Effect of orchiectomy on the alpha adrenergic contractile response of dog prostate

PURPOSE

To investigate the effect of androgen deprivation on the alpha-adrenergic contractile response of the dog prostate using both in vitro and in vivo methods.

MATERIALS AND METHODS

In vitro muscle bath study: One month after surgery, responses to KCl (120 mM.) and norepinephrine (10(-8) to 10(-3)M.) of prostatic tissue strips (of the same size) from castrated (n = 6) and sham-operated (n = 6) adult mongrel dogs were determined. In vivo study: Before and 1 month after surgery, the intraprostatic urethral pressure response to intravenous norepinephrine administration of 6 castrated and 5 sham-operated adult dogs was examined.

RESULTS

(1) Before castration the serum level of testosterone was 1.24 +/- 0.2 ng./ml.; 1 month after castration, it had dropped to an undetectable level. (2) Histological examination of the prostates from castrated animals revealed profound atrophy of glandular tissue with a relatively increased stromal tissue component in each section. (3) In vitro study: The contractile responses to KCl and norepinephrine of individual prostate strips (same size) from castrated animals were significantly higher than control. However, if the response to norepinephrine was normalized to the response to KCl, there was no significant difference in response to norepinephrine between the 2 groups. In addition, the ED50 of the norepinephrine-stimulated contractile response was not changed by castration. (4) In vivo study: There was no significant change in intraprostatic urethral pressure response to intravenous norepinephrine administration after orchiectomy.

CONCLUSIONS

The results of this study show that the sensitivity of the alpha-adrenergic contractile response of the dog prostate is not affected by androgen deprivation, nor is alpha-adrenergic contractile activity of the dog prostate regulated by androgen.

The impact of pneumoperitoneum, pneumoretroperitoneum, and gasless laparoscopy on the systemic and renal hemodynamics

BACKGROUND

The use of therapeutic laparoscopy has become widespread recently. It is important to assess the effects of gaseous and gasless laparoscopy on systemic and renal hemodynamics.

STUDY DESIGN

A prospective controlled animal study was performed on 40 well-hydrated pigs. Systemic and renal hemodynamics were monitored during peritoneal insufflation, retroperitoneal insufflation, and abdominal wall lifting for a period of two hours. A laser Doppler flow meter was applied laparoscopically to measure the renal cortical tissue perfusion.

RESULTS

Peritoneal insufflation of carbon dioxide to a pressure of 15 mm Hg elicited transient elevations of the aortic pressure and carotid arterial blood flow. Unilateral pneumoretroperitoneum caused a smaller change on systemic hemodynamics. Pneumoperitoneum and pneumoretroperitoneum caused oliguria. Superficial renal cortical blood flow reduction decreased by an average of 60 percent in the compressed kidney, and blood flow returned to the pre-insufflation level after the pressure was released. A gradual decrease of tissue perfusion in the contralateral kidney and a concomitant gradual increase of the intra-abdominal pressure were observed when pneumo-retroperitoneum was maintained for two hours. No significant changes in urinary output and in systemic and renal hemodynamics were found when the abdominal wall was lifted up with a force equivalent to 15 mm Hg.

CONCLUSIONS

Significant systemic and renal hemodynamic changes were elicited in gaseous but not in gasless laparoscopy, which may explain the decreased urinary output observed during gaseous laparoscopy. Pneumoperitoneum caused greater systemic and renal hemodynamic alterations than pneumoretroperitoneum; however, the effects were transient and reversible after a period of two hours.

Femoral neuropathy after pelvic surgery

Femoral neuropathy is an uncommon complication following pelvic surgery. We report on 2 cases of femoral nerve injury after pelvic surgery: 1 patient received radical cystectomy due to invasive transitional cell carcinoma of the urinary bladder, and the other patient had a transurethral resection of the bladder and received exploration and biopsy of a tumor mass over the right sacroiliac joint area. Pathogenesis and prevention of the complication of femoral neuropathy are discussed in the following report.

