist of three exons and two introns. The sequences of all exon/intron junctions agree with the GT/AG rule. However, sequence alignment and phylogenetic analysis did not support that the evolution of A and B chain genes are closely related. Comparative analysis of A chain genes with Viperinae and Crotalinae phospholipase A2 genes indicated that genetic divergence of the A chain and phospholipase A2s was in accordance with their family. Moreover, evolutionary divergence of the intron and exon regions of the A chain, as observed for phospholipase A2 genes, was not consistent. Noticeably, the transcription of A and B chain genes may be regulated under different transcription factors as revealed by analyses of their promoter sequences. In terms of the finding that A and B chains are encoded separately by different genes, this strongly supports the view that the intact beta-bungarotoxin molecules should be derived from the pairing of A and B chains after their mRNAs are translated.

Amino Acid Sequence↗

PubMed2000

The correlation between clinical outcome and residual prostatic weight ratio after transurethral resection of the prostate for benign prostatic hyperplasia.

OBJECTIVE: To assess in a prospective study the use of a new variable, the residual prostatic weight ratio (RPWR), for evaluating the clinical outcome after transurethral resection of the prostate (TURP). PATIENTS AND METHODS: From April 1996 to June 1997, 40 men (mean age 70.4 years, range 53-85) with symptomatic benign prostatic hyperplasia were evaluated using the American Urological Association (AUA) symptom score, measurements of the mean and maximum urinary flow rate (Qave and Qmax), and by transrectal ultrasonography (TRUS) before and 16 weeks after TURP. The estimated total prostate weight was derived as 0.52 x length x width x height x the specific gravity of the prostate (1.010). The RPWR was calculated as the prostate weight after TURP divided by the initial weight, where the value after TURP was the initial weight minus that of the TURP specimen. The clinical outcome was evaluated by the difference (Delta) in AUA score, Qmax and Qave before and 16 weeks after surgery. RESULTS: There was a close correlation between the estimated prostate weight and the actual weight of the TURP specimen (r = 0.82 and 0.80 for the adenoma and total prostate, respectively). The mean (SD) RPWR, DeltaAUA score, DeltaQmax and DeltaQave were 50.1 (17.1)%, 11.5 (5. 3), 9.0 (4.2) mL/s and 6.2 (2.9) mL/s, respectively. There was a negative correlation between the RPWR and the DeltaAUA, DeltaQmax and DeltaQave (r = -0.81, -0.68, and -0.70, respectively, P < 0.05). The prostate volume estimated by TRUS decreased significantly 16 weeks after TURP. CONCLUSIONS: TRUS is a useful tool for estimating prostate weight before surgery. The smaller the RPWR at 16 weeks after TURP, the better the clinical outcome.

Aged↗

PubMed2000

Analysis of the human neurofibromatosis type 2 gene promoter and its expression.

OBJECTIVE: It is hypothesized that transcriptional regulation plays an important role for neurofibromatosis type 2 (NF2) expression in Schwann cells and other cell types. The objective of this study is the isolation and characterization of the transcriptional regulatory elements of the NF2 gene. STUDY DESIGN AND SETTING: A bacterial artificial chromosome library and a partial genomic DNA library were used to isolate the human NF2 gene; NF2 promoter-luciferase constructs were generated, and promoter activities were assayed. This study was carried out in a molecular biology laboratory. RESULTS: A bacterial artificial chromosome clone with an approximately 100-kilobase insert containing nearly the entire human NF2 gene has been isolated. An additional 5' NF2 sequence has also been cloned. Transient transfection experiments demonstrate strong promoter activity from the NF2 5' flanking DNA. CONCLUSIONS: The NF2 gene is approximately 100 kilobases long. Both positive and negative regulatory elements are present in NF2 5' flanking regions. SIGNIFICANCE: Better understanding of the NF2 gene and its regulation will improve molecular diagnostics and ultimately treatment of patients with NF2.

