Promotion of sleep mediated by the A2a-adenosine receptor and possible involvement of this receptor in the sleep induced by prostaglandin D2 in rats

A 6-hr continuous infusion of 2-[p-(2-carboxyethyl)phenylethylamino]-5'-N-ethylcarboxamidoadenos ine (CGS21680), a selective A2a-adenosine agonist, into the subarachnoid space underlying the ventral surface region of the rostral basal forebrain, which has been defined as the prostaglandin (PG) D2-sensitive sleep-promoting zone, at rates of 0.02, 0.2, 2.0, and 12 pmol/min increased slow-wave sleep (SWS) and paradoxical sleep (PS) in a dose-dependent manner up to 183% and 202% of their respective baseline levels. The increments produced by the infusion of CGS21680 at 0.2 and 2.0 pmol/min were totally diminished when the rats had been pretreated with an i.p. injection of (E)-1,3-dipropyl-7-methyl-8-(3,4-dimethoxystyryl)xanthine (KF17837; 30 mg/kg of body weight), a selective A2-adenosine antagonist. In contrast, the infusion of N6-cyclohexyladenosine (CHA), a selective A1-adenosine agonist, at 2 pmol/min significantly suppressed SWS before causing an increase in SWS, and a decrease in PS was also markedly visible. Essentially the same effects of CGS21680 and CHA were observed when these compounds were administered to the parenchymal region of the rostral basal forebrain through chronically implanted microdialysis probes. Thus, we clearly showed that stimulation of A2a-adenosine receptors in the rostral basal forebrain promotes SWS and PS. Furthermore, i.p. injections of KF17837 at 30 and 100 mg/kg of body weight dose-dependently attenuated the magnitude of the SWS increase produced by the infusion of PGD2 into the subarachnoid space of the sleep-promoting zone, thus indicating that the A2a-adenosine receptors are crucial in the sleep-promoting process triggered by PGD2.

Haemodynamic changes in early phase reflex sympathetic dystrophy

We studied six patients with early phase reflex sympathetic dystrophy (RSD). Osteoporotic changes were noted in the bones of the affected limb. Despite higher temperatures indicated by thermography, laser speckle image sensing showed no increase in blood flow on the skin surface. Digital subtraction angiography showed arteriovenous shunting or increased density of perfused vessels. Based on these results, we speculate that in RSD persistent vascular contraction caused by pain leads to the formation of arteriovenous shunts in the affected limb with an ischaemic state in the peripheral subcutaneous tissue which is indicated by pain and swelling.

Effective control of methicillin-resistant Staphylococcus aureus in a burn unit

Methicillin-resistant Staph, aureus (MRSA) colonization and infection was studied in 231 patients who were admitted to our burn unit and remained for 3 days or more between 1986 and 1994 (patients with inhalation injury only and no burn wound were excluded). The study was divided into two periods: from 1988 to 1989 and from 1990 to 1994. MRSA was found in 80 patients. They increased from 1986 to 1988, slightly decreasing thereafter. In 1994 the incidence of MRSA was 4.3 per cent. The number of strains of MRSA isolated from burn wounds was significantly reduced in the later period. Comparing the two periods, isolation of patients from MRSA, prevention of contamination during care, and reduction in the number of patients initially given second- or third-generation cephem antibiotics were performed more strictly in the later period. The effectiveness of these measures was confirmed. Moreover, the first operation was carried out significantly earlier in the later period. Early excision and early closure of the wound was more effective in preventing and controlling MRSA colonization and infection.