Characterization of epitopes in native and unfolded cobrotoxin: evidence of an immunodominant C-terminal region related to the production of precipitating and non-precipitating antibodies against cobrotoxin

Rabbits hyperimmunized with cobrotoxin from Taiwan cobra venom produced non-precipitating as well as precipitating antibodies. Both antibody preparations exhibited higher affinity for native cobrotoxin than for reduced and S-carboxymethylated (RCM) cobrotoxin. This indicated that the epitope structures in cobrotoxin are mostly conformation-dependent. In order to identify the conformational epitopes, native cobrotoxin was hydrolyzed with acid protease A, and 12 peptides were obtained on HPLC. Three peptide fragments, AP-10, AP-11, and AP-12, showed pronounced antigenicities toward precipitating as well as non-precipitating antibodies. AP-10, AP-11, and AP-12 contained a common segment in the C-terminal region of cobrotoxin, residues 43 to 62, with intact disulfide linkages. Complete removal of the C-terminal antibodies from antisera and precipitating antibodies on a C-terminal segment-Sepharose affinity column resulted in the loss of their precipitability with cobrotoxin, whilst restoration of precipitability was observed on the addition of the C-terminal antibodies to the C-terminal antibody-depleted antisera and precipitating antibodies. Studies on the antigenic structures of RCM-cobrotoxin revealed that RCM-cobrotoxin contains an immunodominant epitope at positions 22-38. The N-terminal and C-terminal regions of RCM-cobrotoxin encompass other epitopes which exhibit low reactivities toward anti-RCM-cobrotoxin antibodies. However, no precipitated antigen-antibody complexes were observed with the mixture of anti-RCM-cobrotoxin antibodies and RCM-cobrotoxin. These results suggest that the inherently different immunogenicities with different segments might affect the precipitabilities of the resulting antibodies, and that the notable immunogenecity of the C-terminal region is related to the production of precipitating and non-precipitating antibodies against cobrotoxin.

Defective mitochondrial oxidative phosphorylation in varicocele-bearing testicles

OBJECTIVES

Our previous study revealed a decreased blood flow in varicocele-bearing testicles. For further understanding of the possible mechanism of varicocele-induced infertility, we investigated the changes in energy metabolism in varicocele-bearing testicles.

METHODS

Partial ligation of the left renal vein was performed in 40 Wistar rats to induce dilation of the internal spermatic vein, and sham operations were performed in 20 other age-matched Wistar rats serving as controls. Orchiectomy was done at 1, 2, 4, and 6 months after induction of varicocele (or sham operation) in both groups. The histologic changes in the testicles were evaluated under the light microscope. The concentration of adenine nucleotides was determined by high-performance liquid chromatography, and various enzyme activities of mitochondria were determined by a spectrophotometer.

RESULTS

Histologic studies of varicocele-bearing testicles showed a lower Johnsen score (8.5 +/- 0.7 versus 9.3 +/- 0.5) and a decreased mean testicular tubular diameter (280.0 +/- 3.2 versus 295.0 +/- 1.4 microns) compared with the testicles in the sham-operated group. The energy charge decreased from 0.71 +/- 0.04, 0.70 +/- 0.03, 0.69 +/- 0.06, and 0.64 +/- 0.03 to 0.62 +/- 0.08, 0.59 +/- 0.05, 0.58 +/- 0.05, and 0.56 +/- 0.02 at 1, 2, 4, and 6 months, respectively. The reduced nicotinamide-adenine dinucleotide-cytochrome c reductase activities were decreased from 136.6 +/- 4.9, 127.3 +/- 10.7, 121.6 +/- 7.8, and 118.9 +/- 8.5 to 96.3 +/- 13.9, 95.6 +/- 27.8, 88.3 +/- 13.8, and 80.4 +/- 8.7 nmol/min/mg of protein, respectively; the succinate-cytochrome c reductase activities were decreased from 50.4 +/- 2.7, 49.0 +/- 4.7, 49.6 +/- 7.1, and 42.6 +/- 1.6 to 40.3 +/- 7.3, 41.0 +/- 11.5, 40.2 +/- 5.7, and 32.0 +/- 1.3 nmol/min/mg of protein, respectively; and the cytochrome c oxidase activities were decreased from 361.2 +/- 23.4, 350.3 +/- 25.5, 223.5 +/- 12.9, and 194.1 +/- 18.3 to 253.7 +/- 32.9, 256.4 +/- 38.8, 178.2 +/- 15.7, and 147.1 +/- 17.2 nmol/min/mg of protein at 1, 2, 4, and 6 months, respectively.

