Effects of ketamine on voltage-dependent calcium currents and membrane potentials in single bullfrog atrial cells

PURPOSE

This study was undertaken to assess the effect of ketamine on L-type calcium channel current (I(Ca)) and membrane action potential in the bullfrog single atrial myocyte.

METHODS

Bullfrog single atrial myocytes were prepared by enzymatic dispersion. Whole-cell voltage-clamp technique and current clamp technique were used to monitor I(Ca), membrane resting potential, and action potential.

RESULTS

Ketamine (10(-5)-10(-3) M) showed dose-dependent inhibition of I(Ca) in a reversible manner. The 50% inhibitory concentration (IC(50)) of ketamine on I(Ca) was estimated to be 0.92 x 10(-5) M. Use-dependent block of I(Ca) was not observed. The resting membrane potential was depolarized at a high concentration (10(-4) M) of ketamine. Reduction of the plateau phase and prolonged duration of the action potential were observed in the presence of a high concentration of ketamine (10(-4) M).

CONCLUSION

Ketamine has an inhibitory effect on I(Ca) in the bullfrog single atrial myocyte, and a high dose (10(-4) M) of ketamine prolonges the duration of the action potential. The mechanism of inhibition of I(Ca) seems to be a direct effect on the L-type calcium channel, not like an open channel blocker.

Application of artificial neural network modelling to identify severely ill patients whose aminoglycoside concentrations are likely to fall below therapeutic concentrations

OBJECTIVE

Identification of ICU patients whose concentrations are likely to fall below therapeutic concentrations using artificial neural network (ANN) modelling and individual patient physiologic data.

METHOD

Data on indicators of disease severity and some physiologic data were collected from 89 ICU patients who received arbekacin (ABK) and 61 who received amikacin (AMK). Three-layer ANN modelling and multivariate logistic regression analysis were used to predict the plasma concentrations of the aminoglycosides (ABK and AMK) in the severely ill patients.

RESULTS

Predictive performance analysis showed that the sensitivity and specificity of ANN modelling was superior to multivariate logistic regression analysis. For accurate modelling, a predictable range should be inferred from the data structure before the analysis. Restriction of the predictable region, based on the data structure, increased predictive performance.

CONCLUSION

ANN analysis was superior to multivariate logistic regression analysis in predicting which patients would have plasma concentrations lower than the minimum therapeutic concentration. To improve predictive performance, the predictable range should be inferred from the data structure before prediction. When applying ANN modelling in clinical settings, the predictive performance and predictable region should be investigated in detail to avoid the risk of harm to severely ill patients.

Remodelling and healing process of moderately heat-treated bone grafts after wide resection of bone and soft-tissue tumors

INTRODUCTION

In the reconstruction of extensive bone defects after massive resection of malignant musculoskeletal tumors, the clinical results of moderately heat-treated autogenous bone graft have rarely been documented. We evaluated the remodelling and healing process of moderately heat-treated autogenous bone graft by means of imaging features.

MATERIALS AND METHODS

The subjects of this study were 19 patients with bone and soft-tissue tumors treated by heat-treated bone graft at our institution between 1992 and 2001, the mean follow-up period was 4.8+/-2.8 years (range 1-9 years). The remodelling and healing process of heat-treated bone graft was evaluated by means of radiography, bone scintigraphy, and MRI.

RESULTS

The mean period to obtain bone union between host bone and grafted bone was 9.4 months. Infection was noted in 1 patient, and fracture was present in 2 patients. In 6 patients, pseudoarthrosis was found. Bone scintigraphy showed an increased uptake at the host-graft junction in the period between 3 and 36 months (median 10.7 months) postoperatively. A gradually increased diffuse uptake on the grafted side was evident at an average of 29.1 months (range 19-41 months) postoperatively. High signal intensity on T2-weighted images was observed in the early period after surgery, and iso-intense or low signal intensity became evident after an average of 28.3 months. A gradually increased diffuse uptake on scintigraphy and iso-intense or low signal intensity on T2-weighted images indicated remodelling of the grafted bone.

CONCLUSION

Bone union of a moderately heat-treated autogenous bone graft was noted at about 9 months, and its remodelling was proceeding at about 30 months. This method will be useful for bone defects after massive resection of soft-tissue and bone tumors.

Preparation and characterization of glassy celecoxib

Celecoxib, a poorly water-soluble drug, was converted into a glassy state by melt quenching. The properties of glassy celecoxib were studied using infrared (IR) spectroscopy, differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), intrinsic dissolution rate (IDR), and thin-layer-chromatography (TLC). Glass transition occurred at 51.8 degrees C. Infrared spectrum of glass has revealed significant changes due to H-bonding. Celecoxib glass shows around 15 times faster dissolution as compared with the crystalline state. Heckel plot analysis has shown better compressibility in glassy state. Unpulverized glass remained stable for 3 months, whereas after pulverization about 70% crystallinity was gained in 100 hours. Further attempts may be carried out to stabilize the glass.

