Low temperature H2S removal with 3-D structural mesoporous molecular sieves supported ZnO from gas stream

A series of 3-dimensional (3-D) structural mesoporous silica materials, SBA-16, MCM-48 and KIT-6, was synthesized and supported with different ZnO loadings (10, 20, 30, and 40 wt%) by the incipient wetness method to evaluate the performances on H2S removal at room temperature. These materials were characterized by N2 adsorption, XRD, and TEM to investigate their textural properties. All the ZnO-loaded adsorbents exhibited the H2S removal capacity of bellow 0.1 ppmv. With the best ZnO loading percentage of 30 wt% on MCM-48 and KIT-6, 20 wt% on SBA-16 according to the results of breakthrough test, further increasing ZnO loading caused the decrease of the adsorption capacity due to the agglomeration of ZnO. Besides, the H2S adsorption capacities of the supports materials varied in the order of KIT-6>MCM-48>SBA-16, which was influenced primarily by their pore volume and pore size. With the largest pores in these 3-D arrangement materials, KIT-6 showed the best performance of supported material for ZnO, due to its retained superior physical properties as well as large pore diameter to allow faster gas-solid interaction and huge pore volume to disperse ZnO on the surface of it.

Factors affecting the impact of olfactory loss on the quality of life and emotional coping ability

BACKGROUND

Olfactory impaired patients have decreased quality of life and may need to develop a coping ability for the olfactory loss. This study investigated how factors like olfactory function, disease duration, etiology, age, and gender affect patients` quality of life and emotional ability to cope.

METHODS

Four hundred and thirteen consecutive patients with the chief complaint of olfactory dysfunction were evaluated. The Questionnaire of Olfactory Disorders (QOD) included negative statements (QOD-NS) that indicated the impact on the quality of life, and positive statements (QOD-PS) reflecting the emotional coping ability. Relations between studied factors and QOD-NS or QOD-PS were analyzed.

RESULTS

Poorer olfaction and younger age correlated with increased QOD-NS scores, whereas longer disease duration and older age correlated with increased QOD-PS scores. Females had poorer coping than males. QOD-PS scores were inversely related to QOD-NS scores.

CONCLUSIONS

The impact of olfactory loss is more significantly felt by younger patients with poorer olfaction. Older patients or those with longer disease duration develop better emotional coping abilities so as to reduce the impact on quality of life. It may be helpful for the patients with olfactory loss to develop emotional coping as early as possible to decrease the olfactory impact.

Cell cycle G2/M arrest and activation of cyclin-dependent kinases associated with low-dose paclitaxel-induced sub-G1 apoptosis

Paclitaxel is a potential anti-cancer agent for several malignancies including ovary, breast, and head and neck cancers. This study investigated the kinetics of paclitaxel-induced cell cycle perturbation in two human nasopharyngeal carcinoma (NPC) cell lines, NPC-TW01 and NPC-TW04. NPC cells treated with higher concentrations (0.1 or 1 micro M) of paclitaxel showed obvious G2/M arrest and then converted to a cell population with reduced DNA content, which was detected as a sub-G2 peak in the flow cytometric histographs. If a low concentration (5 nM) of paclitaxel was used instead, transient G2/M arrest was observed in NPC cells, which subsequently converted to a sub-G1 form during the treatment period. Internucleosomal fragmentation and chromatin condensation were detectable in these sub-G1 and sub-G2 cells, suggesting that persistent or transient G2/M arrest is a prerequisite step for apoptosis elicited by varying doses of paclitaxel. The levels of cyclins A, B1, D1, E, CDK 1 (CDC 2), CDK 2 and proliferating cell nuclear antigen (PCNA) were unchanged in NPC cells following treatment with any concentration of paclitaxel; however, apoptosis-related cyclin B1-associated CDC 2 kinase was highly activated by paclitaxel even at concentrations as low as 5 nM, which is consistent with the finding that low-dose paclitaxel is also able to induce apoptosis in NPC cells. Activation of cyclin B1-associated CDC 2 kinase seems to be an important G2/M event required for paclitaxel-induced apoptosis, and this activation of cyclin B1/CDC 2 kinase could be attributed to the increased activity of CDK 7 kinase.

Evaluation of GL331 in combination with paclitaxel: GL331's interference with paclitaxel-induced cell cycle perturbation and apoptosis

Combination of selecting agents that act on different cellular mechanisms is a common strategy in cancer chemotherapy. GL331 is a new potent topoisomerase II (Topo II) poison; distinctly, paclitaxel is a microtubule-interfering cancer chemotherapeutic agent. In this study, we intended to evaluate the efficacy of combining GL331 with paclitaxel in cell killing and apoptotic induction in nasopharyngeal carcinoma NPC-TW01 cells. By MTT and internucleosomal DNA cleavage assays, we found that pretreatment or simultaneous treatment of NPC-TW01 cells with GL331 could significantly interfere with paclitaxel's cell killing and apoptosis-inducing activity. When the administration schedule was reversed, the cytotoxicity of GL331 was attenuated by paclitaxel pretreatment. The anti-cancer activity produced by combining GL331 with paclitaxel was obviously lower than the addition of the activities of two individual agents. NPC-TW01 cells were treated with GL331 and 3H-labeled paclitaxel simultaneously or with GL331 before 3H-labeled paclitaxel. In both conditions, GL331 did not reduce the [3H]paclitaxel level in the cells, suggesting that GL331's interference with paclitaxel's cell-killing and apoptosis-inducing efficacy did not result from any inhibition of cellular uptake or retention of paclitaxel. In addition, we found that GL331-induced perturbation of cell cycle progression dramatically over-rode the patterns of mitotic arrest induced by paclitaxel, and the mechanism could be the inhibition of cyclin B1/CDC2 kinase and MAD2 checkprotein activities.

