Reversal of multidrug resistance by two nordihydroguaiaretic acid derivatives, M4N and maltose-M3N, and their use in combination with doxorubicin or paclitaxel

PURPOSE

Multidrug resistance (MDR) continues to be a major obstacle for successful anticancer therapy. One of the principal factors implicated in MDR is the over expression of P-glycoprotein (Pgp), the product of the MDR1 gene.

METHODS

Here we explore the possibility of using the transcription inhibitor tetra-O-methyl nordihydroguaiaretic acid (M4N) to inhibit Sp1-regulated MDR1 gene expression and restore doxorubicin and paclitaxel sensitivity to multidrug resistant human cancer cells in vitro and in vivo.

RESULTS

We found that M4N acted synergistically with doxorubicin and paclitaxel in inhibiting the growth of the cells in culture allowing significant dose reductions of both drugs. We observed no such synergism when M4N was used in combination with cisplatin, another chemotherapeutic agent, but not a Pgp substrate, as analyzed by the combination index and isobologram methods. Analysis of MDR1 mRNA and Pgp levels revealed that at sublethal doses, M4N inhibited MDR1 gene expression in the multidrug resistant NCI/ADR-RES cells and reversed the MDR phenotype as measured by Rhodamine-123 retention. In addition, M4N was found to inhibit doxorubicin-induced MDR1 gene expression in drug sensitive MCF-7 breast cancer cells.

CONCLUSIONS

M4N and maltose-tri-O-methyl nordihydroguaiaretic acid (maltose-M3N), a water-soluble derivative of NDGA, were also able to reverse the MDR phenotype of the tumor cells in a xenograft model system and combination therapy with M4N or maltose-M3N and paclitaxel was effective at inhibiting growth of these tumors in nude mice.

Antibody to severe acute respiratory syndrome (SARS)-associated coronavirus spike protein domain 2 cross-reacts with lung epithelial cells and causes cytotoxicity

Both viral effect and immune-mediated mechanism are involved in the pathogenesis of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) infection. In this study, we showed that in SARS patient sera there were autoantibodies (autoAbs) that reacted with A549 cells, the type-2 pneumocytes, and that these autoAbs were mainly IgG. The autoAbs were detectable 20 days after fever onset. Tests of non-SARS-pneumonia patients did not show the same autoAb production as in SARS patients. After sera IgG bound to A549 cells, cytotoxicity was induced. Cell cytotoxicity and the anti-epithelial cell IgG level were positively correlated. Preabsorption and binding assays indicated the existence of cross-reactive epitopes on SARS-CoV spike protein domain 2 (S2). Furthermore, treatment of A549 cells with anti-S2 Abs and IFN-gamma resulted in an increase in the adherence of human peripheral blood mononuclear cells to these epithelial cells. Taken together, we have demonstrated that the anti-S2 Abs in SARS patient sera cause cytotoxic injury as well as enhance immune cell adhesion to epithelial cells. The onset of autoimmune responses in SARS-CoV infection may be implicated in SARS pathogenesis.

Pycnogenol induces differentiation and apoptosis in human promyeloid leukemia HL-60 cells

Pycnogenol, rich of many phytochemicals of medical value, is a commercialized nutrient supplement extracted from the bark of European coastal pine. In this study, we investigated the anti-tumor effects of Pycnogenol on HL-60, U937 and K562 human leukemia cell lines. We found that Pycnogenol inhibited cell proliferation dose- and time-dependently, and the IC(50)s of Pycnogenol on HL-60, U937 and K562 cells were 150, 40 and 100 microg/ml, respectively. When HL-60 cells were incubated with low concentrations of Pycnogenol (50, 100 and 125 microg/ml) for 24 h, a prominent G0/G1 arrest was observed, followed by gradual accumulation of sub-G0/G1 nuclei. At 48 h of treatment, 50-70% of HL-60 cells differentiated, as evidenced by morphological changes, NBT reduction, induction of NSE activity, and increases of cell surface expression of CD11b. However, results from Annexin V/PI staining, DAPI staining and DNA fragmentation assay indicated that Pycnogenol induced HL-60, U937 and K562 cell apoptosis at their respective IC(50)s after 24 h of treatments. Pretreatment of z-DEVD-fmk, a caspase-3 specific inhibitor, not only decreased caspase-3 activity but also reduced the percentage of apoptotic cells induced by Pycnogenol. This indicated that caspase-3 activation was involved in Pycnogenol induced-apoptosis. In conclusion, Pycnogenol induced differentiation and apoptosis in leukemia cells. Our data suggest that Pycnogenol could serve as a potent cancer chemopreventive or chemotherapeutic agent for human leukemia.

