Biomedical subjects

Y C Lo

Publications and source records attributed to Y C Lo.

At least 37 records · Page 2Linked to original sources

PubMed2000

Properties of an adrenal medullary protein immunorelated to steroid acute regulatory (StAR) protein.

Immunohistochemistry using a StAR peptide antiserum had previously revealed strong staining in rat and bovine adrenal medulla, suggesting the presence of a protein immunogenically related to StAR. Western blots of bovine medulla tissue homogenates showed the principal adrenal medullary immuno-reactive species to have a higher molecular weight (50 kDa) compared to StAR protein (30 kDa). Subcellular fractionation localised the 50 kDa species principally to the medulla cytosol. StAR peptide antiserum binding to both the 30 kDa and 50 kDa species could be specifically competed by the peptide antigen. These data suggest that the adrenal medullary immuno-reactive species and StAR protein are distinct entities, which share some features in common.

Adrenal Medulla↗

PubMed2000

Characterization of tetrandrine-induced inhibition of large-conductance calcium-activated potassium channels in a human endothelial cell line (HUV-EC-C).

The effects of tetrandrine, a blocker of voltage-dependent Ca(2+) channels, on ionic currents were investigated in an endothelial cell line (HUV-EC-C) originally derived from human umbilical vein. In whole-cell configuration, tetrandrine (0.5-50 microM) reversibly decreased the amplitude of K(+) outward currents. The IC(50) value of tetrandrine-induced decrease in outward current was 5 microM. The K(+) outward current in response to depolarizing voltage pulses was also inhibited by iberiotoxin (200 nM), yet not by glibenclamide (10 microM) or apamin (200 nM). The reduced amplitude of outward current by tetrandrine can be reversed by the further addition of Evans' blue (30 microM) or niflumic acid (30 microM). Thus, the tetrandrine-sensitive component of outward current is believed to be Ca(2+)-activated K(+) current. Pretreatment with thapsigargin (1 microM) or sodium nitroprusside (10 microM) for 5 h did not prevent tetrandrine-mediated inhibition of outward current. In outside-out configuration, bath application of tetrandrine (5 microM) did not change the single-channel conductance but significantly reduced the opening probability of large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels. The tetrandrine-mediated decrease in the channel activity was independent on internal Ca(2+) concentration. Tetrandrine (5 microM) can also shift the activation curve of BK(Ca) channels to more positive potentials by approximately 20 mV. The change in the kinetic behavior of BK(Ca) channels caused by tetrandrine is due to a decrease in mean open time and an increase in mean closed time. The present study provides substantial evidence that tetrandrine is capable of suppressing the activity of BK(Ca) channels in endothelial cells. The direct inhibition of these channels by tetrandrine should contribute to its effect on the functional activities of endothelial cells.

Alkaloids↗

PubMed2000

Intraoperative dosimetric representation of the real-time ultrasound-guided prostate implant.

PURPOSE: To describe a method of creating an intraoperative dosimetric representation of the real-time ultrasound-guided prostate implant. MATERIALS AND METHODS: An intraoperative dosimetry system (Multi Media Systems [MMS]) captures transverse ultrasound images after peripheral needles have been implanted in the prostate. The prostate contour and needle positions are outlined on the system. The volume of the prostate with needles in place is calculated. As seeds are deposited in the actual implant, the positions of the seeds are marked on the intraoperative system. Following implantation of the peripheral needles, the resulting isodose lines are displayed. The interior needles are inserted into the prostate, and these positions are captured on the system. As seeds are deposited through these needles into the prostate, their positions are captured on the planning system. When the implant is complete, the final dose coverage and dose volume histogram can be visualized. RESULTS: Ten consecutive patients underwent iodine 125 implants using real-time intraoperative isodose generation. The ratio of the preneedle prostate volume to postneedle prostate volume ranged from 0.89 to 1.0 (median 0.97). The calculated dose delivered to 90% of the prostate volume from the dose volume histogram (D90) ranged from 146.5 to 194 Gy (median 174.75 Gy). The percentage of the prostate covered by 240 Gy ranged from 14.6% to 59% (median 40.75%). CONCLUSION: Dosimetric representation of the real-time ultrasound-guided prostate implant can be achieved and demonstrates the efficacy of this brachytherapy technique.