Base Sequence↗

PubMed2000

Assessment of a three-dimensional operating system with skill tests in a pelvic trainer.

OBJECTIVES: To compare the performance of laparoscopic skill assisted by a traditional two-dimensional (2D) and a three-dimensional (3D) endoscopic video system in a pelvic trainer. MATERIALS AND METHODS: The 3D imaging system (DeepVision((R)), Automated Medical Products Corp.) consists of a traditional single lens optic laparoscope, a light source, an endoscopic camera (Stryker), a DeepVision processor and a DeepVision monitor. The 2D images could be obtained with the same system without turning on the DeepVision processor. Thirty-four medical personnel with no laparoscopic surgical experience were enrolled to perform two skill tests, the object-pick-up and spatial orientation test in a trainer box. They were randomly divided into two groups, one group performed the test under 2D conditions first and 3D later, and another group performed the test under 3D conditions first and 2D later. The duration needed to complete the skill tests was recorded and the differences on performance time under 2D and 3D conditions were calculated for each participant. Two-way ANOVA was used to analyze the statistic difference on the performance time in two conditions. RESULTS: The duration needed to complete the initial skill tests was similar among 2D and 3D conditions. For both tests, the average performance time decreased significantly for the second attempt regardless of 2D or 3D conditions. Statistic analysis disclosed significant difference for learning factor (p < 0.001 for object-pick-up test and p < 0.01 for spatial orientation test), but no significant difference between 2D and 3D conditions (p = 0.276 for object-pick-up test and p = 0.327 for spatial orientation test). CONCLUSION: A significant decrease of the performance time at the second attempt reflected the importance of a learning process in laparoscopic surgery. It appears that no significant benefits were obtained by this 3D operating system for surgeons without laparoscopic surgical experience.

Humans↗

PubMed2000

Effects of aging on mitochondrial enzyme activity of rat urinary bladder.

OBJECTIVES: Our previous study showed that aged rat bladders became fatigued faster than young bladders following repeated contraction induced by electrostimulation. One factor might be a lower energy-producing capability secondary to a decreased mitochondrial enzyme activity of the aged bladder. This study examined this possibility. MATERIALS AND METHODS: Mitochondria from 3- (n = 11) and 24-month-old (n = 10) Sprague-Dawley rats were isolated. Activities of the following enzymes were assayed: two key enzymes in the citric acid cycle, citrate synthase and malate dehydrogenase, and three enzymes in the respiratory chain reaction, NADH-cytochrome c reductase, succinate-cytochrome c reductase and cytochrome c oxidase. The concentration of phosphocreatine and ATP in the aged rat bladders and a separate group of young bladders (n = 12) was determined using high-performance liquid chromatography. RESULTS: (1) The aged bladders have a significantly lower level of phosphocreatine and ATP content than those of young bladders. (2) The activities of all five enzymes assayed were significantly lower in the aged bladders than in young bladders, especially for citrate synthase, which had only 46.8% of the activity of young bladders. CONCLUSIONS: Aging reduces the mitochondrial enzyme activity of the rat bladder resulting in a lower energy-production capability, which might explain some of the voiding dysfunctions found in the elderly.

Adenosine Triphosphate↗

PubMed2000

Morphological and morphometric analysis of human detrusor mitochondria with urodynamic correlation after partial bladder outlet obstruction.

