AIMECS 99--AFMC International Medicinal Chemistry Symposium. 12-15 September 1999, Beijing, China

The Third International Symposium of the Asian Federation for Medicinal Chemistry (AFMC) was held in Beijing from 12 to 15 September 1999. The conference covered pharmacology, molecular biology, medicinal chemistry, computational molecular modeling, biochemistry and organic synthesis. Anticancer therapies, HIV protease inhibitors, anti-inflammatory agents, antiviral chemotherapy, influenza A, adrenergic receptors, 5-HT(1D) agonists and biologically active compounds of natural products were the main topics. The synthesis of combinatorial compound libraries in the search for the lead compounds was also presented.

Activation of adenylate cyclase results in down-regulation of c-jun mRNA expression in rat C6 glioma cells

To investigate the possible mechanisms involved in forskolin-induced c-jun mRNA decrease in rat C6 glioma cells, we examined effects of a PKA inhibitor (H-89), a L-type Ca2+ channel blocker (nimodipine), a calmodulin activation inhibitor (calmidazolium chloride) and a Ca2+/calmodulin-dependent protein kinase II inhibitor (KN-62) on forskolin-induced c-jun mRNA down-regulation. H-89 caused a reversal of forskolin-induced c-jun mRNA decrease. Furthermore, nimodipine, KN-62 and calmidazolium chloride partially blocked forskolin-induced c-jun mRNA down-regulation. Our results suggest that activation of adenylate cyclase appears to be involved in a down-regulation of c-jun mRNA expression through a PKA pathway. In addition, L-type calcium channels, calmodulin and Ca2+/calmodulin-dependent protein kinase II may be partially involved in c-jun mRNA down-regulation induced by forskolin.

The homeodomain protein NK-3 recruits Groucho and a histone deacetylase complex to repress transcription

Transcriptional repression by sequence-specific DNA binding factors is mediated by the recruitment of a corepressor complex to the promoter region. The NK-3 homeodomain protein is a transcriptional repressor that recruits the nuclear protein kinase, homeodomain interacting protein kinase 2 (HIPK2). Here we show that HIPK2 is a component of a corepressor complex containing Groucho and a histone deacetylase complex. Groucho, like HIPK2, acts as a corepressor for NK-3 and binds to NK-3 and HIPK2. Moreover, HIPK2 appears to regulate the corepressor activity of Groucho. Transcriptional repression by NK-3 and Groucho is relieved by the histone deacetylase inhibitor trichostatin A, and both NK-3 and Groucho directly interact with the histone deacetylase HDAC1 that is associated with mSin3A in vivo. Recruitment of the histone deacetylase complex by NK-3 decreases the acetylated histones that are associated with the target gene promoter. These results indicate that NK-3 represses transcription by recruiting a complex containing Groucho and a histone deacetylase complex that leads to histone modification on chromatin and suggest that HIPK2 may play a regulatory role in the corepressor complex formation.

Effect of resection velocity and suction ring on corneal flap formation in laser in situ keratomileusis

PURPOSE

To determine the effects of microkeratome-cutting velocities and the suction ring on corneal flap creation.

SETTING

Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Korea.

METHODS

Procedures were performed under clinical settings in 65 pig eyes. Keratometric diopters (D) were measured before and after application of the suction ring. Corneal thickness was measured before and after resection cutting, and the difference was taken as flap thickness. The microkeratome was initially set at a resection thickness of 160 microns. The blade oscillation (turbine velocity) was set at 30, 35, and 42 psi. The translational velocity was arbitrarily divided into high (1 to 2 seconds), moderate (3 to 5 seconds), and low (6 seconds or more). Data were analyzed by varying the velocities consecutively. Photographs of the cut surface were acquired by scanning electron microscopy to evaluate resection morphology by comparison.

RESULTS

Mean refractive powers were 39.94 D +/- 0.66 (SD) and 39.69 +/- 0.98 D before and after application of the suction ring, respectively; however, no significant difference was observed (P = .216). Lower surgeon translational velocity resulted in a significantly thicker corneal flap in 8 of the 9 paired comparisons (P < .05). Higher turbine velocity resulted in a significantly thicker corneal flap in 7 of the 9 paired comparisons (P < .05). The cut surface was smoother at higher turbine and lower translational velocity. The initial cut margin was steeper at higher translational velocity.

