Protein Arginine Methyltransferase 5 Contributes to Paclitaxel-Induced Neuropathic Pain by Activating Transient Receptor Potential Vanilloid 1 Epigenetic Modification in Dorsal Root Ganglion

BACKGROUND

Paclitaxel (PTX), which is a first-line chemotherapy drug used to treat various types of cancers, exhibits peripheral neuropathy as a common side effect that is difficult to treat. Protein arginine methyltransferase 5 (PRMT 5) is a key regulator of the chemotherapy response, as chemotherapy drugs induce PRMT5 expression. However, little is known about the PRMT5-mediated epigenetic mechanisms involved in PTX-induced neuropathic allodynia.

METHODS

Sprague-Dawley rats were intraperitoneally given PTX to induce neuropathic pain. Biochemical analyses were conducted to measure the protein expression levels in the dorsal root ganglion (DRG) of the animals. The von Frey test and hot plate test were used to evaluate nociceptive behaviors.

RESULTS

PTX increased the PRMT5 (mean difference [MD]: 0.68, 95% confidence interval [CI], 0.88-0.48; P < .001 for vehicle)-mediated deposition of histone H3R2 dimethyl symmetric (H3R2me2s) at the transient receptor potential vanilloid 1 ( Trpv1 ) promoter in the DRG. PRMT5-induced H3R2me2s recruited WD repeat domain 5 (WDR5) to increase trimethylation of lysine 4 on histone H3 (H3K4me3) at Trpv1 promoters, thus resulting in TRPV1 transcriptional activation (MD: 0.65, 95% CI, 0.82-0.49; P < .001 for vehicle) in DRG in PTX-induced neuropathic pain. Moreover, PTX increased the activity of NADPH oxidase 4 (NOX4) (MD: 0.66, 95% CI, 0.81-0.51; P < .001 for vehicle), PRMT5-induced H3R2me2s, and WDR5-mediated H3K4me3 in the DRG in PTX-induced neuropathic pain. Pharmacological antagonism and the selective knockdown of PRMT5 in DRG neurons completely blocked PRMT5-mediated H3R2me2s, WDR5-mediated H3K4me3, or TRPV1 expression and neuropathic pain development after PTX injection. Remarkably, NOX4 inhibition not only attenuated allodynia behavior and reversed the above-mentioned signaling but also reversed NOX4 upregulation via PTX.

CONCLUSIONS

Thus, the NOX4/PRMT5-associated epigenetic mechanism in DRG has a dominant function in the transcriptional activation of TRPV1 in PTX-induced neuropathic pain.

Melatonin Relieves Paclitaxel-Induced Neuropathic Pain by Regulating pNEK2-Dependent Epigenetic Pathways in DRG Neurons

The neurohormone melatonin (MLT) demonstrates promising potential in ameliorating neuropathic pain induced by paclitaxel (PTX) chemotherapy. However, little is known about its protective effect on dorsal root ganglion (DRG) neurons in neuropathic pain resulting from the chemotherapeutic drug PTX. Here, PTX-treated rats revealed that intrathecal administration of MLT dose-dependently elevated hind paw withdrawal thresholds and latency, indicating that MLT significantly reversed PTX-induced neuropathic pain. Mechanistically, the analgesic effects of MLT were found to be mediated via melatonin receptor 2 (MT2), as pretreatment with an MT2 receptor antagonist inhibited these effects. Moreover, intrathecal MLT injection reversed the pNEK2-dependent epigenetic program induced by PTX. All of the effects caused by MLT were blocked by pretreatment with an MT2 receptor-selective antagonist, 4P-PDOT. Remarkably, multiple MLT administered during PTX treatment (PTX+MLTs) exhibited not only rapid but also lasting reversal of allodynia/hyperalgesia compared to single-bolus MLT administered after PTX treatment (PTX+MLT). In addition, PTX+MLTs exhibited greater efficacy in reversing PTX-induced alterations in pRSK2, pNEK2, JMJD3, H3K27me3, and TRPV1 expression and interaction in DRG neurons than PTX+MLT. These results indicated that MLT administered during PTX treatment reduced the incidence and/or severity of neuropathy and had a better inhibitory effect on the pNEK2-dependent epigenetic program compared to MLT administered after PTX treatment. In conclusion, MLT/MT2 is a promising therapy for the treatment of pNEK2-dependent painful neuropathy resulting from PTX treatment. MLT administered during PTX chemotherapy may be more effective in the prevention or reduction of PTX-induced neuropathy and maintaining quality.