Brachytherapy↗

PubMed1999

Expression of chimeric monomer and dimer proteins on the plasma membrane of mammalian cells.

Targeting of proteins to the plasma membrane of cells may be useful for vaccine development, tissue engineering, genetic research, bioseparations, and disease treatment. The ability of different transmembrane domains (TM) to direct a reporter protein (human alpha-feto protein, AFP) to the surface of mammalian cells was examined. High surface expression was achieved with chimeric proteins composed of AFP and the TM and cytosolic tail of murine B7-1 (AFP-B7) as well as with AFP containing a GPI-anchor from decay-accelerating factor (AFP-DAF). Lower surface expression of AFP was observed when the TM of human platelet-derived growth factor receptor or the human asialoglycoprotein receptor H1 subunit were employed. Introduction of the hinge-CH2-CH3 region of human IgG (gamma1 domain) between AFP and TM allowed efficient formation of disulfide-linked dimers. Surface expression of AFP-gamma1-B7 dimers was impaired compared to AFP-B7 whereas AFP-gamma1-DAF dimers were efficiently targeted to the surface. Accumulation of chimeric proteins on the cell surface did not correlate with the level of protein expression. This study demonstrates that high levels of monomeric and dimeric proteins can be targeted to the cell membrane of mammalian cells by proper selection of TM.

Animals↗

PubMed1999

Does prostate brachytherapy treat the seminal vesicles? A dose-volume histogram analysis of seminal vesicles in patients undergoing combined PD-103 prostate implantation and external beam irradiation.

PURPOSE: Combined brachytherapy of the prostate and external beam irradiation (EBRT) of the prostate and seminal vesicles (SV) is becoming a popular treatment for high-risk prostate cancer. Dose-volume histogram (DVH) analysis of the SV in patients undergoing this treatment was performed to determine the dose distribution to the SV and the adequacy of this treatment in patients with potential SV involvement. METHODS AND MATERIALS: Twenty-five consecutive patients were treated with a Pd-103 implant of the prostate alone and 45 Gy of EBRT to the prostate and SV. Attempts were not made to implant the SV but seeds were routinely placed at the junction of the prostate and SV. All patients underwent CT-based postimplant dosimetric analysis 1 month after implantation. As part of this analysis, DVH were generated for the prostate and total SV volume (SVT). In addition, the SV was divided into 6-mm-thick volumes identified as SV1, SV2, SV3, SV4, and SV5 starting from the junction of the prostate and SV and extending distally. DVH were also generated for these structures. Delivered dose was defined as the D90 (dose delivered to 90% of the organ on DVH). RESULTS: The median volumes in cc of the prostate, SVT, SV1, SV2, SV3, SV4, and SV5 were 34.33, 9.75, 2.7, 3.48, 2.92, 3.18, and 1.96 respectively. The SVT contained from 0-9 seeds (median 2). There was little dose delivered to the SVT and SV volumes from the implanted prostate. The median D90 values for the prostate, SVT, SV1, SV2, SV3, SV4, and SV5 were 8615 cGy, 675 cGy, 3100 cGy, 1329 cGy, 553 cGy, 246 cGy, and 67 cGy, respectively. The dose delivered to the prostate covered small percentages of SV. The percents of SV volumes covered by the prostate D90 were 11, 35, 3.3, 0, 0, and 0 for SVT, SV1, SV2, SV3, SV4, and SV5, respectively. CONCLUSIONS: DVH analysis of the SV reveals that dose generated from an implanted prostate contributes little to the SV. Those patients at high risk for SV involvement may be undertreated with combined EBRT to prophylactic doses and prostate implantation.