CONCLUSIONS

The increase in intraocular pressure induced by the suction ring had no significant effect on keratometric power. At higher turbine and lower translational velocities, the corneal flap was thicker and the cut surface smoother. Higher translational velocities made the initial cut margin steeper.

BCG vaccine prevents insulitis in low dose streptozotocin-induced diabetic mice

Autoimmune type 1 diabetes mellitus is caused by the immunologic destruction of pancreatic beta-cells; therefore, there have been many attempts at immunologic modulation as a block or prevention of the underlying process. The aim of this study is to investigate the effect of BCG vaccination on low dose streptozotocin-induced diabetic (LDSD) mice. The mice were pretreated with BCG 7 days before starting low dose streptozotocin (STZ), observed body weight and blood glucose for 2 months, then analyzed the severity of the STZ-induced insulitis after the animals were sacrificed. In this experiment, the mean body weights in the BCG-STZ group on days 1, 19, 33, 47, and 61 of the experiment were 37.5 +/- 3.6, 37.3 +/- 3.6, 37.5 +/- 3.5, 39.4 +/- 3.9, and 39.3 +/- 4.5 (g), respectively. Those in the STZ group were 37.7 +/- 3.5, 38.3 +/- 4.5, 38.4 +/- 3.9, 36.2 +/- 4.5, and 36.3 +/- 4.0 (g), respectively (P < 0.05). The mean blood glucose levels in the BCG-STZ group on days 1, 19, 33, 47, and 61 were 106.5 +/- 8, 150 +/- 37, 147 +/- 54, 143 +/- 60, and 142 +/- 66 (mg/dl), respectively. Those in the STZ group were 103 +/- 12, 196 +/- 90, 261 +/- 236, 236 +/- 91, and 224 +/- 89 (mg/dl), respectively (P < 0.05). The numbers developing grade 0, I, II, III, and IV insulitis in the BCG-treated group were 63, 48, 33, 4, and 2, respectively, and in the control group were 16, 23, 31, 45, and 35, respectively. This study indicates that BCG vaccination reduces the development of insulitis and overt diabetes in LDSD mice.

Tetraparesis associated with ossification of the posterior longitudinal ligament of the cervical spine

This is a case report of tetraparesis associated with extraordinarily severe ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. There was no history of trauma. The object of this paper is to show that OPLL can progress relentlessly to a nearly complete quadriplegia even without trauma, but that adequate decompression can produce almost complete recovery.

CT features of torsion of benign cystic teratoma of the ovary

PURPOSE

The purpose of this work was to evaluate the usefulness of CT scans for distinguishing torsed from uncomplicated benign cystic teratoma (BCT).

METHOD

Retrospective analysis was performed in 14 torsed BCTs (14 patients) and in 23 uncomplicated BCTs (20 patients) for comparison. The features on CT scans were compared to the pathologic findings.

RESULTS

CT findings indicating torsed BCT were the presence of eccentric wall thickening of >1 cm, peritumoral infiltration, and presence of enlarged solid tubal mass adjacent to the uterus (p < 0.05).

CONCLUSION

The present study suggests that CT is useful in differentiating torsed from uncomplicated BCT. Although CT findings are not specific for some patients, detection of certain CT findings could increase the diagnostic accuracy.

Lack of association of Helicobacter pylori infection with gastric hypersensitivity or delayed gastric emptying in functional dyspepsia

OBJECTIVE

We evaluated the relationship between Helicobacter pylori (H. pylori) infection and gastric sensitivity to distention or gastric emptying rate to define the role of H. pylori in the pathogenesis of functional dyspepsia.

METHODS

Gastric barostat, gastric emptying scintigraphy, and 13C urea breath test were performed in 34 consecutive patients with functional dyspepsia.