Continuous recordings of brain regional circulation during sleep/wake state transitions in rats

Continuous measurement of regional blood flow (RBF) in the brain of a freely behaving rat was attained by a combination of laser-Doppler (LD) flowmetry and our originally devised apparatus, which had been developed for the automatic releasing of the twisting of lines connected between experimental apparatus and the freely behaving animal. RBF changes were studied in a ventral region of the rostral basal forebrain along with sleep-wake states. When compared with the RBF level during slow-wave sleep (SWS), levels of RBF during paradoxical sleep (PS) and wakefulness were higher by 24 (P = 0.0001) and 9% (P < 0.05), respectively. The LD signals suggested that the RBF elevation during PS was produced by dilation of both the large brain arteries and small vessels, whereas the elevation during wakefulness was caused by dilation of small vessels that was counteracted by contraction of large arteries. It was noticed that the original circulation tended to begin changing before the onset of SWS. A circadian rhythm was also demonstrated for the RBF, which largely decreased around the onset of the light period and returned to the high level before the beginning of the dark period. Thus continuous and real-time recordings of regional circulation were performed with satisfactorily precision in freely behaving rats.

Relationship between acetone exposure concentration and health effects in acetate fiber plant workers

In order to clarify the effects of acetone (AC) exposure on health, a cross-sectional study was carried out in 110 male AC-exposed and 67 male nonexposed shift workers. The AC workers ranged in age from 18.7 to 56.8 years (mean: 37.6 years) and in length of AC exposure from 0.5 to 34.3 years (mean: 14.9 years). The nonexposed workers ranged in age from 20.7 to 57.5 years (mean: 41.9 years). AC exposure levels assessed by personal passive monitors and biological monitoring indices measured at the end of the workshift were 19.6-1018 ppm in the breathing zone (AC-E, mean: 364 ppm), 2.5-422 ppm in alveolar air (AC-A, mean: 97.3 ppm) 4-220 mg/l in blood (AC-B, mean 66.0 ppm), and 0.75-170 mg/l in urine (AC-U, mean: 37.8 mg/l). Symptoms at the end of the workshift with good exposure-response relationships were eye irritation, tearing, and acetone odor, and symptoms within the previous 6 months with good exposure-response relationships were heavy, vague, or faint feeling in the head, nausea, loss of weight, and slow healing of an external wound. In the 30-44 year age range, simple reaction time and digit span scores in a short computerized neuro-behavioral test battery were significantly lower in AC workers, but exposure-response relationships were not clear. Manifest Anxiety Scale scores, Self-rating Depression Scale scores, R-R interval variation on the ECG, hematological examinations, serum biochemistry examinations for liver function, and phagocytic activity of peripheral neutrophils did not show any AC-related differences between the two groups. In view of the reported findings, the current occupational exposure limit of 750 ppm recommended by many governmental and academic associations seems to be too high to prevent the health effects of AC observed in this study.

Effect of ultrasonic instrumentation on bond strength of three dental cements bonded to nickel-chromium alloy

This study examined the effect of ultrasonic instrumentation on the bond strength of three types of luting material joined to a nickel-chromium alloy. Disk metal specimens were bonded together with zinc phosphate, glass ionomer, and adhesive resin luting agents. The bonded specimens were immersed in water, then vibrated with an ultrasonic unit for 0 to 5 minutes. The shear bond strength in the 0 or nonvibrated group was 50.1 MPa for adhesive resin, 18.4 MPa for glass ionomer, and 4.7 MPa for zinc phosphate cement. Vibration for a period of 5 minutes significantly diminished the bond strength of adhesive resin and glass ionomer materials, whereas the bond strength of zinc phosphate cement was affected after only 1 minute.

Bond strength and durability of porcelain bonding systems

Because the most effective bonding system for ceramic restorations has not been documented, this study examined bond strength and durability of bonding systems joined to a feldspathic porcelain. Disks of porcelain specimens were fired on refractory investment materials and were air-abraded with alumina. The disks were then bonded with six combinations of five silane primers and six luting agents. Durability of the bond was evaluated by means of a thermocycling machine. Shear bond strengths were determined before and after thermocycling. The results showed that reduction in bond strengths after thermocycling was remarkable for five systems (p < 0.05). However, three systems exhibited shear bond strength greater than 20 MPa after 20,000 cycles.