Phosphate NIMA-Related Kinase 2-Dependent Epigenetic Pathways in Dorsal Root Ganglion Neurons Mediates Paclitaxel-Induced Neuropathic Pain

BACKGROUND

The microtubule-stabilizing drug paclitaxel (PTX) is an important chemotherapeutic agent for cancer treatment and causes peripheral neuropathy as a common side effect that substantially impacts the functional status and quality of life of patients. The mechanistic role for NIMA-related kinase 2 (NEK2) in the progression of PTX-induced neuropathic pain has not been established.

METHODS

Adult male Sprague-Dawley rats intraperitoneally received PTX to induce neuropathic pain. The protein expression levels in the dorsal root ganglion (DRG) of animals were measured by biochemical analyses. Nociceptive behaviors were evaluated by von Frey tests and hot plate tests.

RESULTS

PTX increased phosphorylation of the important microtubule dynamics regulator NEK2 in DRG neurons and induced profound neuropathic allodynia. PTX-activated phosphorylated NEK2 (pNEK2) increased jumonji domain-containing 3 (JMJD3) protein, a histone demethylase protein, to specifically catalyze the demethylation of the repressive histone mark H3 lysine 27 trimethylation (H3K27me3) at the Trpv1 gene, thereby enhancing transient receptor potential vanilloid subtype-1 (TRPV1) expression in DRG neurons. Moreover, the pNEK2-dependent PTX response program is regulated by enhancing p90 ribosomal S6 kinase 2 (RSK2) phosphorylation. Conversely, intrathecal injections of kaempferol (a selective RSK2 activation antagonist), NCL 00017509 (a selective NEK2 inhibitor), NEK2-targeted siRNA, GSK-J4 (a selective JMJD3 inhibitor), or capsazepine (an antagonist of TRPV1 receptor) into PTX-treated rats reversed neuropathic allodynia and restored silencing of the Trpv1 gene, suggesting the hierarchy and interaction among phosphorylated RSK2 (pRSK2), pNEK2, JMJD3, H3K27me3, and TRPV1 in the DRG neurons in PTX-induced neuropathic pain.

CONCLUSIONS

pRSK2/JMJD3/H3K27me3/TRPV1 signaling in the DRG neurons plays as a key regulator for PTX therapeutic approaches.

Phosphorylated Upstream Frameshift 1-dependent Nonsense-mediated μ-Opioid Receptor mRNA Decay in the Spinal Cord Contributes to the Development of Neuropathic Allodynia-like Behavior in Rats

BACKGROUND

Nonsense-mediated messenger RNA (mRNA) decay increases targeted mRNA degradation and has been implicated in the regulation of gene expression in neurons. The authors hypothesized that nonsense-mediated μ-opioid receptor mRNA decay in the spinal cord is involved in the development of neuropathic allodynia-like behavior in rats.

METHODS

Adult Sprague-Dawley rats of both sexes received spinal nerve ligation to induce neuropathic allodynia-like behavior. The mRNA and protein expression contents in the dorsal horn of animals were measured by biochemical analyses. Nociceptive behaviors were evaluated by the von Frey test and the burrow test.

