The multiplicity of cardiotoxins from Naja naja atra (Taiwan cobra) venom

Four novel cardiotoxins were isolated from Naja naja atra (Taiwan cobra) venom by successive separation on a SP-Sephadex C-25 column and a reverse phase column. Amino acid sequences of the cardiotoxins were determined by Edman degradation and carboxypeptidase digestion. It shows that these cardiotoxins comprise 60 amino acid residues. Comparative analyses on the amino acid sequences of cardiotoxins from the venoms of N. naja atra and other Naja species indicated that amino acid substitutions of cardiotoxin isoforms frequently occurred at positions 7-11, 27-32 and 45-47. The hypervariable segments encoded by the second and third exon of cardiotoxin genes are located at or near the tips of loop structure of cardiotoxin molecules. These results, together with the suggestions that the residues at the tips of cardiotoxins' loop structure were involved in the manifestation of the biological activities of cardiotoxins, reflect that the preferential mutations may contribute to alterations in the function of cardiotoxin molecules. Analysis on the secondary structure of pre-mRNAs of N. naja atra cardiotoxin 4 gene and N. naja sputatrix cardiotoxin 3 gene has shown that the hypervariable regions of the exon 2 pertain to form intra-exon pairings and are not involved in the formation of intron-exon pairings. Since the pairings of splice sites and gene architecture were supposed to be associated with intron-exon recognition, it is likely that the preferred loci of mutations occurring with the evolution of cardiotoxin genes would not affect the processing of cardiotoxin precursors.

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.

Mitochondrial DNA deletion of the human detrusor after partial bladder outlet obstruction-correlation with urodynamic analysis

OBJECTIVES

To investigate mitochondrial DNA (mtDNA) mutations in human detrusor after partial bladder outlet obstruction (BOO) and correlate the findings with the results of urodynamic studies.

METHODS

Sixty-two male patients with and without BOO were recruited and assessed by the International Prostate Symptom Score, a quality-of-life assessment index, and sonography. The severity of partial BOO was determined by pressure-flow study with an International Continence Society (ICS) nomogram. Random detrusor biopsies obtained cystoscopically were analyzed by polymerase chain reaction (PCR) techniques to detect possible mtDNA deletions. Primer-shift PCR and DNA sequencing were then performed to characterize specific mtDNA deletions. A semiquantitative PCR method was used to determine the proportion of the deleted mtDNA in detrusor. Finally, the mtDNA deletion and the urodynamic results were compared statistically.

RESULTS

A 4977-bp mtDNA deletion was identified in the human detrusor. Its incidence and proportion were found to increase after partial BOO (P = 0.005 and 0.012, respectively). The incidence of the mtDNA deletion was 4.2% (1 of 24) in the unobstructed group, 27.8% (5 of 18) in the equivocal group, and 40% (8 of 20) in the obstructed group. The mean proportion of the 4977-bp deleted mtDNA was 23.7 and 12.7 times higher in the obstructed and equivocal groups, respectively, compared with that of the unobstructed group.

CONCLUSIONS

We found mtDNA with the 4977-bp deletion in human detrusor and an increase of this deletion after partial BOO. This molecular change might account for the previous observations of mitochondrial functional impairment and voiding dysfunction after partial BOO.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Expression of osteopontin mRNA in normal and stone-forming rat kidney

Human urine contains several macromolecules which inhibit calcium oxalate crystallization. Osteopontin (or uropontin), a secreted phosphoglycoprotein with the amino acid sequence Arg-Gly-Asp (RGD) and high affinity to hydroxyapatite, is one such inhibitor. To investigate the action of this protein on renal stone formation, the expression osteopontin gene in normal and chemically induced urolithiasis rat kidney was compared at both mRNA and protein levels. Northern blot analysis shown a significant increase of osteopontin mRNA level in stone-forming rat kidney compared with normal ones. In an in situ hybridization study, we localized the transcripts of the osteopontin gene in epithelial cells of both distal and collective tubules, and found a remarkably strong signal in stone-forming rats. The amount and distribution of the protein in kidney from immunocytochemistry staining showed the same pattern as seen in situ hybridization. These findings indicate that osteopontin may be an important macromolecule in the normal endogenous defence against the formation of urinary calculi.

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.

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.

Effects of outlet obstruction and its reversal on mitochondrial enzyme activity in rabbit urinary bladders

PURPOSE

This study investigated the effects of outlet obstruction and its reversal on mitochondrial enzyme activity in the rabbit urinary bladder.