CONCLUSIONS

We thus suggest that defective energy metabolism plays an important role in the impairment of spermatogenesis of varicocele-bearing testicles.

The subjective assessment and pressure-flow study of outcome of surgical treatment for patients with prostatism and high voiding pressure

BACKGROUND

In 1992, the International Continence Society (ICS) began to conduct an international multicenter study to correlate the symptoms and urodynamics in patients with BPH. Our institute was invited to participate this ICS-BPH study, and the preliminary (phase I) results have revealed poor correlation between preoperative symptoms and parameters of the pressure-flow study. This phase II study continued the phase I ICS-BPH study to assess the changes of subjective symptoms and objective parameters of pressure-flow study before and after TURP.

METHODS

Fifty-two patients with prostatism, aged from 56 to 80, were evaluated using the ICS-BPH questionnaire, free urine flow rate and pressure-flow study. According to the criteria of maximum urine flow rate (Qmax) 15 ml/sec and voiding intravesical pressure at Qmax (Pves at Qmax) 100 cm H2O, low flow-high pressure (LFHP) was proved in 20 patients (38%), high flow-high pressure (HFHP) in 22 (42%), low flow-low pressure (LFLP) in 3 (6%), and high flow-low pressure (HFLP) in 7 (14%). Transurethral resection of the prostate (TURP) was performed for 33 of 42 patients with high voiding pressure (LFHP and HFHP groups).

RESULTS

The weight of the TURP specimen was 28 +/- 6.3 gm. Sixteen patients repeated the questionnaire and pressure-flow study 9.0 +/- 2.1 months after surgery. Both irritative and obstructive symptom scores decreased in 15 (94%) of the 16 patients (p < 0.001). The opening intravesical pressure (openPves) and Pves at Qmax improved from 136 +/- 34 and 124 +/- 30 cm H2O preoperatively to 89 +/- 25 and 94 +/- 22 cm H2O postoperatively respectively (p < 0.004). However, UFRmax, 16.7 +/- 6.0 ml/sec preoperatively and 19.3 +/- 6.4 postoperatively, showed no statistical difference. If the HFHP and LFHP groups were compared separately, the degree of improvement in symptomatology or parameters of pressure-flow study was similar, although changes in HFHP group appeared more evident. UFRmax in LFHP group changed significantly from 11.9 +/- 2.8 preoperatively to 22.1 +/- 6.7 ml/sec postoperatively. For the patients with high flow obstruction (HFHP group), although UFRmax did not increase after TURP, the symptom score, openPves and Pves at Qmax, decreased as much as the LFHP group did.

CONCLUSIONS

Based on the analysis of the pressure flow study, TURP not only offers an advantage to the patient with classical obstruction (LFHP group), but also to patients with high flow obstruction (HFHP group). However, this does not suggest that a pressure-flow study should be performed routinely for a male with prostatism. It is advised only for patients with Qmax > 15 ml/sec but exhibiting typical symptoms.

Direct needle insufflation for pneumoretroperitoneum: anatomic confirmation and clinical experience

OBJECTIVES

The feasibility and safety of direct needle insufflation to create pneumoretroperitoneum was assessed by an imaging study and clinical experience.

METHODS

A total of 10 patients without previous retroperitoneal surgery or diseases received computed tomography scans of the retroperitoneum 2 cm above the iliac crest. Distances between quadratus lumborum and colon (Q-C distance) were measured in the supine and lateral positions. Changes of Q-C distance were calculated when the patient was changed from the supine to the lateral position. Operative charts on 38 retroperitoneoscopic procedures were collected prospectively to assess complications related to direct needle insufflation, which was performed by inserting a 14 G Veress needle blindly along the posterior axillary line 2 cm above the iliac crest.

RESULTS

Q-C distance increased from 8.7 to 27.3 mm (left side) and 4.6 to 18.1 mm (right side) when the patient was changed from the supine to the lateral position, both P values < 0.05. An average distance of 23 mm between colon and quadratus lumborum was found when patients were lying laterally. The misplacement of a Veress needle was encountered in 1 patient, in which a prefascia insufflation resulted in conversion of the endoscopic procedure. Needle puncture caused no visceral or great vessel injury.