PURPOSE: We correlated ultrastructural changes in mitochondria in the human detrusor with the severity of partial bladder outlet obstruction on urodynamics. MATERIALS AND METHODS: We recruited into the study 52 men with and without bladder outlet obstruction symptoms. The severity of partial bladder outlet obstruction was determined by pressure flow study. Random detrusor biopsy specimens obtained by cystoscopy were fixed immediately and processed for transmission electron microscopic observation. Random areas were photographed for further morphological and morphometric analysis using mitochondrial damage score and stereological principles. RESULTS: Mitochondrial damage score and mean mitochondrial volume strongly correlated with the urodynamic severity of partial bladder outlet obstruction, while mitochondrial volume density, surface density of the mitochondrial outer membrane and number of mitochondria per unit of cytoplasm area did not significantly correlate with severity. CONCLUSIONS: Detrusor mitochondrial swelling and structural destruction increased with the severity of partial bladder outlet obstruction. These changes may be associated with impaired mitochondrial function and oxidative metabolism after partial bladder outlet obstruction. Detrusor mitochondrial damage may explain voiding dysfunction after partial bladder outlet obstruction develops.

Adult↗

PubMed1999

Expression and mutagenesis studies of cobrotoxin from Taiwan cobra.

The cDNA encoding cobrotoxin was constructed from the cellular RNA isolated from the venom glands of Naja naja atra (Taiwan cobra). The cDNA was subcloned into the expression vector pET20b(+) and transformed into BL21(DE3) Escherichia coli strain. Expressed cobrotoxin was isolated from inclusion bodies of E. coli and subjected to refolding into its folded structure. The refolded cobrotoxin was purified by high-performance liquid chromatography and exhibited a neurotoxicity in inhibiting acetylcholine-induced muscle contractions. Recombinant cobrotoxin showed a tendency to isomerize its disulfide bonds as that observed with native cobrotoxin. An appreciable decrease in the rate of isomerization reaction was observed when Glu-38 was replaced with Gln-38 or Lys-47 was replaced with Glu-47 or Gln-47. These results reflect that the element in controlling the disulfide isomerization of cobrotoxin is closely associated with the charged side chains in the cobrotoxin molecule.

Acetylcholine↗

PubMed1999

Induction of erythrocyte protein 4.2 gene expression during differentiation of murine erythroleukemia cells.

Protein 4.2 (P4.2) is an important component in the erythrocyte membrane skeletal network that regulates the stability and flexibility of erythrocytes. Recently, we provided the evidence for specific P4.2 expression in erythroid cells during development (L. Zhu et al., 1998, Blood 91, 695-705). Using dimethyl sulfoxide (DMSO)-induced differentiation of murine erythroleukemia (MEL) cells as a model, transcription of the P4.2 gene was found to be induced during erythroid differentiation. To examine the mechanism for this induction, we isolated the mouse P4.2 genomic DNA containing the 5' flanking sequence and defined the location of the P4.2 promoter. Transcription of the mouse P4.2 gene initiates at multiple sites, with the major initiation site mapped at 174 nucleotides upstream of the ATG start codon. The mouse P4.2 promoter is TATA-less and contains multiple potential binding sites for erythroid transcription factors GATA-1, NF-E2, EKLF, and tal-1/SCL. Transient transfection experiments demonstrated that a 1.7-kb mouse P4.2 promoter fused with the luciferase coding regions was induced in DMSO-treated MEL cells. Deletion analysis showed that a 259-bp P4.2 promoter DNA (nucleotide position -88 to +171 relative to the major transcription initiation site designated +1), containing a GATA-binding site at position -29 to -24, could still respond to the induction in differentiated MEL cells. Importantly, mutations in the -29/-24 GATA motif rendered the promoter unresponsive to DMSO induction. Electrophoretic mobility shift assay revealed that GATA-1 could bind to the -29/-24 GATA motif and this was confirmed by the observation that the nuclear protein bound to the motif was supershifted by an anti-GATA-1 monoclonal antibody. Taken together, these results suggest that the erythroid transcription factor GATA-1 plays an important role in the induction of P4.2 gene expression during erythroid cell differentiation.

Animals↗

PubMed1999

Regulation of testosterone secretion by prolactin in male rats.

