Synthesis and blood compatibility evaluation of segmented polyurethanes based on cholesterol and phosphatidylcholine analogous moieties

New segmented polyurethanes based on cholesterol and phosphatidylcholine analogous moieties were synthesized. The soft segments used in this study were the poly(butadiene), poly(isoprene) or hydrogenated poly(isoprene) glycols; the hard segments of these segmented polyurethanes were composed of 4,4'-methylenediphenyl diisocyanate, 2-[bis(2-hydroxyethyl)methylammonio]ethyl 5-cholesten-3 beta-yl phosphate and 1,4-butanediol. The blood compatibilities of synthesized segmented polyurethanes were evaluated by platelet-rich plasma contact studies and scanning electron microscopy observation using glass as the reference. The results show that the blood compatibilities of the synthesized segmented polyurethanes have great difference between the glass contact side and air exposed side for the same cast films. Generally, the hydrogenated poly(isoprene)-based segmented polyurethane is the best surface in terms of platelet adhesion, and the morphology of adhered platelets undergoes the lowest degree of variation among the segmented polyurethanes investigated in this study.     

In vivo biocompatibility and biostability of modified polyurethanes

Modified segmented polyurethanes were examined for biostability and biocompatibility using an in vivo cage implant system for time intervals of 1, 2, 3, 5, and 10 weeks. Two types of materials were used: polyether polyurethanes and polycarbonate polyurethanes. Two unmodified polyether polyurethanes (PEUU A' and SPU-PRM), one PDMS endcapped polyether polyurethane (SPU-S), and two polycarbonate polyurethanes (SPU-PCU and SPU-C) were investigated in this study. Techniques used to characterize untreated materials were dynamic water contact angle, stress-strain analysis, and gel permeation chromatography. Cellular response was measured by exudate analysis and by macrophage and foreign body giant cell (FBGC) densities. Material characterization, postimplantation, was done by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) in order to quantify biodegradation and scanning electron microscopy (SEM) to qualitatively describe the cellular response and biodegradation. The exudate analysis showed that the acute and chronic inflammatory responses for all materials were similar. Lower FBGC densities and cell coverage on SPU-S were attributed to the hydrophobic surface provided by the PDMS endgroups. The polycarbonate polyurethanes did not show any significant differences in cell coverage or FBGC densities even though the macrophage densities were slightly lower compared to polyether polyurethanes. By 10 weeks, biodegradation in the case of PEUU A' and SPU-PRM was extensive as compared to SPU-S because the PDMS endcaps of SPU-S provided a shield against the oxygen radicals secreted by macrophages and FBGCs and lowered the rate of biodegradation. In the case of polycarbonate polyurethanes, the oxidative stability of the carbonate linkage lowered the rate of biodegradation tremendously as compared to the polyether polyurethanes (including SPU-S). The minor amount of biodegradation seen in polycarbonate polyurethanes at 10 weeks was attributed to hydrolysis of the carbonate linkage.     

In vitro effects of GM-CSF on mature peripheral blood neutrophils

GM-CSF can play a crucial role in regulating the neutrophil-mediated inflammatory response. This growth factor is a proliferative stimulus for bone marrow neutrophil stem cell precursors and has at least 3 important roles in regulating neutrophil-mediated immunity: a) a direct effect on the proliferation and development of neutrophil progenitors; b) synergistic activity with other haemopoietic growth factors; c) stimulation of the functional activity of mature neutrophils. The production of GM-CSF may be triggered directly by exogenous factors such as antigens and endotoxins, or indirectly through the release of cytokines by a variety of cells including lymphocytes, activated macrophages and endothelial cells exposed to products of mononuclear phagocytes. Such production of GM-CSF may serve to quickly release mature neutrophils from the bone marrow in response to infections. Moreover, enhancement of the function of mature neutrophils may also augment their ability to migrate to infective sites and then phagocytose and kill pathogens. Increased expression of CD11b/CD18 may play a fundamental part in this mechanism because this receptor is essential for the adhesion of neutrophils to the endothelium. Both phagocytosis and oxidative burst activity increase as a result of the action of GM-CSF and the increased expression of complement- and Fc-receptors can augment opsono-phagocytosis. A further level of neutrophil up-regulation occurs by increasing the functional life span of neutrophils by GM-CSF. Thus, by delaying neutrophil apoptosis, GM-CSF greatly extends the time over which neutrophils may function at inflammatory sites. GM-CSF can thus exert a variety of important regulatory controls of neutrophil function during bacterial infections. Both the number and the functional status of neutrophils is highly regulated by GM-CSF. It is also possible that GM-CSF produced within localised sites of acute inflammation or infection may attract, trap and then activate neutrophils within this site.     

