Evaluation of an in vitro system to simulate equine foregut digestion and the influence of acidity on protein and fructan degradation in the horse's stomach.

The aim of this study was to improve an in vitro system in order to gather optimized information on the digestion of different forages in the horse's upper gastrointestinal tract. Therefore, foregut digestion of several forages was simulated in vitro (Part 1). The effect of different pH values on in vitro fructan degradation of two selected grasses (Part 2) was tested subsequently. Part 1: We hypothesized that our system produces representative results simulating digestive processes in the upper alimentary tract, but neglects microbial fermentation. In vitro digestion of six forages (grass mixture for horses, grass mixture for cows (GMC), tall fescue, English perennial ryegrass (ER), white clover, lucerne) was performed in two phases with pepsin and pancreatin. The results are consistent with current data from in vivo studies, including a degradation of crude protein and monosaccharides as well as a relative increase in fibres. Interestingly, a loss of fructan was measured in two feedstuffs (ER/GMC: 4.1/4.4% DM fructan before and 0.59/0.00% DM after simulated foregut digestion). Part 2: As fructans are thought not to be fragmented by digestive enzymes, another hypothesis was developed: acidic hydrolysis leads to a degradation of fructans. To evaluate the influence of gastric pH on the digestion of fructan and protein, different pH values (2, 3 and 4) were adjusted in a second series of in vitro foregut digestion trials with ER and GMC. As expected, the highest degradation of protein was seen at the lowest pH (protein in ER/GMC at pH 2: 6.11/8.28% DM and at pH 4: 7.73/10.64% DM), whereas fructan degradation was highest at pH 4 (fructan in ER/GMC at pH 2: 1.63/1.95% DM and at pH 4: 1.31/0.91% DM). We presume that not only acidic hydrolysis but also plant enzymes cause the loss of fructans in an acidic environment.

Hard two-body photodisintegration of 3He.

We have measured cross sections for the γ(3)He → pd reaction at photon energies of 0.4-1.4 GeV and a center-of-mass angle of 90°. We observe dimensional scaling above 0.7 GeV at this center-of-mass angle. This is the first observation of dimensional scaling in the photodisintegration of a nucleus heavier than the deuteron.

Precise extraction of the induced polarization in the 4He(e,e'p)3H reaction.

We measured with unprecedented precision the induced polarization P(y) in (4)He(e,e'p)(3)H at Q(2)=0.8 and 1.3 (GeV/c)(2). The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are overestimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin-independent charge-exchange term in the latter calculation.

Polarization transfer in the 4He(e,e'p)3H reaction at Q2=0.8 and 1.3 (GeV/c)2.

Proton recoil polarization was measured in the quasielastic 4He(e,e'p)3H reaction at Q{2}=0.8 and 1.3 (GeV/c){2} with unprecedented precision. The polarization-transfer coefficients are found to differ from those of the 1H(e,e'p) reaction, contradicting a relativistic distorted-wave approximation and favoring either the inclusion of medium-modified proton form factors predicted by the quark-meson coupling model or a spin-dependent charge-exchange final-state interaction. For the first time, the polarization-transfer ratio is studied as a function of the virtuality of the proton.

Amino acids as possible alternative nitrogen source for growth of Euglena gracilis Z in life support systems.

In recent times Euglena gracilis Z was employed as primary producer in closed environmental life-support system (CELSS), e.g. in space research. The photosynthetic unicellular flagellate is not capable of utilizing nitrate, nitrite, and urea as nitrogen source. Therefore, ammonium is supplied as an N-source in the lab (provided as diammonium-dihydrogenphosphate, (NH4)2HPO4) to E. gracilis cultures. While nitrate exerts low toxicity to organisms, ammonium is harmful for many aquatic organisms especially, at high pH-values, which causes the ionic NH4+ (low toxicity) to be partially transformed into the highly toxic ammonia, NH3. In earlier reports, Euglena gracilis was described to grow with various amino acids as sole N-source. Our aim was to investigate alternatives for (NH4)2HPO4 as N-source with lower toxicity for organisms co-cultivated with Euglena in a CELSS. The growth kinetics of Euglena gracilis cultures was determined in the presence of different amino acids (glycine, glutamine, glutamic acid, leucine, and threonine). In addition, uptake of those amino acids by the cells was measured. Cell growth in the presence of glycine and glutamine was quite comparable to the growth in (NH4)2HPO4 containing cultures while a delay in growth was observed in the presence of leucine and threonine. Unlike, aforementioned amino acids glutamate consumption was very poor. Cell density and glutamate concentration were almost unaltered throughout the experiment and the culture reached the stationary phase within 8 days. The data are compared with earlier studies in which utilization of amino acids in Euglena gracilis was investigated. All tested amino acids (glutamate with limitations) were found to have the potential of being an alternative N-source for Euglena gracilis. Hence, these amino acids can be used as a non-toxic surrogate for (NH4)2HPO4.