Salvage surgery for recurrent nasopharyngeal carcinoma

OBJECTIVE

To evaluate the efficacy of salvage surgery in the treatment of recurrent nasopharyngeal carcinoma (NPC) at the primary site.

STUDY DESIGN

A retrospective investigation of the outcome of salvage surgery for 28 patients with recurrent NPC after definite radiation therapy.

METHODS

The nasopharynx was approached anteroposteriorly by the transmaxillary approach (maxillary swing, maxillectomy) or inferior approach (midline mandibulotomy or median labiomandibular glossotomy), or laterally by modified facial translocation or transpterygoid approach; intentional ligation of the internal carotid artery was performed after establishment of extracranial-intracranial (EC-IC) bypass in one patient; postoperative irradiation was given to the patients with positive pathological margins.

RESULTS

Nine patients lived without disease for 20 to 93 months (mean interval, 52 mo) after surgery; among them, eight patients had T1 tumors that were resected totally by surgery via anteroposterior approaches and the other patient had postoperative irradiation to control the disease. Seven patients had local recurrence 8 to 21 months after treatment. Four patients developed distant metastases, including one patient with a T2b tumor that was totally resected through modified facial translocation approach with ligation of internal carotid artery. Eight patients died of other causes; internal carotid artery blowout was the cause of death in four of these eight patients.

CONCLUSIONS

In most cases of recurrence, T1 nasopharyngeal tumors can be resected totally by anteroposterior approaches; for T2 or larger tumors, postoperative irradiation is usually necessary. Otherwise, facial translocation offers a better chance to completely resect the tumors. Internal carotid artery is better ligated if patients have received greater than 70 Gy irradiation or if the artery must be exposed during the surgery. We suggest that EC-IC bypass be used to avoid the possible complications (or cerebral ischemic stroke) caused by ligation of internal carotid artery. The transmaxillary approach is favored in the management of nasopharyngeal tumor recurrence with nasal cavity extension, and midline mandibulotomy is more suitable for resection of posterior margin of nasopharyngeal tumor recurrence. Facial translocation offers the widest operative field and is the most versatile approach for radical resection of nasopharyngeal tumor recurrence, but the surgeon should be skilled in the management of the facial nerves to reduce morbidity.

Activation of MAD 2 checkprotein and persistence of cyclin B1/CDC 2 activity associate with paclitaxel-induced apoptosis in human nasopharyngeal carcinoma cells

Paclitaxel (Taxol) is a microtubule-interfering agent that induced persistent and transient G2/M arrest before apoptosis in human nasopharyngeal carcinoma (NPC) cells at high and low concentrations, respectively. In this study, we intended to explore the underlying molecular events and found that cellular cyclin B1/CDC 2 kinase activity was increased and persisted for >6 h upon paclitaxel treatment both at high and low concentrations. Furthermore, activation of MAD 2 checkprotein could account for the loss of cyclin B1 ubiquitination and the persistence of cyclin B1/CDC 2 activation in the cases. To investigate the involvement of cyclin B1 and MAD 2 activation in paclitaxel-induced apoptosis, we introduced affinity-purified anti-cyclin B1 and MAD 2 antibodies into NPC cells by electroporation before the further paclitaxel treatment. The antibodies against cyclin B1 and MAD 2 indeed attenuated paclitaxel-induced cytotoxicity and DNA fragmentation. Our study suggests that activation of cyclin B1/CDC 2 and MAD 2 were the M-phase events required for paclitaxel-induced apoptosis in NPC cells. The dys-regulated cyclin B1/CDC 2 activation could enhance the prometaphase progression, but activation of MAD 2 rendered cells inable to exit from the metaphase. Under this circumstance, cells were probably going to "mitotic catastrophe" and ultimately, destined to apoptosis.

Prevalence of the Taiwan variant of the Epstein-Barr virus in nasopharyngeal carcinoma patients and normal individuals

BACKGROUND

Latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV) is a potentially oncogenic protein, able to inhibit differentiation and induce transformation of epithelial cells. The LMP1 gene sequence of EBV in nasopharyngeal carcinoma (NPC) differs from that of EBV in B95-8 cells. A change of nucleotide at the XhoI site results in loss of the restriction site in the EBV LMP1 gene from NPC, and this of EBV is designated as the Taiwan variant. In this study, we further investigated the Taiwan variant of EBV in nasopharyngeal biopsies and throat washings of NPC patients and normal controls.

METHODS

DNA was extracted from nasopharyngeal biopsies of 22 NPC patients and 40 normal controls, and from throat washings of 28 NPC patients and 78 normal controls. The DNA was amplified by polymerase chain reaction (PCR) using LMP1 gene-specific primers, then the EBV variant was identified by analysis with the XhoI restriction enzyme.

RESULTS

The LMP1 gene was detected in all NPC tumors, in only 25 of 40 normal nasopharyngeal biopsies, and in 12 of 28 and 44 of 78, respectively, throat washings of NPC patients and normal controls. The Taiwan variant was detected in 84.1% to 100% of EBV isolates. The distribution of Taiwan variant EBV was not statistically different between the NPC group and normal controls in either nasopharyngeal biopsies or throat washings.

CONCLUSIONS

The results indicate that, based on XhoI restriction site analysis, the Taiwan variant of EBV is the predominant EBV strain in NPC patients and normal individuals in Taiwan.