Brachytherapy↗

PubMed1999

Nitrated nonivamide displaying a drawback of proton's role in capsaicin-associated sensory and neuronal activities.

Nitrated nonivamide (NVANO)-induced triad hypotension, and biphasic bradycardia at 0.25-1.0 mg/kg (IV) was inhibited by capsazepine (1.0 mg/kg, IV), atropine (1.0 mg/kg, IV), and vagotomy in rats. NVANO also elicited a hypotensive spinal reflex at 5.0 mg/kg (IA). In the isolated rat vagus, NVANO (10.0-100.0 microM) revealed a sensory C-spike inhibition and membrane depolarization. NVANO (5.0 microM)-induced calcium influx in the isolated rat dorsal root ganglion cells (DRGs) was diminished by capsazepine (10.0 microM). In the isolated guinea pig atria, NVANO (1.0-50.0 microM)-induced positive inotropic and chronotropic activities were antagonized by capsazepine (1.0-10.0 microM) and human calcitonin gene-related peptide(8-37) (hCGRP(837); 0.1-1.0 microM).

Action Potentials↗

PubMed1999

A gene involved in quinate metabolism is specific to one DNA homology group of Xanthomonas campestris.

A gene involved in quinate metabolism was cloned from Xanthomonas campestris pv. juglandis strain C5. The gene, qumA, located on a 4. 2-kb KpnI-EcoRV fragment in plasmid pQM38, conferred quinate metabolic activity to X. c. pv. celebensis. Tn3-spice insertional analyses further located the qumA gene on a region of about 3.0 kb within pQM38. Nucleotide sequencing of this 3.0-kb fragment reveals that the coding region of qumA is 2373 bp, the deduced amino acid sequence of which closely resembles a pyrrolo-quinoline quinone-dependent quinate dehydrogenase of Acinetobacter calcoaceticus. A 0.7 kb SalI-PstI fragment internal to qumA was used as a probe to hybridize against total genomic DNA from 43 pathovars of X. campestris. The fragment hybridized only to total genomic DNA from the four pathovars of DNA homology group 6, X. c. pv. celebensis, X. c. pv. corylina, X. c. pv. juglandis and X. c. pv. pruni, and from X. c. pv. carotae, which belongs to DNA homology group 5. This 0.7 kb fragment was also used as a probe to hybridize BamHI-digested total genomic DNAs from the four pathovars of DNA homology group 6 and X. c. pv. carotae. The restriction fragment length polymorphism pattern of DNA homology group 6 was different from that of X. c. pv. carotae. The probe hybridized to a 5.7-kb BamHI fragment in all four pathovars of group 6 and to a 6.1-kb BamHI fragment in three of four pathovars. It hybridized only to a 9. 9-kb BamHI fragment in X. c. pv. carotae. Quinate metabolism has previously been reported as a phenotypic property specific to X. campestris DNA homology group 6. Accordingly, a combination of the quinate metabolism phenotypic test and Southern hybridization using a qumA-derived probe will be very useful in the identification of pathovars in DNA homology group 6.

Alcohol Oxidoreductases↗

PubMed1999

Isoeugenolol: a selective beta1-adrenergic antagonist with tracheal and vascular smooth muscle relaxant properties.