Clinical significance of pharmacokinetic drug interactions between interferon-alpha and antineoplastic drugs.

The major problems in chemotherapy are occasional low response rates in patients despite favourable in vitro action, the development of drug resistance and long or short term adverse effects. Therefore, in the past decade efforts have been made to circumvent these problems by combining antineoplastic drugs with biomodulating or cytoprotective agents. Most of the clinically useful drug regimens consist of a cocktail of drugs with different mechanisms of action, and hence different toxicity profiles. Dose-limiting factors in regard to toxicity and therapeutic efficacy predominate, and it is therefore clinically essential to know whether or not a pharmacokinetic drug interaction occurs. The introduction of interferon-alpha (IFNalpha) in chemotherapy is an alternative investigational approach to amplify the cytotoxicity of an antineoplastic drug in order to increase tumour response. Most of the clinical studies reported with IFNalpha provide useful information and identify major pharmacodynamic interactions, but only a few focus on and report potential pharmacokinetic interactions between antineoplastic drugs and IFNalpha in patients. The broad spectrum of antineoplastic drugs whose activity can be enhanced by IFNalpha argues for multiple levels of drug-drug interactions: protein binding (cisplatin), alteration in cellular uptake, modulation of drug target enzymes (dihydropyrimidine hydrogenase) and changes in biotransformation (tretinoin) or excretion. Pharmacokinetic and/or pharmacodynamic interactions may be beneficial (fluorouracil) or sometimes detrimental and coincidental (doxorubicin). This article focuses on observed pharmacokinetic drug interactions between IFNalpha and antineoplastic drugs and discusses possible mechanisms of action.

Electrocardiographic and hemodynamic effects of cisapride alone and combined with erythromycin in anesthetized dogs.

The cardiovascular effects of cisapride administered intravenously at escalating doses with and without pretreatment with erythromycin were evaluated in morphine/chloralose anesthetized dogs. Dogs were instrumented to permit simultaneous recording of ECGs, left ventricular (LVP) and aortic (AoP) pressures, as well as programmed electrical stimulation (PES). Escalating intravenous doses of cisapride from 2 to 8 mg/kg (four times the recommended therapeutic dose) increased the heart rate (HR) and prolonged the corrected QT interval (QTc) (p < 0.05) compared to controls. Pretreatment with erythromycin failed to enhance the effect of cisapride on either HR or QTc. Cisapride with or without erythromycin pretreatment had no effect on AoP, but depressed indices of left ventricular contractility (dP/dt(max) decreased while PEP/ET increased) compared to controls. No dogs developed spontaneous arrhythmias, and arrhythmias were not inducible by PES. Cisapride with or without erythromycin pretreatment altered the orientation of the T-wave vector (p < 0.05) compared to controls, indicating a primary effect of cisapride on ventricular repolarization. The QTc and T wave changes observed were consistent with the known action of cisapride on canine I(Kr) channels.

Effect of single- and multiple-dose 0.5% timolol maleate on intraocular pressure and pupil size in female horses.

OBJECTIVE: To determine the effect of single and multiple-dose 0.5% timolol maleate on intraocular pressure (IOP) and pupil size between 8 AM and 8 PM. Animals Nine female horses with normotensive eyes. Procedure IOP, horizontal and vertical pupil size were measured on a single day, between 8 AM and 8 PM at hours 0, 0.5, 1, 2, 4, 6, 8, 10, and 12. A single dose of 0.5% timolol maleate was applied to both eyes immediately after the first measurement at 8 AM. IOP and pupil size were measured at 8 AM and 4 PM in a 5-day experiment of twice-daily application of 0.5% timolol maleate. RESULTS: A significant decrease in IOP from 24.9 +/- 4.2 mmHg prior to application of timolol maleate to 20.7 +/- 3.1 mmHg (4.2 mmHg = 17%) was observed 8 h after single-dose application. A significant decrease in horizontal pupil size (2.0 mm = 11%) was present 6 h after single-dose application. In the multiple-dose experiment, a significant decrease in IOP was present on days 4 and 5 as compared to IOP measured prior to application of timolol maleate. A significant decrease in horizontal and vertical pupil size was present throughout the 5-day study as compared to the values obtained prior to treatment. CONCLUSIONS: 0.5% timolol maleate significantly decreased IOP and pupil size in normo-tensive eyes of this group of female horses in both single and multiple twice daily applications.

