A burn wound healing model in the hairless descendant of the Mexican hairless dog

Wound contraction and epithelialization occur much faster in animals than in humans. Therefore it is sometimes not valid to apply the results of animal wound healing studies to humans. Hairless descendants of Mexican hairless dogs (HD-MHD) have attracted attention because their skin characteristics approximate those of humans. We used this animal and compared the rate of healing of superficial dermal burns (SDB) and deep dermal burns (DDB) in the HD-MHD and normal beagles. We also compared the rate of healing with use of Vaseline (Chesebrough-Ponds) gauze (VG) and hydrocolloid dressings in the HD-MHD. The HD-MHD demonstrated less contraction (p < 0.05). Small pigmented spots could be seen in the HD-MHD wounds, suggesting that epithelialization started from epidermal appendages. SDBs treated with VG and hydrocolloid dressings were both epithelialized on day 18. DDBs treated with hydrocolloid dressings were epithelialized on day 24, whereas DDBs treated with VG were epithelialized on day 30. Like human wounds, burns in the HD-MHD epithelialize from appendages with less wound contraction. These similarities support the use of this burn wound healing model.

Construction of Escherichia coli-Bifidobacterium longum shuttle vector transforming B. longum 105-A and 108-A

A shuttle vector, pBLES100, was constructed by cloning a Bifidobacterium longum plasmid and a gene encoding spectinomycin adenyltransferase AAD(9) from Enterococcus faecalis into the Escherichia coli vector pBR322. Stable transformants with this plasmid were obtained with an efficiency of 2.2 x 10(4) transformants/microgram DNA or 6.9 x 10(-5) transformants/cell/microgram DNA under the optimal conditions of 10.0 kV/cm, 200 omega, and 25 microF, using B. longum 105-A harvested at late log phase of growth.

Bonding of titanium with acidic primers and a tri-n-butylborane-initiated luting agent

Adhesive bonding of titanium was investigated with the use of five primers and two luting agents. All of the primers contained acidic methacrylate monomers for promotion of metal bonding. Titanium metal specimens were bonded with seven combinations of five primers and two luting agents. Durability of the bond was evaluated by means of thermocycling. Although all five primers enhanced the bond strength to titanium, three of the primers (Super-Bond Liquid, Metal Primer and Tokuso Rebase MR. Bond) demonstrated more durable bonds than the other two primers (Acryl Bond and All-Bond 2 Primer B). The tri-n-butylborane (TBB)-initiated luting agent exhibited better bonding ability as compared to conventional composite resin. The strongest and the most consistent bond was achieved by the combination of 4-methacryloyloxyethyl trimellitate anhydride (4-META) primer and TBB resin.

Effect of acidic primers on bonding between stainless steel and auto-polymerizing methacrylic resins

OBJECTIVES

The purpose of this study was to evaluate the effect of acidic primers on bonding between methacrylic resins and SUS 316 stainless steel.

METHODS

The primers were single liquid metal conditioners containing either a phosphate monomer (Cesead opaque primer, CO; Metal primer, MP) or a carboxylic monomer (Super-Bond liquid, SB; Acryl bond, AB; MR bond, MR). Disk metal specimens were air-abraded with alumina followed by priming. The disks were bonded with a methacrylic resin using a brush-dip technique (Super-Bond C & B, CB or Repairsin, RE). Specimens were thermocycled in water and bond strengths were determined.

RESULTS

Shear bond strengths after the thermocycling were 11.9 MPa for CO-CB, 7.6 MPa for CO-RE, 4.9 MPa for SB-RE, 3.9 MPa for MP-RE, 3.3 MPa for AB-RE, 2.5 MPa for MR-RE, 1.9 MPa for None-CB, and 0 MPa for None-RE. The two systems primed with CO primer showed greater bond strengths than the other groups (P < 0.05). Of the two systems conditioned with CO primer, CB resin demonstrated higher value bond strength as compared with RE resin (P < 0.05).

CONCLUSION

Among the systems examined, CO primer used together with CB resin exhibited greater bond strength to SUS 316 stainless steel than other systems after the ageing test. Reduction in bond strength by thermocycling, however, was remarkable for all groups.

