Amino acid sequence analysis of bitter peptides from a soybean proglycinin subunit synthesized in Escherichia coli

The cDNA encoding A1aB1b proglycinin was expressed in E. coli, for the efficient isolation of a single peptide responsible for the bitterness. The 55-kD proglycinin was highly purified, hydrolyzed, and further purified through a series of chromatographic steps to yield fractions with the major bitter peptides. The most bitter-tasting fractions contained peptides with average molecular weights lower than 1,700 Da. An analysis of the amino acid sequences indicated that many small bitter peptides (< 1,000 Da) are composed of uncharged polar amino acids as well as hydrophobic amino acids, with a charged residue often being present at either end. This suggests the involvement of a certain structural requirement in taste perception.

Abnormal cardiac autonomic activity and complexity in newly diagnosed and untreated hypertensive patients after general anesthesia

To investigate change of cardiac autonomic activity and cardiac complexity during general anesthesia in hypertensive patients, we analyzed electrocardiographic (ECG) data using power spectral analysis and approximate entropy (ApEn). Anesthesia was performed by a mixture of enflurane and nitrous oxide. From 10 minutes before induction of anesthesia(resting state) until 20 minutes after induction, ECG data were obtained from newly diagnosed and untreated hypertensive (n = 18) and normotensive patients (n = 18). Period 1 was defined as the initial 10 minutes after induction and period 2 as the following 10 minutes. The low-, mid-, and high-frequency power and the values of ApEn of the two groups were calculated from ECG recording. At resting state, the powers in all frequency bands and the values of ApEn in hypertensive patients did not differ from those of normotensive patients. During periods 1 and 2, the powers of all frequency range significantly decreased in normotensive group (p<0.05), while they did not change in hypertensive group. The values of ApEn in normotensive patients decreased significantly only during period 2, while those in hypertensive patients decreased during periods 1 and 2 (p<0.05 and p<0.05, respectively). These results suggest that, in the hypertensive patients, persistent autonomic activity under the condition of suppressed cardiac complexity may contribute to the unstable hemodynamic insults from the outset of general anesthesia.

Dual mechanisms for glucose 6-phosphate inhibition of human brain hexokinase

Brain hexokinase (HKI) is inhibited potently by its product glucose 6-phosphate (G6P); however, the mechanism of inhibition is unsettled. Two hypotheses have been proposed to account for product inhibition of HKI. In one, G6P binds to the active site (the C-terminal half of HKI) and competes directly with ATP, whereas in the alternative suggestion the inhibitor binds to an allosteric site (the N-terminal half of HKI), which indirectly displaces ATP from the active site. Single mutations within G6P binding pockets, as defined by crystal structures, at either the N- or C-terminal half of HKI have no significant effect on G6P inhibition. On the other hand, the corresponding mutations eliminate product inhibition in a truncated form of HKI, consisting only of the C-terminal half of the enzyme. Only through combined mutations at the active and allosteric sites, using residues for which single mutations had little effect, was product inhibition eliminated in HKI. Evidently, potent inhibition of HKI by G6P can occur from both active and allosteric binding sites. Furthermore, kinetic data reported here, in conjunction with published equilibrium binding data, are consistent with inhibitory sites of comparable affinity linked by a mechanism of negative cooperativity.

Embolization of superior mesenteric artery branches in dogs. Ischemic bowel changes depend on location of vessel occlusion and embolic materials

OBJECTIVE

To evaluate the degree of ischemic changes of the small intestine after arterial embolization of proximal or distal arteries with Gelfoam particles and coils in dogs.

METHODS

Superselective arterial embolization in 18 dogs was performed using a coaxial catheter system. Gelfoam occlusion of the proximal level of ileal or jejunal arteries was performed in four dogs (group A). Gelfoam occlusion of the distal level was performed in four dogs (group B). Coil occlusion of the proximal level was performed in five dogs (group C). Coil occlusion of the distal level was performed in five dogs (group D). All 18 dogs were killed 1 day after the procedure. Gross and microscopic findings were evaluated.