Isoeugenolol (1.0, 3.0, 5.0 mg/kg, i.v.) produced a dose-dependent bradycardia and a decrease in blood pressure in anesthetized Wistar rats. Isoeugenolol inhibited the tachycardia effects induced by (-)isoproterenol, but had no blocking effect on the arterial pressor responses induced by (-)phenylephrine. In isolated guinea pig tissues, isoeugenolol antagonized (-)isoproterenol-induced positive inotropic and chronotropic effects on the atria and tracheal relaxations in a concentration-dependent manner. The apparent pA2 values for isoeugenolol on right atria, left atria and trachea were 7.63+/-0.03, 7.89+/-0.12 and 6.12+/-0.05, respectively, indicating that isoeugenolol was a highly selective beta1-adrenoceptor blocker. On the other hand, isoeugenolol produced a mild direct cardiac depression at high concentration and was without intrinsic sympathomimetic activity (ISA). In isolated rat thoracic aorta, isoeugenolol relaxed more potently the contractions induced by (-)phenylephrine (10 microM) and 5-HT (10 microM) than those by high K+ (75 mM). In isolated guinea pig trachea, isoeugenolol attenuated the carbachol (1 microM)-con-tracted trachea more significantly than those contracted with high K+. Furthermore, the binding characteristics of isoeugenolol and various beta-adrenoceptor antagonists were evaluated in [3H]CGP-12177 binding to rat ventricle, lung and interscapular brown adipose tissue (IBAT) membranes. The -log IC50 values of isoeugenolol for predominate beta1-, beta2- and beta3-adrenergic receptor sites were 5.82+/-0.09, 4.74+/-0.05 and 4.73+/-0.12, respectively. In conclusion, isoeugenolol was found to be a highly selective beta1-adrenoceptor antagonist with tracheal and vascular smooth muscle relaxant activities, but was devoid of alpha-adrenoceptor-blocking action.

Adrenergic beta-1 Receptor Antagonists↗

PubMed1998

Electron wedges for radiation therapy.

PURPOSE: Brain tumors can be advantageously treated with electron over photon radiation, by exploiting the rapid fall-off in dose with depth. This advantage could be further enhanced by utilizing multiple electron beams. However, in some beam configurations, wedged dose profiles would be necessary for the dose uniformity. Unlike photons, shaped pieces of material placed in electron beam severely degrade the energy, give additional scattering and, therefore, are suboptimal. The purpose of this study was to create wedged electron fields, using intensity modulation. The combination of electron wedges enables a more uniform coverage of brain tumors with a reduced dose to normal tissue. METHODS AND MATERIALS: Intensity modulation was performed for 10 to 50 MeV electrons using a narrow scanning elementary beam of a racetrack Microtron accelerator, delivering radiation pulses with coordinates and intensities prescribed by a custom scan matrix. Dispensing more pulses (or longer pulses) within the field to increase the local dose, one can sharpen the penumbra at depth and generate wedged dose distributions of arbitrary angle as well as many other desired profiles. We modulated the electron beams, measured dose distributions using film in an anthropomorphic phantom, and compared the results with conventional techniques. RESULTS: Intensity modulation of electron beams decreases the 50-90% penumbra at depth by 40% and increases the flatness by 80%. Wedged profiles at depth can be created for any angle up to about 70 degrees, depending on the beam energy. Multiple modulated electron beams give smaller 20-70% but larger 70-100% isodose regions than photon beams. CONCLUSIONS: Electron beams can improve dose distributions in brain compared to the same number of photon beams, reducing the 20-70% isodoses region in normal tissue by 30%. Intensity modulation significantly improves the dose distribution from combined electron beams providing a sharper penumbra, better conformity, and reduced margin.

Brain Neoplasms↗

PubMed1998

Selective block by glyceryl nonivamide of inwardly rectifying K+ current in rat anterior pituitary GH3 cells.

The effects of glyceryl nonivamide (GLNVA) on ionic currents were compared and examined in rat pituitary GH3 cells. Hyperpolarization-activated K+ currents in GH3 cells bathed in high-K+ Ca2+-free external solution were studied to assess effects of GLNVA on the an inwardly rectifying K+ current (I(K(IR))). GLNVA is very potent in blocking I(K(IR)) in a concentration-dependent manner, with a half maximal concentrations of 0.1 microM. The complete block of I(K(IR)) achieved with concentrations > or = 1 microM revealed the presence of a non-inactivating current. We also found that GLNVA at a concentration above 30 microM inhibited L-type voltage-dependent Ca2+ current and two components of K+ outward currents, while GLNVA (< or = 3 microM) did not have any effect on them. This study shows that GLNVA, in addition to retaining the capability of eliciting peptidergic neurons, is a selective block of I(K(IR)) in GH3 cells and will provide a useful tool for characterizing I(K(IR)) and understanding its physiological function. In addition, the carefulness should be taken about the interpretation of GLNVA-mediated responses in vivo or in vitro.