Chemistry and biology of phototropism-regulating substances in higher plants

Most people are familiar with the sight of a young seedling bending towards a window or the brightest source of light to which it is exposed. This directional growth response is known as phototropism, which is caused by a lateral growth-promoting auxin in the bending organ (Cholodny-Went theory, cited in high school textbook). Recently, however, Bruinsma et al., Weiler et al., and Hasegawa et al. independently found that the shaded half did not contain more auxin than the illuminated one. Instead it was found that the even distribution of auxin was accompanied by a lateral gradient of growth inhibiting substances during phototropic curvature (Bruinsma-Hasegawa theory). We have isolated some photo-induced growth inhibitory substances related to phototropism, benzoxazolinones from light-grown maize shoots (Zea mays L.), raphanusanins from radish hypocotyl (Raphanus sativus var. hortensis f. gigantissimus M.), indolyacetonitrile from light-grown shoots (Brassica oleacea L.), 8-epixanthatin from sunflower hypocotyl (Helianthus annus L.), and quite recently uridine from oat coleoptile (Avena sativa L.). Chemical analyses have shown phototropic stimulations to cause curvature by inducing a local unequal distribution of growth-inhibiting substances that antagonize auxin in its cell-elongating activity. Finally, a model is presented for further studies on phototropism.

[Treatment outcomes with vinorelbine for metastatic breast cancer patients previously treated with both doxorubicin and docetaxel]

The purpose of this study was to evaluate the efficacy and toxicity of weekly vinorelbine (VNB) in patients with metastatic breast cancer previously treated with both adriamycin (ADM) and docetaxel (TXT). VNB was administered weekly at the dose 20 mg/m2 by i.v. infusion over 20 minutes followed by flushing the vein with 100 ml of normal saline. From June 1999 to August 2000, ten patients were enrolled in this study. Patient characteristics were that the cumulative doses (median) of previous ADM and TXT were 300 mg (range, 120-880 mg), 560 mg (range, 120-960 mg) respectively. The median number of metastatic sites was four, with poor performance status (ECOG 1-2: 40%, 3-4: 60%). The median cycles of weekly VNB were seven (range: 2-12). Two of 10 assessable patients obtained partial response, with an overall response rate of 20%. The main toxicity (NCI grade 4) was leukopenia in 10% of 10 patients. Phlebitis (grade 2) was observed in 4 of 10 patients (40%). VNB is an active agent against metastatic breast cancer pretreated with both ADM and TXT, possessing no severe toxicities.

Myxoid liposarcoma metastatic to the thoracic epidural space without bone involvement: report of two cases

Myxoid liposarcoma can frequently metastasize to extrapulmonary sites. We present two cases of myxoid liposarcoma metastatic to the epidural space. Both patients complained of back pain, but plain radiography revealed no abnormality. MR imaging clearly demonstrated metastatic tumors in the epidural space, but no involvement of vertebra. When patients with myxoid liposarcoma complain of back pain, metastasis in the epidural space should be considered even in patients without bone involvement.

Walking ability and activities of daily living after limb salvage operations for malignant bone and soft-tissue tumors of the lower limbs

We evaluated the number of steps, activities of daily life (ADL) score, Enneking score, active range of motion and muscle strength by muscle manual testing for function in lower limbs after reconstructive procedures in surgical treatment of tumors. The 56 patients with 20 malignant bone tumors and 36 malignant soft-tissue tumors averaged 7119 +/- 3563 steps per day, or 69.8% of the control group. The average ADL score of patients was 14.0 +/- 4.1 points (70.0%), and the average Enneking score 20.4 +/- 6.0 points (68.0%). The scores of the bone tumor group were lower than those of the soft-tissue tumor group. These scores were not correlated with the range of motion. The number of steps and ADL score were correlated with Enneking score (coefficient 0.52 and 0.84, respectively). The number of steps and the ADL score appear to be useful, as is Enneking score.

Differential effects of protein kinase C on human vascular smooth muscle cell proliferation and migration