RESULTS

Between H. pylori-positive and -negative patients with functional dyspepsia, there were no significant differences in basal tone (57.2 +/- 15.0 ml vs 66.8 +/- 18.3 ml), compliance (41.0 +/- 11.2 ml/mm Hg vs 38.2 +/- 11.8 ml/mm Hg), threshold of first sense (3.6 +/- 2.7 mm Hg vs 2.3 +/- 1.5 mm Hg), threshold of abdominal discomfort (9.4 +/- 4.0 mm Hg vs 7.3 +/- 1.9 mm Hg), and postprandial receptive relaxation (115.4 +/- 89.7 ml vs 99.0 +/- 88.7 ml), measured by gastric barostat. Half gastric emptying time (88.6 +/- 24.5 min vs 91.4 +/- 21.6 min) and retention rate at 120 min (32.8 +/- 17.8% vs 41.9 +/- 20.1%) were also similar between the two groups.

CONCLUSION

H. pylori infection was not associated with gastric hypersensitivity to distention or delayed gastric emptying.

The preventive effect of systemic treatment with interferon-alpha2B for infertility from mumps orchitis

OBJECTIVE

To evaluate the effect of interferon-alpha2B on mumps orchitis, often caused by postpubertal mumps and which can result in permanent testicular atrophy.

PATIENTS AND METHODS

The study included 21 patients with mumps orchitis, treated between May 1990 and June 1997. Patients were randomly assigned into two groups: in group 1, 13 patients received therapy with interferon-alpha2B (3 x 10(6) IU per day) and group 2 did not, acting as controls. All were evaluated by measurements of testis size, mumps virus titre, hormone level and semen analysis.

RESULTS

In group 1, the patients' symptoms resolved within 2-3 days and the volume of the testes returned to normal within 11 days; there was no testicular atrophy in any patient during the follow-up. However, asthenospermia continued to be detected in four patients (unilateral in two, bilateral in two). In group 2, the patients' symptoms resolved within 5-6 days and the volume of the testes returned to normal within 10 days; testes atrophied in three patients (unilateral in two, bilateral in one) during the follow-up. Asthenospermia continued in four patients (unilateral in two, bilateral in two).

CONCLUSION

These results suggest that treatment with systemic interferon-alpha2B is effective in preventing testicular atrophy when combined with standard symptomatic treatment.

The homeodomain transcription factor NK-4 acts as either a transcriptional activator or repressor and interacts with the p300 coactivator and the Groucho corepressor

NK-4 (tinman) encodes an NK-2 class homeodomain transcription factor that is required for development of the Drosophila dorsal mesoderm, including heart. Genetic evidence suggests its important role in mesoderm subdivision, yet the properties of NK-4 as a transcriptional regulator and the mechanism of gene transcription by NK-4 are not completely understood. Here, we describe its properties as a transcription factor and its interaction with the p300 coactivator and the Groucho corepressor. We demonstrate that NK-4 can activate or repress target genes in cultured cells, depending on functional domains that are conserved between Drosophila melanogaster and Drosophila virilis NK-4 genes. Using GAL4-NK-4 fusion constructs, we have mapped a transcriptional activation domain (amino acids 1-110) and repression domains (amino acids 111-188 and the homeodomain) and found an inhibitory function for the homeodomain in transactivation by NK-4. Furthermore, we demonstrate that NK-4-dependent transactivation is augmented by the p300 coactivator and show that NK-4 physically interacts with p300 via the activation domain. In addition, cotransfection experiments indicate that the repressor activity of NK-4 is strongly enhanced by the Groucho corepressor. Using immunoprecipitation and in vitro pull-down assays, we show that NK-4 directly interacts with the Groucho corepressor, for which the homeodomain is required. Together, our results indicate that NK-4 can act as either a transcriptional activator or repressor and provide the first evidence of NK-4 interactions with the p300 coactivator and the Groucho corepressor.