Animals↗

PubMed1998

Pseudobacteremia with amoxycillin-clavulanic acid-resistant Escherichia coli traced to cross-contamination during blood culture processing.

Escherichia coli has seldom been reported to cause pseudobacteremia. The investigation of an outbreak of amoxycillin-clavulanic acid-resistant E. coli pseudobacteremia is described. Seventeen cases occurred over a five-day period. The source of the E. coli was traced to the blood culture specimen of a patient (index patient) with genuine bacteremia as a result of urinary tract infection. The other 16 case-patients had pseudobacteremia which was found to be the result of cross-contamination during subculture of blood specimens. The E. coli strain was carried over from the culture bottle of the index patient, through the contaminated gloved hands of a technician to the culture bottles of the other 16 cases. Although the pseudobacteremia occurred over a five-day period, they all resulted from cross-contamination during blood culture processing within one day. An early outbreak investigation was prompted by the unusual finding of amoxycillin-clavulanic acid resistance in the case E. coli isolates in a short period. The relatedness of the E. coli strains from the 17 cases was confirmed by arbitrary-primed polymerase chain reaction. Clinicians should be alerted to the possibility of a blood E. coli isolate being a contaminant despite its predominant role as a true pathogen.

Amoxicillin-Potassium Clavulanate Combination↗

PubMed1997

Total body irradiation with an arc and a gravity-oriented compensator.

PURPOSE: To deliver uniform dose distributions for total-body irradiation (TBI) with an arc field and a gravity-oriented compensator. This technique allows the patient to be treated lying on the floor in a small treatment room. METHODS AND MATERIALS: Through the sweeping motion of the gantry, a continuous arc field can deliver a large field to a patient lying on the floor. The dose profile, however, would not be uniform if no compensator were used, due to the effects of inverse square variation of beam intensity with distance as well as the slanted depth in patient. To solve this problem, a gravity-oriented compensator made of cerrobend alloy was designed. This compensator has a cross-section of an inverted isosceles triangle, with the apex always pointing downward, due to gravity. By properly selecting the thickness of the compensator, the width of the base, and the distance between the pivots to the base, the difference in the path length through the compensator can be made just right to compensate the effects of inverse-square and slanted depth, thus producing a uniform dose profile. RESULTS: Arc fields with a gravity-oriented compensator were used for 6, 10, 15, and 18 MV photon beams. The arc field can cover a patient with a height up to 180 cm. The field width was chosen from 32 to 40 cm at the machine isocenter. The optimal thickness of the compensator was found to be 2.5 cm, and its base was 25 cm wide. The distance from the pivot points to the flat surface of the compensator proximal to the beam ranges from 13 to 14 cm for different beam energies. The dose uniformity at a depth of 10 cm is within +/-5% for all beam energies used in this study. CONCLUSIONS: Highly uniform dose profiles for TBI treatments can be delivered with an arc and a gravity-oriented compensator. The proposed technique is simple and versatile. A single compensator can be used for all energies, because the amount of compensation can be adjusted by changing the distance to the pivot and/or the field size.

Equipment Design↗

PubMed1997

Capsazocaine: a capsaicin-sensitive functional antagonist displays an argument on sensory capsaicin receptor.