RESULTS

On Day 7, spinal nerve ligation significantly increased phosphorylated upstream frameshift 1 (UPF1) expression in the dorsal horn (mean ± SD; 0.34 ± 0.19 in the sham ipsilateral group vs. 0.88 ± 0.15 in the nerve ligation ipsilateral group; P < 0.001; data in arbitrary units) and drove allodynia-like behaviors in rats (10.58 ± 1.72 g in the sham ipsilateral group vs. 1.19 ± 0.31 g in the nerve ligation ipsilateral group, P < 0.001). No sex-based differences were found in either Western blotting or behavior tests in rats. Eukaryotic translation initiation factor 4A3 (eIF4A3) triggered SMG1 kinase (0.06 ± 0.02 in the sham group vs. 0.20 ± 0.08 in the nerve ligation group, P = 0.005, data in arbitrary units)-mediated UPF1 phosphorylation, leading to increased nonsense-mediated mRNA decay factor SMG7 binding and µ-opioid receptor mRNA degradation (0.87 ± 0.11-fold in the sham group vs. 0.50 ± 0.11-fold in the nerve ligation group, P = 0.002) in the dorsal horn of the spinal cord after spinal nerve ligation. Pharmacologic or genetic inhibition of this signaling pathway in vivo ameliorated allodynia-like behaviors after spinal nerve ligation.

CONCLUSIONS

This study suggests that phosphorylated UPF1-dependent nonsense-mediated μ-opioid receptor mRNA decay is involved in the pathogenesis of neuropathic pain.

EDITOR’S PERSPECTIVE

Video-assisted Rigid Endoscopic Laser Ablation for Endobronchial Mucoepidermoid Carcinoma in Pediatrics Without Pulmonary Resections

INTRODUCTION

Mucoepidermoid carcinoma (MEC) is a rare malignancy of primary endobronchial lesions in children. Early diagnosis is crucial for the disease, but it is often misdiagnosed as asthma or lung infection. Chest computed tomography and bronchoscopy are the most important diagnostic tools. Surgical resection is the current treatment of choice for low-grade MEC. In the past, lobectomy, sleeve lobectomy, or segmental resections were the most standard surgeries. Endoscopic treatment was used for lung preservation and effectual removal of the lesions.

METHODS

A retrospective study of pediatric patients with primary endobronchial lesions who underwent rigid bronchoscopic laser ablation since 2010 was conducted. Pre-operative images, endoscopic pictures, post-operative images, histological analyses, and patients' clinical conditions were recorded and illustrated.

RESULTS

Four patients were enrolled. Three patients presented initially with cough or hemoptysis. The lesion sites were the bronchus of the left upper lobe, left lower lobe, left main bronchus, and trachea. All patients underwent bronchoscopic laser ablation for tumor excision without anatomical resection. No major surgical complications were encountered. All patients survived without recurrence after a mean postoperative follow-up of 4.5 years (3-6 years).

CONCLUSION

Video-assisted rigid endoscopic laser ablation for pediatric low-grade endobronchial MEC is a feasible, effective, and safe method. Close follow-up is essential for lung preservation management.

EVIDENCE LEVEL

Level IV.

TYPE OF STUDY

Case series with no comparison group.

MicroRNA-489-3p attenuates neuropathic allodynia by regulating oncoprotein DEK/TET1-dependent epigenetic modification in the dorsal horn

Originally characterized as an oncoprotein overexpressed in many forms of cancer that participates in numerous cellular pathways, DEK has since been well described regarding the regulation of epigenetic markers and transcription factors in neurons. However, its role in neuropathic allodynia processes remain elusive and intriguingly complex. Here, we show that DEK, which is induced in spinal dorsal horn neurons after spinal nerve ligation (SNL), is regulated by miR-489-3p. Moreover, SNL-induced decrease in miR-489-3p expression increased the expression of DEK, which recruited TET1 to the promoter fragments of the Bdnf, Grm5, and Stat3 genes, thereby enhancing their transcription in the dorsal horn. Remarkably, these effects were also induced by intrathecally administering naïve animals with miR-489-3p inhibitor, which could be inhibited by knockdown of TET1 siRNA or DEK siRNA. Conversely, delivery of intrathecal miR-489-3p-mimic into SNL rats attenuated allodynia behavior and reversed protein expression coupled to the promoter segments in the dorsal horn. Thus, a spinal miR-489-3p/DEK/TET1 transcriptional axis may contribute to neuropathic allodynia. These results may provide a new target for treating neuropathic allodynia.