Covalent modification of the homeodomain-interacting protein kinase 2 (HIPK2) by the ubiquitin-like protein SUMO-1

Posttranslational modifications such as ubiquitination and phosphorylation play an important role in the regulation of cellular protein function. Homeodomain-interacting protein kinase 2 (HIPK2) is a member of the recently identified family of nuclear protein kinases that act as corepressors for homeodomain transcription factors. Here, we show that HIPK2 is regulated by a ubiquitin-like protein, SUMO-1. We demonstrate that HIPK2 localizes to nuclear speckles (dots) by means of a speckle-retention signal. This speckle-retention signal contains a domain that interacts with a mouse ubiquitin-like protein conjugating (E2) enzyme, mUBC9. In cultured cells, HIPK2 is covalently modified by SUMO-1, and the SUMO-1 modification of HIPK2 correlates with its localization to nuclear speckles (dots). Thus, our results provide firm evidence that the nuclear protein kinase HIPK2 can be covalently modified by SUMO-1, which directs its localization to nuclear speckles (dots).

Selective hepatic arterial chemoembolization for liver metastases in patients with carcinoid tumor or islet cell carcinoma

In many patients with liver metastases from islet cell or carcinoid tumor, vascular occlusion therapy results in prolonged control of symptoms, biochemical response, and also tumor regression. Chemotherapy agents were added to evaluate safety and efficacy. Thirty patients with liver metastases from either carcinoid tumor or islet cell carcinoma underwent sequential vascular occlusion therapy combined with chemotherapeutic agents. In patients with carcinoid tumor, a combination of cisplatin (150 mg) and doxorubicin (50 mg) was used. In patients with islet cell carcinoma, a combination of 5-fluorouracil (350 mg) and streptozotocin (1000-2000 mg) was used. Sixteen patients had carcinoid tumor and 14 had islet cell carcinoma. Biochemical response was observed in 12 of 16 (75%) carcinoid patients and 9 of 10 (90%) islet cell patients. The overall partial response rate was 37% (11/30 patients). Partial response occurred in 4 of 16 (25%) patients with carcinoid tumor and 7 of 14 (50%) with islet cell carcinoma. The median duration of partial responses was 24 months (range, 6-63+ months). The median survival of all patients was 15 months (range, 2-67+ months). No treatment-related deaths occurred. Our data suggest that the addition of these chemotherapeutic agents to vascular occlusion, although safe, has no additional benefit.

Community-based rehabilitation in South Korea

This paper gives a brief introduction to the geography and demography of the Republic of South Korea. Since 1988 South Korea has been actively legislating and implementing welfare policy for the disabled of the Republic. An overview of these policy changes is presented. The extent to which the policy has been implemented using community-based rehabilitation (CBR) is illustrated using an example from the North Wanju Project. Finally, there is a discussion of the future of CBR in South Korea and the means whereby there can be more social integration of the disabled.

Role of definitive radiation therapy for larynx preservation in patients with advanced laryngeal cancer

OBJECTIVE

Recently, neoadjuvant chemotherapy (CT) and radiation therapy (RT) have been advocated as a standard treatment for laryngeal preservation in patients with locally advanced laryngeal cancer. However, it is still being debated whether adding neoadjuvant CT to conventional RT makes an effective contribution to laryngeal preservation. The current study was designed to resolve this controversy.

DESIGN

Retrospective clinical study.

SETTING

The Severance Hospital, Yonsei Cancer Center, Yonsei University, Seoul, Korea.

METHOD

Eighty patients (stages III, IV) with squamous cell carcinoma of the larynx were divided into two groups according to treatment modalities, which consisted of RT alone (N = 40, Group 1) and neoadjuvant CT plus RT (N = 40, Group 2). Comparative analysis was undertaken to investigate the differences in the organ preservation rate and treatment results between the two groups.

RESULTS

There was no significant difference in the response rate and patterns of treatment failure between the two groups. The 5-year survival rate was similar between Group 1 (24%) and Group 2 (31%) (p = .1556). In addition, the larynx was almost equally preserved in Group 1 (62%) versus Group 2 (63%).

CONCLUSIONS

Radiation therapy without neoadjuvant CT seems to be a valid alternative treatment for the purpose of laryngeal preservation in locally advanced laryngeal cancer.