MATERIALS AND METHODS

We induced mild bladder outlet obstruction in male New Zealand White rabbits. Following two weeks of obstruction, one group of animals (n = 6) was sacrificed, while outlet obstruction was relieved in three additional groups of animals, which were sacrificed one (n = 5), two (n = 5) and four (n = 5) weeks after relieving the obstruction. Seven sham operated rabbits served as controls. We extracted mitochondria from fresh detrusor and assayed activities of key mitochondrial enzymes in the citric acid cycle, citrate synthase and malate dehydrogenase, as well as those in the electron transport chain, succinate cytochrome c reductase, NADH-cytochrome c reductase and cytochrome c oxidase. With high performance liquid chromatography (HPLC) we determined the tissue content of phosphocreatine and the adenine nucleotides (ATP, ADP and AMP), which was used for calculating energy charge. Responses of detrusor strips to 500 microM bethanechol and 120 mM KCl provided the assessment of detrusor contractility.

RESULTS

Contractile response of the detrusor strips to bethanechol stimulation was significantly reduced by outlet obstruction, nevertheless, it recovered gradually toward the control level after the relief of outlet obstruction. Outlet obstruction reduced the detrusor content of phosphocreatine, ATP and energy charge. After relieving the obstruction, however, these recovered gradually, reaching control levels 4 weeks later. The activities of all assayed enzymes were reduced by two weeks of outlet obstruction. Relieving the obstruction restored enzyme activity gradually but at different rates for different enzymes. Activities of the citric acid cycle enzymes citrate synthase and malate dehydrogenase recovered and were similar to control levels four weeks after relief of the obstruction. Of the enzymes in the electron transport chain, NADH cytochrome reductase activity recovered most quickly by one week after relief of the obstruction. The activity of cytochrome c oxidase improved more slowly, but 4 weeks after relieving the obstruction it, also, was restored and was similar to the control level. Succinate cytochrome reductase activity remained lower than the control over the entire four weeks of recovery.

CONCLUSIONS

The close association between mitochondrial enzyme activity, energy metabolism and contractility of the detrusor indicates the important role of mitochondrial enzyme damage in decreasing energy production and impairing contractile function of the urinary bladders following outlet obstruction. Our findings also show that various mitochondrial enzymes exhibit different susceptibilities and reversibilities to pathological stress.

Characterization and cloning of long neurotoxin homolog from Naja naja atra

The cDNA encoding a long neurotoxin homolog was constructed from the cellular RNA isolated fom the venom glands of Naja naja atra (Taiwan cobra) by reverse transcription-polymerase chain reaction. BLAST searches for sequence similarity in the GenBank databases reveal that the cDNA sequence of the long neurotoxin homolog is not highly homologous with long and short neurotoxins. Although the long neurotoxin homolog exhibited an activity to inhibit acetylcholine-induced muscle contractions as Naja naja atra cobrotoxin, the degree of inhibition caused by the addition of long neurotoxin homolog was only approximately 35% of that observed with the addition of cobrotoxin. Moreover, the primary structure of the long neurotoxin homolog did not fulfill the characteristic features of long or short neurotoxins. Together with long neurotoxin homologs from other snake species, they probably represent an evolutionary divergence between long and short neurotoxins.

Complicated urinary tract infection: analysis of 179 patients

BACKGROUND

The aim of our study was to investigate the incidence, bacteriology, management and outcome of complicated urinary tract infections (UTIs) at the Veterans General Hospital-Taipei.

METHODS

Between June, 1993, and July, 1994, medical records of 2,566 patients admitted to the Division of Urology, Veterans General Hospital-Taipei, were retrospectively reviewed. Of these patient, 1,322 had a diagnosis of benign prostatic hyperplasia (BPH), 607 were admitted for renal stones, 496 for ureteral stones, 75 for transitional cell carcinoma (TCC) of the urinary bladder, 47 for renal tumors and 19 for TCC of the ureter. Among all patients studied, 179 (6.98%) acquired a complicated UTI. Of these, 81 were admitted for BPH, 46 for renal stones, 42 for ureteral stones, five for TCC of the urinary bladder, three for renal tumors and two for TCC of the ureter.

RESULTS

Of the 179 patients with complicated UTIs, 155 were men and 24 were women. The urine culture positive rate was 76.0% (136/179) and the most common bacteria were Escherichia coli, Proteus mirabilis and Pseudomonas aeruginosa. The principle mode of treatment included parenteral antibiotics and urinary diversion (percutaneous nephrostomy and Foley catheterization), when necessary. The infection control rate for these complicated UTIs was 96.3% for BPH, 95.5% for renal stone, 97.6% for ureteral stone, 80% for TCC of the urinary bladder, 100% for renal tumor and 100% for TCC of the ureter. Mortality due to complicated UTI was 3.9% (7/179).