CONCLUSIONS

Significant anterior movement of the colon was found when patients were changed from the supine to the lateral position. It provided a window for inserting the Veress needle blindly into the retroperitoneum. The high success rate (97%) and low complication rate of direct needle insufflation were found in actual clinical applications. We considered needle insufflation a safe and effective method of establishing a pneumoretroperitoneum for any retroperitoneoscopic procedure.

Does prediction of epitopes from the primary structure of a protein represent the epitope in the native structure? A study using cobrotoxin

In contrast to observations made with S. aureus V8 protease-digest hydrolysates, the antigenic structures of reduced and S-carboxymethylated (RCM)-cobrotixin were notably affected following hydrolysis of RCM-cobrotoxin with chymotrypsin. The peptide separated from the V8 protease-digest hydrolysates with a sequence at positions 22-38 of cobrotoxin exhibited a nearly equal reactivity toward the anti-RCM-cobrotoxin antibodies as RCM-cobrotoxin. Chymotryptic cleavage on this segment caused a precipitous drop in the antigenicity of RCM-cobrotoxin. Alternatively, the N-terminal and C-terminal regions of RCM-cobrotoxin encompassed other antigenic determinants which exhibited low reactivities toward anti-RCM-cobrotoxin antibodies. The epitope structures of RCM-cobrotoxin are in line with those predicted from the hydrophobicity profile of cobrotoxin, but the notably immunoreactive region in the C-terminal region of native toxin molecule (Ref. 1) cannot be predicted from analysis of its primary structure. Moreover, RCM-cobrotoxin had a superior reactivity toward anti-RCM-cobrotoxin antibodies than cobrotoxin did. These results indicate that the epitope structures in RCM-cobrotoxin and cobrotoxin are different.

Structure of the gene for the catalytic subunit of human DNA polymerase delta (POLD1)

We have isolated genomic DNA clones covering the gene for human DNA polymerase delta catalytic subunit (POLD1) and its 5' flanking sequence. This gene is divided into 27 exons and is distributed over at least 32 kb of DNA. The exons and most of the introns are relatively small. The sizes of the exons range from 55 to 201 bp. Seven introns are smaller than 100 bp. Intron 1 is the largest intron, with a size of greater than 10 kb. All of the intron-exon junctions match well with the reported consensus sequences. Multiple copies of the Alu repetitive sequence and the variable number of tandem repeats were found in several introns. Transcription of POLD1 appears to initiate at multiple sites. The major start site was 53 nucleotides upstream of the ATG start codon. The sequence of the promoter and upstream DNA is G+C rich and does not contain a TATA sequence. Several potential transcription factor-binding sites, including the AP2-, CTF-, Ets1-, GCF-, MBF-1-, NF-E1-, and Sp1-binding sites, were found in this region. A 1.8-kb pol delta promoter DNA directed the expression of a luciferase reporter gene when transfected into HeLa cells.

Purification and characterization of a novel phospholipase A2 from king cobra (Ophiophagus hannah) venom

A novel phospholipase A2, designated as Oh-DE-2, was isolated from the venom of Ophiophagus hannah (king cobra) by successive chromatography on SP-Sephadex C-25, DE-52, and Q-Sepharose columns. Oh-DE-2 with pI 5.1 showed an apparent molecular weight of 14 kD as revealed by SDS-PAGE and gel filtration. The amino acid sequence was homologous with those of PLA2S from Elapidae venoms. Oh-DE-2 was effectively inactivated by p-bromophenacyl bromide, indicating that the conserved His-48 is essential for its enzymatic activity. However, modification of the conserved Trp-19 did not cause a precipitous drop in the enzymatic activity of Oh-DE-2 as observed with PLA2S from Naja naja atra and Bungarus multicinctus venoms. A quenching study showed that the microenvironment of Trp in Oh-DE-2 was inaccessible to acrylamide, iodide, or cesium, a finding which was different from those observed with PLA2S from N. naja atra and B. multicinctus venoms. These results might suggest that, unlike other PLA2 enzymes, Trp-19 in Oh-DE-2 is not directly involved in its enzymatic mechanisms.