In vitro evaluation of GL331's cancer cell killing and apoptosis-inducing activity in combination with other chemotherapeutic agents

GL331 is a novel podophyllotoxin-derived compound and is more efficacious than its congener VP-16 in killing several types of cancer cells, that has promoted considerable interest in its possibility of clinical use. In this study, we found that the higher cytotoxicity of GL331 in nasopharyngeal carcinoma NPC-TW01 cells was attributed to the elevated ability to induce apoptotic cell death. In addition to evaluation of GL331's single agent activity, the use of GL331 in combination with other established therapeutic agents was also evaluated. We found that GL331-induced cell cycle perturbation occurred upon initial 8-h exposure, and pretreatment of NPC-TW01 cells with GL331 for 8 h significantly interfered with the cytotoxicities of VP-16, cisplatin, 5-fluorouracil and adriamycin. When the schedule of drug administration was reversed, high-toxic concentrations of these agents revealed an antagonistic effect on GL331; however, their low-toxic doses had the additive or even more-than-additive effect on the cytotoxicity induced by GL331 at 0.1 microM or less, but for GL331 concentrations of greater than 1 microM, the effect became less than additive. These data suggest that overlapping mechanisms could be elicited by GL331 and other agents, and additional preclinical studies are needed to determine the optimal dose combination and administration schedule that will enhance, rather than interfere with, the efficacy of GL331 in combination with other anti-cancer agents.

Salvage surgery for recurrent nasopharyngeal carcinoma in anterior marginal miss after radiotherapy

Nasopharyngeal carcinoma (NPC) is treated primarily by radiotherapy. Marginal miss after radiotherapy is a potential cause for treatment failure in NPC. Anterior marginal miss after irradiation results in recurrent tumors in the nasal cavity outside the nasopharynx. From 1991 to January 1997, 6 recurrent NPCs arising in the anterior marginal miss zone after radiotherapy were confirmed by pathologic and radiologic evaluation. One patient had infiltrating growth of the original NPC tumor into the anterior part of nasal septum, and the other 5 had microscopic extensions from the original NPC tumors into the nasal cavity that were beyond detection by endoscopy or CT scan. In some cases the tumors extended further to include the hard palate or the lacrimal sac. Medial maxillectomy and partial maxillectomy with or without resection of the hard palate were necessary to encompass the extent of the tumors. Surgical margins were free of cancer cells in 5 patients. No further treatment was given in these 5 patients. Another patient with tumor extending to the lacrimal sac received postoperative radiotherapy. Five of the 6 patients survived with no evidence of disease for 8 to 65 months. One patient had distant metastasis 14 months after surgery but was free from tumor at the primary site. Radical surgery can result in good and sustained local control for anterior marginal miss of NPC after radiotherapy.

A novel podophyllotoxin-derived compound GL331 is more potent than its congener VP-16 in killing refractory cancer cells

PURPOSE

GL331 is a new homolog of VP-16, and has demonstrated more efficacious anti-cancer activity in both the in vitro and in vivo lymphoma systems. To extensively explore GL331's clinical value, we furthermore evaluate the cytotoxicity and apoptosis-inducing activity of GL331 in several human cell lines from cancers that are not normally treated with VP-16.

METHODS

By MTT and clonogenic survival assays, the cytotoxicities of GL331 and VP-16 were evaluated in a variety of cell lines including nasopharyngeal, hepatocellular, gastric, colon, cervical, and neuroblastoma cancer types. Western blot analysis was performed to detect the MDR-1 level in these cell lines. By Annexin V-staining flow cytometry and detection of DNA ladders, the apoptosis-inducing activities of GL331 and VP-16 were also evaluated.

RESULTS

GL331 showed more efficacy than its congener VP-16 in killing cancer cells. The estimated ID50 of GL331 were 2.5 to 17-fold lowerthan those of VP-16. GL331 possessed more cell-killing activity even in MDR-1-overexpressing cell lines such as HCC36 and SW620. Its higher cytotoxicity could be attributed by the elevated ability to induce apoptotic cell death.

CONCLUSION

GL331's overriding drug resistance and higher cancer cell-killing activity suggest its superiority in clinical cancer therapy.

Detection of IgA against Epstein-Barr virus BZLF-1 replication activator (ZEBRA) in sera of nasopharyngeal carcinoma patients with a recombinant ZEBRA protein

BACKGROUND

Epstein-Barr virus (EBV) is closely associated with nasopharyngeal carcinoma (NPC). An EBV-encoded immediate-early antigen, BZLF-1 replication activator (ZEBRA) initiates EBV replication and expression in all NPC tumors. In this study, we investigated whether immunoglobulin A (IgA) against ZEBRA is present in the sera of patients with NPC, and whether it was able to be determined by enzyme-linked immunosorbent assay (ELISA) using a recombinant ZEBRA prepared from Escherichia coli.

METHODS

A polymerase chain reaction-amplified cDNA fragment of the ZEBRA gene was inserted into the expression vector of E coli under the control of an IpL promoter. E coli bacteria containing the CI857 gene served as host to overexpress the ZEBRA protein by heat induction. Recombinant ZEBRA was collected by mechanical disruption of the bacteria, purified by column chromatography, and analyzed by SDS-PAGE and Western blot assay using sera from NPC patients. The recombinant ZEBRA was used to develop the ELISA to detect IgA against ZEBRA.

RESULTS

The amount of ZEBRA produced comprised 30% of total E coli protein. Western blot assay confirmed that affinity of the recombinant ZEBRA to IgA antibody was preserved. IgA against ZEBRA was shown to be positive by ELISA in 36 of 40 NPC sera, but in only nine of 55 patients with other head and neck malignancies, and two of 35 normal individuals. For serologic diagnosis of NPC, the sensitivity of IgA/ZEBRA detected by ELISA was 90% and the specificity was 87.4%.

