Implementation of the CYP Index for the Design of Selective Tryptophan-2,3-dioxygenase Inhibitors

A class of imidazoisoindole (III) heme-binding indoleamine-2,3-dioxygenase (IDO1) inhibitors were optimized via structure-based drug design into a series of tryptophan-2,3-dioxygenase (TDO)-selective inhibitors. Kynurenine pathway modulation was demonstrated in vivo, which enabled evaluation of TDO as a potential cancer immunotherapy target. As means of mitigating the risk of drug-drug interactions arising from cytochrome P450 inhibition, a novel property-based drug design parameter, herein referred to as the CYP Index, was implemented for the design of inhibitors with appreciable selectivity for TDO over CYP3A4. We anticipate the CYP Index will be a valuable design parameter for optimizing CYP inhibition of any small molecule inhibitor containing a Lewis basic motif capable of binding heme.

Aminoisoxazoles as Potent Inhibitors of Tryptophan 2,3-Dioxygenase 2 (TDO2)

Tryptophan 2,3-dioxygenase 2 (TDO2) catalyzes the conversion of tryptophan to the immunosuppressive metabolite kynurenine. TDO2 overexpression has been observed in a number of cancers; therefore, TDO inhibition may be a useful therapeutic intervention for cancers. We identified an aminoisoxazole series as potent TDO2 inhibitors from a high-throughput screen (HTS). An extensive medicinal chemistry effort revealed that both the amino group and the isoxazole moiety are important for TDO2 inhibitory activity. Computational modeling yielded a binding hypothesis and provided insight into the observed structure-activity relationships. The optimized compound 21 is a potent TDO2 inhibitor with modest selectivity over indolamine 2,3-dioxygenase 1 (IDO1) and with improved human whole blood stability.

GluN2A-Selective Pyridopyrimidinone Series of NMDAR Positive Allosteric Modulators with an Improved in Vivo Profile

The N-methyl-d-aspartate receptor (NMDAR) is an ionotropic glutamate receptor, gated by the endogenous coagonists glutamate and glycine, permeable to Ca²⁺ and Na⁺. NMDAR dysfunction is associated with numerous neurological and psychiatric disorders, including schizophrenia, depression, and Alzheimer's disease. Recently, we have disclosed GNE-0723 (1), a GluN2A subunit-selective and brain-penetrant positive allosteric modulator (PAM) of NMDARs. This work highlights the discovery of a related pyridopyrimidinone core with distinct structure-activity relationships, despite the structural similarity to GNE-0723. GNE-5729 (13), a pyridopyrimidinone-based NMDAR PAM, was identified with both an improved pharmacokinetic profile and increased selectivity against AMPARs. We also include X-ray structure analysis and modeling to propose hypotheses for the activity and selectivity differences.

Discovery of GluN2A-Selective NMDA Receptor Positive Allosteric Modulators (PAMs): Tuning Deactivation Kinetics via Structure-Based Design

The N-methyl-D-aspartate receptor (NMDAR) is a Na(+) and Ca(2+) permeable ionotropic glutamate receptor that is activated by the coagonists glycine and glutamate. NMDARs are critical to synaptic signaling and plasticity, and their dysfunction has been implicated in a number of neurological disorders, including schizophrenia, depression, and Alzheimer's disease. Herein we describe the discovery of potent GluN2A-selective NMDAR positive allosteric modulators (PAMs) starting from a high-throughput screening hit. Using structure-based design, we sought to increase potency at the GluN2A subtype, while improving selectivity against related α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). The structure-activity relationship of channel deactivation kinetics was studied using a combination of electrophysiology and protein crystallography. Effective incorporation of these strategies resulted in the discovery of GNE-0723 (46), a highly potent and brain penetrant GluN2A-selective NMDAR PAM suitable for in vivo characterization.

Fragment-based identification of amides derived from trans-2-(pyridin-3-yl)cyclopropanecarboxylic acid as potent inhibitors of human nicotinamide phosphoribosyltransferase (NAMPT)

Potent, trans-2-(pyridin-3-yl)cyclopropanecarboxamide-containing inhibitors of the human nicotinamide phosphoribosyltransferase (NAMPT) enzyme were identified using fragment-based screening and structure-based design techniques. Multiple crystal structures were obtained of initial fragment leads, and this structural information was utilized to improve the biochemical and cell-based potency of the associated molecules. Many of the optimized compounds exhibited nanomolar antiproliferative activities against human tumor lines in in vitro cell culture experiments. In a key example, a fragment lead (13, KD = 51 μM) was elaborated into a potent NAMPT inhibitor (39, NAMPT IC50 = 0.0051 μM, A2780 cell culture IC50 = 0.000 49 μM) which demonstrated encouraging in vivo efficacy in an HT-1080 mouse xenograft tumor model.

Fragment-based design of 3-aminopyridine-derived amides as potent inhibitors of human nicotinamide phosphoribosyltransferase (NAMPT)

The fragment-based identification of two novel and potent biochemical inhibitors of the nicotinamide phosphoribosyltransferase (NAMPT) enzyme is described. These compounds (51 and 63) incorporate an amide moiety derived from 3-aminopyridine, and are thus structurally distinct from other known anti-NAMPT agents. Each exhibits potent inhibition of NAMPT biochemical activity (IC50=19 and 15 nM, respectively) as well as robust antiproliferative properties in A2780 cell culture experiments (IC50=121 and 99 nM, respectively). However, additional biological studies indicate that only inhibitor 51 exerts its A2780 cell culture effects via a NAMPT-mediated mechanism. The crystal structures of both 51 and 63 in complex with NAMPT are also independently described.

Identification of amides derived from 1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid as potent inhibitors of human nicotinamide phosphoribosyltransferase (NAMPT)

Potent, 1H-pyrazolo[3,4-b]pyridine-containing inhibitors of the human nicotinamide phosphoribosyltransferase (NAMPT) enzyme were identified using structure-based design techniques. Many of these compounds exhibited nanomolar antiproliferation activities against human tumor lines in in vitro cell culture experiments, and a representative example (compound 26) demonstrated encouraging in vivo efficacy in a mouse xenograft tumor model derived from the A2780 cell line. This molecule also exhibited reduced rat retinal exposures relative to a previously studied imidazo-pyridine-containing NAMPT inhibitor. Somewhat surprisingly, compound 26 was only weakly active in vitro against mouse and monkey tumor cell lines even though it was a potent inhibitor of NAMPT enzymes derived from these species. The compound also exhibited only minimal effects on in vivo NAD levels in mice, and these changes were considerably less profound than those produced by an imidazo-pyridine-containing NAMPT inhibitor. The crystal structures of compound 26 and the corresponding PRPP-derived ribose adduct in complex with NAMPT were also obtained.