1. Intravenous infusion of capsazocaine (CAPBZ), a molecular fusion product of irritant synthetic capsaicin and local analgesic benzocaine, at 100 micrograms/kg/min for 15 min inhibited capsaicin (10 micrograms/kg, IV)-induced spinal release of substance P-like immunoreactivity and vagus reflex responses in blood pressure and heart rate changes in rats. 2. Intrathecal perfusion of CAPBZ (1.0 nM) also reversed retrograde epigastric intraarterial capsaicin (10 micrograms/kg)-induced hypotensive spinal reflex. 3. In isolated guinea pig tissues, CAPBZ (1.0-100.0 microM) inhibited capsaicin (1.0 microM)-sensitive sensory and functional activities, including cardiatonic, bronchial, tracheal and ileal contractilities. CAPBZ is suggested to be a capsaicin antagonist.

Animals↗

PubMed1997

Multileaf collimation in the treatment of the intact breast.

PURPOSE: To compare multileaf-collimator beam shaping and conventional metal-alloy blocking in irradiation of the intact breast after breast-conserving surgery. MATERIALS AND METHODS: Transmission dose was measured in a phantom, by using both types of blocking with 6- and 15-MV photon beams. Buildup data were collected, using a 6-MV photon beam, comparing open fields to various beam modifiers. RESULTS: Contralateral breast transmission was reduced with the multileaf collimator from 4% to 1%. With the jaws and multileaf collimator, the primary beam component of 0.5% was eliminated. Buildup data for the multileaf collimator most closely resembled the surface dose when a blocking tray is not used and were slightly lower than those for the conventional mounted blocks. This relates to the use of the lower of the two sets of wedges on the multileaf collimator, which is closer to the patient and thus enhances the surface dose relative to the dose with an open field and no wedge. CONCLUSION: Multileaf-collimator blocking for primary breast treatment is similar to conventional blocking, and the transition from one technique to another should be uneventful. The transmission dose to the contralateral breast is decreased with the multileaf collimator.

Breast Neoplasms↗

PubMed1997

Glyceryl nonivamide, a nonpungent analogue of capsaicin, enhances substance P release and renal function in rats.

Effects of glyceryl nonivamide (GLNVA), a nonpungent analogue of capsaicin, on spinal substance P release, blood pressure and renal function were investigated in rats. GLNVA was administered intrathecally or intracerebroventricularly, and renal clearance function was measured. The addition of GLNVA at concentrations of 2, 20 and 200 mumol/l during in vivo spinal superfusion resulted in concentration-dependent increases in the release of substance P. Capsaicin pretreatment (50 mg/kg/day, s.c. for 2 weeks) blunted the GLNVA-induced substance P release, suggesting a stimulation of GLNVA on the spinal terminals of capsaicin-sensitive primary afferent nerves to release substance P. Intracerebroventricular administration of GLNVA at concentrations of 20, 40 and 80 nmol/l evoked a concentration-dependent depressor response. Despite the hypotensive effect, GLNVA caused significant increases in glomerular filtration rate, urine flow, absolute and fractional excretion of sodium and potassium, osmolar clearance and free water reabsorption rate. These data suggest that central administration of GLNVA stimulates spinal substance P release, reduces blood pressure but enhances renal excretion of water and electrolytes due to an increased filtered load and a decreased tubular reabsorption.

Absorption↗

PubMed1997

Glyceryl nonivamide: a capsaicin derivative with cardiac calcitonin gene-related peptide releasing, K+ channel opening and vasorelaxant properties.