Hybrid Retroperitoneoscopic Pyeloplasty for Congenital Ureteropelvic Junction Obstruction in Infants Weighing Less than 10 kg

Introduction: Success rate of laparoscopic pyeloplasty for ureteropelvic junction obstruction (UPJO) in children is comparable with open pyeloplasty. Prolonged ileus and injury to adjacent viscera more often occurred in transperitoneal approach; however, longer operation time is noted in retroperitoneal approach. Purpose: This study presented a hybrid retroperitoneoscopic pyeloplasty (HRP), for congenital UPJO in infants weighing <10 kg. Materials and Methods: From February 2017 to June 2020, 10 HRP procedures were performed in 9 patients by 1 surgeon. Retroperitoneal dissection of the renal pelvis and the upper third ureter was first performed, followed by extracorporeal suturing for pyeloureterostomy. Results: Mean operative age and body weight were 4.23 ± 3.69 months and 6.18 ± 1.57 kg. Operative, CO₂ inflation, and extracorporeal suture time were 147.9 ± 39.5, 40.6 ± 11.2, and 62.9 ± 26.1 minutes, respectively. Surgical outcome was confirmed by renal ultrasound and diuretic renogram. Postoperative follow-up duration was 15.2 ± 7.7 months. Three patients had postoperative febrile urinary tract infection and recovered after antibiotic treatment. Conclusion: In infants or smaller children with UPJO, the HRP procedure may be considered as an effective and minimally invasive alternative with shorter learning curve for inexperienced surgeons.

Genistein Suppressing the ROS-Induced Hypersensitivity of Rat Vagal Lung C-Fiber Afferents through an ERα-Mediated Mechanism

Reactive oxygen species (ROS) may induce hypersensitivity of vagal lung C-fibers (VLCFs) through the interaction of transient receptor potential ankyirn 1 (TRPA1) and P2X receptors. Genistein is a soy-derived isoflavone that exerts antioxidant effects by binding to estrogen receptors (ERs), ERα and ERβ. We investigated whether ER activation by genistein can suppress H₂O₂-mediated VLCF hypersensitivity and identified the types of ERs involved. Results revealed that subcutaneous injection of genistein or 4,4',4"-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT, a selective ERα agonist) can attenuate H₂O₂-induced VLCF hypersensitivity. The suppressive effects of genistein and PPT were inhibited by an additional treatment with ICI182780 (a nonselective ER antagonist) or 1,3-bis(4- hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP, a selective ERα antagonist). Treatment with a combination of PPT, HC030031 (a TRPA1 receptor antagonist), and iso-pyridoxalphosphate-6-azophenyl-2',5'-disulphonate (iso-PPADS, a P2X receptor antagonist) did not further inhibit H₂O₂-induced VLCF hypersensitivity as compared with combined HC030031 and iso-PPADS treatment. In conclusion, ERα activation by genistein can suppress H₂O₂- induced VLCF hypersensitivity through its functional interaction with TRPA1 and P2X receptors.

Perioperative parameter analysis of neonates and infants receiving laparoscopic surgery

BACKGROUND

The field of laparoscopic surgery in neonates or younger infants has benefitted from recent progress. This study aimed to determine the correlation between patient characteristics and perioperative parameters, and to explore the feasibility of laparoscopic surgery in neonates and infants.

METHODS

We retrospectively collected and analyzed data on neonates and infants who received laparoscopic surgery at our institute between January 2007 and August 2015. Perioperative data, surgical outcomes, and related complications were analyzed using Spearman rank correlation coefficient.