Structure-based identification of ureas as novel nicotinamide phosphoribosyltransferase (Nampt) inhibitors

Nicotinamide phosphoribosyltransferase (Nampt) is a promising anticancer target. Virtual screening identified a thiourea analogue, compound 5, as a novel highly potent Nampt inhibitor. Guided by the cocrystal structure of 5, SAR exploration revealed that the corresponding urea compound 7 exhibited similar potency with an improved solubility profile. These studies also indicated that a 3-pyridyl group was the preferred substituent at one inhibitor terminus and also identified a urea moiety as the optimal linker to the remainder of the inhibitor structure. Further SAR optimization of the other inhibitor terminus ultimately yielded compound 50 as a urea-containing Nampt inhibitor which exhibited excellent biochemical and cellular potency (enzyme IC50 = 0.007 μM; A2780 IC50 = 0.032 μM). Compound 50 also showed excellent in vivo antitumor efficacy when dosed orally in an A2780 ovarian tumor xenograft model (TGI of 97% was observed on day 17).

Heteroaromatic side-chain analogs of pregabalin

A series of heteroaromatic analogs of pregabalin has been identified that possess anticonvulsant activity in the DBA/2 mouse model. The methods of synthesis and preliminary pharmacology are discussed herein.

The association of E-cadherin expression and the methylation status of the E-cadherin gene in nasopharyngeal carcinoma cells

Loss of E-cadherin (E-cad) has been associated with progression and poor survival in nasopharyngeal carcinoma (NPC). In this study, we investigated the role of methylation on E-cad inactivation in NPC cell lines, as well as in NPC tissue samples. Using 6 NPC cell lines, we found that methylation of the E-cad 5' CpG island promoter region was correlated with the loss of both mRNA and E-cad protein expression in these cell lines. In addition, using 29 NPC and 10 non-malignant nasopharyngeal samples, we also observed 5' CpG methylation of the E-cad gene in 52% (15 out of 29) NPC samples, but in only 10% (1 out of 10) of the non-malignant nasopharyngeal tissues. Our findings indicate that 5' CpG island methylation of the E-cad gene may play an important part in the inactivation of E-cad in NPC. Our results also suggest that reducing the methylation of the E-cad gene may be a potential therapeutic strategy for NPC.

Establishment of two immortalized nasopharyngeal epithelial cell lines using SV40 large T and HPV16E6/E7 viral oncogenes

Nasopharyngeal carcinoma (NPC) is a common cancer in Southeast Asia, especially in southern China. One of the most striking features of this disease is its close relationship with Epstein-Barr Virus (EBV). However, to date there is no direct study on the mechanisms involved in the role of EBV in the tumorigenesis of NPC, largely due to lack of an experimental model. Available hypotheses on the association between EBV and NPC are generated from non-nasopharyngeal epithelial cell systems such as human keratinocytes or mouse epithelial cells, which may not truly represent the biological properties of nasopharyngeal epithelial (NP) cells. In this study, we report the establishment of two immortalized NP cell lines, NP69SV40T and NP39E6/E7, using SV40T and HPV16E6/E7 oncogenes. We found that NP60SV40T and NP39E6/E7 cell lines not only maintained many characteristics of normal NP cells (i.e. keratin profile and responsive to TGFbeta inhibition) but also highly responsive to one of the EBV encoded genes, LMP1. Comparative genome hybridization (CGH) analysis showed that these two cell lines contained multiple genetic alterations, some of which have been described in NPC. The immortalized NP cell lines are non-tumorigenic and exhibit anchorage-dependent growth. These cell lines may provide a possible cell model system for studying the mechanisms involved in the tumorigenesis of NPC.

Management of extensive cervical nodal metastasis in nasopharyngeal carcinoma after radiotherapy: a clinicopathological study

OBJECTIVES

To evaluate the efficacy of afterloading brachytherapy following radical neck dissection (RND) in the management of extensive cervical lymph node disease in nasopharyngeal carcinoma after radiotherapy; and to examine prospectively prognostic factors and the pathologic behavior of neck disease.

PATIENTS

Twenty-seven patients with nasopharyngeal carcinoma who had extensive cervical lymph node metastasis following external radiotherapy were treated with RND. Thirteen of them also underwent afterloading brachytherapy with iridium wire (Ir 192). The RND specimens of the 27 patients were also examined with step serial whole-specimen sectioning.

RESULTS

All patients survived and their wounds healed primarily. Pathologic examination revealed 183 tumor-bearing lymph nodes that contained tumors in the neck: level I, 4% (8/183); level II, 53% (96/183); level III, 34% (62/183); level IV, 5% (9/183); and level V, 4% (8/183). Extracapsular tumor extension was seen in 84% of patients. Multivariate analysis identified the number of tumor-bearing lymph nodes detected in the specimens to be the only significant factor that affected control of disease. Although the neck disease in the group of patients who had afterloading brachytherapy was more extensive, the 3-year actuarial tumor control for the groups with and without brachytherapy were 60% and 61%, respectively.

CONCLUSIONS

Recurrent cervical lymph nodes after radiotherapy in nasopharyngeal carcinoma are extensive and RND is mandatory for a successful salvage. When the nodal metastasis infiltrate or adhere to surrounding tissue, afterloading brachytherapy with iridium wire can provide satisfactory local tumor control.