CONCLUSIONS

A recombinant ZEBRA was produced at high levels in E coli and retained affinity to IgA against ZEBRA. The recombinant ZEBRA was successfully used to develop an ELISA for the detection of IgA against ZEBRA. The high sensitivity and specificity of IgA against ZEBRA show that the ELISA is feasible for serologic diagnosis of NPC.

Chromosomal aberrations in nasopharyngeal carcinoma analyzed by comparative genomic hybridization

To investigate the genomic imbalances associated with nasopharyngeal carcinoma (NPC), we have performed chromosome analysis by comparative genomic hybridization (CGH) on 51 tumors, including 25 primary and 26 recurrent tumors. The most common copy number increases occurred on chromosome arms 12p (59%), 1q (47%), 17q (47%), 11q (41%), and 12q (35%). The minimal overlapping regions were at 12p12-13, 1q21-22, 17q21, 17q25, 11q13, and 12q13. The most frequent losses were from chromosome arms 3p (53%), 9p (41%), 13q (41%), 14q (35%), and 11q (29%). The minimal overlapping regions were at 3p12-14, 3p25-26, 9p21-23, 13q21-32, 14q12-21, and 11q14-23. Compared with the primary cancers, no additional chromosomal change was found in the recurrent tumors; however, the most frequent gain in the recurrent NPCs was at 11q13 (53%) instead of 12p in the primary tumors. An increase of gene alterations correlated with clinical stage. Our results provide a first comprehensive view of the genomic changes associated with NPC and reveal several new sites of genomic imbalance, indicating the possible involvement of novel oncogenes/tumor suppressor genes in the carcinogenesis of NPC.

Malignant otitis externa

BACKGROUND

Malignant otitis externa is an infrequent but severe infection of the external auditory canal, most often affecting elderly diabetic patients. Early diagnosis is necessary due to its high morbidity and mortality.

METHODS

From 1990 to 1997, all patients with malignant otitis externa at the Veterans General Hospital-Taipei were reviewed retrospectively. The clinical features and the strategy of diagnosis and treatment are discussed.

RESULTS

Twelve patients with an average age of 65.3 years were included. Eleven of these patients were diabetic. All had the presenting symptoms of otalgia and otorrhea at diagnosis. Bacterial cultures grew Pseudomonas aeruginosa in eight patients and methicillin-resistant Staphylococcus aureus in four patients. The mean duration of admission was 82 days. Appropriate antibiotics were given according to the results of bacterial culture and sensitivity test. 99Technetium scans and 67gallium scans were performed to evaluate the extent of involvement and monitor the effects of treatment. Eventually, four patients died due to renal failure, meningitis, pneumonia and upper gastrointestinal bleeding, respectively.

CONCLUSIONS

Malignant otitis externa is a life-threatening infection arising from the external auditory canal. A high degree of suspicion for malignant otitis externa is mandatory. Vigorous local and systemic antimicrobial treatment should be initiated early in the course of the disease to achieve a satisfactory outcome. 99Technetium and 67gallium scans are important for the diagnosis and evaluation of the treatment results.

cAMP mediates transepithelial K+ and Na+ transport in a strial marginal cell line

Because cytoplasmic cAMP has been reported to be the secondary messenger mediating K+ transport in marginal cells of freshly isolated stria vascularis, the possible role of cAMP in ion transport processes of an immortalized marginal cell line (MCPV-8) showing evidence of K+ and Na+ reabsorption was evaluated in this study. Confluent MCPV-8 monolayers were mounted into Ussing chambers and perfused on both sides with perilymph-like Ringer's solution. Transepithelial short-circuit current (I(SC)), resistance (R(T)) and open-circuit voltage (V(T)) were measured using voltage clamp technique. The following results were obtained. (1) Addition of forskolin (10(-4) M) to the basolateral perfusate increased I(SC) to 311 +/- 42%; no significant change in RT was observed. Addition of BaCl2 (2 mM) to the apical perfusate at the maximal response of forskolin blocked 50-60% of I(SC) and subsequent addition of amiloride (10(-5) M) to the apical perfusate further blocked I(SC) to a value close to 0. (2) To evaluate the effect of cellular cAMP on Ba2+-sensitive K+ current, amiloride-sensitive Na+ current was blocked first by addition of amiloride (10(-5) M) to the apical perfusate; subsequent addition of 3-isobutyl-1-methylxanthine (IBMX, 1 mM) or N6,2'-O-dibutyryladenosine 3',5'-cyclic monophosphate (dbcAMP, 1 mM) to the basolateral perfusate increased I(SC) to 175 +/- 13 and 411 +/- 32%, respectively. The stimulated I(SC) was blocked to close to 0 by addition of BaCl2 (2 mM) to the apical perfusate. N2,2'-O-Dibutyrylguanosine 3',5'-cyclic monophosphate (dbcGMP, 1 mM) had no effect on I(SC). (3) To assess the effect of cellular cAMP on amiloride-sensitive Na+ current, Ba2+-sensitive K+ current was blocked in advance by addition of BaCl2 to the apical perfusate; subsequent addition of IBMX or dbcAMP to the basolateral perfusate increased I(SC) to 219 +/- 21% and 388 +/- 39%, respectively. The stimulated I(SC) was blocked to close to 0 by addition of amiloride to the apical perfusate. dbcGMP had no effect on I(SC). Hence, these results suggest that cellular cAMP is the secondary messenger that mediates the transepithelial transport of both K+ and Na+ in MCPV-8 monolayers.