RESULTS

A total of 82 patients (42 male and 40 female) were included in this study. The median operative age and the median operative body weight were 2.2 months and 4.2 kg, respectively. The median operative time was 3.5 hours, and the median insufflation time was 2.0 hours. The mean intraoperative end-tidal carbon dioxide (EtCO2) level was 37.6 mmHg, the median body temperature (BT) was 35.8°C, and the mean peak inspiratory pressure was 23.3 cmH2O. The median follow-up duration was 23.4 months. The intraoperative BT was significantly influenced by the operative age (p < 0.001, rs = 0.52) and body weight (p < 0.001, rs = 0.59). The intraoperative EtCO2 level was higher for longer operative time (p = 0.01, rs = 0.28) and insufflation time (p < 0.001, rs = 0.39); however, all values returned to normal when the CO2 insufflation was stopped.

CONCLUSION

Laparoscopic surgery for neonates and infants can be safely performed by experienced surgeons. However, transient hypercarbia may rapidly ameliorate after CO2 insufflation is stopped.

Chylothorax after left side pneumothorax surgery managed by OK-432 pleurodesis: an effective alternative

Chylothorax, a relatively rare complication of thoracic surgery, mostly occurs on the right side. We present a 16-year-old male who received thoracoscopic surgery for left spontaneous pneumothorax. Chylothorax developed on the postoperative 2(nd) day and resolved after diet control on the 4(th) day. Unfortunately, chylothorax recurred 2 weeks later. Chest drainage and nil per os with total parental nutrition were given but in vain. Thereafter, chemical pleurodesis with OK-432 was performed. Chylothorax resolved on the next day. The relevant literature is reviewed and possible pathogenesis clarified.

Detection of human JCPyV and BKPyV in diffuse large B-cell lymphoma of the GI tract

Previous studies have demonstrated that infection with human polyomavirus, such as JCPyV and BKPyV, might be associated with various human tumors. However, an association between human JCPyV and BKPyV infection and diffuse large B-cell lymphoma (DLBCL) has not been reported. The purpose of this study was to examine DLBCLs of the gastrointestinal tract for evidence of human polyomavirus infection. Nested PCR and DNA sequencing were employed for viral DNA detection and viral genotype identification. In addition, two viral proteins, the large tumor antigen (LT) and the major structural protein (VP1), were detected by immunohistochemistry (IHC). Human JCPyV and BKPyV DNA was detected in 14 out of 16 tissue samples (87.5%), whereby nine cases were infected with JCPyV and five cases were infected with BKPyV. Both archetypal and rearranged genotypes of JCPyV and BKPyV were detected in the tissues. LT was detected in 11 tissue samples (68.75%). However, VP1 was not detected in any of the tissue samples. The presence of human JCPyV and BKPyV DNA and protein in DLBCL tissues of gastrointestinal tract were first reported in this study. The current results provide evidence of a possible association between human JCPyV and BKPyV infection and DLBCL.

Detection of human JCPyV and BKPyV in diffuse large B-cell lymphoma of the GI tract

Previous studies have demonstrated that infection with human polyomavirus, such as JCPyV and BKPyV, might be associated with various human tumors. However, an association between human JCPyV and BKPyV infection and diffuse large B-cell lymphoma (DLBCL) has not been reported. The purpose of this study was to examine DLBCLs of the gastrointestinal tract for evidence of human polyomavirus infection. Nested PCR and DNA sequencing were employed for viral DNA detection and viral genotype identification. In addition, two viral proteins, the large tumor antigen (LT) and the major structural protein (VP1), were detected by immunohistochemistry (IHC). Human JCPyV and BKPyV DNA was detected in 14 out of 16 tissue samples (87.5%), whereby nine cases were infected with JCPyV and five cases were infected with BKPyV. Both archetypal and rearranged genotypes of JCPyV and BKPyV were detected in the tissues. LT was detected in 11 tissue samples (68.75%). However, VP1 was not detected in any of the tissue samples. The presence of human JCPyV and BKPyV DNA and protein in DLBCL tissues of gastrointestinal tract were first reported in this study. The current results provide evidence of a possible association between human JCPyV and BKPyV infection and DLBCL.

Hybrid combination of small subxiphoid incision and thoracoscopic thymectomy for juvenile myasthenia gravis

BACKGROUND/PURPOSE

Myasthenia gravis is an autoimmune disease that usually responds positively to treatment with thymectomy. Various approaches via video-assisted thoracic thymectomy as a substitute for conventional sternotomy have been reported. We reported a less invasive technique for thymectomy in pediatric groups.

