Middle-ear pressure variations during total intravenous anesthesia with propofol, fentanyl, and ketamine

Purpose As the middle-ear cavity is one of the noncompliant gas-filled cavities, an increase in middle-ear pressure (MEP) instead of volume expansion is observed with inhalation of nitrous oxide (N₂O). Changes in MEP cause many complications, such as ear pain, temporary hearing impairment, and postoperative emesis. Therefore, we investigated changes in MEP during total intravenous anesthesia (TIVA) with propofol, fentanyl, and ketamine (PFK) and inhalation of N₂O. Methods Twelve patients were anesthetized with PFK until 60 min after the induction of anesthesia, and then N₂O (60%) inhalation was started. MEP was measured by impedance audiometry (ranging from −300 daPa to +200 daPa) at 10-min intervals during PFK, and at 2-min intervals after the inhalation of N₂O. Results MEP gradually but significantly increased from the preanesthetic value of 16±8 to 34±12 (SEM) daPa 50 min after the induction of PFK. However, MEP did not exceed the normal limit. The values of MEP in all patients were more than 200 daPa within 36 min after the start of inhalation of N₂O in oxygen. Conclusion PFK had a minimal effect on MEP, whereas addition of N₂O to PFK increased MEP dramatically. Therefore, TIVA, or at least PFK, would be a better choice for patients with middle-ear or upper-airway diseases.     

Synaptic loss following depletion of noradrenaline and/or serotonin in the rat visual cortex: a quantitative electron microscopic study

Biogenic amines have a trophic-like role for the formation and the maintenance of synapses in the CNS. We examined the changes in the number of synaptic profiles in the developing and adult rat visual cortex following selective depletion of noradrenaline and/or serotonin. By the drug-induced decreases in levels of noradrenaline or serotonin between 1 and 2 weeks after birth, the number of synaptic profiles was decreased by 29-55% compared with that of control animals. The magnitude of reduction in the number of synaptic profiles was virtually the same following simultaneous depletion of both noradrenaline and serotonin compared with the depletion of noradrenaline or serotonin alone. Later in the developmental period, the function of noradrenaline and serotonin in facilitating synapse formation and maintenance became less prominent than that in younger animals. In the control animals, the number of axosomatic synapses was the highest at around 2 weeks after birth, and decreased with development. The number of axodendritic synapses was the highest between 2 and 7 weeks after birth, and decreased to 50% at 11 weeks after birth. These data demonstrate that synapses in the rat visual cortex are overproduced during the early developmental period. We suggest that both serotonin and noradrenaline are necessary for synapse formation during the early stages of development of the rat visual cortex.     

Immunocytochemical Evidence of Amyloid-enhancing Factor (AEF) in Polymorphonuclear Leukocytes

Amyloid enhancing factor (AEF) was extracted from spleens of mice that had received amyloidogenic stimulation. Sephacryl S 300 gel filtration of the crude AEF yielded five fractions, among which strong AEF activity was present in the first peak (Fl), and confirmed by an amyloid induction experiment. An anti AEF antiserum was obtained from a rabbit by immunization with Fl. This antibody reacted strongly with splenic polymorphonuclear leukocytes (PML) from mice given amyloidogenic stimulation, and weakly with those from normal untreated mice. Isoelectric focusing (IEF) analysis of both Fl and sera from mice given amyloidogenic stimulation was performed. A single band was observed on IEF analysis of Fl, whereas many bands were seen on IEF analysis of the sera. After the substances in the gel had been transferred to nitrocellulose membranes by capillary blotting, the membranes were made to react with the anti-AEF antiserum. The results suggested that AEF is a high molecular-weight substance derived from PML and increases in the serum at the time of, or shortly prior to, amyloid deposition in the spleen. Acta Pathol Jpn 39: 349∼355, 1989.     

Vascularization in vivo caused by the controlled release of fibroblast growth factor-2 from an injectable chitosan/non-anticoagulant heparin hydrogel

Addition of various heparinoids to the lactose-introduced, water-soluble chitosan (CH-LA) aqueous solution produces an injectable chitosan/heparinoid hydrogel. In the present work, we examined the capability of the chitosan/non-anticoagulant heparin (periodate-oxidized (IO(4)-) heparin) hydrogel to immobilize fibroblast growth factor (FGF)-2, as well as the controlled release of FGF-2 molecules from the hydrogel in vitro and in vivo. The hydrogel was biodegraded in about 20 days after subcutaneous injection into the back of a mouse. When the FGF-2-incorporated hydrogel was subcutaneously injected into the back of both mice and rats, a significant neovascularization and fibrous tissue formation were induced near the injected site. These results indicate that the controlled release of biologically active FGF-2 molecules is caused by biodegradation of the hydrogel, and that subsequent induction of the vascularization occurs.     

Hindlimb suspension inhibits air-righting due to altered recruitment of neck and back muscles in rats

Effects of 9-week hindlimb suspension and 8-week recovery on air-righting reaction in response to drop from a supine position were studied in adult rats. The righting time in rats at the end of suspension (approximately 220 ms) was longer than the age-matched controls (approximately 120 ms, p <0.05). The unloading-related change in righting time was accompanied by lowered activities of electromyogram (EMG) and altered recruitment of both neck and back muscles at a specific stage of drop. After 8 weeks of reambulation, righting time recovered toward the control level (approximately 153 ms, p <0.05), but the EMG activity of back muscle was still less than controls. In contrast, the EMG of neck muscle during fall was even increased. The differences in the characteristics of the muscle fibers between two groups were minor. It is suggested that inhibition of recruitment, rather than the changes in the fiber characteristics, of neck and back muscles is one of the major causes of the slow air-righting.     