Vascular smooth muscle cell (SMC) migration and proliferation contribute to intimal hyperplasia, and protein kinase C (PKC) may be required for both events. In this report, we investigated the role of PKC in proliferation and migration of SMC derived from the human saphenous vein. Activation of PKC by phorbol-12,13-dibutyrate (PDBu) or (-)-indolactam [(-)-ILV] increases SMC proliferation. Downregulation of PKC activity by prolonged incubation with phorbol ester or inhibition of PKC with chelerythrine in SMC diminished agonist-stimulated proliferation. In contrast, stimulation of PKC with PDBu or (-)-ILV inhibited basal and agonist-induced SMC chemotaxis. Moreover, downregulation of PKC or inhibition with chelerythrine accentuated migration. We postulated that the inhibitory effect of PKC on SMC chemotaxis was mediated through cAMP-dependent protein kinase (protein kinase A, PKA). In support of this hypothesis, we found that activation of PKC in SMC stimulated PKA activity. The cAMP agonist forskolin significantly inhibited SMC chemotaxis. Furthermore, the inhibitory effect of PKC on SMC chemotaxis was completely reversed by cAMP or PKA inhibitors. In search of the PKC isotype(s) underlying these differential effects of PKC in SMC, we identified eight isotypes expressed in human SMC. Only PKC-alpha, -beta I, -delta, and -epsilon were eliminated by downregulation, suggesting that one or more of these four enzymes facilitate the observed phorbol ester-dependent effects of PKC in SMC. In summary, we found that PKC activation enhances proliferation but inhibits migration of human vascular SMC. These differential effect of PKC on vascular cells appears to be mediated through PKC-alpha, -beta I, -delta, and/or -epsilon.

The cytotoxic effects of bile acids in crude bile on human pancreatic cancer cell lines

Pancreatic cancer frequently causes extrahepatic cholestasis. To identify the direct effects of bile acids in jaundiced serum on pancreatic cancer, the proliferation of PANC-1 and MIA PaCa-2 cells as well as the ultrastructural alteration of PANC-1 cells cultured in crude bile modified media were studied. The growth of these cells in the RPMI-1640 media with or without 1%, 2%, and 4% of the refined crude bile was assessed after 48 and 96 h of incubation. The ultrastructure of PANC-1 cells was investigated by scanning and transmission electron microscopy after 24 and 48 h of incubation. The proliferation of both cell lines in the bile-treated media was greatly inhibited. The inhibitory rates of bile on PANC-1 ranged from 24.1% +/- 3.3% to 66.9% +/- 6.6% (P < 0.01) and those on MIA PaCa-2 ranged from 16.7% +/- 3.8% to 50.7% +/- 5.5%. (P < 0.01). When the bile-added media were replaced, the cells were able to restore their proliferating ability. The PANC-1 cells incubated in the bile-supplied media indicated that the mirovilli, mitochondria, and other organelles had thus been injured. These results suggest that bile acids appear to inhibit the proliferation of PANC-1 and MIA PaCa-2 cells, and the probable inhibitory mechanism is mainly considered to be due to the cytotoxicity of such bile acids.

A species-selective allelopathic substance from germinating sunflower (Helianthus annuus L.) seeds

From the exudate of germinating sunflower (Helianthus annuus L.) seeds was isolated a stereoisomer of diversifolide, 4, 15-dinor-3-hydroxy-1(5)-xanthene-12,8-olide (designated sundiversifolide) as determined by analysis of its IR, APCI-, ESI- and HR-MS and 13C and 1H NMR spectra. This substance inhibited shoot and root growth of cat's-eyes by about 50% at a concentration of 30 ppm. It also showed species-selective activity on the shoot and root growth of tested plants. When cat's-eyes seeds were incubated together with sunflower seeds, the cat's-eyes growth was inhibited. Furthermore, it was detected from an extract of river sand when sunflower seeds were incubated on the sand. These results indicate that sundiversifolide has an allelopathic function in sunflower plants.

Production of antimicrobial defensin in Nicotiana benthamiana with a potato virus X vector

A recombinant plasmid, pTXS.TH, was constructed to express the gene-encoding wasabi (Wasabia japonica) defensin with the potato virus X (PVX) vector. pTXS.TH allows the expression of defensin in the host Nicotiana benthamiana, and the defensin protein WT1 can be purified from virus-infected leaves by heat treatment and affinity chromatography. WT1 exhibits strong antifungal activity toward the phytopathogenic fungi Magnaporthe grisea (50% inhibitory concentration [IC50] = 5 microg/ml) and Botrytis cinerea (IC50 = 20 microg/ml) but is weakly active against the phytopathogenic bacterium Pseudomonas cichorii. This virus-mediated expression system is a rapid and efficient method to produce and characterize antimicrobial proteins in plants. It is particularly useful for the study of proteins that are difficult to produce with other expression systems.