The goal of this study was to characterize the mechanism by which hyperprolactinemia alters testosterone production in rat testicular interstitial cells (TICs). Hyperprolactinemia was induced by grafting 2 anterior pituitary (AP) glands under the subcapsular space of the kidney in experimental rats. Control rats were grafted with brain cortex (CX). Six weeks post-grafting, rats were challenged with human chorionic gonadotropin (hCG) then, the changes in either plasma testosterone or luteinizing hormone was measured. Additionally, TICs were isolated and challenged in vitro with hCG or prolactin, and the testosterone release measured by radioimmunoassay. Further investigation in signal transduction as intracellular 3':5' cyclic adenosine monophosphate (cAMP) production was observed under a regulation of forskolin or SQ22536. After the challenge of hCG or GnRH, the AP-grafted rats showed a suppressed response in testosterone release as compared to those in the CX-grafted group. The in vitro data from the AP-grafted rats compared to the CX-grafted animals showed a diminished response in testosterone release upon hCG stimulation. Administration of forskolin or SQ22536 disclosed dysfunction of adenylate cyclase in TICs from the AP-grafted rats. When 8-Br-cAMP was incubated with TICs, the testosterone production was lower in the AP-grafted compared to the CX-grafted group. These results suggest that in addition to adenylate cyclase dysfunction, inefficiency of post-cAMP pathways are also involved in the hypogonadism elicited by hyperprolactinemia in rats.

Animals↗

PubMed1999

Disulfide isomers of alpha-neurotoxins from King cobra (Ophiophagus hannah) venom.

Two novel alpha-neurotoxins, Oh-6A and Oh-6B, isolated from the king cobra (Ophiophagus hannah) venom, consist of 70 amino acid residues with 10 cysteine residues and share the same amino acid sequences as determined by Edman degradation on the peptide fragments generated from the proteolytic hydrolysates. Their sequences share 46-53% homology with Oh-4, Oh-5, Toxin a, and Toxin b from the same venom. The finding that Oh-6A and Oh-6B had different retention times in the reversed-phase column suggested that the two toxin molecules should not have the same conformation. Selective reduction on the disulfide bond, Cys26--Cys30, at the tip of their loop II structures resulted in the production of the partially reduced derivatives eluted at the same position. Under redox conditions, the partially reduced Oh-6A and 6B exclusively converted into native Oh-6A as evidenced by HPLC analyses. This suggests that Oh-6A and Oh-6B are disulfide isomers which probably arise from cis-trans isomerization of the Cys26--Cys30 disulfide bond. Alternatively, the two toxins exhibited binding activity toward nAChR and lethal toxicity equally. It reflects that the diversity around the extra loop at the loop II structure does not exert a significant effect on the manifestation of the neurotoxicity of Oh-6A and Oh-6B.

Amino Acid Sequence↗

PubMed1999

Postchemotherapy retroperitoneal residual mass in infantile yolk sac tumor.

BACKGROUND: Persistent postchemotherapy retroperitoneal residual mass with normalization of alpha-fetoprotein (AFP) in infantile yolk sac tumor is rare. METHODS/RESULTS: A 38-month-old boy with recurrent yolk sac tumor was treated with cisplatin-based combination chemotherapy. After chemotherapy, the retroperitoneal lymph node metastasis, 7 x 6 cm in size, decreased to 2 x 2 cm. Serum AFP levels returned to normal. The retroperitoneal residual mass was resected and histologically showed complete necrosis without viable cancer cells. CONCLUSION: The patient has remained free of disease for 36 months after operation.

Antineoplastic Agents↗

PubMed1999

Dopaminergic neurotransmission at the paraventricular nucleus of hypothalamus in central regulation of penile erection in the rat.