Changes in blood pressure and muscle sympathetic nerve activity during water drinking in humans

To investigate the possible involvement of the sympathetic nervous system in pressor response during water drinking, muscle sympathetic nerve activity (MSNA), blood pressure (BP), and heart rate (HR) were continuously measured in healthy young volunteers throughout the experiments of a 5-min control, 2 min of drinking 500 ml water, and a 28-min recovery. To avoid the effects of water passing through the oropharyngeal and esophageal regions and/or effects of swallowing, an equal amount of water was directly infused to the stomach through a stomach tube for 2 min. Water drinking caused a transient increase in mean arterial pressure (MAP) and HR immediately after drinking (DeltaMAP, 12.6 +/- 2.1 mmHg; DeltaHR, +19.9 +/- 1.7 beats/min at the peak). An abrupt decrease of MSNA was observed directly during water drinking (Deltaburst rate, -6.9 +/- 1.3 bursts/min; Deltatotal activity, -2,606 +/- 491 U/min), and it increased to the baseline level thereafter. Gastric infusion had little or no effect on MAP, HR, and MSNA. The present study demonstrated that a pressor response during water drinking was associated with the attenuation of MSNA and not generated by gastric infusion of water at the same rate as in this drinking manner. In conclusion, the rapid rise in BP might be caused through stimulations from the oropharyngeal region, swallowing-induced factors, and/or a feedforward mechanism by a central descending signal from the higher brain centers.     

Contamination of transplantable human tumor-bearing lines by Helicobacter hepaticus and its elimination

Helicobacter hepaticus contaminating nonfrozen tumors was transmissible to severe combined immunodeficient (SCID) mice, but the organism in cryopreserved samples was not. This suggests that H. hepaticus has the ability to spread via biomaterials and that freezing-thawing is able to reduce the numbers of organisms to levels insufficient for subcutaneous infection of SCID mice.     

Relationships between the serum levels of soluble leptin receptor and free and bound leptin in non-pregnant women of reproductive age and women undergoing controlled ovarian hyperstimulation

BACKGROUND: The aim of this study was to investigate the relationships between the serum levels of soluble leptin receptor (SLEPR), and total, free and bound leptin, and the change in the serum SLEPR level during an IVF cycle. METHODS: Serum concentrations of leptin and SLEPR were measured in 50 Japanese women of reproductive age, and 20 patients participating in an IVF programme. The total leptin was fractionated into free and bound portions by gel filtration chromatography. RESULTS: The SLEPR level was negatively correlated with the body mass index (BMI) (r = -0.548, P < 0.0001), total leptin (r = -0.433, P < 0.0001), the percentage of free leptin (r = -0.732, P < 0.0001) and the absolute free leptin concentration (r = -0.506, P < 0.0001). The SLEPR level was positively correlated with the percentage of bound leptin (r = 0.730, P < 0.0001), whereas there was little variation in the absolute bound leptin concentration, regardless of the BMI or SLEPR concentration. During the IVF cycle, total and free leptin elevated during maximal ovarian stimulation, whereas there was no significant difference in the SLEPR concentration. CONCLUSIONS: The results demonstrate a skillful mechanism where a change in the serum SLEPR level regulates, in part, the biological activity of leptin in the circulation.     

Nuclear magnetic resonance studies on polymer carbanions, 5. Polystyryl carbanion with lithium as counter cation and its dimer model compounds

Oligostyryllithium was synthesized by the reaction of sec-butyllithium with styrene in diethyl ether at ?40°C. Dimer model anions (counter cations: Li and K) of the growing chain ends were synthesized by metallation of 1-methoxy-1,3-diphenylpropane. The structures of the lithium compounds were corroborated by ¹³C NMR spectroscopy and compared with those of the potassium compounds. As for polystyryllithium and its model compounds, the charge density on the α-carbon increased and that on the phenyl ring of the growing end decreased with increasing molecular weight, while, in polystyrylpotassium and its model compounds, the charge density on the α-carbon increased and the one on the phenyl ring did not change with increasing molecular weight. The temperature change of the ¹H NMR spectrum of oligostyryllithium in diethyl ether indicated rotation around the C-1? C_α bond at lower temperatures than in tetrahydrofuran, but the activation energy was the same in both solvents. T₁ values of the phenyl carbons in model compound 2b were one to two orders of magnitude shorter than those of the protonated compound.     

Importance of a biofouling-resistant phospholipid polymer to create a heparinized blood-compatible surface

Heparinization is believed to be one of the methods to suppress thrombus formation on blood-contacting surfaces. However, this study hypothesizes that heparinization alone might not be sufficient to provide a blood-compatible surface; that is, a surface property that resists biofouling is necessary to obtain an effective heparin-modified surface. 2-Methacryloyloxyethyl phosphorylcholine (MPC) polymers with 2-aminoethyl methacrylate (AEMA) were synthesized to immobilize heparin through ionic bonding. The primary amino groups of AEMA were considered to be the polymer surface because the zeta-potential of the surface was positive when the mole fraction of the AEMA units was above 0.2. The antithrombogenic character of the polymer surface modified with heparin was evaluated by both Lee-White and microsphere column methods. The coagulation period of human whole blood in the absence of anticoagulant in glass tubing coated with the MPC polymer was longer than that in the original glass tube. Cell adhesion was completely inhibited on the MPC polymer surface after contact with human whole blood without anticoagulant. However, many adherent blood cells were observed on poly(2-ethylhexyl methacrylate-co-AEMA) (no MPC unit) even after heparinization. These results strongly indicate that the MPC polymer is a useful substrate where the heparin works well and that the heparin-immobilized MPC polymer has superior blood compatibility to the simple MPC polymer.