The novel calpain inhibitor SJA6017 improves functional outcome after delayed administration in a mouse model of diffuse brain injury

A principal mechanism of calcium-mediated neuronal injury is the activation of neutral proteases known as calpains. Proteolytic substrates for calpain include receptor and cytoskeletal proteins, signal transduction enzymes and transcription factors. Recently, calpain inhibitors have been shown to provide benefit in rat models of focal head injury and focal cerebral ischemia. The present study sought to investigate, in experiment 1, the time course of calpain-mediated cytoskeletal injury in a mouse model of diffuse head injury by measuring the 150- and 145-kDa alpha-spectrin breakdown products (SBDP). Secondly, in experiment 2, we examined the effect of early (20 min postinjury) administration of the novel calpain inhibitor SJA6017 on functional outcome measured 24 h following injury and its effect on posttraumatic alpha-spectrin degradation. Lastly, in experiment 3, we examined the effect of delayed (4 or 6 h postinjury) administration of SJA6017 on 24-h postinjury functional outcome. In experiment 1, isoflurane-anesthetized male CF-1 mice (18-22 g) were subjected to a 750 g-cm weight drop-induced injury and were sacrificed for SBDP analysis at postinjury times of 30 min, and 1, 2, 6, 24 and 48 h (plus sham). In experiments 2 and 3, mice were injured as described, and delivered a single tail vein injection of either SJA6017 (0.3, 1, or 3 mg/kg) or vehicle (administered immediately, 4 or 6 h postinjury [3 mg/kg]). Functional outcome was evaluated in both studies, and, in experiment 2, 24-h postinjury assessment of SBDPs was determined. Following injury, the level of SBDP 145 was significantly different from sham at 24 and 48 h in cortical and at 24 h in the hippocampal tissues and at 48 h in the striatum. Immediate postinjury administration of SJA6017 resulted in a dose-related improvement in 24-h functional outcome (p < 0.05 at 3 mg/kg). Significance was maintained after a 4-h delay of the 3 mg/kg, but was lost after a 6-h delay. Despite improvement in functional outcome at 24 h, SJA6017 did not reduce spectrin breakdown in cortical or hippocampal tissues. These results support a role for calpain-mediated neuronal injury and the potential for a practical therapeutic window for calpain inhibition following traumatic brain injury. However, measurements of regional spectrin degradation may not be the most sensitive marker for determining the effects of calpain inhibition.

The clinicopathologic significance of p53 and p21 expression in the surgical management of lingual squamous cell carcinoma

The aim of the present study was to evaluate the clinicopathologic significance of p53 and p21 expression in lingual squamous cell carcinomas. Immunohistochemical staining was performed with p53 and p21 monoclonal antibodies on surgical specimens from 87 patients who underwent primary surgical treatment for lingual carcinoma between 1976 and 1996. We found positive expression of p53 in 45 (52%) of 87 cases and of p21 in 49 (56%) of 87 cases. There was no correlation of p53 and p21 expression with cancer stage, T stage, nodal metastasis, and tumor grade. Univariate analysis revealed that p21 expression, tumor stage, T stage, and nodal stage were significant prognostic factors for survival. However, only p21 expression and tumor stage were significant independent prognostic factors for survival in a multivariate Cox regression analysis. Overexpression of p21 but not p53 has prognostic value for survival in the surgical treatment of lingual carcinomas. The combination of stage with p21 expression is recommended for evaluation of prognosis and for management planning.

Microsatellite allelotyping of chinese nasopharyngeal carcinomas

BACKGROUND

Chinese nasopharyngeal carcinoma (NPC) specimens were analyzed by microsatellite allelotyping to evaluate their usefulness as biomarkers for cancer detection.

MATERIALS AND METHODS

A panel of eight microsatellite markers localized to chromosomes 3p, 6p, 9p, I1q and 14q were used to study 47 specimens.

RESULTS

A moderately low loss of heterozygosity (LOH) frequency (8% to 35%) was observed; 23 (49%) specimens showed LOH with at least one marker while microsatellite instability (MSI) was detected in 10 specimens (21%).

CONCLUSION

Poor survival was significantly associated with LOH detected by a chromosome 3 marker. Interestingly, tumors with multiple genetic alterations were significanty associated with earlier staging

Comparative genomic hybridization analysis of nasopharygeal carcinoma: consistent patterns of genetic aberrations and clinicopathological correlations

To define the patterns of genetic imbalances in nasopharyngeal carcinoma (NPC), we studied 30 primary NPC tumors with comparative genomic hybridization (CGH). The common sites of chromosomal gains were found in descending order of frequency in 12p11.2-p12 (36%), 12q14-q21 (33%), 2q24-q31 (23%), 1q31-qter (20%), 3q13 (20%), 1q13.3 (20%), 5q21 (17%), 6q14-q22 (13%), 7q21 (13%), 8q11.2-q23 (13%) and 18q12-qter (13%). The common sites of chromosomal loss were at 3p14-p21 (20%), 11q23-qter (20%), 16q21-qter (17%) and 14q24-qter (13%). Correlation with clinicopathologic features showed that 3p loss was associated with a significantly higher risk of death related to recurrence as compared with patients without 3p loss (50% vs. 9%, P=.029). The presence of 16q loss was associated with more advanced stage tumors (stages I & II: 6% vs. stages III & IV: 33%, P=.046). We conclude that consistent patterns of genetic imbalances can be observed in NPC. Deletion of 3p and 16q were associated with higher risk of tumor recurrence and advanced stage cancer.

Downregulation of hemidesmosomal proteins in nasopharyngeal carcinoma cells

Hemidesmosome (HD) is a transmembrane complex that mediates attachment of epithelial cells to the basement membrane. Abnormal expression of HD components has been reported in several types of human cancers and is believed to play a role in tumor invasion and metastasis. Using differential gene display, we have identified downregulation of BPAG1 expression in nasopharyngeal carcinoma cells. BPAG1 is a major component of hemidesmosome. In the present study, we have extended our work to investigate the expression pattern of other components in the HD complex, namely, BPAG2, ITGalpha6 and ITGbeta4 in three distinct biological groups of nasopharyngeal epithelial cells: (a) non-malignant nasopharyngeal epithelial cells established from primary culture of nasopharyngeal explants, (b) non-malignant nasopharyngeal epithelial cells immortalized by viral oncogenes, SV40 or HPV16E6E7, and (c) nasopharyngeal carcinoma (NPC) cells. Both non-malignant primary cultured nasopharyngeal epithelial cells and immortalized nasopharyngeal epithelial cell lines expressed all the HD components examined, although the immortalized cells expressed a lower level of HD components compared with the non-malignant nasopharyngeal cells established from primary culture. In contrast, downregulation of HD components is commonly observed in nasopharyngeal carcinoma cells. Loss of HD expression in NPC may be associated with the undifferentiated properties of NPC cells and may have prognostic significance.