In vitro effect of dextran-benzene-tetra-carboxylate hemoglobin on human blood rheological properties

While conducting pharmacological investigations into oxygen carriers, it is important to study the in vitro and in vivo rheological behavior of blood cells in the presence of such preparations. With regard to the original nature of human hemoglobin bound to benzene tetracarboxylate substituted dextran (Dex-BTC-Hb), it seemed necessary to study its rheological effect in a simulated in vitro hemorrhagic shock compensated by a blood substitute. The viscosity of substitutes was determined as well as several rheological parameters after 0, 3 and 6 hours incubation periods of red blood cells with substitutes: viscosity of blood-substitute mixtures at different levels of plasma substitution erythrocyte aggregation of blood-substitute mixtures by determining the velocity of rouleau formation and the cohesion of rouleau network. This work yielded several observations: The viscosity of Dex-BTC-Hb was slightly higher than those of solutions of native Hb, Dex-BTC T10, Dextran 40 (Plasmacair, modified fluid gelatin (Plasmion and hydroxyethyl starch 200 (Elohes). The substitution of a blood volume with Dex-BTC-Hb, corresponding to a compensated 45% hemorrhagic shock, slightly increased the viscosity of hemodiluted blood as compared to other substitutes. In the presence of Dex-BTC-Hb, the aggregation of erythrocytes appears to be increased as compared to standard solutions. Yet, the effect was close to that of Plasmion or Elohes.     

In vitro radioautographic studies of the biodistribution of radiopharmaceuticals on blood elements

Alpha-tocopherol and bilirubin antioxidant properties were evaluated in sickle cell disease. The total peroxyl radical trapping antioxidant activity of plasma (TRAP) was measured with a polarographic method using hemin as oxidative stress initiator. The TRAP was not correlated with plasma alpha-tocopherol concentration. The TRAP was correlated with plasma total bilirubin concentration [TRAP = 8.1 (total bilirubin) +363.7 (r = 0.67)] and the correlation was even better with the sum (alpha-tocopherol + total bilirubin) plasma concentration [TRAP = 9.1(alpha-tocopherol + total bilirubin)+ 170.5(r = 0.77)]. The alpha-tocopherol contribution in the antioxidant capacity of plasma was significant but bilirubin level acted as the limiting factor of plasma antioxidant capacity in sickle cell anemia. This result can be explained by the antioxidant property of bilirubin but also by coantioxidant activity towards oxidized alpha-tocopherol.     

In vitro blood schizonticidal activity of sera containing mefloquine-quinine against Plasmodium falciparum