Effects of acute brainstem compression on auditory brainstem response in the guinea pig

BACKGROUND

The purpose of this study was to establish the norm for parameters of auditory brainstem response (ABR) in the guinea pig and to investigate if acute brainstem compression results in significant changes to these parameters.

METHODS

Thirty-six guinea pigs with positive Preyer's reflex were anesthetized. A craniectomy was performed to remove the right occipital bone and the dura mater was opened to expose the brain, cerebellum and cerebellopontine angle (CPA). A small inflatable balloon was placed into the CPA precisely and slowly. ABR was recorded before incision of the skin as a baseline value, after placement and after inflation of the balloon with water at 0.1-ml intervals.

RESULTS

Five stable peaks were recorded in 27 experimental animals. When the balloon was inflated with 0.1 ml water, the absolute latency (AL) of peaks IV and V and the interpeak latency (IPL) of peaks III and IV, and IV and V were prolonged. The amplitude ratios (AR) of peaks II, III, IV and V to peak I decreased. Inflation of the balloon with 0.2 ml of water caused further elongation of ALs of peaks IV and V and decreases in each AR. When the balloon volume increased to 0.3 ml, peak V became unrecognizable and peaks III and IV showed significant elongation of AL; peaks I and II did not show significant change in ALs. Further increase of the balloon volume to 0.4 ml resulted in disappearance of peaks III, IV and V; AL of peak II was also elongated. However, the amplitude and AL of peak I remained unchanged. Similar changes were observed in IPLs.

CONCLUSIONS

This study establishes the norm of parameters of ABR in guinea pigs and demonstrates that acute brainstem compression causes elongation of ALs and IPLs of peaks II, III, IV and V. This suggests that peaks II, III, IV and V come from the brainstem and that peak I is not generated from the brainstem in the guinea pig.

Establishment and characterization of a strial marginal cell line maintaining vectorial electrolyte transport

E6/E7 genes of human papilloma virus type 16 were used to immortalize a primary culture of marginal cells (MC) from gerbils. One of the cloned lines was selected which demonstrated preservation of the main characteristics of the MC, both morphologically and physiologically. Electron microscopic examination showed well-developed junctional complexes and apical microvilli which suggested its epithelial origin. Polymerase chain reaction (PCR) demonstrated the incorporation of E6/E7 genes with the genome. Reverse transcription PCR revealed the existence of mRNA of the IsK channel, a unique marker of MC among the inner ear cells, in this clone. Flow cytometric analysis of this cell line's DNA content was diploid. Numerous large domes formed after confluence of the cell monolayer. Electrophysiologic studies displayed evidence of apical K+ and Na+ channels which were blocked by Ba2+ (2 mM) and amiloride (10(-5) M), respectively. Existence of basolateral Na,K-ATPase and Na+/Cl-/K+ cotransporter was shown by blockage by ouabain (10(-3) M) and bumetanide (50 microM), individually. Injection of the cell line to nude mice failed to induce growth of tumors. This cell line was serum-, density- and anchorage-dependent when cultured in plastic dishes. In conclusion, this cell line shows characteristics of well-differentiated MC maintaining the major ionic transport processes, and provides us a good model to study the possible mechanisms and regulating factors of endolymph production.

Activation of CDC 25 phosphatase and CDC 2 kinase involved in GL331-induced apoptosis

CDC 25 is a dual phosphatase responsible for dephosphorylation and, thus, activation of CDC 2 kinase in G2. Abnormal activation of cyclin B-associated CDC 2 kinase has been implicated in apoptosis induced by cancer chemotherapeutic agents such as paclitaxel (Taxol) and etoposide (VP-16). In this study, we found that the CDC 2 kinase could be transiently activated when nasopharyngeal carcinoma NPC-TW01 cells were treated for 3 h with a new anticancer agent, GL331. GL331 treatment also induced a concomitant increase in CDC 25A phosphatase activity and a reduced level of Tyr-15-phosphorylated CDC 2 in NPC-TW01 cells. Furthermore, subsequent apoptotic DNA fragmentation induced by GL331 could be interrupted by treatment of the cells with the cyclin B1-specific antisense oligonucleotides, suggesting that abnormal activation of cyclin B1-associated CDC 2 kinase and CDC 25A phosphatase was involved in GL331-induced apoptosis. Raf-1 has been shown to associate with CDC 25A and, thus, to stimulate its phosphatase activity. Our results revealed that GL331 could facilitate the association of CDC 25A with Raf-1, resulting in the cascade of CDC 25A phosphatase activation and CDC 2 kinase activation, as well as related signaling pathways, and ultimately causing apoptosis in cancer cells.

Identification of a promoter for the latent membrane protein 1 gene of Epstein-Barr virus that is specifically activated in human epithelial cells

Latent membrane protein 1 (LMP 1) is one of two Epstein-Barr virus (EBV)-encoded proteins that expressed in nasopharyngeal carcinoma (NPC) cells. Previous studies showed that a 3.5-kb transcript of the LMP 1 gene, in addition to the 2.8-kb transcript, was detected in a B95-8-EBV-containing, nude mice-passaged NPC tumor, C15. This indicated that a transcript was initiated from a region 5' to the putative promoter, ED-L1. We have isolated an EBV variant from a NPC tissue, and this virus strain contained a more pathogenic LMP 1 gene. DNA sequence analysis of the 5'-upstream region showed distinct variations as compared to that of B95-8 strain. To test if the LMP 1 gene of the NPC strain also contained an upstream promoter, we generated a series of deletion plasmids encompassing positions -1,030 to +20 of the LMP 1 promoter and tested for their abilities to drive the expression of the reporter gene in human epithelial cell lines, C-33A and NPC-TW076. We found that the region between -643 and -496 contained a promoter activity that was approximately five-fold higher than the putative promoter, ED-L1. This region between -643 and -496 was designated as ED-L1E. C-33A cells containing the genomic clone pT7(E) or the clone that had deleted a 94-bp ED-L1 sequence (delta94) was used to determine the transcription initiation sites by RNase protection assay. Results showed that a transcription initiation site was located at nucleotide 170,099 ("A") of EBV genome. The transcript was expressed in NPC biopsies and in human primary normal epithelial cells transfected with pT7(E) and delta94, respectively, as examined by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Furthermore, the ED-L1E was not regulated by the EBV-encoded nuclear antigen 1-mediated transcriptional enhancer family of repeats (FR) in C-33A cells. Our results suggested that the ED-L1E was specifically activated in epithelial cells. The biological significance of the selective usage of the ED-L1E promoter was discussed.