Relationship between the size of neopharynx after laryngectomy and long-term swallowing function: an assessment by scintigraphy

OBJECTIVES

To study the relationship between the size of neopharynx after total laryngectomy and long-term swallowing function by means of scintigraphy.

STUDY DESIGN

The width of pharyngeal remnant was measured during surgery in 11 patients. Their swallowing function was assessed by scintigraphy 8 to 10 years after surgery.

METHODS

The width of pharyngeal remnant at its narrowest point in both relaxed and stretched state was measured during surgery. Postoperative scintigraphy data on swallowing were obtained and computed along 3 lines, (1) transit time through neopharynx, (2) percentage of bolus transferred, and (3) swallowing efficiency. The relationship between the 2 sets of data was analyzed by linear regression analysis.

RESULTS

(1) No statistically significant relationship was found between the size of neopharynx and swallowing function. (2) All patients are clinically asymptomatic.

CONCLUSIONS

The swallowing function is not affected by the size of the neopharynx in 11 patients with pharyngeal remnant width ranging from 3 to 8 cm (stretched).

Correlation of endoscopic and histologic findings before and after treatment for nasopharyngeal carcinoma

BACKGROUND

The endoscopic and histologic findings before and after radiotherapy (RT) for nasopharyngeal carcinoma (NPC) were correlated to study the sensitivity and specificity of endoscopic findings in predicting histologic results. The efficiacy of endoscopic examination and post-RT multiple site biopsies in detecting persistent disease was also evaluated.

METHODS

Seven hundred forty-six patients were evaluated. Pre-RT, biopsies were taken from both sides of the nasopharynx to assess the extent of tumor. Four to 16 weeks after RT, routine six-site biopsy specimens were taken from both roofs, lateral, and posterior walls of the nasopharynx and repeated 2 weeks later. Endoscopic findings of exophytic growth, nodule, ulcer, and submucosal bulge were considered "residual tumor," others were considered "no residual tumor." Persistent disease was defined as positive histologic findings 12 weeks after RT.

RESULTS

Before RT, sensitivity of endoscopic findings and biopsy specimens in detecting malignancy were 99.7% and 94.2%, respectively. After RT, sensitivity and specificity of endoscopic findings in predicting positive histologic findings were 29% and 85.8%, respectively, with a positive predictive value of 34.9% and a negative predictive value of 82.2%. Of positive histologic findings, 27.7% were missed in the first session of biopsies; 33.5% of those with positive histologic findings turned out to have persistent disease. For prediction of persistent disease, the sensitivity and specificity of endoscopic findings were 40.4% and 84.4%, with a positive predictive value of 16.3% and a negative predictive value of 95%, and that of histologic findings in the first session of biopsies were 59.6% and 88.3%, respectively, with a positive predictive value of 27.7% and a negative predictive value of 96.7%.

CONCLUSIONS

Endoscopic findings alone have low sensitivity in predicting persistent disease, multiple sites biopsy specimens are indicated. Because only 1.9% of patients with endoscopic findings of "no residual tumor" and negative histologic findings in first session of biopsies had persistent disease, this group can be spared second biopsies. Repeat biopsies are indicated for those with endoscopic findings of "residual tumor" or positive histologic findings in first session of biopsies to improve detection of persistent disease.

Clinicopathological significance of p53 and p21 expression in the surgical treatment of laryngeal carcinoma

BACKGROUND

This study aimed at resolving the clinicopathological significance of p53 and p21 expression in patients undergoing surgical treatment for laryngeal carcinoma.

MATERIALS AND METHODS

p53 and p21 expression were studied by immunohistochemical method on surgical specimens of 193 patients. The expressions of p53 and p21 were correlated with the clinicopathological data.

RESULTS

Of the 193 tumors, 60% had positive p53 expression and 46% had positive p21 expression. Nodal metastasis was significantly correlated with p53 overexpression, supraglottic involvement and moderate- to poor-differentiation of the tumor. There was significant cumulative effect with increasing risk of nodal metastasis with increasing number of risk factors: 0% without any risk factor, 13% with 1 risk factor, 37% with 2 risk factors and 55% with all 3 risk factors.

CONCLUSION

Positive expressions p53 and p21 were common in laryngeal carcinoma. Overexpression of p53 but not p21 was associated with nodal metastasis. The use of p53 expression has added value in providing more accurate prognostic analysis of risk of nodal metastasis in conjunction with site of tumor involvement and tumor grade.

Microsatellite alterations in squamous cell carcinoma of the head and neck - clustering of loss of heterozygosity in a distinct subset

Loss of heterozygosity (LOH) and microsatellite instability (MSI) have been recognized as important events in the carcinogenesis of many cancers, including squamous cell carcinoma of head and neck (SCCHN). However, microsatellite alterations have not been documented in SCCHN from Chinese patients. We investigated the frequency and clinical significance of LOH and MSI in 30 SCCHN from Hong Kong Chinese using polymerase chain reaction on 17 microsatellite markers on chromosomes 3p, 4q, 7q, 9p, 17p and 18q. LOH was present in nine tumours (30%) and MSI in four (13%). The incidence of LOH (7/13; 53.8%) in hypopharyngeal-laryngeal cancers was significantly higher than that (2/17; 11.8%) in the oral cancers (P=0.020). LOH was more often detected at the loci on chromosomes 7 and 9. Patients with tumours having LOH had slightly poorer outcome compared with those without, although the differences did not reach statistical significance. Our data show that the incidence of microsatellite alterations in SCCHN from Hong Kong Chinese is low. However, LOH may be one of the genetic mechanisms in the carcinogenesis of a subset of SCCHN (hypopharyngeal-laryngeal cancers).

Differential gene expression in nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a common cancer among southern Chinese. The profile of gene expression in NPC cells is largely unknown. In this study, we have examined differential gene expression in non-malignant and malignant nasopharyngeal epithelial (NPE) cells using a cDNA array hybridization method. A total of 42 genes were identified to be expressed in either non-malignant and malignant NPE cells or both. Thirteen of these genes were overexpressed in malignant NPE cells. These includes nuclear factor (NF90), FOS-related antigen 1 (FRA- 1), cytoplasmic dynein light chain (HDLC1), replication factor C (RFC1), nucleoside diphosphate kinase B, UV excision repair protein (RAD23A), insulin-like growth factor receptor II, transcription initiation factor TFIID subunit (TAFII31), growth factor receptor-bound protein 2 (GRB2), UV excision repair protein (RAD23B), glutathione peroxidase, Y box binding protein 1 and heat shock protein 86. In contrast, expression of nine genes was suppressed in malignant NPE cells. These includes calgranulin A, calgranulin B, neutrophil activating protein (ENA-78), heat shock protein 27, integrin beta-1, integrin beta-4, cyclin-dependent kinase inhibitor 1A (p21), interleukin-8 and tyrosine protein kinase receptor (RET). Differential expression of calgranulin A, calgraunlin B, ENA-78, FRA-1 and NF90 in non-malignant and malignant nasopharyngeal epithelial cells was confirmed by RT-PCR analysis.