METHODS

Four adolescents with juvenile myasthenia gravis all underwent hybrid combination of small subxiphoid incision and thoracoscopic thymectomy at our institute. Clinical characteristics and surgical outcome were consecutively collected.

RESULTS

In these 4 patients, 2 presented with Osserman class III and 2 with class IIb. The mean operative time was 180 minutes. There was no conversion to sternotomy, and there was only minimal blood loss. Follow-up duration was 3 to 64 months. Postoperatively, 1 patient had complete remission and 3 patients had improvement in clinical symptoms.

CONCLUSION

Hybrid combination of small subxiphoid incision and thoracoscopic thymectomy may be an effective alternative with low surgical invasiveness for treating juvenile myasthenia gravis.

Early repair of acquired tracheoesophageal fistula

We report early direct repair of a cuff-related tracheoesophageal fistula in a 30-year-old alcoholic man with diabetic ketoacidosis who fell unconscious and was ventilated via an endotracheal tube. He was successfully weaned from the ventilator 1 week after the operation.

Absorption characteristics of EC-MPS – an enteric-coated formulation of mycophenolic sodium

Enteric-coated mycophenolate sodium is an advanced formulation delivering mycophenolic acid (MPA), designed to improve MPA-related upper gastrointestinal adverse events by delaying MPA release until the small intestine.

OBJECTIVE

Two studies were undertaken to identify the absolute bioavailability and dose-proportionality of enteric-coated mycophenolate sodium in stable renal transplant patients receiving cyclosporine.

METHODS

Study 1: The mean MPA AUC(0-t) was shown to be greater after MPA infusion than after oral enteric-coated mycophenolate sodium (42.1 vs. 28.9 microg x h/ml). Mean absolute bioavailability was 0.71 +/- 0.21 (SD). Study 2: The AUC(0-t) and C(max) for MPA were proportional to the dose of enteric-coated mycophenolate sodium, similarly mean AUC(0-infinity) and C(max) for MPA glucuronide were proportional to dose administered.

RESULTS AND CONCLUSIONS

In patients receiving cyclosporine the absolute bioavailability of MPA provided by enteric-coated mycophenolate sodium is equivalent to that provided by mycophenolate mofetil when administered in combination with cyclosporine, and exhibits dose-proportionality. Enteric-coated mycophenolate sodium was well tolerated from 180 - 2,160 mg with no serious adverse events reported.

Evaluation of the pharmacokinetic interaction between fluvastatin XL and cyclosporine in renal transplant recipients

OBJECTIVE

To assess the pharmacokinetic interaction between cyclosporine and extended-release fluvastatin (fluvastatin XL), 80 mg for 7 days, in stable renal transplant recipients.

METHODS

This was a single-center, open-label study. 17 renal transplant recipients received their standard cyclosporine therapy (Days 1 - 9) plus a once-daily single oral dose of fluvastatin XL, 80 mg (Days 2 - 8). Blood samples were collected and cyclosporine (whole blood) and fluvastatin (plasma) concentrations determined by radioimmunoassay and HPLC fluorescence detection, respectively. Pharmacokinetic parameters were calculated using non-compartment analysis and fluvastatin results were compared with historical controls.

RESULTS

Treatment with fluvastatin XL, 80 mg for 7 days, had no significant effect on either the AUC0-12 (3,644 ng x h/ml in the absence of fluvastatin vs. 3,534 ng x h/ml in the presence of fluvastatin) or the Cmax of cyclosporine (983 ng/ml in the absence of fluvastatin vs. 945 ng/ml in the presence of fluvastatin). Co-administration of fluvastatin XL also had no effect on the tmax, t1/2 or apparent clearance (CL/F) of cyclosporine in renal transplant patients. The AUC and Cmax for fluvastatin XL in the presence of cyclosporine (AUC0-24 1,192 ng. x h/ml, Cmax 271 ng/ml) were approximately 2-fold higher compared with historical data for fluvastatin XL alone in healthy volunteers (AUC0-24 630 ng x h/ml, Cmax 102 ng/ml) but lower than the historical data for fluvastatin IR, 40 mg b.i.d. alone in healthy volunteers (AUC0-24 1,340 ng x h/ml, Cmax 443 ng/ml). Tmax, t1/2 and trough levels of fluvastatin in the presence of cyclosporine were also similar to the historical controls. Concomitant administration of cyclosporine and fluvastatin XL was well tolerated by renal transplant recipients.