Antibody-mediated endothelial cell damage via nitric oxide

Vascular disorders, resulting from endothelial cell dysfunction, may be caused by various stimuli, including infectious pathogens, cytotoxic reagents, and pathophysiological mechanisms mediated by immune responses. Endothelial cell dysfunction characterized by apoptosis and abnormal immune activation is, at least in part, induced by anti-endothelial cell antibody (AECA) in some cases of autoimmune disease. However, the molecular mechanisms of AECA-mediated pathogenetic damage to host vascular system remain unclear. The dual role of nitric oxide (NO) both in endothelial cell apoptosis and survival has been described. In this paper, endothelial cell apoptosis caused by the presence of cross-reactive AECA via a NO-mediated mechanism is demonstrated in dengue virus infection. Endothelial cells undergo apoptosis via the mitochondria-dependent pathway that is regulated by NO production. NO-regulated endothelial cell injury thus may play a role in the disruption of vessel endothelium and contribute to the AECA-induced pathogenesis of vasculopathy. The modulation of NO may provide the therapeutic strategies for autoimmune diseases by preventing the AECA-mediated endothelial cell damage.

Motorcycle emissions and fuel consumption in urban and rural driving conditions

This work reports sampling of motorcycle on-road driving cycles in actual urban and rural environments and the development of representative driving cycles using the principle of least total variance in individual regions. Based on the representative driving cycles in individual regions, emission factors for carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO(x)=NO+NO(2)) and carbon dioxide (CO(2)), as well as fuel consumption, were determined using a chassis dynamometer. The measurement results show that the representative driving cycles are almost identical in the three largest cities in Taiwan, but they differ significantly from the rural driving cycle. Irrespective of driving conditions, emission factors differ insignificantly between the urban and rural regions at a 95% confidence level. However, the fuel consumption in urban centers is approximately 30% higher than in the rural regions, with driving conditions in the former usually poor compared to the latter. Two-stroke motorcycles generally have considerably higher HC emissions and quite lower NO(x) emissions than those of four-stroke motorcycles. Comparisons with other studies suggest that factors such as road characteristics, traffic volume, vehicle type, driving conditions and driver behavior may affect motorcycle emission levels in real traffic situations.

Surgical treatment of adult idiopathic scoliosis - comparison of two instrumentations

In this study, 22 women patients with adult idiopathic scoliosis treated surgically with Cotrel-Dubousset instrumentation (CDI) or Texas Scottish Rite Hospital instrumentation (TSRHI) were followed up for 56.2+/-4.0 months. The overall immediate and final corrections were respectively 21.5+/-40 (58%) and 26.6+/-2.90 (48%), giving a loss of correction of 5.1+/-1.00 (10%). No significant differences were found in these two parameters between the two groups. The functional outcomes were good in 21 patients. There was no difference between CDI and TSRHI in deformity correction.

Arterial blood pressure and blood lipids as cardiovascular risk factors and occupational stress in Taiwan

BACKGROUND

This study is to determine whether occupational stress (defined as high psychological demands and low decision latitude on the job) is associated with increased blood pressure and abnormal level of blood lipids as cardiovascular risk factors.

METHODS

We conducted a cross-sectional study at three work sites of 526 white-collar male workers aged 20 to 66 years without evidence of cardiovascular disease. Systolic, diastolic blood pressure, serum total, high-density lipoprotein cholesterol and plasma triglyceride were measured. Occupational stress index was derived from data collected in the job strain questionnaire.

RESULTS

In multiple linear regression models, occupational stress index was significantly related to diastolic blood pressure and plasma triglyceride, after adjusting for age, education, smoking, and alcohol consumption. A higher occupational stress index was directly associated with higher systolic, diastolic blood pressure and higher level of plasma triglyceride.