RESULTS

The embolizations were successful in all dogs. In group B, significant mucosal destruction, lymphocyte proliferation of the submucosa and mucosa, and diffuse swelling in all layers of the intestine were found in all four dogs. Three revealed diffuse ischemic changes and one showed focal ischemic changes. In groups A and C, all the layers of the intestine were intact and did not show any ischemic changes. In group D, one dog showed erosion of a small portion of mucosa and lymphocytic infiltration. The other dogs showed nonspecific findings in all layers of the intestine.

CONCLUSIONS

Proximal embolization with Gelfoam and coils as well as distal embolization with coils did not cause ischemia. However, ischemic changes in the intestinal wall could be observed after distal embolization with Gelfoam.

Effectiveness of preoperative transarterial chemoembolization in presumed inoperable hepatoblastoma

PURPOSE

To evaluate the effectiveness and therapeutic role of preoperative transarterial chemoembolization (TACE) of hepatoblastoma.

MATERIALS AND METHODS

Four patients (one boy, three girls) with unresectable hepatoblastoma were treated twice with preoperative TACE in an effort to improve the surgical and clinical outcome. The patients ranged in age from 8 to 27 months (mean, 15 months). The first TACE was performed superselectively in tumor feeding arteries. The second TACE was performed 3 weeks later. Surgical hepatic resection was performed 1 month after the second TACE. Contrast-enhanced computed tomography (CT) was used to evaluate changes in size, volume, internal texture, and margin of the masses. The toxicity of the chemotherapeutic drugs was evaluated by blood chemistry analysis (AST/ALT, alpha-FP) performed before and after TACE, and after surgery.

RESULTS

TACE allowed subsequent surgical resection in all four patients, who remained disease free 16-52 months after operation. There were no major problems related to TACE. There was no chemotherapeutic agent toxicity from TACE. The average largest diameters and volumes of the tumors decreased by 31% (8.3 to 5.6 cm) and 69% (317 to 93 cm2), respectively.

CONCLUSION

TACE provided subsequent successful surgical resection and good long-term results in all four patients. The hepatoblastomas were initially considered inoperable because of extensive hepatic involvement and indistinct margins.

Interleukin (IL)-5 downregulates tumor necrosis factor (TNF)-induced eotaxin messenger RNA (mRNA) expression in eosinophils. Induction of eotaxin mRNA by TNF and IL-5 in eosinophils

An eotaxin is a chemoattractant specific for eosinophils that are known to play a role in helminth infection and allergic responses. Although several cellular sources have been reported to produce eotaxin, it would be interesting to know whether eosinophils are able to produce their own eotaxin and participate in recruitment of themselves in response to inflammation. To this end, a cloned eotaxin complementary DNA was transcribed in vitro to use as a probe for detecting eotaxin messenger RNA (mRNA), and eotaxin protein levels were determined by enzyme-linked immunosorbent assay. Eotaxin mRNA was, as analyzed by in situ hybridization, rarely detectable in unstimulated eosinophils, but was strongly induced in eosinophils when stimulated with tumor necrosis factor (TNF). Interleukin (IL)-5, which is known to be a major factor of eosinophil survival in vivo and in vitro, was also able to induce a modest level of eotaxin mRNA but inhibited TNF-induced eotaxin mRNA expression in a dose-response manner. Dexamethasone inhibited TNF-induced eotaxin mRNA expression. This result was consistent with that from reverse transcription/polymerase chain reaction followed by Southern blot analysis. Unlike the little expression of eotaxin mRNA in the absence of stimuli, the measurement of eotaxin protein revealed that a considerable amount of eotaxin protein was constitutively produced in unstimulated eosinophils. Its expression was upregulated by TNF and IL-5 as well. However, the inhibitory effect of IL-5 on TNF-mediated eotaxin protein production was not as pronounced as that on eotaxin mRNA induction. Collectively, these data reflect the complex physiology of eosinophils in the expression of eotaxin gene upon the exposure to their survival and/or death factors.