A phase II study of carboplatin in nasopharyngeal carcinoma

This is a phase II study to evaluate the efficacy and toxicity of short-course carboplatin in advanced-stage nasopharyngeal carcinoma (NPC). Thirty-three previously untreated stage III-IV NPC patients were studied. Carboplatin was given as a rapid intravenous injection every 3 weeks. The dose of carboplatin was calculated according to the individual patient's creatinine clearance and desired platelet nadir of 75,000/microliter according to the Egorin formula. Response and toxicity were evaluated. Thirty-two patients were evaluated for response. The median age was 54 years, range 30-70 years. Twenty-four patients had local regional disease and 8 patients had metastatic disease. The median dose of carboplatin given was 415 mg/m2 (range 91-791 mg/m2). Fourteen (44%) patients had a partial response with a 95% confidence interval of 26-62%. Fifteen (47%) patients had stable disease and 3 (9%) progressive disease. The overall median survival rate was not reached at 43 months. Overall toxicity was tolerable. Grade III-IV myelosuppression occurred in 4 (12%) patients. There were no other major toxicity- or treatment-related deaths. We conclude that carboplatin has a significant anticancer effect in advanced NPC. Thus carboplatin combination chemotherapy for the treatment of NPC is worthy of future clinical investigations.

Protein tyrosine phosphatase activities are involved in apoptotic cancer cell death induced by GL331, a new homolog of etoposide

GL331 is a semisynthetic topoisomerase II inhibitor derived from a plant toxin podophyllotoxin. In 72-h exposure assays, LD50 values of GL331 range from 0.5 to 2 microM, which are three- to ten-fold lower than those of its homologous compound etoposide (VP-16), depending on different cancer cell lines including nasopharyngeal, hepatocellular, gastric, cervical and colon cancer types. Apoptotic DNA ladders could be detected when cancer cells were treated with GL331 for 24 h even if the Bcl-2 and Bax protein levels were not altered during the period. Besides acting as topoisomerase II inhibitors, both GL331 and VP-16 decrease the cellular protein tyrosine kinase (PTK) activities in cancer cells. The activities of protein tyrosine phosphatase (PTP) are significantly increased after GL331 treatment but are not affected by VP-16. GL331-induced internucleosomal cleavage can be efficiently prevented by two inhibitors of PTP, sodium orthovanadate and zinc chloride, but not by okadaic acid, which inhibits serine/threonine phosphatase activity. These results indicate that GL331 may induce apoptotic cell death, and that activation of protein tyrosine phosphatases may be involved in this process.

Kinetics of continuous GM-CSF production by recombinant Saccharomyces cerevisiae in an airlift bioreactor

Continuous production of murine GM-CSF by recombinant Saccharomyces cerevisiae in an airlift bioreactor was studied at three different dilution rates. The reactor was initially fed with a selective medium to increase cell concentration, and then was fed with a rich, nonselective medium for GM-CSF production. Ethanol was used as the main carbon source to provoke GM-CSF expression. In continuous culture, GM-CSF production was maintained for over 150 h, even though the fraction of plasmid-carrying cells continuously dropped to lower than 20%. The stable GM-CSF production during the later phase of the continuous culture was attributed to increased specific cell productivity possibly resulting from an increase in the plasmid copy number in plasmid-carrying cells. This also indicated the possibility of natural selection of high-copy number cells in continuous culture. Plasmid stability was found to be growth rate (dilution rate) dependent; it increased with the dilution rate. Reactor productivity and specific productivity also increased with the dilution rate. A two-parameter kinetic equation was used to model the plasmid stability kinetics. The growth rate ratio between plasmid-carrying and plasmid-free cells increased from 0.996 to 0.998 while the segregational instability or the probability of plasmid loss from each cell division increased from 1.1% to 16% as the dilution rate decreased from 0.11 h-1 to 0.05 h-1. Oscillation of the dilution rate between 0.05 h-1 and 0.11 h-1 stabilized the plasmids and gave a higher productivity than that achieved without oscillation.

Kinetics and stability of GM-CSF production by recombinant yeast cells immobilized in a fibrous-bed bioreactor

The continuous production of murine granulocyte-macrophage colony-stimulating factor (GM-CSF) by recombinant yeast cells immobilized in a fibrous-bed bioreactor was studied. A high cell density of approximately 68 g/L and a GM-CSF productivity of approximately 3.5 mg/L.h were attained in the fibrous-bed bioreactor-fed with a rich (nonselective, pH 6.7) medium at a dilution rate of 0.16 h-1. The GM-CSF production was stable even though the fraction of plasmid-carrying cells in the reactor effluent gradually dropped below 5% over a period of 2 weeks. At the end of that period, the immobilized cells in the fibrous matrix still had a high fraction, approximately 26%, of plasmid-carrying cells. Similar results were obtained with reactors operated at 0.05 h-1 dilution rate and pH 4.0. Although the GM-CSF production was lower at pH 4, the reactor was stably operated for over 4 weeks without contamination or significant loss of productivity. The stable long-term GM-CSF production from the fibrous-bed bioreactor was attributed to the effect of cell immobilization on plasmid stability. Because GM-CSF production was growth-associated, as was found in batch fermentation with free cells, this stabilization effect cannot be attributed solely to the reduced cell growth in the immobilized cell environment. Plasmid-carrying cells were preferentially retained in the fibrous matrix, perhaps because their abilities to adhere to the fiber surface and to form cell aggregates were higher than those of plasmid-free cells.