Effect of auriculopalpebral nerve block and intravenous administration of xylazine on intraocular pressure and corneal thickness in horses.

Intraocular pressure (IOP) was measured, using applanation tonometry, in both eyes of 20 horses after topical application of 0.5% proparacaine to the cornea. Ultrasonic pachymetry was used to measure central, mid-peripheral, and peripheral corneal thickness (CT) in all 4 quadrants of both eyes of 25 horses. All measurements were repeated after auriculopalpebral nerve block, sedation by IV administration of xylazine, or combination of nerve block and sedation. Mean IOP after topical anesthesia of the cornea was 20.6 +/- 4.7 mm of Hg for the left eye and 20.35 +/- 3.7 mm of Hg for the right eye. Mean central CT was 793.2 +/- 42.3 microns. The peripheral part of the cornea was significantly (P < 0.05) thicker, on average, than the central part of the cornea. Auriculopalpebral nerve block had no significant effect on IOP or CT. Intravenous administration of xylazine resulted in a significant (P < 0.05) decrease in IOP, but had no effect on CT.

Normal variation in, and effect of 2% pilocarpine on, intraocular pressure and pupil size in female horses.

OBJECTIVE: To determine normal variation in, and effect of 2% pilocarpine hydrochloride on, intraocular pressure (IOP) and pupil size in female horses during a specified period. ANIMALS: 10 female horses with normotensive eyes. PROCEDURE: IOP and horizontal and vertical pupil size were measured on a single day between 8 AM and 8 PM at hours 0, 0.5, 1, 2, 4, 6, 8, 10, and 12. Measurements were repeated after single- dose application of 2% pilocarpine to both eyes. IOP and pupil size were measured at 8 AM and noon in a 5-day experiment of twice-daily application of 2% pilocarpine. RESULTS: Variation in IOP and pupil size was not significant between 8 AM and 8 PM. Change in IOP or pupil size after a single dose of 2% pilocarpine also was not significant. In the multiple-dose experiment, the IOP at noon on the fifth day was significantly higher than the IOP in the morning on the first and second days. The IOP in the morning on the fifth day was significantly higher than the IOP in the morning and at noon on the first and second days. The IOP at noon on the fourth day was significantly higher than the morning IOP on the first and second days and at noon on the first day. The decrease in vertical pupil size was significant. CONCLUSIONS: Between 8 AM and 8 PM, variation in IOP and pupil size in normotensive eyes of horses is not significant. Two percent pilocarpine does not significantly change IOP between 8 AM and 8 PM in clinically normal horses after a single dose or multiple twice-daily applications. After multiple twice-daily applications, a trend toward an increase in IOP was seen, and the decrease in vertical pupil size was significant.

Effects of chronic, oral amiodarone on left ventricular pressure, electrocardiograms, and action potentials from myocardium in vivo and from Purkinje fibers in vitro.

Left ventricular pressure, electrocardiograms, and action potentials from myocardium and Purkinje fibers were recorded from five untreated controls and five dogs given amiodarone at 25 mg/kg every 12 hours for 4 weeks, followed by 25 mg/kg once daily for an additional 6 weeks. QT interval and action potential duration were more prolonged following treatment with amiodarone, but there were no significant changes in Purkinje fibers except that automaticity was suppressed. This study demonstrated that amiodarone given orally for 10 weeks to healthy dogs lengthens action potential duration of myocardium but has no effect on Purkinje fibers or heart rate variability. This is contrary to previous reports of dogs given amiodarone at a lower dose and for shorter times.

The influence of microgravity on Euglena gracilis as studied on Shenzhou 8.

The German Aerospace Center (DLR) enabled German participation in the joint space campaign on the unmanned Shenzhou 8 spacecraft in November 2011. In this report, the effect of microgravity on Euglena gracilis cells is described. Custom-made dual compartment cell fixation units (containing cells in one chamber and fixative - RNA lysis buffer - in another one) were enclosed in a small container and placed in the Simbox incubator, which is an experiment support system. Cells were fixed by injecting them with fixative at different time intervals. In addition to stationary experiment slots, Simbox provides a 1 g reference centrifuge. Cell fixation units were mounted in microgravity and 1 g reference positions of Simbox. Two Simbox incubators were used, one for space flight and the other as ground reference. Cells were fixed soon after launch and shortly before return of the spaceship. Due to technical problems, only early in-flight samples (about 40 min after launch microgravity and corresponding 1 g reference) were fully mixed with fixative, therefore only data from those samples are presented. Transcription of several genes involved in signal transduction, oxidative stress defence, cell cycle regulation and heat shock responses was investigated with quantitative PCR. The data indicate that Euglena cells suffer stress upon short-term exposure to microgravity; various stress-induced genes were up-regulated. Of 32 tested genes, 18 were up-regulated, one down-regulated and the rest remained unaltered. These findings are in a good agreement with results from other research groups using other organisms.