Subtype-selective N-methyl-D-aspartate receptor antagonists: benzimidazalone and hydantoin as phenol replacements

Previous work in our laboratories investigating compounds with structural similarity to ifenprodil (5) and 6 (CP101,606) resulted in compound 7 as a potent and selective antagonist of the NR1/2B subtype of the NMDA receptors. Replacement of the phenol group of 7 with a benzimidazalone group tethered by a three-carbon chain to 4-benzylpiperidine resulted in a slightly less active, but selective, compound. Lengthening the carbon tether resulted in a decrease in NR1/2B potency. Replacement of the phenol ring with a hydantoin resulted in weak antagonists. Compound 11a was one of the most potent NR1/2B antagonists from this study. Compound 11a also potentiated the effects of L-DOPA in a rat model of Parkinson's disease (the 6-hydroxydopamine-lesioned rat), dosed at 30 mg/kg orally.

A prospective evaluation of recurrent laryngeal nerve paralysis during thyroidectomy

HYPOTHESIS

Recurrent laryngeal nerve paralysis after thyroidectomy can be unrecognized without routine laryngoscopy, and patients have a good potential for recovery during follow-up.

DESIGN

A prospective evaluation of vocal cord function before and after thyroidectomy. Periodic vocal cord assessment was performed until recovery of cord function. Persistent cord palsy for longer than 12 months after the operation was regarded as permanent.

SETTING

A university hospital with about 150 thyroid operations performed by 1 surgical team per year.

PATIENTS

From January 1, 1995, to April 30, 1998, 500 consecutive patients (84 males and 416 females) with documented normal cord function at the ipsilateral side of the thyroidectomy were studied.

MAIN OUTCOME MEASURES

Vocal cord paralysis after thyroidectomy.

RESULTS

There were 213 unilateral and 287 bilateral procedures, with 787 nerves at risk of injury. Thirty-three patients (6.6%) developed postoperative unilateral cord paralysis, and 5 (1.0%) had recognizable nerve damage during the operations. Complete recovery of vocal cord function was documented in 26 (93%) of 28 patients. The incidence of temporary and permanent cord palsy was 5.2% and 1.4% (3.3% and 0.9% of nerves at risk), respectively. Among factors analyzed, surgery for malignant neoplasm and recurrent substernal goiter was associated with an increased risk of permanent nerve palsy. Primary operations for benign goiter were associated with a 5.3% and 0.3% incidence (3.4% and 0.2% of nerves at risk) of transient and permanent nerve palsy, respectively.

CONCLUSIONS

Unrecognized recurrent laryngeal nerve palsy occurred after thyroidectomy. Thyroid surgery for malignant neoplasms and recurrent substernal goiter was associated with an increased risk of permanent recurrent nerve damage. Postoperative vocal cord dysfunction recovered in most patients without documented nerve damage.

Malignant otitis externa caused by Malassezia sympodialis

BACKGROUND

Malignant otitis externa caused by fungal infections is rare. A review of the literature showed only 9 cases, and the causative fungus in all cases was Aspergillus. This article reports an unusual case caused by Malassezia sympodialis.

METHODS

A 53-year-old man with non-insulin dependent diabetes presented with malignant otitis externa. He deteriorated despite treatment with intravenous antipseudomonal therapy and surgical debridement. Microbiologic tests revealed M. sympodialis. He responded rapidly to intravenous amphotericin.

RESULTS

Systemic human infections caused by M. sympodialis have not been reported. M. furfur systemic infection is rare and has been associated lipid hyperalimentation by means of a central catheter. Only 1 other case of M. fungemia without these associated risk factors has been reported.

CONCLUSIONS

The first case of malignant otitis externa caused by M. sympodialis is presented. It highlights the difficulty of initial biologic diagnosis and the need for lipid-enriched media to grow this fastidious organism.

Structure-activity relationship of N-(phenylalkyl)cinnamides as novel NR2B subtype-selective NMDA receptor antagonists

A novel series of N-(phenylalkyl)cinnamides related to N-(4-phenylbutyl)-3,4-dihydroxy-beta-cyanocinnamide (6, an EGFR-K inhibitor with high antiproliferative activity) was synthesized and tested for antagonism at N-methyl-D-aspartate (NMDA) receptor subtypes. Potency and subunit selectivity were assayed by electrical recordings in Xenopus oocytes expressing three binary combinations of cloned rat NMDA receptor subunits: NR1A expressed in combination with either NR2A, NR2B, or NR2C. The N-(phenylalkyl)cinnamides are selective antagonists of NR1A/2B receptors. Assayed under steady-state conditions, N-(4-phenylbutyl)-4-hydroxycinnamide (16) has an IC(50) value of 77 nM and >1000-fold selectivity with respect to NR1A/2A and NR1A/2C receptors. Potency at alpha(1) adrenergic receptors is low for the four cinnamides tested. Inhibition of NR1A/2B receptors does not correlate with EGFR and ErbB2/neu tyrosine kinase inhibitor activity. The N-(phenylalkyl)cinnamide series we describe provides a novel and structurally diverse framework for designing new NR2B-selective NMDA antagonists as potential CNS therapeutics.

The time course of histologic remission after treatment of patients with nasopharyngeal carcinoma

BACKGROUND

The objective of this study was to define the time course of histologic remission and to evaluate the prognostic significance of delayed histologic remission of patients with nasopharyngeal carcinoma (NPC).

METHODS

Between 1986-1994, 803 patients underwent serial postradiotherapy nasopharyngeal biopsies. Patients with positive histology underwent repeated biopsies every 2 weeks until the biopsies were found to be negative or, if remission did not occur by the 12th week after radiotherapy, treatment was initiated for persistent disease. Patients with positive histology found after the fifth week but who achieved spontaneous remission before the twelfth week were considered to have delayed histologic remission. Negative histology by the sixth week was considered early histologic remission. The outcome of patients with delayed histologic remission, early histologic remission, and persistent disease were compared.