INTRODUCTION: Since patient cooperation in neonates and infants up to 5 years is always reduced, deep sedation is usually recommended to obtain constant high-quality images during MRI. According to the widely accepted AAP Guidelines, deep sedation is not always distinguishable from general anesthesia, substantiating the demand for state-of-the-art anaesthesia. This is particularly true in this age group, where pharmacokinetics and pharmacodynamics show wide interindividual variation. In this review we outline the techniques required to provide safe and effective patient care in the unique MRI environment. CHOICE OF DRUGS AND PROCEDURE: From the viewpoint of induction time, half-life of action and success rate, we have found that inhalation anesthetics and propofol present clear advantages. Both offer rapid induction and emergence, allowing outpatient examinations in a tight schedule with a reliable sedation state. Tracheal intubation or a laryngeal mask airway is required to supply volatile anesthetics and to secure the airway, since propofol in appropriate doses causes respiratory depression and loss of the protective reflexes. Positive-pressure ventilation is recommended since the reduction of tidal volumes by sedative drugs (including high-dose chloral hydrate, barbiturates) may cause atelectasis and decreased oxygen saturation. ANESTHESIA MACHINES: Several respirators work well outside a critical magnetic field strength of 10 mT (e.g. Draeger: Titus, Siemens: Servo 900). The use of long low-compliance tubing (4-5 m) allows the respirator to be placed at the distal end of the patient table. Sidestream capnometry and spirometry at the proximal tube connector facilitate compensation for losses in tidal volume due to gas compression. Syringe pumps work properly when kept outside the 10 mT line. Some defibrillators (e.g., Lifepac, Physiocontrol) are approved for use in strong magnetic fields. MONITORING: State-of-the-art monitoring is also attainable for high-risk patients, including invasive pressure measurement. Since wiring without special filters may not cross the HF shield of the examination room, hydraulic and pneumatic systems are used (blood pressure by oscillometry, airway monitoring by side-stream spirometry). Optical fibers are used for pulse oximetry. A telemetric EKG is usually provided by the MRT manufacturer. Because oscilloscopes are distorted by the magnetic field, the monitors are placed outside the examination room. In addition, this eliminates the possibility of erasing the EPROMs contained in most monitors. PERSONNEL: With the setup described, the presence of a second anesthetist within the examination room is superfluous. A second anesthesia team can shorten the time lag between examinations by overlapping induction if a separate anesthesia induction and emergence room is provided. CONCLUSION: The level of sedation required for MRI in newborn and infants can only be achieved safely and efficiently by general anesthesia performed by trained staff. Complete state-of-the-art anesthesia care can be delivered if appropriate instrumentation is used.     

In vitro binding of pentobarbital sodium--a component of nembutal--to human blood serum albumins

Comparisons were made of the sexual behaviour of sham-operated male hamsters and castrated males receiving testosterone, dihydrotestosterone or androstenedione (1-5 mg/week), or oil alone. Tests of short duration (10 min) were conducted at Week 3 (when the animals were sexually naive), Week 6 and Week 9. Sham-operated males showed marked increases in many elements of behaviour between Weeks 3 and 9, while castrated males receiving no androgen replacement showed marked decreases. Males receiving each of the three androgens showed marked increases in behaviour, but androstenedione-treated males showed less facilitation of sexual behaviour than controls. Dihydrotestosterone was as effective as testosterone. The three androgens were comparable in maintaining seminal vesicle weight after castration and in preventing the customary rise in pituitary and body weights. These data suggest that, unlike the situation in the rat, aromatization of androgens is unnecessary for the display of sexual behaviour in the hamster.     

Gas transfer and in vitro and in vivo blood compatibility of a fluorinated polyimide membrane with an ultrathin skin layer

The authors have synthesized fluorinated polyimides to develop a novel membrane oxygenator combining excellent gas transfer and blood compatibility. Gas exchange membranes of fluorinated polyimides prepared by a dry/wet process showed an asymmetric structure and consisted of an ultrathin and defect-free skin layer supported by a porous substructure. The asymmetric polyimide membranes never incurred plasma leakage because of the defect-free skin layer of the membrane surface. The calculated, apparent defect-free skin layer thickness of the asymmetric membrane was approximately 20 nm. Carbon dioxide and oxygen transfer rates through the membranes were dramatically enhanced because of the ultrathin skin layer and were 96 and 64 times larger than those determined in currently available oxygenator polymer membranes, such as polydimethylsiloxane (PDMS). For the evaluation of in vitro blood compatibility, platelet adhesion and plasma protein adsorption on the polyimide membranes were measured by using scanning electron microscopic examination and an amino acid analyzer. Deformation and aggregation of platelets adherent to the membranes were not observed, and the number of platelets was 1.6 micrograms/cm2, which was one-sixth less than the value measured in PDMS. For in vivo evaluation, the polymer tubes were implanted in the femoral vein of a mongrel dog for 7 days. Thrombus formation and fibrin were found on the surface of PDMS. However, thrombus formation was not observed on the polyimide. These results indicate that the fluorinated polyimides show excellent blood compatibility and are a promising membrane material for an oxygenator.     