Biowaiver monographs for immediate release solid oral dosage forms: mefloquine hydrochloride.

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release solid oral dosage forms containing mefloquine hydrochloride as the only active pharmaceutical ingredient (API) are reviewed. The solubility and permeability data of mefloquine hydrochloride as well as its therapeutic use and therapeutic index, its pharmacokinetic properties, data related to the possibility of excipient interactions and reported BE/bioavailability studies were taken into consideration. Mefloquine hydrochloride is not a highly soluble API. Since no data on permeability are available, it cannot be classified according to the Biopharmaceutics Classification System with certainty. Additionally, several studies in the literature failed to demonstrate BE of existing products. For these reasons, the biowaiver cannot be justified for the approval of new multisource drug products containing mefloquine hydrochloride. However, scale-up and postapproval changes (HHS-FDA SUPAC) levels 1 and 2 and most EU type I variations may be approvable without in vivo BE, using the dissolution tests described in these regulatory documents.

Biowaiver monographs for immediate release solid oral dosage forms: lamivudine.

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release (IR) solid oral dosage forms containing lamivudine as the only active pharmaceutical ingredient were reviewed. The solubility and permeability data of lamivudine as well as its therapeutic index, its pharmacokinetic properties, data indicating excipient interactions, and reported BE/bioavailability (BA) studies were taken into consideration. Lamivudine is highly soluble, but its permeability characteristics are not well-defined. Reported BA values in adults ranged from 82% to 88%. Therefore, lamivudine is assigned to the biopharmaceutics classification system (BCS) class III, noting that its permeability characteristics are near the border of BCS class I. Lamivudine is not a narrow therapeutic index drug. Provided that (a) the test product contains only excipients present in lamivudine IR solid oral drug products approved in the International Conference on Harmonization or associated countries in usual amounts and (b) the test product as well as the comparator product fulfills the BCS dissolution criteria for very rapidly dissolving; a biowaiver can be recommended for new lamivudine multisource IR products and major post-approval changes of marketed drug products.

The beating pattern of the flagellum of Euglena gracilis under altered gravity during parabolic flights.

The unicellular freshwater flagellate Euglena gracilis shows negative gravitactic behavior. Previous experiments have revealed that the orientation is most likely an active physiological process in which the beating pattern of the flagellum is controlled by gravity and mediated by a change in the calcium concentration inside the cell. In a signal transduction chain, the calcium signal activates a calmodulin, which in turn raises the concentration of cAMP. This alters the beating pattern of the flagellum; reorientation is therefore not a passive process driven by buoyancy. In a recent parabolic flight experiment (ESA 45th parabolic flight campaign), we observed the beating of the flagellum with a high-resolution light microscope. Transition from hyper g to microg as well as from microg to hyper g caused a change of the beating pattern of the flagellum, which confirmed the physiological nature of the process. In microg cells stopped moving the flagellum or tried to reorient, while in hyper g, the cells realigned consecutively. The reaction times for the flagellar responses in previous experiments are confirmed.

Biowaiver monographs for immediate release solid oral dosage forms: Doxycycline hyclate.

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release (IR) solid oral dosage forms containing doxycycline hyclate are reviewed. According to the Biopharmaceutics Classification System (BCS), doxycycline hyclate can be assigned to BCS Class I. No problems with BE of IR doxycycline formulations containing different excipients and produced by different manufacturing methods have been reported and hence the risk of bioinequivalence caused by these factors appears to be low. Doxycycline has a wide therapeutic index. Further, BCS-based dissolution methods have been shown to be capable of identifying formulations which may dissolve too slowly to generate therapeutic levels. It is concluded that a biowaiver is appropriate for IR solid oral dosage forms containing doxycycline hyclate as the single Active Pharmaceutical Ingredient (API) provided that (a) the test product contains only excipients present in doxycycline hyclate IR solid oral drug products approved in the International Conference on Harmonization (ICH) or associated countries; and (b) the comparator and the test products comply with the BCS criteria for "very rapidly dissolving" or, alternatively, when similarity of the dissolution profiles can be demonstrated and the two products are "rapidly dissolving.".