Laparoscopic nephrolysis for chyluria: case report of long-term success

Laparoscopic nephrolysis was performed in an 81-year-old man with recurrent chyluria. A total of five trocars were used for approaching the lymphatic ducts over the right ureter and renal hilum. The lymphatic ducts identified were easily ligated under laparoscopic magnification. The recovery of this patient was quick and uneventful. The follow-up urinalysis for chyle was negative, and his serum albumin concentration increased from 3.0 g/dL to 4.2 g/dL at 2 years postoperatively. This case report attests to the long-term efficacy of a laparoscopic approach to ligation of lymphatic fistulas for the treatment of recalcitrant chyluria.

Role of amino and carboxyl groups of cobrotoxin in the conformational stability and the interaction with acetylcholine receptor

To study the functional involvements of the common interaction of the Leu-1 alpha-amino group and Asp-58 in cobrotoxin, the lysine epsilon-amino groups of cobrotoxin were initially guanidinated with o-methylisourea. The alpha-amino group of Leu-1 was them modified with TNBS after the guanidination of cobrotoxin. Both modified derivatives displayed no significant changes in the secondary structure and antigenicity of cobrotoxin, whereas the binding affinity for nicotinic acetylcholine receptor (nAChR) was pronouncedly decreased when Leu-1 was modified. Six out of seven free carboxyl groups and the remaining buried Glu-21 carboxyl group of cobrotoxin were modified with glycine methyl ester in the absence and presence of guanidine HCl, respectively. Alternation in the beta-sheet secondary structure of cobrotoxin was observed with the carboxyl-group modified derivatives, which caused a decrease in the binding activity of the toxin molecule to the antibody and nAChR. Moreover, modification of the Glu-21 carboxyl group of cobrotoxin further reduced the nAChR binding activity, while the antigenicity remained unchange. Thus, our results conclude that the Glu-21 residue and the common interaction of the terminal Leu-1 alpha-amino group and the Asp-58 carboxyl group are related to the nAChR-binding activity of cobrotoxin, and the free carboxyl groups in cobrotoxin are conformation-essential.

Chemical modification of cationic groups of a novel alpha-neurotoxin (Oh-4) from king cobra (Ophiophagus hannah) venom

The cationic groups of arginine and lysine residues in Oh-4, a novel alpha-neurotoxin from king cobra (Ophiophagus hannah) venom were subjected to modification with p-hydroxyphenylglyoxal (HPG) and trinitrobenzene sulfonate (TNBS), respectively. Monoderivatization of Arg-35, resulted in a drastic loss in neurotoxicity to 25% of the native toxin. The activity was decreased to a greater extent with the derivative extensively modified on Arg-35, -9, and -37. The Arg-35-modified derivative retained about a half of the antigenicity of the native toxin, and extensive modification on Arg-9 and Arg-37 caused a further decrease in the antigenicity of the toxin molecule. Selective trinitrophenylation (TNP-) of Lys-51 caused losses of neurotoxicity and antigenicity by 77 and 83%, respectively. These results indicate that Arg-35 and Lys-51 in Oh-4 have important roles in the neurotoxicity. In contrast to the Arg residues at 9, 35, and 37, Lys-51 plays a more critical role in the antigenicity.

Differential roles of two tandem E2F sites in repression of the human p107 promoter by retinoblastoma and p107 proteins

Although many lines of evidence indicate that the cellular protein p107 is closely related to the retinoblastoma protein, the exact function of the p107 gene and its regulation are presently not known. To investigate the molecular mechanism controlling expression of the human p107 gene, a 5' flanking sequence of this gene was isolated and shown to promote high-level expression of a luciferase reporter gene in cycling human 293 and Saos-2 cells. Sequencing and transcription mapping analyses showed that the human p107 promoter is TATA-less and contains a tandem, direct repeat of E2F-binding sites, with the 3' copy overlapping the major transcription initiation site. Deletion analysis of the p107 promoter showed that a promoter DNA fragment containing only the two E2F sites together with the leader sequence could direct relatively efficient expression in 293 cells. Site-directed mutagenesis of these E2F sites revealed that although both sites were important for p107 promoter activity, mutation on the proximal, initiation site copy of the E2F site showed a stronger effect. The human p107 promoter could be repressed by the retinoblastoma protein and its own gene product. Interestingly, the repression was found to be mediated through the 5' copy of the E2F site. These studies demonstrate for the first time differential roles of two tandem E2F sites in promoter regulation.