三维大孔氮化碳材料的制备及其血液相容性

以粒径640nm的单分散二氧化硅胶体晶体为模板,由四氯化碳和乙二胺回流加热制备出氮化碳的前驱物;将其填入模板的缝隙中,在氮气中热处理,形成氮化碳/二氧化硅的复合物;用氢氟酸除去二氧化硅模板,制备出三维大孔氮化碳材料.通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、选区电子衍射(SAED)、元素分析、红外光谱(FT-IR)、X射线光电子能谱(XPS),对其形貌结构、元素组成、键合状态进行了形貌和结构的表征.采用部分凝血活酶时间(APTT)、凝血酶原时间(PT)和凝血酶时间(TT)对其体外抗凝血活性作了初步的评价,发现制备的大孔氮化碳对血液不会造成促凝,说明其可能成为一种新的血液相容性材料.     

In vitro corrosion of titanium

Titanium is used in dentistry for implants and frame work because of its sufficient chemical, physical and biological properties. The corrosion behaviour is from high interest to value biocompatibility. A static immersion test was undertaken with a titanium test specimen (30 mm x 10 mm x 1 mm, immersion time = 4 x 1 w, n = 3 for each series). The following parameters were investigated: specimen preparation, grinding, pH-value, different casting systems, comparison with CAD/CAM, influence of: chloride, thiocyanate, fluoride, lactate, citrate, oxalate, acetate. Atomic absorption spectroscopy was used to analyse the solutions weekly. The course of corrosion was investigated photometrically. Titanium reveals ion releases [(0.01-0.1) microg/(cm2 x d)] in the magnitude of gold alloys. There is little influence of grinding and casting systems in comparison with organic acids or pH value. The ion release increases extreme (up to 500 microg/(cm2 x d)) in the presence of fluoride. Low pH values accelerate this effect even more. Clinically, no corrosion effects were observed. Nevertheless it is recommended that it is best to avoid the presence of fluoride or to reduce contact time. In prophylactic fluoridation of teeth, a varnish should be used.     

In vitro expansion of CD34+ cells from peripheral blood of myeloma and lymphoma patients

We studied the feasibility of in vitro expansion of CD34+ cells from patients with multiple myeloma (MM) or follicular non Hodgkin lymphoma (NHL). CD34+ cells were selected from peripheral blood (PB) using avidinbiotin immunoadsorption columns: purified CD34+ cells from three MM and five NHL patients were expanded. First, CD34+ cells (2 MM, 4 NHL) were grown for 14 days in 5 ml of IMDM plus 12.5% horse serum (HS), 12.5% fetal calf serum (FCS) and a commonly used combination of cytokines: IL1alpha, IL3, IL6, SCF, GM-CSF, G-CSF (10 ng/ml each) and EP (4 UI/ml). In these conditions, at day 14, average increase in CD34+, CFU-GM and total cell numbers were, respectively: x 6.0 x 23 and x 2,113 fold with 20 to 35% of granulocytic cells. In terms of CD34+ cell, CFU-GM and total cell outputs, MM cultures were comparable to NHL cultures, but MM cultures seemed to produce less granulocytic cells than NHL cultures. Next, in vitro expansion of PB CD34+ cells was tested in culture media suitable for clinical use. Two cultures (1 MM, 1 NHL) were carried out for 14 days in 20 ml of X-Vivo 10 medium, 2% human serum, IL1alpha, IL3, IL6, SCF, GM-CSF, G-CSF (6 ng/ml each) and EP (2 UI/ml). Increase in CD34+, CFU-GM and total cell numbers in these conditions were, respectively: x 5.7 and x 19.7, x 11.9 and x 40.9, x 424 and x 408 fold, with at least 75% of granulocytic cells in both cultures. We conclude that, although further improvements are necessary, in vitro expansion of PB CD34+ cells can presumably be carried out successfully for MM patients as well as for NHL patients, including in conditions suitable for clinical use.     