RESULTS

Six hundred and seventeen patients (76.8%) had negative histology within 12 weeks of the completion of radiotherapy and 55 (6.9%) had persistent disease at Week 12. In 131 patients (16.3%) spontaneous remission was observed in repeat biopsies after initial positive histology. With increasing time after radiotherapy, the incidence of positive histology decreased but more patients were found to have persistent disease. Patients with early and delayed histologic remission had 5-year NPC control rates of 82.4% and 76.8%, respectively (P = 0.35) versus a 40% NPC control rate among patients with persistent disease (P < 0.001). The 5-year survival rates were 75.3%, 79.4%, and 54.2%, respectively, for the 3 groups (P < 0.001).

CONCLUSIONS

A high proportion of early positive histology remitted spontaneously. Delayed histologic remission in NPC patients is not a poor prognostic factor and additional treatment is not necessary. A confirmatory biopsy at 10 weeks is recommended before the initiation of salvage treatment.

Identification of genes differentially expressed in nasopharyngeal carcinoma by messenger RNA differential display

We have applied the mRNA differential display method to compare and analyze mRNAs prepared from five normal nasopharyngeal epithelial cell cultures and five nasopharyngeal carcinoma cell lines. A total of 24 differential display experiments was performed using different combinations of PCR primers. Sixty-nine cDNA fragments differentially expressed in either normal or malignant nasopharyngeal epithelial cells were identified. Subsequent cloning and sequencing of these differentially expressed cDNA fragments resulted in the identification of seventeen distinct sequences. Seven of these sequences were shown to be novel cDNA sequences not previously reported. Ten of the remaining cDNA fragments showed sequence homology to previously reported genes. Differential expression of four of these seventeen cDNA fragments in normal nasopharyngeal epithelial cells was confirmed by reverse Northern hybridization. One of these cloned cDNA fragments is a novel cDNA sequence while the other three matched to previously reported cDNA sequences involved in cell growth and migration. Homologous sequences identified to be differentially expressed in normal nasopharyngeal epithelial cells in this study are: human 26 kDa cell surface protein (TAPA-1) mRNA, NF-E2 like basic leucine zipper transcriptional activator and the human bullous pemphigoid antigen. The mRNA differential display is a useful tool to identify candidate genes involved in the pathogenesis of nasopharyngeal carcinoma.

Current status of pharyngolaryngo-esophagectomy and pharyngogastric anastomosis

BACKGROUND

Pharyngolaryngo-esophagectomy and pharyngogastric anastomosis (PLO & PGA) is one of the surgical options in the management of tumors arising from the hypopharynx and cervical esophagus. Indications of the operation and the outcome are changing over the years. To examine these, the experience of this operation in one Institute (the Head and Neck Division of the Department of Surgery, The University of Hong Kong at Queen Mary Hospital, Hong Kong) over the last 30 years was reviewed.

METHODS

From 1966 to 1995, a total of 317 patients underwent PLO & PGA. The clinical results of 69 patients operated on between 1986 and 1995 were analyzed and compared with those of the two groups of patients reported previously from the same Institute to establish the current status of PLO & PGA.

RESULTS

The demographic data of three groups of patients were similar. In previous years, 53% of the primary tumors were advanced laryngeal carcinomas extending to the hypopharynx, whereas the other 47% originated from hypopharyngeal and cervical esophageal regions. In recent years, all patients belonged to the latter group.

CONCLUSIONS

The hospital mortality has decreased from 31% to 9%, and the incidence of morbidity such as anastomotic leakage and bleeding has also been reduced, from 20% to 10%. This may be related to the introduction of transthoracic endoscopic mobilization of the esophagus and patient selection. The overall minor morbidity has, however, remained at about 49%, and the 5-year actuarial survival rate has improved, from 18% in the 1970s to 24.5% at present.

Clinicopathological analysis of local spread of carcinoma of the tongue

BACKGROUND

The aims of the study are three-dimensional analysis of mode and distance of local spread of oral tongue carcinoma.

METHODS

The glossectomy specimens were examined in the coronal plane in 3 mm thickness section.

RESULTS

There were 50 glossectomy specimens. The maximum spread was 1.8 cm. Ninety-six percent of specimens had local spread within 1.2 cm. The distance of spread was not correlated with tumor size, including the diameter, depth, and volume. The incidence of local recurrence was 27% with positive histological margin. Perineural infiltration was the most important prognostic factor for local recurrence and survival.

CONCLUSIONS

A minimum of 1.5-cm surgical resection margin is recommended. A smaller margin is not recommended as it has significant risk of local recurrence. A maximum of 2-cm surgical resection margin is recommended; larger margins will increase the surgical morbidity without a significant advantage of local control.

N-(2-(4-hydroxyphenyl)ethyl)-4-chlorocinnamide: a novel antagonist at the 1A/2B NMDA receptor subtype

A series of N-(2-phenethyl)cinnamides was synthesized and assayed for antagonism at three N-methyl-D-asparate (NMDA) receptor subtypes (NR1A/2A-C). N-(2-(4-hydroxyphenyl)ethyl)-4-chlorocinnamide (6) was identified as a highly potent and selective antagonist of the NR1A/2B subtype.

Telomerase activation in nasopharyngeal carcinomas

Nasopharyngeal carcinomas (NPC) are common in Hong Kong and southern China but rare in Western countries. Telomerase activation is common in human cancers but has not been reported previously in NPC. Telomerase activation in NPC was determined using the sensitive TRAP (telomerase rapid amplification protocol) assay in 45 nasopharyngeal biopsies (36 NPC, nine normal nasopharyngeal mucosae) in four xenografted NPC tumours established in nude mice and in five in vitro NPC cell lines. Telomerase activation is common in NPC and can be detected at high frequencies (85% in primary tumours and 100% in recurrent tumours). The frequency of telomerase activation was lowest in NPC biopsies without lymph node involvement (60%) compared with those with positive lymph node involvement (100%), and the difference is statistically significant (P < 0.05; Fisher exact test). All the xenografted NPC tumours and in vitro NPC cell lines were strongly positive for telomerase activity. Our results suggest that telomerase activation is common in NPC and it may be useful as a diagnostic marker in the detection of tumour cells in nasopharyngeal biopsies. The high frequency of telomerase activation in stage I NPC (80% positive) suggests that it is an early event in tumour progression.