Alterations in local cerebral glucose utilization in rats after chronic amphetamine administration without subsequent challenge

The 2-deoxyglucose (2-DG) method was used to study regional metabolic changes in rats following chronic d-amphetamine treatment without subsequent challenges. Four groups of rats were pretreated (intraperitoneal administration) with d-amphetamine (0, 1, 5, or 10 mg/kg) once per day for 14 days. After a 7-day abstinence period without further challenge, the 2-DG method was used to measure the rates of local cerebral glucose utilization (LCGU). Significant metabolic changes among the four groups were found in five brain regions, including the nucleus accumbens and the lateral habenular nucleus. Another four groups of rats with the same pretreatment regimens, challenged with 5 mg/kg d-amphetamine, were used for behavioral testing. The results showed intense stereotyped behaviors in the 5 mg/kg and the 10 mg/kg groups. In the steady state, however, there were no significant glucose utilization changes in the nigrostriatal system, which is thought to be related to stereotyped behaviors. During steady state, metabolic changes were found in a limited number of brain regions. No difference in LCGU was found in the sensitization-related regions. Further challenges with stimulants may be necessary to investigate the metabolic responses after sensitization.

The murine erythrocyte protein-4.2-encoding gene: similarities and differences in structure and expression from its human counterpart

We have isolated a complete cDNA encoding for the mouse erythrocyte protein 4.2 (P4.2). The entire P4.2 cDNA consists of 3465 nt with an open reading frame (ORF) of 691 amino acids. Northern blot analysis of mouse reticulocyte or spleen RNA using the P4.2 cDNA as a probe, detected a 3.5-kb message. The size of the mouse P4.2 cDNA or message that we obtained, appears to be different from those reported recently. Despite the similarity to the human P4.2 cDNAs, the mouse cDNA has a longer 3' untranslated region. A genomic clone covering the first exon and flanking sequences of the mouse P4.2 gene was isolated. Sequencing results from the first exon-intron junction region and polymerase chain reaction (PCR) experiments revealed that the mouse reticulocyte P4.2 RNA does not exhibit alternative splicing in the region identified in the human P4.2 RNA.

Determination of soluble nAChR-binding activity of alpha-neurotoxins by an innovative precipitation with DEAE-Sephacel

A simple and convenient method for determining the binding activity of alpha-neurotoxins toward soluble nicotinic acetylcholine receptor (snAChR) by precipitation with DEAE-Sephacel was established. The determination was carried out by incubation of 125I-neurotoxin with snAChR, followed by precipitation with DEAE-Sephacel. The DEAE-Sephacel particles bind negatively charged snAChR with high affinity and simultaneously precipitate the 125I-neurotoxin bound to the receptors. After centrifugation, the free 125I-neurotoxin in the supernatant was counted, and the amounts of neurotoxins bound to snAChR could be determined. Two alpha-neurotoxins, cobrotoxin and alpha-bungarotoxin, were employed to verify the feasibility of this determination. The different binding characteristics of cobrotoxin and alpha-bungarotoxin to snAChR could be distinguished. This method required only small quantities of DEAE-Sephacel (7 mg), snAChR (0.54 micrograms), and 125I-neurotoxin (90 fmol) for each reaction, and minimized the handling of isotopic materials as compared with the conventional methods. This method is reliable, reproducible, and superior to current methods for the determination of the snAChR-binding activity for alpha-neurotoxins.