Seasonal variation in levels of prostaglandins D2, E2 and F2(alpha) in the brain of a mammalian hibernator, the Asian chipmunk

Seasonal changes in the in vivo levels of the prostaglandins (PGs) PGD2, PGE2, and PGF2(alpha) were measured in the brain of the male Asian chipmunk, Tamias asiaticus (n = 111), which underwent hibernation during the period between November and March. The mean level of PGD2 ranged from 36.0 to 85.2 pg/g tissue from June to October and remained essentially unchanged (80.5 pg/g tissue) in December. However, the mean PGD2 level rose significantly to 128.6 pg/g tissue in February, and returned to 75.2 pg/g tissue in the following April, suggesting a correlation between PGD2 and hibernation phenomenon. While PGE2 level did not vary significantly throughout the year, PGF2(alpha), which appeared to be the most abundant among the three prostanoids, showed a marked circannual rhythm with a trough of 51.6 pg/g tissue in July, rising to 391.6 pg/g tissue in February and reaching the peak value of 492.7 pg/g tissue in April, the reproduction period.

Functional and biochemical evaluation of the preserved lung in a rat model

Lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) activities and total protein concentrations were examined in the postrinsing solutions from rat lungs preserved in phosphate-buffered saline (PBS), Euro-Collins (E-C) solution, or low-potassium E-C solution for 8 h at 4 degrees C, 10 degrees C, or 20 degrees C. The LDH and AST activities were higher when the organs were preserved in PBS for 8 h at 20 degrees C than at 4 degrees C or 10 degrees C, while the total protein concentration did not differ according to the temperature or solution. The activities were also higher when the lungs were preserved in Euro-Collins (E-C) solution than in PBS or the low-potassium E-C solution. On examining pulmonary functions utilizing an ex vivo reperfusion model, the lungs preserved at 20 degrees C showed poorer gas exchange than those preserved at 4 degrees C or 10 degrees C. Moreover, the organs preserved in E-C solution showed poorer function than those preserved in any other solution. These findings suggest that some enzymatic activities in the postrinsing solution could be indicators of lung viability after preservation.

Effect of occlusion on human skin

In order to investigate the effect of occlusion on the skin, the flexor sides of both upper arms were covered with column-shaped with column-shaped closed chambers, 30 mm in outer diameter, 20 mm in inner diameter, and 5 mm in height, which were made of polyethylene foam. The tops of the chambers were sealed by plastic films with various levels of water vapor permeability to control moisture in each chamber. The raised chamber walls prevented direct contact between the skin and the plastic film. After 24 h of application, morphological changes of the skin surface were observed microscopically by the nitrocellulose-replica method. Although no visual alterations were found on all areas of occluded skin, microscopic evaluation showed that simple occlusion by films induced an increase in the number of deepened skin furrows on the skin surface. this increase was associated with lower water vapor permeability of the films, as well as with higher values of both temperature and humidity of the test day. Thus, since conditions which facilitate perspiration from the skin tend to cause skin irritation, prolonged exposure of the skin to sweat by simple occlusion may act as a primary skin irritant.

Concentration of prostaglandin D2 in cerebrospinal fluid exhibits a circadian alteration in conscious rats

Cerebrospinal fluid (CSF) was withdrawn from the cisterna magna of unanesthetized conscious rats (n = 14) through a chronically implanted catheter, and prostaglandins (PGs) D2, E2, and F2 alpha were measured. From each rat, CSF samples were taken at different clock-hours of the day (1000, 1400, and 1800 hr) and night (2200, 0200, and 0600 hr) in succession at 76-hour intervals. The concentration of PGD2 alone exhibited a significant circadian fluctuation, with its peak value at 1400 hr (mean +/- SEM: 1197 +/- 361 pg/ml) and its lowest level at 0600 hr (438 +/- 106 pg/ml). Thus, the mean level of PGD2 during the daytime (903 +/- 162 pg/ml) was significantly higher than that during the night (503 +/- 78 pg/ml). The results obtained are consistent with the postulated role of PGD2, acting in the surface layer of the rostral basal forebrain, as an endogenous factor to promote sleep.