PURPOSE: To investigate whether the paraventricular nucleus of hypothalamus (PVN) is involved in the central regulation of apomorphine-induced penile erection in the rat, and to decipher dopamine receptor subtypes in the PVN that are involved in apomorphine-induced penile erection. MATERIALS AND METHODS: Male adult Sprague-Dawley rats (200 to 300 gm.) anesthetized with pentobarbital sodium were used. The intracavernous pressure (ICP), recorded along with systemic and mean arterial pressure (SAP, MAP) as well as heart rate (HR), was measured via a 26-gauge needle inserted into one corpus cavernosum. The PVN was activated by stereotaxically delivered apomorphine hydrochloride (0.1 nmol./100 nl.). Injection of saline into PVN served as a vehicle control. To investigate the participation of dopamine receptor subtypes in the PVN on apomorphine-induced penile erection, D1 or D2 receptor antagonist, SCH-23390 (100 pmol./100 nl.) or sulpiride (100 pmol./100 nl.) respectively, was administered into the PVN prior to subcutaneous application of apomorphine (80 microg./kg.). The effects on ICP of microinjection of D1, D2 or D3 receptor agonist, SKF-38393 (200 pmol./100 nl.), lisuride (200 pmol./100 nl.) or 7-hydroxy-DPAT (200 pmol./100 nl.) respectively, into the PVN were also evaluated. RESULTS: The mean resting ICP was 5.2+/-0.4 mm. Hg. Upon administration of apomorphine into the PVN, there was a significant increase in ICP that peaked at 50.7+/-5.3 mm. Hg and persisted for 45.2+/-18.0 minutes after an onset latency of 677.7+/-311.6 seconds. Yawning and teeth gnashing were also observed in most of animals during the period of ICP increase. There was no significant change in SAP, MAP or HR. In addition, there was no elevation in ICP after administration of saline to the PVN or direct injection of apomorphine into the cavernous tissue. Microinjection of D1 or D2 receptor antagonist into the PVN blocked the increase in ICP after subcutaneous administration ofapomorphine. Direct application of D2, but not D1 or D3 receptor agonist into the PVN, on the other hand, increased the ICP. CONCLUSIONS: Our results demonstrate that application of apomorphine to the paraventricular nucleus of hypothalamus elicited penile erection in the rat. Such an increase in ICP to apomorphine was due mainly to activation of the D2 receptor subtype in the PVN. These observations indicate that PVN may be involved in the central regulation of apomorphine-induced penile erection in the rat.

Animals↗

PubMed1999

Testicular yolk sac tumors in children.

BACKGROUND: Testicular tumors in children are uncommon, comprising about 1% of pediatric malignancies. Yolk sac tumor is the most common malignant testicular tumor in children. Because yolk sac tumor in children is rarely seen, its treatment has been controversial. We reviewed the records of 15 children with testicular yolk sac tumor treated at our hospital in order to evaluate optimal management and treatment outcome. METHODS: From February, 1981, to August, 1996, 15 children with testicular yolk sac tumor were treated. Mean patient age at diagnosis was 15.8 months (range, 7-22 months). Fourteen patients presented with stage I disease and one presented with stage III disease. Mean follow-up was 88 months (range, 2-156 months). RESULTS: All 15 patients received radical inguinal orchiectomy as initial treatment. Serum alpha-fetoprotein (AFP) concentrations were measured in 14 stage I patients preoperatively and were elevated in all of them. During follow-up, the one stage III patient died of the disease. Of the remaining 14 patients, two (14.3%) had recurrence with elevated AFP at three months and 10 months postorchiectomy, respectively. These patients were managed with cisplatin-based combination chemotherapy. To date, they are both alive with no further recurrence, and AFP concentrations returned to normal after chemotherapy. Overall, of the 15 patients with testicular yolk sac tumor, 14 (93.3%) survived without disease. CONCLUSIONS: Our results suggest that testicular yolk sac tumor in children is a tumor with a favorable prognosis. Serum AFP concentration is extremely useful in diagnosis and monitoring of treatment response. Radical inguinal orchiectomy alone seems adequate for patients with stage I disease if serum AFP concentrations return to normal postoperatively. Cisplatin-based combination chemotherapy should be administered in patients with tumor recurrence or metastasis.