In this study, the aorta vasorelaxant, coronary calcitonin gene-related peptide (CGRP) releasing, and atrial contractility effects of glyceryl nonivamide (GLNVA) were investigated in guinea pigs. In the isolated thoracic aorta, although GLNVA (0.01-50 microM) concentration dependently induced endothelium-independent relaxations and relaxed phenylephrine-(1.0 microM) induced contractions, it failed to relax 80 mM KCI-induced contractions. The GLNVA (1.0 microM) relaxation response in the aorta was significantly inhibited by tetraethylammonium (2.5-10 mM) or ouabain (5.0 microM) and was attenuated by increased extracellular potassium gradient (10-30 mM). Glibenclamide (0.01-10 microM) dose dependently antagonized the GLNVA relaxant effect. In the isolated perfused guinea pig heart, GLNVA (0.1-10 microM) increased CGRP-like immunoreactivity outflow from coronary circulation in a concentration-dependent manner. In the isolated right and left guinea pig atria, GLNVA (0.01-10 microM) produced concentration-dependent positive inotropic and chronotropic effects, but these effects were inhibited by pretreatments with ruthenium red (1.0 microM), capsazepine (10 microM), human calcitonin-gene-related peptide (CGRP(8-37)) (1.0 microM) and sensory neuron denervation, respectively. Based on these findings, we suggest that CGRP may be released by GLNVA from cardiovascular sensory neuron, and it then activates CGRP receptors on the coronary artery and atrium. The GLNVA-induced vasorelaxant effect in the vascular smooth muscle of the aorta is due to CGRP release associated K+ channel opening, and this effect eliminates capsaicin-derived excitability-associated K+ channel blocking activities.

Animals↗

PubMed1996

The effect of setup uncertainties on the radiobiological advantage of fractionation in stereotaxic radiotherapy.

PURPOSE: There may be radiobiological advantages in administering stereotaxic radiation treatment in multiple fractions instead of by a single irradiation. However, a larger planning target volume may be required for fractionated stereotaxic radiotherapy than for a single session treatment, if decreased geometrical precision and increased setup uncertainty are associated with multiple-fraction treatments. This factor may partially offset the radiobiological gain. The purpose of this study is to estimate the potential therapeutic gain of fractionated treatments for brain tumors, and to assess the effect of increased setup uncertainty on the potential gain. METHODS AND MATERIALS: The concept of biologically effective dose (BED), based on the linear quadratic (LQ) model, was used to quantify the therapeutic efficacy of the respective treatment schema. Therapeutic gain (TG) was defined as the ratio of tumor BEDs, for multiple fractions and single treatment, respectively, for the same normal brain BED. To include the effect of increased planning volume in fractionated treatment, a power-law relationship was assumed for the volume dependence of prescription dose, and the TG was recalculated using the "volume-adjusted" doses. RESULTS: The therapeutic gain for fractionated treatment increases with fraction number, and is smaller for larger single treatment doses. For example, in going from 1 to 10 fractions, the TG is 1.40, 1.32, or 1.27 for single treatment dose of 20, 30, or 40 Gy, respectively. Also, the TG is more significant for the initial few fractions. The benefit of fractionation is diminished if larger planning volume is needed for multiple fraction treatments. For example, the above TG are reduced to 1.19, 1.11, or 1.06, if a 2 cm planning target volume in single fraction treatment is enlarged to 2.3 cm in fractionated treatment. CONCLUSION: Consideration of the therapeutic gain with fractionation should include estimates of setup uncertainty for multiple-fraction treatments, relative to that of single fraction radiosurgery.

Brain Neoplasms↗

PubMed1996

Multiple sensory and functional effects of non-phenolic aminodimethylene nonivamide: an approach to capsaicin antagonist.

1. Hexylaminodimethylene nonivamide (CAPCNC6, 0.1-10 microM) inhibited the contractility of isolated guinea pig right atria, toxically revealed positive inotropic, chronotropic and then a cardiac arrest effect at 100 microM and inhibited capsaicin (1.0 microM)-induced cardiotonic effects. 2. CAPCNC6 (0.1-10 microM)-induced aorta contractions were inhibited in the presence of flunarizine, atropine, phentolamine, Ca(2+)-free solution and pre-treatment of the animal with capsaicin. 3. CAPCNC6 (1.0-300 microM)-induced trachea contractions were inhibited in the presence of capsazepine, ruthenium red, hCGRP8-37 and pre-treatment of the animal with capsaicin.

Amides↗