Role of papillary muscle in the generation and maintenance of reentry during ventricular tachycardia and fibrillation in isolated swine right ventricle

BACKGROUND

The role of papillary muscle (PM) in the generation and maintenance of reentry is unclear.

METHODS AND RESULTS

Computerized mapping (477 bipolar electrodes, 1.6-mm resolution) was performed in fibrillating right ventricles (RVs) of swine in vitro. During ventricular fibrillation (VF), reentrant wave fronts often transiently anchored to the PM. Tissue mass reduction was then performed in 10 RVs until VF converted to ventricular tachycardia (VT). In an additional 6 RVs, procainamide infusion converted VF to VT. Maps showed that 77% (34 of 44) of all VT episodes were associated with a single reentrant wave front anchored to the PM. Purkinje fiber potentials preceded the local myocardial activation, and these potentials were recorded mostly around the PM. When PM was trimmed to the level of endocardium (n = 4), sustained VT was no longer inducible. Transmembrane potential recordings (n = 5) at the PM revealed full action potential during pacing, without evidence of ischemia. Computer simulation studies confirmed the role of PM as a spiral wave anchoring site that stabilized wave conduction.

CONCLUSIONS

We conclude that PM is important in the generation and maintenance of reentry during VT and VF.

Phospholipase C-delta1 is activated by capacitative calcium entry that follows phospholipase C-beta activation upon bradykinin stimulation

To characterize the regulatory mechanism of phospholipase C-delta1 (PLC-delta1) in the bradykinin (BK) receptor-mediated signaling pathway, we used a clone of PC12 cells, which stably overexpress PLC-delta1 (PC12-D1). Stimulation with BK induced a significantly higher Ca(2+) elevation and inositol 1,4,5-trisphosphate (IP(3)) production with a much lower half-maximal effective concentration (EC(50)) of BK in PC12-D1 cells than in wild type (PC12-W) or vector-transfected (PC12-V) cells. However, BK-induced intracellular Ca(2+) release and IP(3) generation was similar between PC12-V and PC12-D1 cells in the absence of extracellular Ca(2+), suggesting that the availability of extracellular Ca(2+) is essential to the activation of PLC-delta1. When PC12-D1 cells were treated with agents that induce Ca(2+) influx, more IP(3) was produced, suggesting that the Ca(2+) entry induces IP(3) production in PC12-D1 cells. Furthermore, the additional IP(3) production after BK-induced capacitative calcium entry was detected in PC12-D1 cells, suggesting that PLC-delta1 is mainly activated by capacitative calcium entry. When cells were stimulated with BK in the presence of extracellular Ca(2+), [(3)H]norepinephrine secretion was much greater from PC12-D1 cells than from PC12-V cells. Our results suggest that PLC-delta1 is activated by capacitative calcium entry following the activation of PLC-beta, additively inducing IP(3) production and Ca(2+) rise in BK-stimulated PC12 cells.

N-Methyl-D-aspartate receptor blockade induces neuronal apoptosis in cortical culture

Whereas excessive activation of the NMDA receptor may contribute to ischemic neuronal injury, physiologic activation may promote neuronal survival under certain conditions. Consistently, it has recently been shown that NMDA antagonists induce apoptosis of central neurons in immature rats. In the present study, we have examined whether NMDA antagonists induce neuronal apoptosis also in a culture condition. Exposure of cortical cultures (DIV 10-13) to MK-801 (1-10 microM) for 48 h resulted in death of about 30-40% of neurons. Similar neuronal death was induced by exposure to other NMDA antagonists, D-AP5 and dextromethorphan. The neuronal death was dependent on the culture age; MK-801 induced much less neuronal death in younger (DIV 7) and older (DIV 16-19) cultures. The NMDA antagonist-induced neuronal death was accompanied by cell body shrinkage, nuclear fragmentation, and cleavage/activation of caspase-3. Furthermore, it was attenuated by cycloheximide and zVAD-fmk, indicating that the death occurred mainly by the apoptosis mechanism. As in several other apoptosis models, high-potassium medium blocked the NMDA antagonist-induced apoptosis, which was reversed by voltage-gated calcium channel blockers. The present results demonstrate that NMDA antagonists induce neuronal apoptosis in cortical culture, consistent with the findings obtained in immature rats. Since the activation of the voltage-gated calcium channels attenuated the NMDA antagonist-induced apoptosis, it may be another example of the "calcium set point hypothesis."