CONCLUSIONS

These data from a white-collar working population confirm independent relations between occupational stress defined in the job demand-control model and diastolic blood pressure observed in predominantly Western populations and extend the range of associations to plasma triglyceride than do previous studies.

Effect of elbow flexion on upper extremity impact forces during a fall

OBJECTIVE

The overall objectives are to develop a biomechanical model for a simulated fall with outstretched hand.

DESIGN

Cross-sectional study involving young healthy volunteers in a university research laboratory setting.

BACKGROUND

Little is known about the factors which influence fracture risk during a fall on outstretched hand.

METHODS

A group of 11 male subjects volunteered for this investigation. A set of eight reflective markers was placed bilaterally on selected anatomic landmarks. Subjects were suspended with both elbows extended and wrists dorsiflexed, preparing to impact the ground and force plates from two different fall heights: 3 and 6 cm. Two different postures for the elbows were employed. In the elbow extension experiment, the elbows were extended at all times. In the elbow flexion experiment, the elbows were extended at impact, but then flexed immediately, as though in the initial downward phase of a push-up exercise.

RESULT

Increasing the fall height significantly increased the upper extremity axial forces by 10% and 5%. No significantly different differences were found in the axial forces applied to the wrist, elbow or shoulder between the elbow flexion and elbow extension trials, but the elbow mediolateral shear force was 68% larger (P=0.002) in the extension trials.

CONCLUSIONS

Performing an elbow flexion movement at impact reduces the first peak impact force value and postpones the maximum peak value. Although changing the fall arrest strategy from elbow extension to elbow flexion did not affect the peak impact force on the hand, it did require substantially greater elbow and shoulder muscle strengths.

RELEVANCE

This paper yields insights into how the physical demands of arresting mild falls may relate to upper extremity muscle capacity, joint dislocation and bony fracture.

Sequence influence of nonidentical InGaAsP quantum wells on broadband characteristics of semiconductor optical amplifiers--superluminescent diodes

Extremely broadband emission is obtained from semiconductor optical amplifiers-superluminescent diodes with nonidentical quantum wells made of InGaAsP/InP materials. The well sequence is experimentally shown to have a significant influence on the emission spectra. With the three In(0.67) Ga(0.33) As(0.72) P(0.28) quantum wells near the n -cladding layer and the two In(0.53) Ga(0.47) As quantum wells near the p -cladding layer, all bounded by In(0.86) Ga(0.14) As(0.3)P(0.7) barriers, the emission spectrum could cover from less than 1.3 to nearly 1.55 microm, and the FWHM could be near 300 nm.

Intertrochanteric fractures in adults younger than 40 years of age

This study reviewed 66 intertrochanteric fractures in patients younger than 40 years old (average 33.0 years old; range 17-40 years old). In contrast to the usual population with intertrochanteric fractures, the factors male predominance (46/66), less pre-injury comorbidity (9/66), more outdoor high energy trauma (47/66), and more associated injuries (32/66) were evident. The distribution of associated injuries was wide. Some of them were life threatening. According to Boyd's classification, 20 were type I, 24 were type II, 13 were type III, and 9 were type IV. Twenty-nine were stable, and 37 were unstable. Stratified by the mechanism of injury, the difference in distribution between the subgroups was significant (p = 0.027, two-tail Fisher's exact test). Simple falls only caused Boyd type I and II fractures. Boyd type III or IV fractures were found more often after vehicular trauma or falls from a height. All the intertrochanteric fractures healed on average 70.5 days (range 31-213 days) after operation. The fractures resulting from vehicular trauma or fall from a height healed significantly more slowly (p = 0.02, univariant log-rank test). There were 6 intertrochanteric fracture-related complications. The mechanism of injury determines the character of intertrochanteric fractures in young adults. Given tougher bone stock, better healing ability, and less co-morbidity, proper management can lead to healing of all intertrochanteric fractures. The extent of functional recovery was also determined by the associated injuries.