Cloning, sequencing and expressing the carotenoid biosynthesis genes, lycopene cyclase and phytoene desaturase, from the aerobic photosynthetic bacterium Erythrobacter longus sp. strain Och101 in Escherichia coli

Two genes which encode the enzymes lycopene cyclase and phytoene desaturase in the aerobic photosynthetic bacterium Erythrobacter longus sp. strain Och101 have been cloned and sequenced. The gene for lycopene cyclase, designated crtY, was expressed in a strain of Escherichia coli which contained the crtE, B, I and Z genes encoding geranylgeranyl pyrophosphate synthase, phytoene synthase, phytoene desaturase, and beta-carotene hydroxylase, respectively. As a result, zeaxanthin production was observed in E. coli transformants. In addition, expression of the E. longus gene crtI for phytoene desaturase in E. coli containing crtE and B resulted in the accumulation of lycopene in transformants. Zeaxanthin and lycopene were also determined by mass spectrum. Nucleotide sequence similarities between E. longus crtY gene and other microbial lycopene cyclase genes are 40.2% (Erwinia herbicola), 37.4% (Erwinia uredovora) and 22.9% (Synechococcus sp.), and those between phytoene desaturase genes are 50.3% (E. herbicola), 54.7% (E. uredovora) and 39.6% (Rhodobacter capsulatus).

Bonding of silver-palladium-copper-gold alloy with thiol derivative primers and tri-n-butylborane initiated luting agents

This in vitro study elevated the effect of two primers on bond strengths and durability of luting agents joined to a silver-palladium-copper-gold alloy. One primer (Metal Primer) contained methacryloyloxyalkyl thiophosphate derivative (MEPS). The other primer (V-Primer) contained 6-(4-vinylbenzyl-n-propyl)amino-1,3,5-triazine-2,4-dithiol (VTD). The luting agent was a methyl methacrylate (MMA)-based adhesive resin that contained 4-methacryloyloxyethyl trimellitate anhydride (4-META) and was initiated with tri-n-butylborane derivative (TBB). In order to evaluate the function of 4-META, MMA-TBB resin without 4-META was used as a control. The alloy specimens were bonded with six combinations of two primers and two luting agents. Shear bond strengths were determined before and after thermocycling. Both primers significantly elevated the bond strengths of the luting agents joined to the alloy. For unprimed groups, 4-META resin showed a more durable bond than did MMA-TBB resin. Combined use of Metal Primer with 4-META resin reduced the bond strength, while combination of V-Primer and 4-META resin did not affect the bond strength.

CSF levels of prostaglandins, especially the level of prostaglandin D2, are correlated with increasing propensity towards sleep in rats

The concentration of PGD2, PGE2, and of PGF2 alpha was measured in the cerebrospinal fluid (CSF) collected from the cisterna magna of conscious rats (n = 29), which, chronically implanted with a catheter for the CSF sampling, underwent deprivation of daytime sleep. Significant elevation of the CSF level of PGD2 was observed following 2.5-h sleep deprivation (SD), and the elevation became more marked following 5- and 10-h SD, apparently reaching the maximum at 5-h SD (703 +/- 140 pg/ml (mean +/- S.E.M.) for baseline vs. 1734 +/- 363 pg/ml for SD, n = 10). The levels of PGE2, and PGF2 alpha also significantly increased following 5- and 10-h SD, but not following 2.5-h SD. It is unlikely that these changes were simply caused by some responses of the animals to stress stimuli, because stress stimuli derived from restraint of the animal at the supine position to a board for 1 h did not produce any acute responses in the CSF levels of prostaglandins (n = 13). In a different group of animals (n = 11) implanted with electrodes for recording electroencephalogram (EEG) and electromyogram (EMG) in addition to the catheter, the levels of the prostaglandins in CSF were determined for slow-wave sleep (SWS) and wakefulness in the day and for SWS and wakefulness in the night. The highest PGD2 value was obtained at daytime SWS, whereas the lowest was at night wakefulness; furthermore, a significant difference was observed between SWS and wakefulness rather than between day and night. The CSF level of PGE2 also showed a similar tendency. In an additional group of animals (n = 6), not only PGD2 but also PGE2 and PGF2 alpha significantly increased the sleeping time of the animal when applied into the subarachnoid space underlying the ventral surface area of the rostral basal forebrain, the previously defined site of action for the sleep-promoting effect of PGD2. The promotion of sleep by PGE2 applied to the subarachnoid space was an effect completely opposite to the well-established awaking effect of the same prostaglandin demonstrated in the hypothalamic region in a series of previous studies. Based on these results, we conclude that increases in CSF levels of prostaglandins, especially that of PGD2, are correlated in rats with heightened propensity towards sleep and further with the depth of sleep under normal as well as SD conditions.