Effects of pranidipine, a calcium channel antagonist, in an avian model of heart failure

We have previously demonstrated that turkey poults fed furazolidone (Fz) in high concentrations (700 ppm) develop dilated cardiomyopathy (DCM) which approximates the human condition [1-3]. We wanted to study the effects of a calcium channel blocker in an animal model with a documented decrease in beta-receptor density, increased levels of circulating catecholamines, and abnormal calcium metabolism. The effects of a third generation calcium channel blocker has not been studied in our model. We hypothesized that the model would be predictive of the human condition and provide additional insights into the potential use of Ca2+ channel blockers in the setting of DCM. In the present study, we examined the effect of pranidipine, a new dihydropyridine calcium antagonist, in the setting of DCM on the gross and microscopic morphology of the heart and the overall contractile performance of the myocardium. A state of symptomatic to mild cardiomyopathy was induced in Broad-Breasted White turkey poults by administration of Fz for three weeks. Blood pressure, heart rate, fractional shortening, and body weight were monitored and compared in DCM animals treated with pranidipine and those given a placebo. After four weeks of treatment or no treatment with pranidipine, animals were euthanized and heart weight, cardiac dimensions, and microscopic morphology were compared. Progressive left ventricular (LV) dilatation and wall thinning was prevented with pranidipine treatment. In addition, microscopic examination demonstrated myocyte hypertrophy regression in DCM animals treated with pranidipine. In DCM animals, treatment with pranidipine resulted in significantly smaller left ventricular dimensions. We conclude that the calcium channel blocker pranidipine was not detrimental to global cardiac function in animals with dilated cardiomyopathy.

Human heart failure: cAMP stimulation of SR Ca(2+)-ATPase activity and phosphorylation level of phospholamban

Failing human myocardium has been associated with decreased sarcoplasmic reticulum (SR) Ca(2+)-ATPase activity. There remains controversy as to whether the regulation of SR Ca(2+)-ATPase activity is altered in heart failure or whether decreased SR Ca(2+)-ATPase activity is due to changes in SR Ca(2+)-ATPase or phospholamban expression. We therefore investigated whether alterations in cAMP-dependent phosphorylation of phospholamban may be responsible for the reduced SR Ca(2+)-ATPase activity in human heart failure. Protein levels of phospholamban and SR Ca(2+)-ATPase, detected by Western blot, were unchanged in failing compared with nonfailing human myocardium. There was decreased responsiveness to the direct activation of the SR Ca(2+)-ATPase activity by either cAMP (0.01-100 micromol/l) or protein kinase A (1-30 microgram) in failing myocardium. Using the backphosphorylation technique, we observed a decrease of the cAMP-dependent phosphorylation level of phospholamban by 20 +/- 2%. It is concluded that the impaired SR function in human end-stage heart failure may be due, in part, to a reduced cAMP-dependent phosphorylation of phospholamban.

Synthesis and in vitro antibacterial activity of C-3' pyridinium cephalosporin derivatives

The quaternary ammonium cephalosporin derivatives were prepared with various pyridines substituted at the 3 or/and 4 position. Their in vitro antibacterial activities were determined and substituent effect on pyridine nucleus was studied. Preparation of substituted pyridines are also described.

Twelve-year tracking of blood pressure in Korean school children: the Kangwha Study

Longitudinal data from different populations have shown different degrees of tracking of blood pressure (BP). To examine BP tracking in Korean school children, 219 of 430 children (100 males, 119 females) who were 6 years old in 1986 in Kangwha County, Korea have been examined annually up to 1997 in the Kangwha Study. BP was measured twice with standard mercury sphygmomanometers and the average of the two measurements was used for the level of BP. Diastolic BP were measured at the fourth Korotkoff sound. Tracking was examined using a time-lag correlation analysis and McMahan's tracking index tau, which indicates the proportion of variation attributable to tracking apart from the natural growth component. As well the jackknife method was used to obtain the confidence interval of tau. Correlation coefficients between systolic BP from age 6 to 17 ranged from 0.39-0.54 for males and 0.44-0.57 for females. Taus for systolic BP were 0.875 (95% CI: 0.803-0.947) and 0.900 (95% CI: 0.809-0.991) in males and females, respectively. Correlation coefficients between diastolic BP from age 6 to 17 ranged from 0.28-0.47 for males and 0.14-0.47 for females. Taus for diastolic BP were 0.983 (95% CI: 0.897-1.000) and 0.800 (95% CI: 0.717-0.883) in males and females, respectively. These findings showed strong evidence for BP tracking in Korean school children from childhood to late adolescence.

Primary malignant fibrous histiocytoma of the liver: imaging features of five surgically confirmed cases

BACKGROUND

The purpose of the present study was to describe the various imaging features of primary malignant fibrous histiocytoma (MFH) of the liver, a rare tumor of mesenchymal origin.