Cefuroxime-impregnated cement at primary total knee arthroplasty in diabetes mellitus. A prospective, randomised study

We have performed a prospective single-blinded randomised study to evaluate the role of antibiotic-impregnated cement in the prevention of deep infection at primary total knee arthroplasty (TKA) in patients with diabetes mellitus. We studied prospectively 78 arthroplasties performed for osteoarthritis in such patients. They were randomly separated into two groups. In group 1 (41 knees), cefuroxime-impregnated cement was used while in group 2 (37 knees) cefuroxime was not added to the cement. The preoperative, intraoperative and postoperative management was the same for both groups. The mean follow-up was 50 months (26 to 88). There were no cases of deep infection in group 1, but five (13.5%) occurred in group 2 (p = 0.021). We conclude that cefuroxime-impregnated cement is effective in the prevention of deep infection at primary TKA in patients with diabetes mellitus.

Characterization of the replication region of the Lactobacillus reuteri plasmid pTC82 potentially used in the construction of cloning vector

A 3.2 kb DNA fragment containing the replication region (RR) from pTC82 was cloned, sequenced, and found to contain elements typical of plasmids that replicate via a rolling-circle mechanism of replication (RCR), including double-strand origin (DSO), replication protein gene (rep), and single-strand origin (SSO). The DSO of pTC82 contains two domains showing 55.5% and 84.6% similarities in nucleotide (nt) sequence to the conserved functional elements bind and nic, respectively, which are required for the initiation of the leading strand typical of the pC194-RCR family. Although the predicted rep gene product of pTC82 (Rep82) shares little identity (less than 24%) with other known Reps, a region containing three motifs, characteristic of the pC194-family Reps, was identified, indicating the Rep82 as a novel Rep protein of this family. Downstream of the rep82 gene, strong similarity to the typical palT type-SSO could be detected. This is the first palT type-SSO to be identified from Lactobacillus. Through a series of deletion studies, the minimal replicon of the cloned RR was found to be 2.66 kb in size including the DSO region and rep gene. This RR was further identified as being highly stable in L. reuteri and also bearing a very narrow host-range property, suggesting it to be a good replicon potentially useful in vector construction for developing L. reuteri as a vaccine carrier.

A series of enediynes as novel inhibitors of topoisomerase I

A series of acyclic enediynes, 2-((6-substituted)-3-hexen-1,5-diynyl)benzonitriles (8--11), display potent inhibition against topoisomerase I without the formation of active biradical intermediates and show inhibitory activity against topoisomerase I at 10 microM, which is five times that of camptothecin from the results of agarose gel electrophoresis.

Effect of functional groups of humic substances on uf performance

The role of different functional groups present in humic substances on the membrane flux is unclear. This study is undertaken to (1) separate the carboxyl and phenolic groups from a humic solution, and (2) evaluate the effect of each fractionated humic substances on the ultrafiltration (UF) performance. A weak-base amine resin was used for the adsorption (pH 7) and the subsequent desorption (pH 13) of the phenolic groups from a commercial humic solution. These fractions were evaluated qualitatively (via Fourier transform infrared spectroscopy) and quantitatively (titration); they were further subjected to the analyses of the trihalomethane formation potential (THMFP) and ultrafiltration performance. Although, a complete separation of the phenolic and carboxyl groups is not possible, the results nevertheless provide useful information about their effects on UF performance. The fraction with a higher content of the phenolic OH group exhibits the highest THMFP (190 microg/mg C), whereas the fraction with a higher content of the carboxyl groups exhibits more flux decline. The UF system evaluated is unable to remove a significant portion of THM precursors, resulting in high THMs in permeate. The use of powdered activated carbon for the pretreatment of these fractions fails to improve membrane fouling. The pore size of UF membrane does not appear to affect the membrane flux, and the switch from the hydrophobic to hydrophilic membrane only slight improves the permeate flux.

Determination of source contributions to ambient PM2.5 in Kaohsiung, Taiwan, using a receptor model

Ambient particulates of PM2.5 were sampled at three sites in Kaohsiung, Taiwan, during February and March 1999. In addition, resuspended PM2.5 collected from traffic tunnels, paved roads, fly ash of a municipal solid waste (MSW) incinerator, and seawater was obtained. All the samples were analyzed for twenty constituents, including water-soluble ions, organic carbon (OC), elemental carbon (EC), and metallic elements. In conjunction with local source profiles and the source profiles in the model library SPECIATE EPA, the receptor model based on chemical mass balance (CMB) was then applied to determine the source contributions to ambient PM2.5. The mean concentration of ambient PM2.5 was 42.69-53.68 micrograms/m3 for the sampling period. The abundant species in ambient PM2.5 in the mass fraction for three sites were OC (12.7-14.2%), SO4(2-) (12.8-15.1%), NO3- (8.1-10.3%), NH4+ (6.7-7.5%), and EC (5.3-8.5%). Results of CMB modeling show that major pollution sources for ambient PM2.5 are traffic exhaust (18-54%), secondary aerosols (30-41% from SO4(2-) and NO3-), and outdoor burning of agriculture wastes (13-17%).