Effect of antipsychotic drugs on the gene expression of NMDA receptor subunits in rats

It has been hypothesized that glutamatergic neurons play an important role in clinical manifestations of schizophrenia and that the therapeutic effect of antipsychotic drugs is related to glutamatergic neurotransmission. To elucidate the effect of antipsychotic drugs on glutamatergic transmission, we examined gene expressions of NMDA receptor subunits R1, R2A, R2B and R2C in the whole brains of rats after acute and chronic administrations of haloperidol and sulpiride, using the Northern blot technique. The levels of NMDAR2B mRNAs decreased after the acute administration of haloperidol, but showed no change after the chronic administration. The levels of NMDAR2A and R2B mRNAs decreased after the acute administration of sulpiride, whereas the levels of R2A and R2B increased following the chronic administration. Neither haloperidol nor sulpiride influenced NMDAR1 mRNA levels. These data support differential expression of NMDA receptor subunits in rats upon treatment with haloperidol and sulpiride. The results imply that NMDAR2 subunits may be crucial in the regulation and modification of antipsychotic drugs.

Decreased renal accumulation of biotinylated chimeric monoclonal antibody-neocarzinostatin conjugate after administration of avidin

Murine monoclonal antibodies (mAbs) such as A7 administered to humans induce a human anti-mouse antibody response. Moreover, because Fab fragments of mAbs are able to penetrate target tumors easily, they may be more suitable than intact mAb to be carriers of anticancer agents such as neocarzinostatin (NCS), which are rapidly inactivated in the blood. To address these problems, chimeric A7 Fab fragment-NCS conjugate (chA7Fab-NCS) was produced. However, large amounts of 125I-labeled chA7Fab-NCS accumulate in the kidney and can lead to renal dysfunction. To decrease renal accumulation of chA7Fab-NCS, chA7Fab was biotinylated and administered with a subsequent injection of avidin. Human pancreatic carcinoma-bearing nude mice were injected with 125I-labeled biotinylated chA7Fab-NCS with or without subsequent administration of avidin. The accumulation of 125I-labeled biotinylated chA7Fab-NCS in tissue samples was measured at appropriate time intervals. 125I-labeled biotinylated chA7Fab-NCS was cleared more rapidly from the blood and the kidney with the administration of avidin than without it. There was no difference between tumor accumulation in these groups. The tumor/blood ratio of radioactivity of 125I-labeled biotinylated chA7Fab-NCS was significantly higher with subsequent administration of avidin than without avidin. The administration of biotinylated chA7Fab-NCS followed by avidin may enhance safety and permit the administration of larger doses of NCS without the subsequent development of renal failure. A larger amount of 125I-labeled biotinylated chA7Fab-NCS was retained in the liver and spleen with the subsequent administration of avidin than without avidin.

A metal halide light source for laboratory curing of prosthetic composite materials

A high-intensity laboratory photo-curing unit has been developed with the aim of improving the post-curing properties of composite veneering materials. This study introduces the structure of the curing unit and examines the resulting properties of a representative composite material. The curing unit is equipped with two metal halide lamps that radiate both ultraviolet and visible light. Unlike conventional metal halide lamps for industrial use, these metal halide lamps radiate an increased intensity of visible radiation. Properties of a microfilled composite veneering material cured with the new metal halide unit were ascertained. A xenon photo-curing unit was also used as a control. The specimens cured with the metal halide unit exhibited greater Knoop hardness numbers and flexural moduli as compared with those cured with the xenon unit, and also showed reduced water solubility values. These results suggest that the metal halide light source is effective in curing composite materials within a shorter period of time and with improved conversion.

Cooperative inhibition of acetylcholinesterase activities by hexachlorophene in human erythrocytes

Hexachlorophene (HCP), pentachlorophenol (PCP), 2,4,5-trichlorophenol (2,4,5-TCP) and 2,4,6-trichlorophenol (2,4,6-TCP) all hemolyzed washed human erythrocytes and inhibited acetylcholinesterase (AchE) activities in erythrocyte membrane. HCP was much more potent in either effect than any other compound examined. The inhibition of AchE activities by HCP was reversed on adding albumin. The dose-response curves by HCP and PCP were sigmoidal, indicating cooperative inhibition, while those by 2,4,5-TCP and 2,4,6-TCP were not. Furthermore, the cooperativity of the inhibition by HCP was greater than by PCP. Differing from that by PCP, the cooperativity of inhibition increased depending on the temperature (13, 25, 37 degrees C) and decreased when the membrane was treated with Triton X-100. The cooperativity was also decreased in the presence of albumin. On a Scatchard plot analysis, erythrocyte membranes appeared to have multiple binding sites of different affinities for HCP; binding of HCP to the low affinity site [dissociation constant (Kd) 4.7 x 10(-5) M] seemed to be responsible for the observed cooperative inhibition of AchE activities. Neither neostigmine nor fenitrothion altered the cooperativity. HCP seems to be the most potent cooperative inhibitor of AchE in human erythrocyte membranes known to date. HCP may be useful to examine AchE and milieu in human erythrocyte membranes.