METHODS

Sonography (n = 5), computed tomography (CT; n = 5), magnetic resonance (MR) imaging (n = 2), and hepatic arteriography (n = 3) in five patients who underwent partial hepatectomy for tumor resection were retrospectively reviewed and correlated with pathologic findings.

RESULTS

All tumors were clearly demarcated from surrounding hepatic parenchyma in sectional imaging with (n = 2) or without (n = 3) a fibrous capsule, which was pathologically verified. Internal architecture of abundant fibrosis, myxoid degeneration, and/or hemorrhagic necrosis reflected the sonographic, CT and MR imaging findings. Marginal tumor staining without definite tumor vasculature was the main feature of hepatic arteriography. There was no intratumoral calcification. All three tumors involving the right lobe of the liver invaded the right hemidiaphragm.

CONCLUSION

Although there were no unique findings of primary hepatic MFH, a combined interpretation of various imaging modalities may elucidate the malignant nature of the tumor.

Alterations of Fas (APO-1/CD95) gene in transitional cell carcinomas of urinary bladder

Fas (Apo-1/CD95) is a cell-surface receptor involved in cell death signaling. The key role of the Fas system in negative growth regulation has been studied mostly within the immune system, and somatic mutations of Fas in cancer patients have been described solely in lymphoid-lineage malignancies. We analyzed somatic mutations and loss of heterozygosity of Fas gene in 43 transitional cell carcinomas of urinary bladder. Overall, 12 tumors (28%) were found to have Fas mutations, including 11 missense mutations and 1 frameshift mutation. Ten of the 12 mutations were located in the death domain known to be involved in the transduction of an apoptotic signal, and 8 of these 10 mutations showed an identical G to A transition at bp 993, indicating a potential hotspot in bladder cancers. Three of eight (38%) informative tumors carrying Fas mutations showed LOH at polymorphic sites in the promoter region. This is the first report on the Fas gene mutations in nonlymphoid malignancies, and our data suggest that alterations of the Fas gene might lead to the loss of its apoptotic function and contribute to the pathogenesis of some bladder cancers.

Nonaggregating mutant of recombinant human hexokinase I exhibits wild-type kinetics and rod-like conformations in solution

Hexokinase I governs the rate-limiting step of glycolysis in brain tissue, being inhibited by its product, glucose 6-phosphate, and allosterically relieved of product inhibition by phosphate. On the basis of small-angle X-ray scattering, the wild-type enzyme is a monomer in the presence of glucose and phosphate at protein concentrations up to 10 mg/mL, but in the presence of glucose 6-phosphate, is a dimer down to protein concentrations as low as 1 mg/mL. A mutant form of hexokinase I, specifically engineered by directed mutation to block dimerization, remains monomeric at high protein concentration under all conditions of ligation. This nondimerizing mutant exhibits wild-type activity, potent inhibition by glucose 6-phosphate, and phosphate reversal of product inhibition. Small-angle X-ray scattering data from the mutant hexokinase I in the presence of glucose/phosphate, glucose/glucose 6-phosphate, and glucose/ADP/Mg2+/AlF3 are consistent with a rodlike conformation for the monomer similar to that observed in crystal structures of the hexokinase I dimer. Hence, any mechanism for allosteric regulation of hexokinase I should maintain a global conformation of the polypeptide similar to that observed in crystallographic structures.

Alterations of Fas (Apo-1/CD95) gene in non-small cell lung cancer

Fas (Apo-1/CD95) is a cell-surface receptor involved in cell death signaling. The key role of the Fas system in negative growth regulation has been studied mostly within the immune system, and somatic mutations of Fas gene in cancer patients have been described solely in lymphoid-lineage malignancies. However, many non-lymphoid tumor cells have been found to be resistant to Fas-mediated apoptosis, which suggests that Fas mutations, one of the possible mechanisms for Fas-resistance, may be involved in the pathogenesis of non-lymphoid malignancies as well. In this study, we have analysed the entire coding region and all splice sites of the Fas gene for the detection of the gene mutations in 65 human non-small cell lung cancers by polymerase chain reaction, single strand conformation polymorphism and DNA sequencing. Overall, five tumors (7.7%) were found to have the Fas mutations, which were all missense mutations. Four of the five mutations identified were located in the cytoplasmic region (death domain) known to be involved in the transduction of an apoptotic signal and one mutation was located in the transmembrane domain. This is the first report on the Fas gene mutations in non-lymphoid malignancies, and the data presented here suggests that alterations of the Fas gene might lead to the loss of its apoptotic function and contribute to the pathogenesis of some human lung cancers.