Mucosal changes of the free jejunal graft in response to radiotherapy

BACKGROUND

Microvascular free jejunal transfer was employed for reconstruction of pharyngeal defect resulting from circumferential resection of the hypopharynx. Postoperative radiotherapy to the neck might affect the graft, but this information was lacking. The mucosal changes of the jejunum in response to radiation were identified in this prospective study.

METHODS

Normal jejunal mucosa was obtained at operation, and endoscopic jejunal mucosal biopsies were taken during and at completion of radiotherapy. Endoscopic biopsies were repeated at 1, 3, 6, 12, and 24 months afterwards. All jejunal biopsies were subjected to histologic and scanning electron microscopic (SEM) examinations. Nine patients had a complete set of biopsy while 5 other patients who received no radiotherapy also went through a similar sequence of biopsies as controls.

RESULTS

Histologic examination showed mucosal edema and extensive blunting of jejunal villi at the completion of radiotherapy. Increased fibrosis with focal loss of glands was noticed at 3 months after radiotherapy, and this remained throughout the 2-year period. SEM revealed patchy loss of microvilli at completion and at 1 month after radiotherapy, but this feature was not apparent in biopsies taken at 3 months onwards, showing that it was only a transient event.

CONCLUSIONS

Transient responses and persistent changes of jejunal mucosa to radiotherapy were identified and characterized. The presence of these mucosal lesions was not associated with any clinically significant adverse effect in the graft up to 2 years postradiotherapy.

Sequence variations in EBNA-1 may dictate restriction of tissue distribution of Epstein-Barr virus in normal and tumour cells

In seropositive individuals Epstein-Barr virus (EBV) establishes a virus reservoir in peripheral blood lymphocytes (PBLs). Transmission from one individual to another occurs via saliva due to a lytic (virion productive) phase of infection in the oropharynx. EBNA-1 is responsible for maintaining viral episomes in the host cell and could, therefore, also affect the persistence of the virus in different cell lineages. Based on sequence analysis of EBNA-1 we now demonstrate that (i) in addition to the prototype EBNA-1 (identical to the B95.8 virus EBNA-1), EBV in normal individuals encompasses multiple EBNA-1 subtypes, both in PBLs and in oral secretions; (ii) although EBV with prototype EBNA-1 is the predominant virus in normal individuals, it is very rarely associated with either nasopharyngeal carcinoma (NPC) or Burkitt's lymphoma (BL); (iii) EBV with an EBNA-1 subtype (V-val) frequently associated with NPC is also selectively detected in oral secretions and not in PBLs; (iv) EBV with the EBNA-1 subtype V-pro is restricted to PBLs, while a mutated version of this subtype is present in BL, but not in NPC. These findings suggest that the variations in EBNA-1 may be relevant to the ability of EBV to persist in different cell types, and hence relevant to its oncogenic potential.

Crystal structure of calcium bound domain VI of calpain at 1.9 A resolution and its role in enzyme assembly, regulation, and inhibitor binding

The three dimensional structure of calcium-bound domain VI of porcine calpain has been determined to 1.9 A resolution. The crystal structure reveals five EF-hands, one more than previously suggested. There are two EF-hand pairs, one pair (EF1-EF2) displays an 'open' conformation and the other (EF3-EF4) a 'closed' conformation. Unusually, a calcium atom is found at the C-terminal end of the calcium binding loop of EF4. With two additional residues in the calcium binding loop, the fifth EF-hand (EF5) is in a 'closed' conformation. EF5 pairs up with the corresponding fifth EF-hand of a non-crystallographically related molecule. Considering the EF5's role in a homodimer formation of domain VI, we suggest a model for the assembly of heterodimeric calpain. The crystal structure of a Ca2+ bound domain VI-inhibitor (PD150606) complex has been refined to 2.1 A resolution. A possible mode for calpain inhibition is discussed.

Cervical lymph node metastatic patterns of squamous carcinomas in the upper aerodigestive tract

The radical neck dissection specimens of 384 ethnically Chinese patients with different primary squamous carcinomas in the head and neck region were studied. Over 50 per cent of the specimens showed metastatic disease at one level in the neck. For oral cavity carcinoma, the levels of metastasis frequently involved were I, II and III while for carcinoma of the oropharynx, hypopharynx and larynx the levels were II, III and IV. Extracapsular spread was present in 112/384 of patients (29 per cent) and this increased with advancing N-stages. Based on these findings, different selective neck dissections could be used for patients harbouring different primary head and neck carcinomas with limited neck disease.

Sensorineural hearing loss in patients treated for nasopharyngeal carcinoma: a prospective study of the effect of radiation and cisplatin treatment

PURPOSE

The pattern of sensorineural hearing loss (SNHL) after primary treatment for nasopharyngeal carcinoma (NPC) was studied, and the effect of cisplatin, radiotherapy does, and fractionation were evaluated.

METHODS AND MATERIALS

One hundred thirty-two patients, 227 ears, and 1100 audiogram reports were analyzed. Radiotherapy dose ranged from 59.5 to 76.5 Gy. Fifty-two patients received preirradiation cisplatin, total dose 100-185 mg/m(2). Serial postirradiation bone conduction thresholds at 0.5 kHz, 1 kHz, 2 kHz, and 4 kHz were compared with pretreatment thresholds at respective frequencies. Increase of at least 15 dB was considered as significant and was further grouped as transient or persistent SNHL. Univariate and multivariate analyses were performed to identify predicting factors for persistent SNHL.

RESULTS

At median follow-up of 30 months, 24.2% of ears developed persistent SNHL. High frequency was more affected than low frequencies, 22 vs. 5.3%. Males were more affected than females, 29.4 vs. 15.5%, p = 0.0132. Incidence of persistent SNHL increased with age, with 0, 17.2, and 37.4% of patients aged under 30, between 30-50 and over 50 affected, respectively, p = 0.0001. High incidence was found in patient with postirradiation serous otitis media (SOM), 46.9%. Chemotherapy with cisplatin and radiation dose or fractionation had no significant effect. Multivariate analysis confirmed age, sex, and postirradiation SOM as significant prognostic factors for persistent SNHL.