cDNA cloning, expression and characterization of nitric-oxide synthase from the salivary glands of the blood-sucking insect Rhodnius prolixus

Rhodnius prolixus, a blood-sucking bug, is a unique insect that is known to produce nitric oxide (NO) in the salivary glands to use as a vasodilator for blood sucking. We report here the cloning of the NO synthase (NOS) cDNA from these salivary glands and its expression in a baculovirus system. This cDNA encodes a protein of 1174 amino acids with a calculated molecular mass of 132,331 Da. The primary structures of mammalian NOS, including the putative cofactor-recognition sites for heme, tetrahydrobiopterin (BH4), calmodulin. FMN, FAD and NADPH are all conserved in salivary-gland NOS. Recombinant salivary-gland NOS differed from nerve NOS and endothelial NOS in that it lacked a large N-terminal domain and an N-terminal myristylation sequence, respectively. Salivary-gland NOS produced in a baculovirus system showed NOS activity and demonstrated that salivary-gland NOS was soluble and was Ca2+ and calmodulin dependent, similarly to mammalian constitutive NOS isoforms. Recombinant salivary-gland NOS was purified to near homogeneity and migrated at 130 kDa on SDS/PAGE.

Cranial defect and decrease in cerebral blood flow resulting from deep contact burn of the scalp in the neonatal period

A case of cranial defect in the anterior fontanelle region is reported. The patient suffered a deep contact burn on the right parietofrontal region in the neonatal period. At age 3 years, a bone defect of 30 x 20 mm was observed in the right parietofrontal region, including the anterior fontanelle, and the pulsation of the brain was palpable. Moreover, scintigraphy of cerebral blood flow using SPECT with 99mTc-HMPAO demonstrated extensive decrease in blood flow in the right parietosquamosal region. Cranioplasty was performed at 3 years and 4 months using split ribs grafts and at age 5 years and 4 months using split-thickness calvarial bone grafts. After the cranioplasty, there was no bony defect and no region of reduced blood flow. The child is developing well.

Adhesive bonding to dentin with ferrous chloride primers and tri-n-butylborane-initiated luting agents

A variety of surface modifications with metal chlorides has been used to enhance the bond of resins to dentin. This study investigated the effectiveness of ferrous chloride in terms of the initiation of polymerization in dentin bonding. The efficacy of experimental dentin primers was evaluated via the bonding of two luting agents to dentin. The 16 primers evaluated were ferrous chloride (FeCl2) aqueous solutions, eight with and eight without 35% 2-hydroxyethyl methacrylate (HEMA). The concentrations of FeCl2 in the primers ranged from 2.0 x 10(-6) to 5.0 x 10(-4) mol/g. One luting agent (Super-Bond C&B) consisted of methyl methacrylate (MMA), 4-methacryloyloxyethyl trimellitate anhydride (4-META), and tri-n-butylborane (TBB) initiator. The other luting agent was prepared with MMA and TBB, but without 4-META. Bovine dentin surfaces were flattened, etched with an aqueous solution of 10% phosphoric acid, primed, and then bonded with stainless steel rods. Tensile strengths of the bonded specimens were measured after one-day immersion in water. Tensile testing revealed that the bond strength was influenced by the application of FeCl2 and/or HEMA. The maximum bond strength of 33.0 MPa was recorded with the use of primer containing FeCl2 and HEMA in MMA-TBB resin. In the case of Super-Bond, only surface treatment of dentin with aqueous primers containing 5.0 x 10(-5) to 2.0 x 10(-4) mol/g ferrous chloride resulted in bond strength values above 22.0 MPa. This bonding technique, combining the use of ferrous chloride primer with Super-Bond resin, may potentially be applied for seating resin-bonded restorations.