Elimination of dose limiting toxicities of cisplatin, 5-fluorouracil, and leucovorin using a weekly 24-hour infusion schedule for the treatment of patients with nasopharyngeal carcinoma

BACKGROUND

Cisplatin, 5-flourouracil (5-FU), and leucovorin (PFL) chemotherapy has been reported to be effective in the treatment of cancers but severe mucositis or neutropenia are dose limiting toxicities. This Phase II study evaluated the anticancer effect and the toxicities of a new weekly 24-hour infusional PFL chemotherapy in patients with nasopharyngeal carcinoma (NPC).

METHODS

Forty-two patients with stage IV NPC were studied. Cisplatin 25 mg/m2/d, 5-FU 2200 mg/m2/d, and leucovorin 120 mg/m2/d were adminstered weekly by 24-hour intravenous continuous infusion in an outpatient setting. Clinical response and toxicity were evaluated weekly.

RESULTS

The complete response rate (CR) was 30% and the partial response (PR) rate 60% in the localized previously untreated group. The CR rate was 22.7% and PR rate 45.5% in local recurrent/metastatic group. The overall response rate was 79%. Eighty-one percent of patients who had no previous chemotherapy and 67% of patients who had previous chemotherapy responded to weekly PFL. There were no dose limiting toxicities. No patient had grade 3 or 4 mucositis or neutropenia. Thirty-two patients (76%) had no oral mucositis. Seven patients (17%) had grade 1 mucositis and 3 patients (7%) had grade 2 mucositis.

CONCLUSIONS

Elimination of dose limiting toxicities is possible using a weekly 24-hour infusion schedule of PFL chemotherapy while retaining significant anticancer activity as demonstrated in these patients with advanced NPC. To discover whether this schedule is superior to cisplatin and 5-FU or other PFL chemotherapy regimens requires further investigation.

Detection of an Epstein-Barr-virus variant in T-cell-lymphoma tissues identical to the distinct strain observed in nasopharyngeal carcinoma in the Taiwanese population

An EBV variant has been identified in NPC tissues in Taiwan. This EBV variant contains a point mutation in exon I of the LMP I gene. This mutation results in the loss of an XhoI site at nt 169,426, which is present in strain B95-8. In addition, this variant contains a 30-bp deletion in exon 3 of the gene. The recent demonstration of the prevalence of EBV-containing nasal and peripheral T-cell lymphoma in this region drove us to evaluate the presence of this NPC-EBV strain in 7 cases of T-cell lymphoma, as well as in 48 NPC tissues, 2 cases of Hodgkin's disease and I B-cell lymphoma. Four samples of normal lymph node tissue, 40 of normal nasopharynx tissue and 78 throat washings of healthy individuals were included for comparison. We used sequence-specific primers and the polymerase chain reaction (PCR) method to amplify LMP I gene fragments containing these variations. Mutations were then confirmed by restriction-enzyme digestion and the DNA sequencing analysis. Our results showed that 57 of 58 tumor-tissues samples were EBV-positive. Among them, 56, including 6 T-cell-lymphoma samples, belonged to the NPC strain. This strain of EBV was also present in 92% of EBV-positive normal nasopharynx tissues and in 84% of EBV-positive throat washings of the healthy individuals tested. These results suggest that the NPC-EBV strain is prominently present in Taiwan.

Metastatic nasopharyngeal carcinoma with epidural spinal cord compression: report of an unusual and catastrophic event

Nasopharyngeal carcinoma (NPC) with epidural metastasis of spinal cord has rarely been reported. We present an NPC patient with epidural spinal cord compression due to metastasis. In spite of emergent radiotherapy and large dose decadron treatment, this patient still had severe sequela of paraplegia and incontinence. The epidemiology, clinical findings, diagnosis, treatment and outcome of this metastatic epidural tumor compression were discussed.

Expression of the Epstein-Barr virus DNA polymerase in Escherichia coli for use as antigen for the diagnosis of nasopharyngeal carcinoma

Epstein-Barr virus (EBV) encoded DNA polymerase (POL) was cloned and over-expressed in Escherichia coli. Western blot analysis confirmed the presence of antibody to this POL protein in sera from nasopharyngeal carcinoma (NPC) patients. By Western blot analysis, moderate to high concentration of IgG POL-specific antibodies were present in 43 of 48 NPC sera and only 4 of 48 healthy, seropositive controls. The POL-specific IgG antibodies appear as early as stage I of NPC, suggesting that the recombinant POL protein can be a useful diagnostic marker for early diagnosis of the disease. It was also found that human sera containing high titer of cytomegalovirus (CMV) antibodies or herpes simplex virus type 1 (HSV-1) antibodies did not cross-react with the recombinant EBV POL, despite the homology shared by DNA polymerase proteins of these viruses.