In vivo expression of soluble Fas and FAP-1: possible mechanisms of Fas resistance in human hepatoblastomas

Many tumour cells express both Fas and its ligand (FasL) on their surface and it has remained a mystery why such cells do not simply kill themselves. It remains to be determined whether Fas and FasL are expressed in human hepatoblastomas and if so, what is responsible for the possible Fas resistance of these tumours. In this study, the expression of Fas and FasL was examined in 23 cases of human hepatoblastoma by immunohistochemical staining. To elucidate possible Fas resistance in hepatoblastomas, Fas-resistance pathways including the expression of bcl-2 and Fas-associated phosphatase-1 (FAP-1), and the expression of soluble Fas (sFas) mRNA, were analysed by immunohistochemistry and in situ reverse transcription-polymerase chain reaction (in situ RT-PCR). Fas gene mutation in the death domain was also examined. Fas and FasL were expressed in all hepatoblastomas analysed. Twenty (87 per cent) and 18 (78 per cent) cases of hepatoblastoma were positive for sFas mRNA and FAP-1, respectively, but none of the hepatoblastomas expressed bcl-2. Mutation in the death domain of the Fas gene was not found in hepatoblastomas. Taken together, these findings demonstrated that Fas, a death receptor, and its ligand are co-expressed in hepatoblastomas in vivo, but some inhibitors of Fas-mediated apoptosis are also expressed in these tumours. These results suggest that it is probably due to the action of inhibitory molecules of the Fas pathway that the tumour cells of hepatoblastomas do not kill themselves in an autocrine-driven cycle and that in this manner hepatoblastomas avoid apoptosis.

Cellular and molecular remodeling in a heart failure model treated with the beta-blocker carteolol

Broad-breasted white turkey poults fed furazolidone developed dilated cardiomyopathy (DCM) characterized by ventricular dilatation, decreased ejection fraction, beta1-receptor density, sarcoplasmic reticulum (SR) Ca2+-ATPase, myofibrillar ATPase activity, and reduced metabolism markers. We investigated the effects of carteolol, a beta-adrenergic blocking agent, by administrating two different dosages (0.01 and 10.0 mg/kg) twice a day for 4 wk to control and DCM turkey poults. At completion of the study there was 59% mortality in the nontreated DCM group, 55% mortality in the group treated with the low dose of carteolol, and 22% mortality in the group treated with the high dose of carteolol. Both treated groups showed a significant decrease in left ventricle size and significant restoration of ejection fraction and left ventricular peak systolic pressure. Carteolol treatment increased beta-adrenergic receptor density, and the high carteolol dose restored SR Ca2+-ATPase and myofibrillar ATPase activities, along with creatine kinase, lactate dehydrogenase, aspartate transaminase, and ATP synthase activities, to normal. These results show that beta-blockade with carteolol improves survival, reverses contractile abnormalities, and induces cellular remodeling in this model of heart failure.

Cellular and biochemical response of the human lung after intrapulmonary instillation of ferric oxide particles

Bronchoalveolar lavage (BAL) was used to sample lung cells and biochemical components in the lung air spaces at various times from 1 to 91 d after intrapulmonary instillation of 2.6 microm-diameter iron oxide particles in human subjects. The instillation of particles induced transient acute inflammation during the first day post instillation (PI), characterized by increased numbers of neutrophils and alveolar macrophages as well as increased amounts of protein, lactate dehydrogenase, and interleukin-8 in BAL fluids. This response was subclinical and was resolved within 4 d PI. A similar dose-dependent response was seen in rats 1 d after intratracheal instillation of the same particles. The particles contained small amounts of soluble iron (240 ng/mg) and possessed the capacity to catalyze oxidant generation in vitro. Our findings indicate that the acute inflammation after particle exposure may, at least partially, be the result of oxidant generation catalyzed by the presence of residual amounts of ferric ion, ferric hydroxides, or oxyhydroxides associated with the particles. These findings may have relevance to the acute health effects associated with increased levels of ambient particulate air pollutants.