Quantitative analysis of crystalline pharmaceuticals in powders and tablets by a pattern-fitting procedure using X-ray powder diffraction data

A pattern-fitting procedure for quantitative analysis of crystalline pharmaceuticals in solid dosage forms using X-ray powder diffraction data is described. This method is based on a procedure for pattern-fitting in crystal structure refinement, and observed X-ray scattering intensities were fitted to analytical expressions including some fitting parameters, i.e. scale factor, peak positions, peak widths and degree of preferred orientation of the crystallites. All fitting parameters were optimized by the non-linear least-squares procedure. Then the weight fraction of each component was determined from the optimized scale factors. In the present study, well-crystallized binary systems, zinc oxide-zinc sulfide (ZnO-ZnS) and salicylic acid-benzoic acid (SA-BA), were used as the samples. In analysis of the ZnO-ZnS system, the weight fraction of ZnO or ZnS could be determined quantitatively in the range of 5-95% in the case of both powders and tablets. In analysis of the SA-BA systems, the weight fraction of SA or BA could be determined quantitatively in the range of 20-80% in the case of both powders and tablets. Quantitative analysis applying this pattern-fitting procedure showed better reproducibility than other X-ray methods based on the linear or integral intensities of particular diffraction peaks. Analysis using this pattern-fitting procedure also has the advantage that the preferred orientation of the crystallites in solid dosage forms can be also determined in the course of quantitative analysis.

Bilateral isolated tarsal navicular fracture dislocation: a case report

Fracture-dislocation of the tarsal navicular is rare injury because of strong ligamentous support on both its plantar and dorsal sides. The authors report a case of a twenty-five-year-old man who sustained bilateral isolated tarsal navicular fracture-dislocations, treated by open reduction and internal fixation combined with external fixation. The patient reported no difficulty in activities of daily living, but T1-weighted magnetic resonance imaging showed a low-intensity area in right tarsal navicular, raising suspicion of osteonecrosis when he was last seen two year three months after operation.

Synthesis and anti-HIV activity of unusual nucleoside oxanosine derivatives

A series of the oxanosine and carbocyclic oxanosine derivatives were synthesized to evaluate for their anti-HIV activity. Compound 1, 7 and 9 showed weak anti-HIV activities.

Synthesis and biological activity of unusual nucleosides having 3,4-bis(hydroxymethyl) thietane ring as a sugar moiety

The enantiomerically pure synthesis of 9-[(2'S, 3'S)-bis(hydroxymethyl)thietan-1'-yl]adenine 2,3'-thio analog of oxetanocin A, was achieved via coupling of silylated 6-chloropurine and sulfoxide 16 under Pummerer reaction conditions.

Phototropic stimulation induces the conversion of glucosinolate to phototropism-regulating substances of radish hypocotyls

The distribution of natural growth inhibitors, the raphanusanins (isomers of 3-(methylthio)methylene-2-pyrrolidinethione) and their precursors (4-methylthio-3-butenyl glucosinolate (MTBG) and 4-methylthio-3-butenyl isothiocyanate (MTBI), between illuminated and shaded halves of radish hypocotyls during phototropic curvature was analyzed using a physicochemical assay. Phototropic stimulation rapidly decreased MTBG content, and abruptly increased contents of MTBI and raphanusanins in the illuminated halves of radish hypocotyls within 30 min after the onset of unilateral illumination. Content in the shaded halves was similar to that in dark controls. When MTBG, MTBI, and raphanusanins at endogenous levels were applied unilaterally to etiolated hypocotyls, MTBI and raphanusanins caused hypocotyls to bend but MTBG showed no activity. Blue illumination promoted myrosinase (thioglucosidase) activity, which releases MTBI from MTBG, in hypocotyls after 10 min, although enzyme activity in dark controls did not change. These results suggest that phototropic stimulation promotes myrosinase activity in the illuminated side of radish hypocotyls, releasing bioactive MTBI from inactive MTBG and simultaneously producing bioactive raphanusanins.

[Efficacy of UFT in the treatment of para-aortic lymph node metastasis following gastric cancer surgery: case report]

The patient was a 68-year-old man who underwent pyloric gastrectomy for advanced stomach cancer on December 6, 1996. The histopathological diagnosis was poorly differentiated adenocarcinoma, ss, ly3, v1, n2 (+), and stage IIIa. Postoperative adjuvant chemotherapy consisted of short-term intravenous infusion of 5-FU, 320 mg/m2/day (= 480 mg/body) for 5 days beginning on postoperative day (POD) 1, and oral 5-FU, 200 mg/day, for 1 year beginning on POD 14. The preoperative CEA value was 316.2 ng, but it fluctuated below 10 ng postoperatively. About one year after the operation, the patient began to complain of epigastric pain, loss of appetite, and general malaise. CT of the upper abdomen revealed a 1.5-cm para-aortic lymph node, and the CEA value of 319.0 ng was abnormally high. 5-FU was stopped, oral UFT at 300 mg/day was started, and the patient's course was followed. Three months after the start of UFT, the lymph node had shrunk on CT (shrinkage rate: 66.7%), and the CEA value had decreased to 14.3 ng. As though corresponding to these changes there was a gradual decrease in the epigastric pain, general malaise, etc., and the patient's appetite also returned. There were no subsequent elevations in the CEA values or increases in the size of the para-aortic lymph nodes, and the patient's general condition was favorably maintained. UFT appeared to be effective against the lymph node metastasis around the aorta in this case.