A comparison of water temperatures for thermocycling of metal-bonded resin specimens

The thermocycling test to evaluate the bonding durability of the adhesive interface against water penetration and thermal stress is one of the most important studies before clinical application of metal-bonded resin systems is performed. Researchers have adopted various water temperatures for thermocycling adhesion specimens, which makes a direct comparison with thermocycling data attained by other researchers difficult. In this study tensile and shear bond strengths of metal-bonded resin specimens were measured after 20,000 thermocycles with the temperatures of the hot bath at 50 degrees C, 60 degrees C, and 70 degrees C. The results indicated that adhesive bonding strengths attained after thermocycling at 50 degrees C may be nearly comparable with those at 60 degrees C.

Circadian variations of prostaglandins D2, E2, and F2 alpha in the cerebrospinal fluid of anesthetized rats

Circadian variations in the levels of prostaglandins (PGs) D2, E2, and F2 alpha were studied in the cerebrospinal fluid (CSF) of rats. We collected CSF samples from the cisterna magna of anesthetized rats at different clock-hours (1000, 1400, 1800, 2200, 0200, and 0600 hr), and measured the concentrations of the three PGs. PGD2, which appeared to be the most abundant among the three, showed a circadian variation; and the mean of the day-time levels (145 pg/ml) was significantly higher than that of the nighttime ones (111 pg/ml). Day/night variations were also noticed with the levels of PGE2 and PGF2 alpha; however, these levels remained 3-4 times lower than those of PGD2. The general day/night variation seen in the CSF concentration of PGD2 conforms well with the postulated role of PGD2 as an endogenous sleep-promoting factor acting on a certain brain surface area defined as its site of action.

Adhesive bonding of titanium with a methacrylate-phosphate primer and self-curing adhesive resins

The adhesive bonding of titanium was evaluated with the use of a metal primer and three types of self-curing luting agent. The primer contained 10-methacryloyloxydecyl dihydrogen phosphate (MDP). One luting agent was a composite material that contained the MDP monomer in its liquid part. The other luting agent was based on methyl methacrylate (MMA), initiated with tri-n-butylborane derivative (TBB), and contained 4-methacryloxyethyl trimellitate anhydride (4-META). The MMA-TBB resin without 4-META was used for the control. Pure titanium metal specimens were bonded with various combinations. Shear bond strengths were determined after repeated thermocycles in water. Both MDP and 4-META were effective in bonding titanium. The decrease in bond strength was minimum when the titanium was primed with MDP and then bonded with the TBB-initiated resins.

Structural features resulting in convulsive activity of carbapenem compounds: effect of C-2 side chain

The neurotoxicity of meropenem was much lower than that of both imipenem and panipenem after intraventricular administration to mice. To clarify the major structural features responsible for the induction of convulsions by carbapenem antibiotics, the structure-activity relationship on convulsant activity was investigated in N-acetyl-2-pyrroline and cyclopentene derivatives which correspond to the 5-membered ring containing the C-2 side chain of carbapenem antibiotics. Among these derivatives, compounds with strong basicity in the side chain showed convulsant activity similar to that of the parent carbapenem compounds. In addition to the strength of the basicity of the amino group, the distance from the carboxyl to the amino group and steric crowding around the amino group also appeared to play an important role in the induction of convulsions. The results of gamma aminobutyric acid (GABAA) receptor binding assays indicated that the induction of convulsions was caused predominantly by the inhibition of GABAA-mediated inhibitory transmission. However, the in vivo convulsant activity of some of these compounds did not correlate with their in vitro inhibitory effect on GABAA receptor binding.