Plasma lycopene concentrations in humans are determined by lycopene intake, plasma cholesterol concentrations and selected demographic factors

Higher plasma lycopene concentrations have been associated with a reduced risk of several chronic diseases. Determinants of lycopene concentrations in humans have received limited attention. We had blood lycopene concentrations and lycopene consumption data available from 111 participants in a two-center cancer prevention trial involving beta-carotene and examined determinants of plasma lycopene levels cross-sectionally. The median plasma lycopene level was 0.59 micromol/L (range 0.07-1.79). Low plasma concentrations of lycopene were associated with the following variables in univariate analyses: study site (Florida lower than Connecticut, P = 0.001), being nonmarried (P = 0.02), having lower income (P = 0.003), being nonwhite race/ethnicity (P = 0.03), having lower dietary lycopene intake (r = 0.29, P = 0.002), having lower plasma cholesterol (r = 0. 43, P = 0.0001) and triglyceride levels (r = 0.26, P = 0.005), and consuming less vitamin C (r = 0.20, P = 0.03). Women had slightly higher plasma lycopene levels than men (0.65 vs. 0.58 micromol/L; P = 0.31), despite lower dietary intake of lycopene (1,040 vs. 1,320 microg/d; P = 0.50). Plasma lycopene levels did not differ in smokers and nonsmokers. In stepwise regression analyses, the determinants of plasma lycopene were plasma cholesterol, dietary lycopene, and marital status; these three variables explained 26% of the variance in plasma lycopene. Relatively few lifestyle and demographic factors were important determinants of plasma lycopene levels, with plasma cholesterol, marital status, and lycopene intake being of greatest importance.

Paclitaxel, 5-fluorouracil, and cisplatin combination chemotherapy for the treatment of advanced gastric carcinoma

BACKGROUND

Although the clinical efficacy of paclitaxel in the treatment of gastric carcinoma has not been clearly defined, recent reports have suggested a possible role in the treatment of upper gastrointestinal carcinomas in vitro and in vivo. In this study, the authors evaluated the efficacy and toxicity of a combination chemotherapy that included paclitaxel, 5-fluorouracil (5-FU), and cisplatin in the treatment of patients with advanced gastric carcinoma.

METHODS

Forty-one gastric carcinoma patients with metastatic disease, unresectable advanced disease, or relapsed disease were treated with the following regimen, administered every 28 days: paclitaxel 175 mg/m2 by 3-hour intravenous (i.v.) infusion on Day 1, 5-FU 750 mg/m2 by 24-hour continuous i.v. infusion on Days 1-5, and cisplatin 20 mg/m2 by 2-hour i.v. infusion on Days 1-5. Twenty-six patients had measurable disease, and 15 had evaluable disease. All patients were assessable for toxicity.

RESULTS

Twenty-one of the 41 patients (51%; 95% confidence interval [CI], 36.5-65.7%) demonstrated an objective response, including 4 complete responses (10%; 95% CI, 3.9-22.5%). Sixty-five percent of the patients with measurable disease (17 of 26; 95% CI, 58-92.5%) and 27% of the patients with evaluable disease (4 of 15: 95% CI, 11.1-52.3%) achieved a complete response or a partial response. The median response duration was 17 weeks (range, 4-90 weeks), and the median survival duration for all patients was 26 weeks (range, 8 to 118+ weeks). The major toxicity of this treatment was myelosuppression with neutropenia of World Health Organization Grade 3 and 4 in 24% and 10% of the patients, respectively. Nonhematologic toxicity included mucositis, nausea/vomiting, diarrhea, neurotoxicity, and alopecia. Fluid retention occurred in two patients, and one patient had an anaphylatic reaction. Dose reduction was necessary for one patient, because Grade 4 neutropenia and mucositis occurred.

CONCLUSIONS

Paclitaxel, 5-FU, and cisplatin was an active combination regimen in the treatment of advanced gastric carcinoma. The toxicity of this regimen was tolerable. Based on these findings, this combination regimen could be an attractive treatment in the preoperative setting.