Effects of naturally occurring flavonoids on nitric oxide production in the macrophage cell line RAW 264.7 and their structure-activity relationships

Flavonoids affect the inflammatory process of the mammalian system and possess anti-inflammatory as well as immunomodulatory activities in vitro and in vivo. Since nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) is one of the inflammatory mediators, the effects of various naturally occurring flavonoids on NO production in LPS-activated RAW 264.7 cells were evaluated in vitro. Flavonoids such as apigenin, wogonin, luteolin, tectorigenin, and quercetin inhibited NO production, as measured by nitrite formation at 10-100 microM. The most active among 26 flavonoid derivatives tested were apigenin, wogonin, and luteolin, having IC50 values of 23, 17, and 27 microM, respectively, while AMT, a synthetic selective iNOS inhibitor, had an IC50 value of 0.09 microM. In contrast, flavanones, such as naringenin, and flavonoid glycosides, such as apiin, did not demonstrate significant inhibition up to 100 microM. These results clearly indicated that a C-2,3 double bond might be important, and that the potency of inhibition depended upon the substitution patterns of the flavonoid molecules. The inhibitory activity of flavonoids was not due to direct inhibition of iNOS enzyme activity because they did not reasonably inhibit iNOS activity, as measured by [3H]citrulline formation from [3H]arginine, up to 100 microM. In contrast, wogonin and luteolin concentration-dependently reduced iNOS enzyme expression, when measured by western blotting, at 10-100 microM. All these results clearly demonstrated that certain flavonoids inhibit NO production in lipopolysaccharide-activated RAW 264.7 cells, and their inhibitory activity might be due to reduction of iNOS enzyme expression.

Relation between ligament of Marshall and adrenergic atrial tachyarrhythmia

BACKGROUND

The mechanism of the adrenergic atrial tachyarrhythmia is unclear. We hypothesize that the ligament of Marshall (LOM) is sensitive to adrenergic stimulation and may serve as a source of the adrenergic atrial tachyarrhythmia.

METHODS AND RESULTS

We performed computerized mapping studies in isolated-perfused canine left atrial tissues from normal dogs (n=9) and from dogs with chronic atrial fibrillation (AF) induced by 10 to 41 weeks of rapid pacing (n=3). Before isoproterenol, spontaneous activity occurred in only one normal tissue (cycle length, CL >1300 ms). During isoproterenol infusion, automatic rhythm was induced in both normal tissues (CL=578+/-172 ms) and AF tissues (CL=255+/-29 ms, P<0.05). The origin of spontaneous activity was mapped to the LOM. In the AF tissues, but not the normal tissues, we observed the transition from rapid automatic activity to multiple wavelet AF. Ablation of the LOM terminated the spontaneous activity and prevented AF. Immunocytochemical studies of the LOM revealed muscle tracts surrounded by tyrosine hydroxylase-positive (sympathetic) nerves.

CONCLUSIONS

We conclude that the LOM is richly innervated by sympathetic nerves and serves as a source of isoproterenol-sensitive focal automatic activity in normal canine atrium. The sensitivity to isoproterenol is upregulated after long-term rapid pacing and may contribute to the development of AF in this model.

Mechanism of procainamide-induced prevention of spontaneous wave break during ventricular fibrillation. Insight into the maintenance of fibrillation wave fronts

BACKGROUND

Ventricular fibrillation (VF) is maintained by 2 mechanisms: first by reentry formation and second by spontaneous wave break or wave splitting. We hypothesized that spontaneous wave break results from a critical shortening of the action potential duration (APD) during VF and that its prevention by procainamide eliminates spontaneous wave break.