In vitro production of cyanide in normal human blood and the influence of thiocyanate and storage temperature

Normal human blood stored at room temperature (about 20 degrees C) may, over a period of weeks, undergo a slow transformation of its cyanide content. In contrast, when normal blood is stored at -20 degrees C there is formation of cyanide, usually occurring most rapidly during the first few days of storage. Peak concentrations are never greater than 20 microgram/100 ml, and although some fluctuation in concentration occurs over several months of storage at deep freeze temperature, levels are always higher than in the freshly drawn blood. The amount of cyanide produced appears to be a function of both the initial thiocyanate concentration and the freezing and/or thawing of blood. Blood stored at refrigerator temperature (about 4 degrees C) has the least fluctuation in cyanide concentration over a storage period up to three months. During this study it was found that there is significant difference in whole blood cyanide concentration between smokers and nonsmokers.     

In vitro expression and inhibition of procoagulant activity produced by bovine alveolar macrophages and peripheral blood cells

Local and systemic activation of coagulation is frequently associated with bacterial sepsis. The coagulopathy is due, at least in part, to expression of tissue factor (TF) by monocytes and macrophages. The purpose of this study was to evaluate the expression of procoagulant activity by bovine alveolar macrophages, leukocytes and platelets, and to determine the relative potency of three chemical inhibitors of TF expression (pentoxifylline, retinoic acid, and cyclosporin A). Bovine alveolar macrophages were stimulated with lipopolysaccharide (LPS) derived from Pasteurella haemolytica or recombinant bovine tumour nervous factor (TNF) and dose- and time-dependent effects on TF expression were studied. LPS and TNF induced TF expression in alveolar macrophages and LPS treatment of whole blood induced TF expression in mononuclear cells. Neutrophils and platelets also expressed procoagulant activity, but this activity was not inhibited by anti-bovine TF monoclonal antibody. Pentoxifylline (40 mumol/L), retinoic acid (0.01 mmol/L) and cyclosporin A (0.08 mumol/L) inhibited TF expression when added concurrently with LPS or TNF, but not when added 4 h after stimulation. TF mRNA was not detected in unstimulated alveolar macrophages by Northern blot analysis. In contrast, exposure to LPS or TNF for 6 h induced marked expression of TF mRNA, which was inhibited by treatment with pentoxifylline, retinoic acid and cyclosporin A. Expression of TNF by alveolar macrophages stimulated with LPS was also inhibited by these compounds. Our results indicate that procoagulant activity expressed by alveolar macrophages and monocytes is associated with expression of TF, whereas procoagulant activity expressed by neutrophils and platelets is not. The concentrations of pentoxifylline and retinoic acid necessary for inhibition of TF expression in vitro may not be achievable in vivo owing to their toxic effects. However, the in vitro concentration of cyclosporin A that inhibited TF expression did not exceed the plasma concentration observed in humans, and therefore may be useful for inhibition of TF expression in vivo.     