Adrenal cortical carcinoma with tumor thrombus invasion of inferior vena cava

A case of adrenal cortical carcinoma with inferior vena cava (IVC) involvement is presented. Ultrasonography, computed tomography, and venacavography all presumptively showed a large mass over the upper pole of the left kidney with tumor thrombus in the IVC. However, aortography demonstrated that this mass was receiving its blood supply from the left inferior phrenic artery, aorta, and left renal artery. Radical surgery, including resection of the tumor and its adjacent organs (kidney, distal pancreas, spleen) and the tumor thrombus in the IVC, with the aid of cardiopulmonary bypass, was performed. We emphasize that adrenal cortical carcinoma can have tumor thrombi invading the IVC, and in such cases we suggest radical surgical removal of the tumor and the thrombus.

A conserved region in the amino terminus of DNA polymerase delta is involved in proliferating cell nuclear antigen binding

Synthetic peptides to selected sequences in human DNA polymerase delta (pol delta) were used to identify the region involved in the interaction of pol delta to proliferating cell nuclear antigen. Peptides corresponding to sequences in five regions in the amino terminus of human pol delta and three in the carboxyl terminus, which are conserved with the yeast homologs of pol delta, were tested. These studies showed that the peptide corresponding to the N2 region (residues 129-149) selectively and specifically inhibited the PCNA stimulation of pol delta. This inhibition was relieved by titration with excess PCNA. The identification of the N-2 region as being involved in PCNA binding was supported by studies that demonstrated that the N2 peptide could bind PCNA. Deletion mutants of pol delta expressed in Sf9 cells provided evidence that the binding region for PCNA was located in the first 182 residues of the amino terminus. These studies provide reasonable evidence that residues within the region 129-149 of pol delta are involved in the binding site for PCNA.

Evidence showing a different repertoire of antibodies against unfolded cobrotoxin in anticobrotoxin and anti-reduced and S-carboxymethylated cobrotoxin antisera

Antibodies which specifically reacted with reduced and S-carboxy-methylated(RCM) cobrotoxin were purified from anticobrotoxin antisera and anti-RCM-cobrotoxin antisera, respectively. Results using a competitive immunoassay revealed that the antibodies from anti-RCM-cobrotoxin antisera had a greater affinity for RCM-cobrotoxin than for cobrotoxin. Whereas the reactivity of the antibodies from the anticobrotoxin antisera toward cobrotoxin and RCM-cobrotoxin had a reversed order of binding. In contrast to observations made with S. aureus V8 protease-digest hydrolysates, the antigenic structures of RCM-cobrotoxin recognized by antibodies from anti-RCM-cobrotoxin antisera were notably affected following hydrolysis of RCM-cobrotoxin with chymotrypsin. Moreover, the chymotryptic hydrolysates showed a comparable reactivity as RCM-cobrotoxin toward the antibodies purified from anticobrotoxin antibodies, but a decrease in antigenicity with the V8 protease hydrolysates. These results reveal that the repertoire of antibodies against the unfolded cobrotoxin are not the same in anticobrotoxin and anti-RCM-cobrotoxin antisera. Moreover, it suggests that the repertoire of antibodies from the different sources against the same antigen can be differentiated by measurement of their reactivities with the proteolytic hydrolysates of the antigen.

Analysis of a conformation-independent epitope and a conformational epitope in a protein: a study on cobrotoxin from Taiwan cobra venom

The antibodies against cobrotoxin were separated into two antibody preparations by successive affinity chromatographies on reduced and S-carboxymethylated (RCM)-cobrotoxin-Sepharose, and cobrotoxin-Sepharose columns. The antibodies (abbreviated as Abcf-i) that bound with the RCM-cobrotoxin-Sepharose were verified to specifically recognize the continuous epitopes of cobrotoxin, which were insensitive to conformational changes. Whilst the antibodies (abbreviated as Abcf-d) that did not bind with the RCM-cobrotoxin-Sepharose column recognized the conformational epitopes in cobrotoxin. The two antibody preparations were employed to screen the antigenic peptides derived from the proteolytic hydrolysate of cobrotoxin and RCM-cobrotoxin. Five antigenic peptides (AP-4, AP-5, AP-10, AP-11, and AP-12) were obtained from the acid protease A-digested hydrolysate of cobrotoxin, and two antigenic peptides (V8-2 and V8-4) were found in the hydrolysate of RCM-cobrotoxin after hydrolysis with Saccharomyces aureus V8 protease. The segments at positions 1-21 and 22-38 encompassed the peptide fractions, AP-4, AP-5, V8-2, and V8-4, that reacted with Abcf-i, indicating that the two segments bore the continuous epitopes of cobrotoxin. Alternatively, AP-10, AP-11, and AP-12 reacted with both Abcf-i and Abcf-d. The structures of the three peptides had a common segment at positions 43-62, suggesting that this region comprised the conformation-independent epitopes as well as conformational epitopes in cobrotoxin. These results reflected that the conformation-independent and conformational epitopes in a protein can be separately identified.