METHODS AND RESULTS

The endocardial surfaces of 7 isolated, perfused swine right ventricles were mapped with a 3.2x3.8 cm plaque with 477 bipolar electrodes. Activation pattern during VF was visualized dynamically while simultaneously recording epicardial action potentials with a glass microelectrode. APD restitution curves were constructed during VF (dynamic) and during S(1)S(2) protocols. At baseline, VF was maintained by 5.3+/-1 wavelets. Procainamide (PA) at 10 microgram/mL decreased the number of wavelets to 3.5+/-1 (P<0.05). At baseline VF was maintained by spontaneous wave break and by new reentrant wave front formation. PA eliminated spontaneous wave break during VF while having no effect on reentry formation. PA increased the cycle length of the VF (148.5+/-41.2 ms vs 81+/-10 ms, P<0.01) and the core area of the reentry from 5.8 to 14.5 mm(2) (P<0.05). Dynamic APD restitution curve during VF showed that PA eliminated the initiation of activation with APDs shorter than 30 ms. The effects of PA on cellular properties and wave front dynamics were reversed during 60 minutes of drug-free perfusion.

CONCLUSIONS

Critically short APDs during VF promote spontaneous wave break. Their elimination with PA, however, maintains VF by generating new reentrant wave front.

Relation between cellular repolarization characteristics and critical mass for human ventricular fibrillation

INTRODUCTION

The critical mass for human ventricular fibrillation (VF) and its electrical determinants are unclear. The goal of this study was to evaluate the relationship between repolarization characteristics and critical mass for VF in diseased human cardiac tissues.

METHODS AND RESULTS

Eight native hearts from transplant recipients were studied. The right ventricle was immediately excised, then perfused (n = 6) or superfused (n = 2) with Tyrode's solution at 36 degrees C. The action potential duration (APD) restitution curve was determined by an S1-S2 method. Programmed stimulation and burst pacing were used to induce VF. In 3 of 8 tissues, 10 microM cromakalim, an ATP-sensitive potassium channel opener, was added to the perfusate and the stimulation protocol repeated. Results show that, at baseline, VF did not occur either spontaneously or during rewarming, and it could not be induced by aggressive electrical stimulation in any tissue. The mean APD at 90% depolarization (APD90) at a cycle length of 600 msec was 227+/-49 msec, and the mean slope of the APD restitution curve was 0.22+/-0.08. Among the six tissues perfused, five were not treated with any antiarrhythmic agent. The weight of these five heart samples averaged 111+/-23 g (range 85 to 138). However, after cromakalim infusion, sustained VF (> 30 min in duration) was consistently induced. As compared with baseline in the same tissues, cromakalim shortened the APD90 from 243+/-32 msec to 55+/-18 msec (P < 0.001) and increased the maximum slope of the APD restitution curve from 0.24+/-0.11 to 1.43+/-0.10 (P < 0.01).

CONCLUSION

At baseline, the critical mass for VF in diseased human hearts in vitro is > 111 g. However, the critical mass for VF can vary, as it can be reduced by shortening APD and increasing the slope of the APD restitution curve.

Total synthesis of (+/-)-homoepibatidine

Total synthesis of (+/-)-homoepibatidine (2), which contains the 8-azabicyclo[3.2.1] octane ring system, was achieved by using palladium-catalyzed Heck-type coupling reaction from 3.

[A case of adriamycin and methotrexate-resistant recurrent breast cancer treated with doxifluridine and mitomycin C]

A 49-year-old woman was diagnosed with local recurrence and cervical lymph node and bone metastases 55 months after surgery for breast cancer. She was treated with goserelin acetate and tamoxifen but the disease was assessed as progressive after 8 months. Five courses of CMF therapy were performed but lung, pleural and mediastinal lymph node metastases were detected. Then, five courses of CAF therapy were carried out, but a contralateral breast metastasis was detected and the patient complained of shortness of breath. The CAF therapy was assessed as PD. We attempted administration of doxifluridine (5'-DFUR) and mitomycin C (MMC) on an outpatient basis. After 6 months, no progressive disease was detected and she was relieved of her shortness of breath. The combination therapy was assessed as long NC. Combination therapy with 5'-DFUR and MMC is thus a useful treatment for adriamycin- and methotrexate-resistant breast cancer, especially in terms of quality of life.