Generation of IgM anti-platelet autoantibody in dengue patients

Dengue virus infection causes a wide range of diseases from dengue fever to life-threatening dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS). The mechanisms involved in DHF/DSS pathogenesis remain unclear. Patient sera collected from an outbreak in southern Taiwan from November 1998 to January 1999 were studied. The presence of antibodies which cross-reacted with platelets could be detected in patient sera, and the isotype of these autoantibodies was IgM. The anti-platelet IgM levels were higher in DHF/DSS than in dengue fever patient sera in disease acute phase. These autoantibodies were still detectable in convalescent stage (1-3 weeks after acute phase) and even eight to nine months after illness. The platelet binding activity was not observed in other virus-infected patient sera tested. Further investigation showed that dengue patient sera caused platelet lysis in the presence of complement. The platelet cytotoxicity induced by DHF/DSS patient sera was higher than that by dengue fever sera. Dengue patient sera also inhibited platelet aggregation which, however, appeared to be not related to DHF/DSS development.

Modeling Competitive Adsorption of Molybdate, Sulfate, and Selenate on gamma-Al(2)O(3) by the Triple-Layer Model

Competitive adsorption of molybdate, sulfate, and selenate onto gamma-Al(2)O(3) was investigated in the present study. Binary solute systems of MoO(2-)(4)+SO(2-)(4), MoO(2-)(4)+SeO(2-)(4), and SO(2-)(4)+SeO(2-)(4) and a ternary solute system of MoO(2-)(4)+SO(2-)(4)+SeO(2-)(4) were evaluated to determine their relative effects on competitive adsorption on the gamma-Al(2)O(3) surface. Anionic competitive adsorption efficiency was pH dependent. The higher the pH, the lower the efficiency of MoO(2-)(4) in preventing SO(2-)(4) and SeO(2-)(4) adsorption; similar results were found in SeO(2-)(4) depressing SO(2-)(4) adsorption. This research found that more sites are occupied in mixed anionic adsorbate systems than when either ion is present alone. The results suggest that the gamma-Al(2)O(3) surface is composed of many groups of binding sites. Because of the heterogeneity of adsorption sites, the triple-layer model (TLM) predicted the competitive effects qualitatively but not quantitatively. TLM gave reasonable descriptions of molybdate adsorption in the presence of sulfate and selenate, indicating that the model may be useful in predicting molybdate adsorption on gamma-Al(2)O(3). Copyright 2001 Academic Press.

Sludge dewatering using centrifuge with thermal/polymer conditioning

Sludge dewatering is preceded by a conditioning operation to enhance water removal efficiency. In the conditioning operation, chemical coagulants or polymers are added to promote sludge particle aggregation for easier dewatering. In this study, an alternative conditioning method for sludge thermal treatment at temperatures up to 80 degrees C was extensively investigated. Dewatering characteristics such as sludge capillary suction time and specific resistance to filtration, sludge viscosity and concentration of solid cakes were examined thoroughly. A good correlation between capillary suction time and specific resistance to filtration was established for sludges from water treatment, but not for biological sludge. Cationic polymer exhibits the best enhancement on sludge moisture removal. The sludge rheogram varies from 60 to 5 cP as temperature changes from 20 to 80 degrees C for sludges from water treatment plant. The dewatering ability of sludge can be greatly enhanced by thermal treatment in conjunction with the use of polymers.

Surgical treatment of full thickness rotator cuff tear in patients younger than 40 years

BACKGROUND

Full thickness tear of the rotator cuff is a well-known entity in the middle-aged and elderly population and the results of surgical repair are well documented. Rotator cuff tear in patients under the age of 40 years is unusual and the cause and treatment are not well established. The present study reports 12 young patients with full thickness tear of the rotator cuff treated surgically.