Endodermal Sinus Tumor↗

PubMed1999

Life-threatening germ cell tumor arising in cryptorchidism: a case report.

We report a case of life-threatening germ cell tumor in abdominal cryptorchidism. A 32-year-old man presented with a three-month history of dyspnea, loss of appetite, general weakness and a large abdominal mass. Physical examination revealed vacancy of the right scrotal contents. Chest radiograph showed massive left pleural effusion. Abdominal ultrasound revealed ascites, right hydronephrosis and the presence of an 18 x 15-cm heterogeneous echogenic mass in the upper abdomen and right iliac fossa. Abdominal computerized tomography (CT) revealed the presence of a large heterogeneous tumor and an enlarged (4 x 4-cm) retroperitoneal lymph node. Sonoguided needle biopsy of the abdominal mass demonstrated malignant cells of an uncertain type and origin. Serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (beta-HCG) concentrations were elevated. Under the diagnosis of metastatic nonseminomatous germ cell tumor in abdominal cryptorchidism, the patient received three cycles of cisplatin-based combination chemotherapy followed by resection of the abdominal residual cryptorchid tumor. Histologically, the tumor showed marked necrosis without viable cancer. The patient had remained free of disease for seven months following surgery.

Adult↗

PubMed1999

Clinical experiences of germ cell tumor in cryptorchid testis.

The increased risk of malignancy occurring in the cryptorchid testis is well established. In order to investigate the management and outcome of germ cell tumor in cryptorchid testis, we retrospectively reviewed the records of 11 patients with cryptorchid tumor treated at our hospital between January 1973 and December 1996. Mean patient age at diagnosis was 47.6 years (range, 22-80). Of these patients, 3 were found in the inguinal area and 8 in the abdomen. Six occurred in the right cryptorchid testis and 5 in the left. Four patients presented with stage I disease, 4 with stage II, and 3 with stage III. Median follow-up period was 48.0 months (range 1-163). All 3 inguinal cryptorchid tumors and 6 of 8 abdominal cryptorchid tumors were seminoma. The remaining 2 abdominal cryptorchid tumors were nonseminomatous germ cell tumor. Of the 3 patients with inguinal cryptorchid seminomas, 2 with stage I disease were treated with prophylactic radiotherapy to nodal areas and 1 with stage III disease was treated with chemotherapy. Eight patients with abdominal cryptorchid tumors were treated with multidisciplinary approaches, including radiotherapy, cisplatin-based combination chemotherapy, and surgery. The overall survival rate for patients with inguinal and abdominal cryptorchid tumor was 81.8%. Two patients with stage III disease died during treatment and the remaining 9 patients are still alive without evidence of disease.

Adult↗

PubMed1999

Observations after orchiectomy in clinical stage I nonseminomatous germ cell tumors of the testis.

BACKGROUND: The optimal management of clinical stage I nonseminomatous germ cell tumor (NSGCT) of the testis remains controversial. For years, retroperitoneal lymph node dissection in combination with orchiectomy, has been the standard treatment in patients with clinical stage I NSGCT. Recently, with advancement of effective cisplatin-based chemotherapy and clinical staging procedures, a new approach of observation after orchiectomy is being evaluated. We reviewed cases of orchiectomy and observation for clinical stage I NSGCT of the testis in order to evaluate the treatment outcome. METHODS: We retrospectively reviewed the records of 13 patients with clinical stage I NSGCT of the testis treated at our hospital from February, 1981 to August, 1996. The patient age at diagnosis ranged from 0.6 to 44 years. Nine patients had yolk sac tumors, and four had mixed germ cell tumors. Median follow-up was 42 months (range, 20-132 months). RESULTS: Prior to orchiectomy, serum beta-human chorionic gonadotropin and alpha-fetoprotein (AFP) were raised to abnormal concentrations in four and in 13 patients, respectively. With a median follow-up of 42 months, three of 13 patients relapsed at a median of three months after orchiectomy. Two patients showed elevated AFP and radiographically identifiable tumors simultaneously, and one patient showed elevated AFP as the only evidence of relapse. Following treatment with cisplatin-based chemotherapy, the three patients who relapsed responded successfully and the elevated AFP returned to normal. The patients are currently alive and disease free. CONCLUSIONS: Observation after orchiectomy is a reasonable approach for patients with clinical stage I NSGCT of the testis.