Beam-helicity asymmetries in double-charged-pion photoproduction on the proton.

Beam-helicity asymmetries for the two-pion-photoproduction reaction gammap-->ppi(+)pi(-) have been studied for the first time in the resonance region for center-of-mass energies between 1.35 and 2.30 GeV. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons incident on an unpolarized hydrogen target. Beam-helicity-dependent angular distributions of the final-state particles were measured. The large cross-section asymmetries exhibit strong sensitivity to the kinematics and dynamics of the reaction. The data are compared with the results of various phenomenological model calculations, and show that these models currently do not provide an adequate description for the behavior of this new observable.

[Graded chemotherapy and reduced radiotherapy in Hodgkin's disease in childhood. Intermediate report on the cooperative HD 82 therapy study]. / Abgestufte Chemotherapie und reduzierte Strahlentherapie beim Morbus Hodgkin im Kindesalter. Zwischenbericht der kooperativen Therapiestudie HD 82.

The results of 111 children with Hodgkin's disease, who were treated with chemotherapy of different intensity and reduced radiotherapy (Cooperative Therapy Study HD 82, 12/81 - 9/83) are presented. There is no evidence that reduction of radiotherapy and selective splenectomy (splenectomy only in case of high probability of splenic involvement) induce a higher rate of relapses. All 87 patients with pathological stage I, II and IIIA are in first remission. 2 of 24 patients with stage IIIB/IV died of sepsis, 1 of those 24 patients relapsed. Splenectomy could be omitted in 2/3 of patients, in 75% of splenectomy splenic involvement was proved. 7% of all children get splenic irradiation.

Effects of disopyramide on the electrocardiogram and ventricular function in the unanesthetized dog.

The antiarrhythmic compound disopyramide has been shown to possess negative inotropic effects. The present study was conducted to establish the effects of graded doses of disopyramide on ventricular function and electrocardiograms from healthy, awake dogs. Electrocardiograms and echocardiograms were obtained during a control period, and during an experimental period in which the six dogs on test received 7.5, 15 or 30 mg disopyramide per kg body weight orally three times per day. Six other dogs served as vehicle controls. No changes of statistical significance occurred in heart rate. The PQ interval was prolonged at all doses, the QRS complex was prolonged only at the highest dose, and the QT interval was prolonged at the intermediate and high doses. Left ventricular pre-ejection period (PEP) was prolonged in a dose-dependent relationship, and the left ventricular ejection time (ET) was shortened only at the highest dose. The percent shortening fraction of the left ventricle (% delta D) decreased significantly at intermediate and high doses, while the ratio of pre-ejection period to ejection time increased in a dose-dependent relationship. Conclusions are that even in therapeutic levels disopyramide produces significant reduction in left ventricular function, and that ratio of PEP/ET correlates better with the dose of disopyramide than did % delta D. This study demonstrates the feasibility of evaluating cardiac effects of compounds by non-invasive means.

Effects of tricyclic antidepressant drugs on the electrophysiological properties of drug Purkinje fibers.

Microelectrode techniques were used to study the electrophysiologic effects of the tricyclic antidepressant (TCA) drugs imipramine , amitriptyline, doxepin, desipramine, protriptyline, and nortriptyline on isolated Tyrode's ([K +]o= 4.0 mM) superfused dog Purkinje fibers. Drug concentrations ranged from 10(-7) to 10(-5) M. TCA drug concentrations greater than 10(-6) M resulted in decreases in action potential amplitude, duration, and maximum slope of phase O (Vmax). Simultaneously with decreases in action potential duration, the effective refractory period decreased. In addition, the voltage time course of repolarization between proximally and distally recorded action potentials became less obvious. Imipramine, doxepin, protriptyline, and nortriptyline (10(-6), 10(-5) M) depressed membrane responsiveness. Superfusion of dog Purkinje fibers with 10(-5) M concentrations of TCA drugs resulted in conduction delay, postrepolarization refractoriness and, occasionally, total inexcitability. TCA drugs caused an increase in escape time and a decrease in spontaneous rate of spontaneously automatic Purkinje fibers equilibrated with epinephrine (10(-7) M) in 5 X 10(-5) M EDTA. Imipramine, doxepin, protriptyline, and nortriptyline abolished extra nondriven action potentials, and diminished oscillatory afterpotentials in dog Purkinje fibers exposed to toxic concentrations of ouabain (2 X 10(-7) M).