CONCLUSIONS

We concluded that the prognosis of complicated UTI is good if diagnosis and appropriate treatment are given promptly. Early drainage to relieve obstruction and intravenous antibiotics are initially necessary. Surgical intervention is required to resolve functional or structural abnormalities after the UTI has been controlled.

Successful treatment of a bulky seminoma in an abdominal undescended testis: a case report

An undescended testis is a major risk factor for the development of testicular malignancy. Herein we report the case of a 40-year-old man with a bulky seminoma arising in an uncorrected abdominal undescended testis. The definitive diagnosis was established by results of sonoguided biopsy and tumor marker studies. The patient was successfully treated with initial cisplatin and etoposide combination chemotherapy followed by resection of the residual tumor. The optimal diagnosis and treatment of this rare disease is discussed.

Identification of arg-30 as the essential residue for the enzymatic activity of Taiwan cobra phospholipase A2

Taiwan cobra (Naja naja atra) phospholipase A2 (PLA2) was inactivated by arginine-specific reagents, phenylglyoxal and 1, 2-cyclohexanedione. Kinetic analyses of the modification reaction revealed that the inactivation of PLA2 followed pseudo-first-order kinetics and the loss of activity was correlated with the incorporation of one molecule of modification reagent per PLA2 molecule. This was confirmed by the results of amino acid composition determination, that showed that a marked decrease in enzymatic activity was associated with the modification of one arginine residue. Tryptic cleavage of the modified protein and microsequencing revealed that Arg-30 was the functionally essential residue. The incorporation of a modifier into the PLA2 did not significantly affect the secondary structure of the enzyme, as revealed by the CD spectrum, and Ca2+-binding of the modified PLA2 was unaffected. Nevertheless, the nonpolarity of the active site of PLA2 markedly decreased with the arginine modification, as evidenced by the decreases in the enhancement of Trp and 8-anilinonaphthalene sulfonate fluorescence. These results, together with those of X-ray crystallographic analysis of N. naja atra PLA2 [Scott et al. (1990) Science 250, 1541-1546], demonstrate that Arg-30 is one of the residues involved in the interfacial binding of a PLA2 molecule with its substrate.

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.

Unfolding/folding studies on cobrotoxin from Taiwan cobra venom: pH and GSH/GSSG govern disulfide isomerization at the C-terminus

Refolding of cobrotoxin was assessed by the exposure degree of its single Trp determined by an acrylamide quenching study. The change in the accessibility of Trp for acrylamide quantitatively reflected the formation of folded cobrotoxin, and the data were confirmed by HPLC and gel electrophoresis analyses. However, the site-specific information provided by quenching Trp fluorescence revealed that the ordered structure in the neighborhood of Trp was attained prior to the complete formation of the tertiary structure of cobrotoxin. HPLC analyses showed that, in addition to refolded cobrotoxin, two novel species (cobrotoxin II and cobrotoxin III) with isomerization of disulfide bonds at the C-terminus of the toxin molecule were produced along the folding reaction. The disulfide pairings in cobrotoxin II and cobrotoxin III were Cys43-Cys55 and Cys54-Cys60 and Cys43-Cys60 and Cys54-Cys55, respectively. Among the three possible two-disulfide species at the C-terminus, the disulfide linkages Cys43-Cys60 and Cys54-Cys55 of cobrotoxin III caused a marked decrease in lethality and resulted in a conformation which was notably different from that observed with the native toxin molecule as evidenced by CD spectra. The refolding reaction was accelerated by the addition of GSH/GSSG, and the resulting products were mostly folded cobrotoxin. However, if GSH/GSSG was not added into the initial folding materials, the yields of cobrotoxin II and cobrotoxin III greatly increased. The conversion of cobrotoxin to its isomers was to be irreversible and pH-dependent: the higher the pH, the faster the rate of conversion. However, this conversion could be partly inhibited by GSH/GSSG. Cobrotoxin II and cobrotoxin III were purified from Taiwan cobra venom as well, and their yields in comparison to that of cobrotoxin in venom were similar to that noted with the folded products in the presence of GSH/GSSG. Moreover, the rate of disulfide isomerization was expected to be slow in venom fluid in which the pH was approximately pH 6.2. Thus, the finding that cobrotoxin represents the predominant neurotoxin species in Taiwan cobra venom is probably associated with the synergistic effects of GSH/GSSG and pH.