Metabolic and behavioral response in rats treated with amphetamine chronically with and without challenge

Chronic amphetamine (AMPH) treatment may cause behavioral sensitization in animals and can be used as an animal model of psychosis. The aim of the study was to check the behavioral and metabolic response in this animal model. In rats pretreated with normal saline (NS) or AMPH, with or without AMPH challenge, the [14C]deoxyglucose method was employed to check the metabolic changes in 42 regions. Behavioral testing was performed in rats with the same treatment. The results showed that after challenge with AMPH, glucose utilization was enhanced in most of the regions investigated. However, metabolic enhancement of the AMPH-pretreated group was lower in the caudate nucleus when compared with that of the NS-pretreated group though the stereotypy rating was higher in the former. Dissociation between the metabolic enhancement and behavioral response was noted. Furthermore, more significant differences between the two pretreated conditions of glucose utilization were found with challenge than without challenge. Further evaluation using procedures which include advanced techniques can be applied in further investigation.

The structural loop II of cobrotoxin is the main binding region for nAChR and epitope in the region is conformation-dependent

Modification of positively charged residues, Lys and Arg, in cobrotoxin revealed that Lys-27, Lys-47, Arg-28, Arg-30, Arg-33, and Arg-36 of cobrotoxin were essential for the lethality and binding activity to nicotinic acetylcholine receptor (nAChR). The antigenicity of cobrotoxin was drastically diminished when Lys-47, Arg-28, Arg-30, Arg-33, and Arg-36 were modified, while that of the Lys-27-modified derivative was not significantly changed. The CD spectra of cobrotoxin displayed similar patterns after modification of Lys-27, Lys-47, and Arg-28. These findings suggest that Lys-27, Lys-47, and Arg-28 residues may be related to the direct binding to nAChR, and that there is no involvement of Lys-27 in the antigenic determinants of cobrotoxin. Extending the modification to Arg-30, Arg-33, and Arg-36 caused progressive conformational changes of cobrotoxin and resulted in decreased binding activity to antibody and nAChR. This indicates that Arg-30, Arg-33, and Arg-36 may be of structural importance for maintaining the active conformation of cobrotoxin. These results, together with the facts that Tyr-25, Tyr-35, and Trp-29 of cobrotoxin are important in nAChR binding activity, but Trp-29 and Tyr-35 residues are not essential for the antigenicity, suggest that the structural loop II of cobrotoxin is the main binding region for nAChR and the epitope in that region is conformation-dependent.

Chemical modification of tryptophan residues in alpha-neurotoxins from Ophiophagus hannah (king cobra) venom

Two alpha-neurotoxins, Oh-4 and Oh-7, from the king cobra (Ophiophagus hannah) venom were subjected to Trp modification with 2-nitrophenylsulfenyl chloride (NPS-Cl). One major NPS derivative was isolated from the modified mixtures of Oh-4 and two from Oh-7 by HPLC. Amino acid analysis and sequence determination revealed that Trp-27 in Oh-4, and Trp-30 and Trp-26 and 30 in the two Oh-7 derivatives, were modified, respectively. Sulfenylation of Trp-27 in Oh-4 caused about 70% drop in lethal toxicity and nicotinic acetylcholine receptor-binding activity. Modification of Trp-30 in Oh-7 resulted in the decrease of lethal toxicity by 36% and binding activity by 61%. The activities were further lost when the conserved Trp-26 in Oh-7 was modified. Sulfenylation of the Trp residues did not significantly affect the secondary structure of the toxins as revealed by the CD spectra. These results indicate that the Trp residues in these two long alpha-neurotoxins may be involved in the receptor binding.