Morphologic and biologic changes of experimentally induced cholesteatoma in Mongolian gerbils with anticytokeratin and lectin study

HYPOTHESIS

Aural cholesteatoma has different morphologic and biologic characteristics from the normal epithelial cells.

BACKGROUND

The exact pathophysiology of aural cholesteatoma has not been proved. There are certain factors that can be involved in the development of the aural cholesteatoma, which makes it necessary to find the morphologic and biologic changes in aural cholesteatoma.

METHODS

The animal model of aural cholesteatoma was induced in gerbils with the external auditory canal (EAC) ligation method. Using immunohistochemical method, the distribution of cytokeratin and the binding patterns of lectin were observed to show the biologic and morphologic changes that take place in aural cholesteatomas.

RESULTS

The successful induction rate was 86.7%. The cytokeratin distribution of aural cholesteatoma was similar to that of EAC but different from that of the middle ear mucosa. The cytokeratin distribution in the cholesteatoma did not change with the different duration of EAC ligation. The results of the lectin-binding study indicate that the mucin-type cells are mainly distributed in the suprabasal cells of aural cholesteatoma and that the basal cells of cholesteatoma lack a D-galactosyl sugar residue.

CONCLUSION

This study suggests that the origin of aural cholesteatoma may be the external auditory canal epidermal cells, and the characteristics of these cells do not change once the cholesteatoma develops. This study also suggests that cholesteatoma has different biologic nature from that of the normal epithelial cell, especially in the basal cells.

CDK4 down-regulation induced by paclitaxel is associated with G1 arrest in gastric cancer cells

Paclitaxel induces a cell cycle block at G2-M phase by preventing the depolymerization of microtubules and induces p53-independent apoptosis in many cancer cells. We observed that gastric cancer cells treated with paclitaxel have shown a cyclin-dependent kinase (CDK)4 down-regulation. This paclitaxel-induced CDK4 down-regulation resulted in a cell cycle arrest at G1-S phase. To confirm this observation, we prepared stable transfectants that overexpressed CDK4 and analyzed the cell cycle progression. Ectopic expression of CDK4 in SNU cells resulted in a release of paclitaxel-induced G1 arrest. The release of G1 arrest by enforced expression of CDK4 seems to make the cells more sensitive to paclitaxel-induced apoptosis. From this finding, we could then suggest that paclitaxel treatment induces both G1-S and G2-M blocks in the cell cycle progression of gastric cancer cells.

Synthesis of praziquantel derivatives and their in vitro activity against adult Clonorchis sinensis

Several praziquantel derivatives have been prepared by the acylation of compound 5, and examined on their biological activity in vitro a against adult Clonorchis sinensis collected from rabbits infected with metacercariae which was isolated from Pseudorasbora parva, a second intermediate host, captured in Nakdong river in Korea.

Effect of simultaneous pulsed hyperthermia and pulsed radiation treatment on survival of SiHa cells

Relatively mild temperatures (40-41.5 degrees C) can sensitize human cells to radiation without the development of thermal tolerance to radiosensitization. Therefore there may be a therapeutic benefit to adding mild hyperthermia to brachytherapy regimens for the treatment of cancer. However, the required heating times are long (approximately 48 h) which renders this approach somewhat impractical. A novel alternative is to combine pulsed brachytherapy with pulsed hyperthermia to enable the total radiation dose to be given at an elevated temperature while the total heating time is kept short. A treatment schedule in which 1 Gy radiation pulses were given once per hour during 5-min heating pulses also delivered once per hour, was investigated in vitro in the human cervical carcinoma line, SiHa. The degree of cytotoxicity and thermoradiosensitization of the cells were assessed by cell survival using the colony forming assay. Cells were exposed to pulsed hyperthermia alone (5 min at 45 degrees C, delivered once per hour), acute hyperthermia alone (45 degrees C), pulsed radiation alone (1 Gy per hour), acute radiation alone, and simultaneous pulsed hyperthermia and pulsed radiation. Pulsed heating alone caused little cytotoxicity. However when pulsed heating was added to pulsed radiation, the level of cytotoxicity was greater than for pulsed radiation alone or acute radiation alone. The effect was also greater than would be predicted from a simple additive effect of pulsed radiation and pulsed heating. In conclusion, pulsed heating at 45 degrees C sensitized cells to pulsed radiation without the development of thermal tolerance.