Detection of Epstein-Barr virus and human papillomavirus in head and neck tumors

The presence of Epstein-Barr virus (EBV) DNA and human papillomavirus (HPV) DNA in 74 head and neck tumor tissues was examined by the polymerase chain reaction and DNA sequencing analysis. EBV DNA sequence was detected in all 30 nasopharyngeal-carcinoma tissue samples and in 30 of 44 other head and neck tumor samples. HPV DNA sequence was detected in 14 of 30 nasopharyngeal-carcinoma tissue samples and in 11 of 44 other tumor samples. Coinfection of both viruses was observed in 14 nasopharyngeal-carcinoma tissue samples but only in 5 other head and neck tumor samples including 3 hypopharyngeal-carcinoma tissue samples. Our data indicate that EBV is closely associated with nasopharyngeal- carcinoma and may also be related to hypopharyngeal-carcinoma. In addition, a relatively high percentage of EBV-positive nasopharyngeal- and hypopharyngeal-carcinoma tissue specimens contained HPV sequence. The significance of the coexistence of EBV and HPV in these tumor tissues requires further study.

Detection of mutations in the p53 gene in human head and neck carcinomas by single strand conformation polymorphism analysis

Using the polymerase chain reaction (PCR)-based single strand conformation polymorphism (SSCP) analysis, we have examined the highly conserved regions of the p53 gene in 58 biopsy samples of head and neck tumors. Mutations were found in 13/58 (23%) tumor specimens, but not in 6 normal tissues. Ten of 13 mutations were due to single base changes and the remaining 3 were 1- or 8-base deletion mutants. These mutations were clustered in exons 5 and 7 and resulted in amino acid changes. Our results seem to indicate that mutations in the p53 gene contribute to a significant number of cases of the head and neck tumors including 20% of nasopharyngeal carcinoma biopsies. The relationship of Epstein-Barr virus or human papillomavirus and p53 gene mutations in this group of cancers was also analyzed and discussed.

Cloning and characterization of the latent membrane protein (LMP) of a specific Epstein-Barr virus variant derived from the nasopharyngeal carcinoma in the Taiwanese population

A DNA fragment containing Epstein-Barr virus (EBV) terminal fragment sequence was obtained from a genomic library of nasopharyngeal carcinoma (NPC). One of the clones (clone 1510) contained the gene encoding latent membrane protein (LMP). Sequence analysis revealed that this gene had 95% homology with the LMP sequence of the B95-8 strain. Among the sequence variations, there was a change from G to T at nucleotide position 169,426, resulting in the loss of an XhoI site in exon 1 of the LMP gene. A pair of primers bracketing the XhoI site were designed to synthesize the EBV DNA fragment from nucleotides 169,081-169,577 by using the polymerase chain reaction (PCR) method. The PCR products were then subject to XhoI digestion and to DNA sequencing analysis. This restriction enzyme site polymorphism along with the sequence variations were also observed in 50 biopsy tissues as well as in the throat washings of 6 out of 20 healthy individuals that we examined, indicating that the EBV strain predominantly existing in these biopsy tissues was different from strains of B95-8, Jijoye or nude mouse passaged cells (C15) with an African origin, but closely resembled other nude mouse passaged CAO cells which were originally derived from China. Balb/c 3T3 cells carrying this NPC-LMP gene showed a transformed cell morphology and were tumorigenic in nude mice. The relationship between this unique type of EBV and NPC has yet to be established.

Distribution of type A and type B EBV in normal individuals and patients with head and neck carcinomas in Taiwan

The subtypes of Epstein-Barr virus (EBV) according to the EBNA 2 gene were investigated in Taiwan by the polymerase chain reaction (PCR) and by Southern blot hybridization. The materials included 53 nasopharyngeal carcinoma (NPC) biopsies, 49 other head and neck cancers and 32 throat washings of normal individuals. EBV DNA was found in all NPC biopsies, 27 of 49 other head and neck carcinomas and 81% of normal individuals. Type A EBV was the predominant type of EBV in both normal individuals and patients with head and neck carcinomas in Taiwan. Type B EBV or coexistence of the A and B types comprised a small number of samples in this study.

Distribution of type A and type B EBV in patients with nasopharyngeal carcinoma

The subtypes of Epstein-Barr virus (EBV) according to EBNA 2 genes were investigated in 53 nasopharyngeal carcinoma (NPC) biopsies in Taiwan by polymerase chain reaction (PCR) and by Southern blot hybridization method. EBV DNA was found present in all NPC biopsies. Type A was the predominant type and comprised of 94.3% of the EBV of NPC. Type B or coinfection of type A and type B comprised of only 3.8% and 1.9% respectively.

Polymorphic reticulosis: a malignant lymphoma of B-cell lineage

Whether the pathogenesis of polymorphic reticulosis is from T cells, B cells, or histiocytes has been controversial. In this study, the Southern blot hybridization technique was used to analyze immunoglobulin and T-cell receptor beta-chain genes and to perform the conventional surface marker analysis in two patients with polymorphic reticulosis. The immunophenotype demonstrated the presence of predominantly mature, activated T-lymphocytes, minimal B-cells, and no natural killer cells or monocytes/granulocytes. The mature T-cell phenotype could be due to either inflammatory infiltrates or neoplastic cells of peripheral T-cell type, because the two coexist in polymorphic reticulosis tumors. The value of surface marker examination is limited in the analysis of PMR tumors. However, genetic analysis revealed that only Ig genes were rearranged, with no rearrangement of the TCR beta gene. Rearrangement of immunoglobulin genes occurs in B-lineage lymphoid neoplasms and is thought to be a criterion for diagnosis of lymphoid neoplasms. Based on genetic analysis and clinicopathologic information, this study concluded that polymorphic reticulosis is a malignant lymphoma of B-cell lineage.