CONCLUSIONS

Transient and persistent SNHL occurred after radiotherapy, more commonly affecting high frequency. A low dose of preirradiation cisplatin did not increase the risk. A dose fractionation effect of radiotherapy was not confirmed in this study.

Primary closure of pharyngeal remnant after total laryngectomy and partial pharyngectomy: how much residual mucosa is sufficient?

After total laryngectomy with or without partial pharyngectomy, the remaining pharyngeal defect can be repaired either by primary closure or with additional tissue, depending on the amount of pharyngeal tissue remnant available. The aim of this study was to determine the minimum width of the pharyngeal remnant that could be safely closed primarily without causing difficulty in swallowing. A total of 52 consecutive patients who underwent total laryngectomy were entered into the study. The relaxed and stretched widths of the pharyngeal remnant were measured after removal of the specimen. The widths of the pharyngeal mucosa ranged from 1.5 to 5.0 cm relaxed (mean, 3.24 cm) and from 2.5 to 8.0 cm stretched (mean, 4.83 cm). All neopharynx was reconstructed by closing the pharynx primarily. Seven of the 52 patients developed recurrent tumor with concomitant dysphagia. Two of the 45 patients without recurrence presented with acute dysphagia from food bolus obstruction, and 1 patient developed benign inflammatory stricture following an episode of fish-bone impaction. The narrowest widths of the pharyngeal remnant in this group of 45 were 1.5 cm relaxed and 2.5 cm stretched. As these patients do not have swallowing difficulty, we conclude that in the absence of tumor recurrence, this amount of residual pharyngeal tissue is sufficient both for primary closure of the pharynx and in restoring swallowing function.

Maxillary swing approach for resection of tumors in and around the nasopharynx

The efficacy of the anterolateral approach to the nasopharynx and its vicinity was evaluated. Using this maxillary swing approach, we have removed tumors in and around the nasopharyngeal region in 26 patients. Among them, 18 suffered from recurrent primary nasopharyngeal carcinoma after external radiotherapy, three patients had chordoma, two had schwannoma, one had adenocarcinoma of the nasopharynx, and one had malignant fibrous histiocytoma. The last patient had a recurrent deep-lobe parotid gland tumor localized in the paranasopharyngeal space. The facial wounds in all 26 patients healed primarily with no evidence of necrosis of the maxilla. Seven patients developed palatal fistula, five of them subsequently healed, whereas one patient required surgical closure and one had to wear a dental plate. This group of patients was followed up from 4 to 42 months (median, 15 months). Among the 18 patients with recurrent nasopharyngeal carcinoma, five had local recurrence, four died of other conditions, and nine of them are still alive with no evidence of disease. This gives an actuarial control of tumor in the nasopharynx of 42% at 3.5 years. In the eight patients remaining, one died of recurrent chordoma, two are alive with recurrent disease, and five are free of disease. Exposure of the nasopharynx and the paranasopharyngeal space is possible using the anterolateral approach. The associated morbidity is low.

Aurintricarboxylic acid is an inhibitor of mu- and m-calpain

Aurintricarboxylic acid (ATA) is an endonuclease inhibitor which has been shown to block apoptotic cell death. We have now demonstrated that ATA is also an inhibitor of the Ca(2+)-activated neutral protease (calpain), a class of cytosolic enzyme that may also be activated during apoptosis. The two major calpain isoforms (mu- and m-calpain) were both inhibited by ATA with IC50's of 22 microM and 10 microM, respectively. The autolysis of purified mu-calpain was prevented by ATA in a concentration-dependent manner. Using casein zymography, it was found that the inhibition of mu-calpain by ATA was reversible. Finally, in a fetal rat cerebrocortical culture model of excitotoxicity, pre- and post-treatment of ATA (50 microM) reduced N-methyl-D-aspartate (NMDA)-induced spectrin breakdown and neuronal death, while application of ATA concurrent to NMDA challenge alone had no effect. This pattern of protection could not be explained by simple NMDA receptor antagonism. We thus propose that the neuroprotective effect of ATA could be in part due to its ability to inhibit calpain.

Calpain inhibition: an overview of its therapeutic potential

Increasing evidence now suggests that excessive activation of the Ca(2+)-dependent protease calpain could play a key or contributory role in the pathology of a variety of disorders, including cerebral ischaemia, cataract, myocardial ischaemia, muscular dystrophy and platelet aggregation. In this review, Kevin Wang and Po-Wai Yuen discuss the evidence linking these disorders to calpain overactivation. At present, it is difficult to confirm the exact role of calpain in these disorders because of the lack of potent, selective and cell-permeable calpain inhibitors. However, given the multiple therapeutic indications for calpain, it appears that achievement of selective calpain inhibition is an important pharmacological goal.

Recurrence of laryngeal or hypopharyngeal primary tumor after radical neck dissection for postradiotherapy neck nodal metastases

BACKGROUND

When the primary tumor in the larynx or hypopharynx responds well to radiotherapy, nodal metastasis in the neck may persist or recur. The primary site is usually left alone when no lesion is evident, but its long-term control is uncertain.

METHODS

Radical neck dissection was performed in 23 patients who had nodal metastasis, while the primary tumor in the larynx or hypopharynx was controlled after radiotherapy. The primary site was left alone and kept under surveillance.

RESULTS

Seven patients (30%) had recurrence at the primary site on follow-up. Two significant risk factors for development of recurrences at the primary site were identified; the neck node staging at presentation (p < 0.03) and presentation with persistent neck lymph nodes (p < 0.03). The 2-year survival of those patients with recurrences at the primary site was 29%.

CONCLUSION

Radical neck dissection alone was justified, but close surveillance of the primary site after surgery is mandatory, especially for those patients with high-risk factors.

Ofloxacin eardrop treatment for active chronic suppurative otitis media: prospective randomized study

This report presents a prospective randomized study of 0.3 percent ofloxacin eardrops for the treatment of active chronic suppurative otitis media. Twenty-nine patients were treated with ofloxacin eardrops for 1 week, and another 27 patients were treated with Augmentin for 1 week. One week after completion of treatment, 22 (76%) patients of the group treated with ofloxacin had dry ears, and only seven (26%) patients treated with Augmentin had dry ears. Ofloxacin eardrops were effective in the initial treatment of active chronic suppurative otitis media.