CONCLUSIONS

Fluvastatin XL, 80 mg, and cyclosporine do not show clinically relevant pharmacokinetic interactions.

OctreoTher: ongoing early clinical development of a somatostatin-receptor-targeted radionuclide antineoplastic therapy

OctreoTher ((90)Y-DOTA-D-Phe(1)-Tyr(3)-octreotide, a.k.a. (90)Y-SMT 487) consists of a somatostatin peptide analogue (Tyr(3)-octreotide), coupled with a complexing moiety (DOTA), and labeled with a tightly bound beta-emitter (yttrium-90). By targeting somatostatin receptor-positive tumors (as imaged by OctreaScan it may deliver a tumoricidal dose of radiation. Phase I clinical trials, conducted in patients with neuroendocrine tumors, established the safety and tolerability of the dose selected for further study and demonstrated the capacity of OctreoTher to deliver radiation doses to tumors that resulted in significant neuroendocrine tumor shrinkage. Novartis-sponsored phase II studies will soon begin to test the efficacy of OctreoTher in breast and small cell lung cancer. A fixed-dose regimen of 120 mCi/cycle x 3 cycles administered with concomitant amino acid infusion has been chosen for the study. Phase I data and published literature support that this fixed dose regimen will be safely tolerated.

Combinatorial liquid-phase synthesis of structurally diverse benzimidazole libraries

An expedient liquid-phase synthesis for construction of the diverse benzimidazole libraries is described. Nucleophilic aryl substitution of poly(ethylene glycol)-supported 4-fluoro-3-nitrobenzoic acid 3 with several primary amines under basic conditions, followed by Zn/NH(4)Cl mediated nitro group reduction, gave the PEG bound diamines 5. Subsequent cyclization of immobilized o-phenylenediamine 5 using thiocarbonyldiimidazole (TCD) or thiophosgene in dichloromethane furnished benzimidazole-2-thiones 6. Treatment of 6 with alkyl halides and benzylic halides in the presence of triethylamine provided 1-substituted-2-alkylthio-5-carbamoylbenzimidazoles on the support. The desired products 8 were severed from the PEG under mild conditions in high yield and high purity.

Improved translational efficiency of subtilisin YaB gene with different initiation codons in Bacillus subtilis and alkalophilic Bacillus YaB

The ale gene specifying the subtilisin YaB produced by alkalophilic Bacillus YaB, has an unusual start codon UUG. Changing this codon to AUG and GUG increased expression of the ale gene in B. subtilis DB104 and in an ale deficient mutant strain YaB-DEC4. The relative translational efficiency order of the three initiation codons is AUG > GUG > UUG in B. subtilis DB104 and in YaB-DEC4. These data suggest that the preferred initiation codon is AUG for ale gene expression in Bacillus.

Purification and partial characterization of an alkaline lipase from Pseudomonas pseudoalcaligenes F-111

An extracellular alkaline lipase of alkalophilic Pseudomonas pseudoalcaligenes F-111 was purified to homogeneity. The apparent molecular weight determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 32,000, and the isoelectric point was 7.3. With p-nitrophenyl esters as its substrates, the enzyme shows preference for C12 acyl and C14 acyl groups. It was stable in the pH range of 6 to 10, which coincides with the optimum pH range.