In vitro studies of PDR brachytherapy

BACKGROUND: Calculations on the basis of the LQ-model have been focussed on the possible radiobiological equivalence between common continuous low dose rate irradiation (CLDR) and a superfractionated irradiation (PDR = pulsed dose rate) provided that the same total dose will be prescribed in the same overall time as with the low doserate. A clinically usable fractionation scheme for brachytherapy was recommended by Brenner and Hall and should replace the classical CLDR brachytherapy with line sources with an afterloading technique using a stepping source. The hypothes is that LDR equivalency can be achieved by superfractionation was tested by means of in vitro experiments on V79 cells in monolayer and spheroid cultures as well as on HeLa monolayers. MATERIALS AND METHODS: Simulating the clinical situation in PDR brachytherapy, fractionation experiments were carried out in the dose rate gradient of afterloading sources. Different dose levels were produced with the same number of fractions in the same overall incubation time. The fractionation schedules which were to be compared with a CLDR reference curve were: 40 x 0.47 Gy, 20 x 0.94 Gy, 10 x 1.88 Gy, 5 x 3.76 Gy, 2 x 9.4 Gy given in a period of 20 h and 1 x 18.8 Gy as a "single dose" exposition. As measured by flow cytometry, the influence of the dose rate in the pulse on cell survival and on cell cycle distribution under superfractionation was examined on V79 cells. RESULTS: V79 spheroids as a model for a slowly growing tumor, reacted according to the radiobiological calculations, as a CLDR equivalency was achieved with increasing fractionation. Rapidly growing V79 monolayer cells showed an inverse fractionation effect. A superfractionated irradiation with pulses of 0.94 Gy/h respectively 0.47 Gy/0.5 h was significantly more effective than the CLDR irradiation. This inverse fractionation effect in log-phase V79 cells could be attributed to the accumulation of cycling cells in the radiosensitive G2/M phase (G2 block) during protected exposure which was drastically more pronounced for the pulsed scheme. HeLa cells were rather insensitive to changes of fractionation. Superfractionation as well as hypofractionation yielded CLDR equivalent survival curves. CONCLUSIONS: The fractionation scheme, derived from the PDR theory to achieve CLDR equivalent effects, is valid for many cell lines, however not for all. Proliferation and dose rate dependend cell cycle effects modify predictions derived from the sublethal damage recovery model and can influence acute irradiation effects significantly. Dose rate sensitivity and rapid proliferation favour cell cycle effects and substantiate, applied to the clinical situation, the possibility of a higher effectiveness of the pulsed irradiation on rapidly growing tumors.     

In vitro biosynthesis of rabbit blastokinin

Changes of the height of retinal detachments up to 0.1 mm can be visualized by A-scan-ultrasonography; such small changes cannot be ascertained by means of ophthalmoscopy. Based on echooculometric measurements of the maximal height of retinal detachments during the first hours and days after surgery without subretinal drainage, the final success (24 cases) or failure (2 cases) could be predicted 24 hours at latest. Thus in cases of retarded resorption of the subretinal fluid it can be decided by means of echography, wether a reattachment of the retina can be expected or a failure, the cause of which needs early detection.     

In vitro induction of primary DNA double-strand breaks in leukemic and normal blood cells by ultraviolet irradiation

The yield of UV-induced DNA double-strand breaks was studied for white blood cells ("light" fraction) derived from peripheral blood, and from patients with lymphomas, chronic lymphoid leukemia (CLL), and chronic myeloid leukemia (CML). The method employed was constant-field electrophoresis of plug-embedded DNA in agarose gel. Characteristic dose-response curves were obtained for various cell populations. Lymphoid cells, both from healthy subjects and CLL patients, revealed less damage to DNA under UV-irradiation, whereas CML cells were much more affected. Possible interpretation of these results includes species-specific differences in UV-induced DNA damage, as well as sufficient DNA crosslinking, thus interfering with DNA dsbs detection in irradiated cells.     

In vitro antibacterial activity of cefoperazone-sulbactam

This study was conducted to evaluate the antibacterial activity of CPZ-SBT in 1,146 clinical isolates and compared with that of CPZ and other antimicrobial agents. CPZ-SBT has much better antibacterial activity than CPZ against B-lactamase producing organisms. Of the 834 gram negative organisms tested, 165 were CPZ resistant, but 94 (57.0%) of them were still susceptible to CPZ-SBT, CPZ-SBT broadens the antibacterial spectrum of CPZ, it has good activity against Acinetobacter spp and B fragilis. Compared with other antimicrobial agents tested, CPZ-SBT is as active as ceftazidime, amikacin and ciprofloxacin against Enterobacteriaceae, P aeruginosa and Acinetobacter spp, but slightly less active than imipenem. It is as active as imipenem, timentin and metronidazole against B fragilis and other anaerobes. The results show that CPZ-SBT is a new member of the broad spectrum antimicrobial agents. It may become a promising agent for the treatment of severe infections caused by cefoperazone-resistant Gram negative bacilli including P aeruginosa.