Adolescent↗

PubMed1999

Immunohistochemical analysis of nm23-H1 protein in bladder cancer.

BACKGROUND: The nm23 gene was first identified from murine K-1735 melanoma cell lines and possesses metastasis-suppressor activity. However, conflicting results concerning the metastasis-suppressor activity of nm23-H1 gene product have been reported in human solid tumors. The significance of nm23-H1 protein in bladder cancer remains to be determined. Therefore, we examined nm23-H1 protein expression immunohistochemically in bladder cancer. METHODS: Formalin-fixed, paraffin-embedded tissue specimens were obtained from 39 patients with primary bladder cancer who had undergone radical cystectomy between 1987 and 1994. The specimens were examined immunohistochemically using a monoclonal antibody to nm23-H1, and the results of immunostaining were compared with clinicopathologic factors and patient survival. RESULTS: Positive nm23-H1 protein expression was confined primarily to the cytoplasm of bladder cancer cells. A higher frequency of nm23-H1 positive expression was seen in higher stage tumors. There was a positive trend for the expression of nm23-H1 protein with the progression of the tumor (p < 0.025). No relationship was found between nm23-H1 protein expression and patients' clinicopathologic factors including age, tumor size, tumor morphology and tumor grade. Furthermore, nm23-H1 protein expression was not correlated with patient survival. CONCLUSIONS: These results suggest that in bladder cancer nm23-H1 protein expression may play an important role in tumor progression rather than in metastasis suppression.

Adult↗

PubMed1998

Cloning and functional expression of B chains of beta-bungarotoxins from Bungarus multicinctus (Taiwan banded krait).

The cDNA species encoding the B chains (B1 and B2) of beta-bungarotoxins (beta-Bgt) were constructed from the cellular RNA isolated from the venom glands of Bungarus multicinctus (Taiwan banded krait). The deduced amino acid sequences of the B chains were different from those determined previously by a protein sequencing technique. One additional Arg residue is inserted between Val-19 and Arg-20 of the B1 chain. Similarly the insertion of one additional Val residue between Val-19 and Arg-20 of the B2 chain is noted. Thus the B chains should comprise 61 amino acid residues. Moreover, the residues at positions 44-46 are Gly-Asn-His, in contrast with a previous result showing the sequence His-Gly-Asn. Instead of Asp, the residues at positions 41 and 43 are Asn. The B chain was subcloned into the expression vector pET-32a(+) and transformed into Escherichia coli strain BL21(DE3). The recombinant B chain was expressed as a fusion protein and purified on a His-Bind resin column. The yield of affinity-purified fusion protein was increased markedly by replacing Cys-55 of the B chain with Ser. However, the isolated B(C55S) chain became insoluble in aqueous solution after removal of the fused protein from the affinity-purified product, suggesting that protein-protein interactions might be crucial for stabilizing the structure of the B chain. The B(C55S) chain fusion protein showed activity in blocking the voltage-dependent K+ channel, but did not inhibit the binding of beta-Bgt to synaptosomal membranes. These results, together with the finding that modification of His-48 of the A chain of beta-Bgt caused a marked decrease in the ability to bind toxin to its acceptor proteins, suggest that the B chain is involved in the K+ channel blocking action observed with beta-Bgt, and that the binding of beta-Bgt to neuronal receptors is not heavily dependent on the B chain.

Amino Acid Sequence↗