METHODS

Open anteroinferior acromioplasty and cuff repairs were performed on every patient after failure of nonsurgical treatment. The average follow-up was 59.5 months (range, 36-100 months).

RESULTS

The average patient age at the time of surgery was 30.2 years (range, 17-39 years). Symptoms included pain and dysfunction in all patients and weakness in eight patients. The duration of symptoms before surgery ranged from 6 to 60 months (average, 22.8 months). Ten patients were able to return to their preinjury status within an average of 4.5 months (range, 3-9 months) after surgery. Three athletes were able to return to previous levels of competition. Nine patients had excellent functional results with regard to pain, motion, strength, function and satisfaction. Eleven patients were satisfied with the operation and had significant pain reduction compared with their preoperative status.

CONCLUSIONS

An acute traumatic event was the etiology of the rotator cuff tears in this study. The results of surgical treatment in this younger group of patients were satisfactory and were comparable to the outcomes reported for surgical treatment of rotator cuff tears in older patients and athletes.

Purification and properties of ornithine racemase from Clostridium sticklandii

Ornithine racemase has been purified to homogeneity from Clostridium sticklandii, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This is the first racemase known to be highly specific to ornithine. This PLP-dependent enzyme has an M(r) of 92, 000, with a K(m) for L-ornithine of 0.77 +/- 0.05 mM and a k(cat) of 980 +/- 20 s(-1).

Growth, pigment production and protease activity of Monascus purpureus as affected by salt, sodium nitrite, polyphosphate and various sugars

The effect of different levels of salt, sodium nitrite, polyphosphate and various sugars on growth, pigment production, protease activity and culture pH caused by Monascus purpureus was studied in broth medium and ground meat. The addition of sodium chloride (> 50.0 g l(-1)) and polyphosphate (> 3.0g l(-1)) to broth medium decreased mycelial growth, pigment production and protease activity of M. purpureus, whereas low concentrations of sodium nitrite (< 0.2 g l(-1)) promoted mycelial growth and pigment production. When the basal medium and ground meat contained salt, 150.0 g l(-1), the mould growth was stopped. The medium with fructose as carbon source proved to be the most suitable for mycelium growth and pigment production, with maltose and glucose being the second most productive. When sucrose and lactose were used as carbon sources, mycelium growth and pigment production were inhibited but the protease activity increased significantly. The mould showed more tolerance to salt and polyphosphate in ground meat than in broth medium and used sucrose as a carbon source as well as glucose for growth and pigment production in the meat mixture.

Use of alternative therapy among pediatric oncology patients in Taiwan

Both alternative medicine and western medicine have been commonly used to treat pediatric cancer patients in Taiwan. Each has its own intrinsic strengths and weaknesses and they can be complementary. Little is known about medical help-seeking behaviors of parents of pediatric cancer patients, especially those related to alternative therapies. This study investigated the extent and parental expectations on use of alternative therapies. All primary caregivers of 63 eligible patients were interviewed. Use of alternative therapies, regardless of education level or social status of their families, is prevalent (n = 46, 73%) in Taiwan. Commonly used alternative therapies included, in order of popularity, formulated functional food (n = 22, 48%), temple worship/shamanism (n = 19, 40%), traditional Chinese medicine (n = 9, 20%), secret recipes/herbs (n = 13, 28%), and diet supplements (n = 9, 19%). Such practices generally occur without medical guidance from oncologists, largely because of poor interactions between parents and oncologists. Future efforts should be made to encourage both parents and oncologists to discuss this issue. Nurses may serve as mediators by developing mutual trust and a sharing relationship between these groups.

Double Anionic Cycloaromatization of 2-(6-Substituted-3-hexene-1,5-diynyl)benzonitriles Initiated by Methoxide Addition

[reaction: see text] Treatment of 2-((3Z)-undecene-1,5-diynyl)benzonitrile with 5 equiv of sodium methoxide in refluxing methanol for 16 h gave 1-pentyl-6-methoxyphenanthridine in 12% yield, 1-pentyl-6-phenanthridone in 6% yield, and 2-(2-pentyl-6-methoxyphenyl)benzonitrile in 4% yield. Under the same reaction conditions, methanolysis of several other benzonitriles gave similar results. Phenanthridine and biphenyl derivatives were obtained as the major products. A mechanism for this novel cycloaromatization reaction of enediynes is proposed.