Molecular mechanism of sleep regulation by prostaglandin D2

Recent biochemical, molecular biological, and pharmacological experiments revealed that prostaglandin D synthase as well as prostaglandin D2 circulated in the ventricular system, subarachnoidal space, and extracellular space in the brain. Prostaglandin D2 then interacts with chemosensors or receptors on the ventro-medial surface of the rostral basal forebrain to initiate the signal to promote sleep. Prostaglandin D2 is, therefore, not a typical neurotransmitter but rather a 'neurohormone' or an 'informational substance' that circulates through the cerebrospinal fluid and transmits certain chemical messages to promote sleep. The mode of communication through the cerebrospinal fluid in the ventricular system and the extracellular space has advantages for global regulation of the brain to induce sleep.

Bonding of a cobalt-chromium alloy with acidic primers and tri-n-butylborane-initiated luting agents

Limited information is available about chemical bonding of cobalt-chromium alloys for resin-retained fixed partial dentures. This study evaluated the effect of acidic primers on the bonding of luting agents joined to a cobalt-chromium alloy. Disk alloy specimens were bonded with eight combinations of five primers and two luting agents. Shear bond strengths were determined before and after thermocycling. The effect of priming on bond strength varied among the combinations of primer and luting agent. In particular, after thermocycling three groups demonstrated greater bond strengths than the other groups did. These were (1) specimens treated with a phosphate-methacrylate primer (Cesead Opaque Primer), (2) specimens bonded with an adhesive resin (Super-Bond Opaque), or (3) a combination of both.

Distribution of neocarzinostatin conjugated to biotinylated chimeric monoclonal antibody Fab fragments after administration of avidin

We have developed chimeric Fab fragments of MAb A7 (chA7Fab) and have reported on their potential usefulness as a carrier of neocarzinostatin (NCS). However, a large amount of chA7Fab accumulates in the kidneys which might cause renal failure. This was one of the major side-effects of the chA7Fab-NCS immunoconjugate administered to humans. To decrease the kidney accumulation of chA7Fab, chA7Fab was biotinylated and administered with a subsequent injection of avidin to nude mice with pancreatic cancer. The accumulation of biotinylated chA7Fab in the blood and the kidneys decreased significantly after the injection of avidin. In a separate experiment with biotinylated chA7Fab-NCS, the blood and kidney accumulation decreased significantly after the injection of avidin. These findings suggest that the injection of biotinylated chA7Fab complexed with NCS followed by avidin may be safer and may permit the administration of larger doses of NCS without the subsequent development of renal failure.

Creatine kinase activities in brain and blood:possible neurotoxic indicator of acrylamide intoxication

OBJECTIVES

To examine whether the activities of creatine kinase (CK) correlate with neurological disturbances caused by acrylamide.

METHODS

The activities of CK and other enzymes reported to be inhibited by acrylamide in the brain and plasma, and landing foot spread (LFS) were measured in mice and rats intoxicated with acrylamide.

RESULTS

Activity of CK was suppressed by acrylamide in the brain of mice in parallel with the neurological dysfunction measured by LFS. No clear alterations were found in glyceraldehyde-3-phosphate dehydrogenase, neuron-specific enolase, and lactate dehydrogenase activities over the experimental period (eight days for the exposure and 43 days for the recovery). In rats, among the plasma enzymes examined, suppression of CK activity was most notable, but thyroid activity was not affected.

CONCLUSIONS

Among the enzymes so far examined, the CK activities in the brain and blood seem to be the most sensitive indicators of acrylamide intoxication.

Bonding of a mica-based castable ceramic material with a tri-n-butylborane-initiated adhesive resin

Adhesive bonding of a mica-based castable ceramic material (Olympus Castable Ceramics, OCC) was evaluated in vitro with the use of a silane primer in conjunction with an adhesive luting material. The primer contained a silane coupler and 4-methacryloxyethyl trimellitate anhydride (4-META), while the methyl methacrylate (MMA)-based luting agent was initiated with a tri-n-butylborane derivative (TBB) and contained 4-META (4-META/MMA-TBB resin). Ceramic specimens were sanded with No. 600 silicon carbide paper followed by blasting with alumina and/or etching with ammonium bifluoride. The specimens were bonded with various combinations and shear bond strengths were determined. Both priming and alumina blasting enhanced the bond between 4-META resin and OCC. Although etching with ammonium bifluoride roughened the ceramic surface, this procedure did not improve the bond strength. Electron probe microanalysis of the ceramic surface revealed a decrease in silicon and aluminium elements after etching with ammonium bifluoride.

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.