Liver function, plasma dexamethasone, and DST results in detoxified alcoholics

Alcohol abuse, alcohol withdrawal, and deterioration of hepatic function have been associated with abnormal dexamethasone suppression test (DST) results. Chronic alcohol abuse may also directly alter the pharmacokinetic disposition of dexamethasone. Plasma dexamethasone concentrations following a DST were determined in 53 detoxified alcoholics. Those with abnormal liver function had higher 4 p.m. plasma dexamethasone concentrations and lower DST cortisol concentrations. Those with normal liver function had lower plasma dexamethasone and higher DST cortisol concentrations consistent with induction of hepatic metabolic enzymes from chronic use of alcohol. The data indicate that liver function is one of the variables influencing dexamethasone disposition and DST cortisol suppression.

Hypothalamo-pituitary-adrenal activity in endogenously depressed post-traumatic stress disorder patients

We studied the hypothalamo-pituitary-adrenal (HPA) system in Vietnam veterans with post-traumatic stress disorder (PTSD) who also met Research Diagnostic Criteria for endogenous depression (MDD-ED). Over half also abused alcohol, and many complained of pain-confounding factors usually associated with increased HPA activity. Nonetheless, not even one patient had elevated basal plasma cortisol concentrations or an abnormal dexamethasone suppression test (DST); the subjects' post-dexamethasone cortisol values and plasma cortisol per ng plasma dexamethasone were in the low-normal range. These results highlight the biological heterogeneity of endogenous depression and its possible influence by past psychological trauma, and they raise questions about the use of current typological criteria for research purposes.

Cortisol suppression per nanogram per milliliter of plasma dexamethasone in depressive and normal subjects

It has been suggested that dexamethasone pharmacokinetics may affect cortisol suppression during the Dexamethasone Suppression Test (DST). In depressed patients the cortisol response has been shown to negatively correlate with dexamethasone plasma concentrations, which also influence the sensitivity and specificity of the DST. These findings have been interpreted as weakening the utility of the DST. However, the analysis of pre- and post-1 mg DST cortisol concentrations corrected for plasma dexamethasone concentrations suggest that compared with normals (n = 52), patients with major depressive disorder (MDD) as a group (n = 71) had less suppressibility of cortisol to the same plasma dexamethasone concentrations. Moreover, when the MDD patients were evaluated based on DST status, the suppressors had cortisol/dexamethasone ratios (micrograms/dl of cortisol per ng/ml of plasma dexamethasone) similar to the normal controls, whereas the nonsuppressors had ratios that were significantly higher. These data suggest that DST non-suppression, as well as sensitivity and specificity of the DST in depression, is not only attributable to altered dexamethasone disposition, but indeed, there is a genuine reduced sensitivity of cortisol to dexamethasone that still points to an abnormality of the delayed feedback mechanism of the hypothalamic-pituitary-adrenal system in some depressed patients.

Altered plasma dexamethasone and cortisol suppressibility in patients with panic disorders

Some abnormalities in the hypothalamic-pituitary-adrenal (HPA) axis in patients with panic disorders were recently reported. The possibility that the disposition of dexamethasone, which has been reported to influence the Dexamethasone Suppression Test (DST), might be altered in this subgroup of patients has not, as yet, been reported. We report that 4:00 PM dexamethasone plasma concentrations following a 1-mg oral DST were significantly (p less than 0.01) lower in 23 patients with panic disorders (0.49 +/- 0.44 ng/ml) compared to 52 normal control subjects (1.09 +/- 0.64 ng/ml). This is in addition to the significantly higher (p less than 0.05) 4:00 PM postdexamethasone cortisol values per nanogram per milliliter of dexamethasone in the panic disorder patients compared to normal controls (17.7 +/- 29.6 versus 5.0 +/- 11.2 micrograms/dl). The mean percent suppression of cortisol from baseline in panic disorder was normal despite one-half the dexamethasone concentrations in these subjects. The cortisol suppression versus dexamethasone concentration curve was also shifted lower (greater fraction of cortisol suppression) and to the left (toward lower dexamethasone concentrations). These results further suggest that the HPA system is indeed altered in panic disorders, but in a manner that is not readily apparent from the DST alone.