Reconstruction of the sole and heel and infancy in childhood followed up for more than 10 years

We evaluated 10 patients in which the initial reconstruction of the weight-bearing area of the sole and heel was performed in infancy or childhood and which had been followed up more than 10 years. In the initial operations, a cross-leg flap was used in 5, full-thickness skin graft in 5, and split-thickness skin graft in 1 (in 1 patient, both a cross-leg flap and a full-thickness skin flap was used). Secondary reconstruction was performed using skin graft from non-weight-bearing areas in 6 patients and a cross-leg flap in 1 patient. In infancy and childhood, temporary closure of a wound by skin graft from the inguinal area or a cross-leg flap was attempted. Initial reconstruction using the non-weight-bearing area must be performed carefully in infancy and childhood.

Effect of unfilled resins and a silane primer on bonding between layers of a light-activated composite resin veneering material

This investigation evaluated the effect of unfilled resins and a silane primer on bonding between layers of a urethane-based composite resin veneering material. Shear bond strengths between the layers were determined with a two-liquid silane primer and three unfilled resin bonding agents. The silane primers and unfilled resins enhanced the bond between layers of the veneering material. Durability of the bond, however, was influenced by the composition of the bonding agent. Among the systems investigated, combined use of the silane primer with triethyleneglycol dimethacrylate-based unfilled resin exhibited durable and consistent bond strength.

A novel apparatus that permits multiple routes for infusions and body-fluid collections in a freely-moving animal

A novel apparatus is described for simultaneous performance of multi-channel infusions/body-fluid collections and multichannel electrical recordings/stimulations in a freely behaving animals. This apparatus consists of a cylindrical cage and other devices described below. Electrical contacts are achieved via a slip-ring commutator. A rotation detector detects the turning of the animal in the cage, and a controller rotates the floor under the animal in the opposite direction by means of a stepping motor. Thus, excessive twisting of the fluid tubing between the animal and experimental equipment is released by rotation of the floor. Floor rotation starts when the animal turns in either direction and exceeds a present number of rotations. When the turning exceeds certain rates, the floor is rotated with higher angular velocities. This floor rotation little affected sleep-wake activities, brain temperature, food and water intake, and general behavior of the rat. Thus, multi-channel fluid routes have been realized; and by excluding the swivel apparatus from the fluid lines, advantages such as no fluid leakage at the swivel, no extra dead volume, and low torque to rotate the device have been gained.

Three-body wear of light-activated composite veneering materials

The in vitro wear of two types of composite resin veneering materials was determined by use of a three-body wear testing device. The wear of a microfilled high-filler content composite resin (Dentacolor) was less than that of a hybrid low-filler content one (Visio-Gem). The worn surface of Dentacolor material was smoother than that of Visio-Gem material. The wear-testing results and scanning electron micrographs demonstrated that the findings obtained by this wear-testing device correlated well with clinical findings.

Effect of two metal primers on adhesive bonding with type IV gold alloys

Bond strengths of an adhesive resin bonded to two types of gold alloys were investigated in vitro with two different metal primers. Disk specimens were cast in a type IV gold alloy designed for resin-bonded restorations and in a low-temperature age-hardenable gold alloy. The specimens were primed with either a vinyl-thiol primer or a thiophosphate primer, then bonded with an adhesive resin initiated with tri-n-butyl borane derivative. Both primers effectively enhanced bond between gold alloys and the adhesive. The use of metal primers in conjunction with type IV gold alloys is useful for resin-bonded fixed partial dentures.

Presence of free D-glutamate and D-aspartate in rat tissues

The presence of free D-glutamate was demonstrated for the first time in rat liver, kidney and brain. This is based on the findings that the D-glutamate as well as D-aspartate in the tissue extracts co-chromatographed exactly with the authentic standards on HPLC, and that the treatment of the extracts with D-aspartate oxidase mostly abolished the HPLC peaks of these compounds. Contents of these acidic D-amino acids in the liver and kidney, as well as the percentages of D/(D + L), were lower in female than in male, while D-aspartate oxidase activities in the same tissues were inversely lower in male than in female, in agreement with a probable role of the enzyme. A significant correlation was observed between D-aspartate and D-glutamate contents in the liver, kidney and brain of individual animals, with the D-glutamate contents always higher than the D-aspartate contents.