Effects of perineural capsaicin treatment on compound action potentials of superior laryngeal nerve afferents in sevoflurane-anesthetized dogs

Effects of perineural capsaicin (CAPS) treatment on compound action potentials of the superior laryngeal nerve (SLN) afferents were studied in 6 sevoflurane-anesthetized dogs. Perineural CAPS (100 microg/ml) to the bilateral SLNs reduced (P<0.01) the peak and integral amplitudes of the C-wave of the compound action potential. By contrast, the perineural CAPS had no effect on the A-wave component (P>0.05). Removal of the perineural CAPS recovered the C-wave to pretreatment level. The perineural CAPS treatment selectively blocks C-wave compound action potentials of the SLN afferents, providing a useful tool for studies of laryngeal C-fibers in respiratory physiology.     

In vitro but not in planta encapsidation of Rice gall dwarf virus core particles by the outer capsid P8 protein of Rice dwarf virus expressed in transgenic rice plants

Transencapsidation of the Rice gall dwarf virus (RGDV) inner core by the Rice dwarf virus (RDV) outer capsid P8 protein was examined in vitro and in planta. When RGDV core particles were incubated with an extract from RDV P8-transgenic rice leaf tissue, RDV P8 encapsidated the RGDV core particles to form double-shelled virus-like particles in vitro. In contrast, when RDV P8-transgenic rice plants were inoculated with RGDV, progeny RGDV particles contained RGDV P8 but RDV P8 was not detectable in the virions. No significant differences were found in acquisition by the vector insects and subsequent transmission rates between RGDV infecting nontransgenic rice plants and those infecting RDV P8-transgenic rice plants. These results indicate that mechanisms of and/or requirements for interactions between P8 and the inner core particles of phytoreoviruses differ between in vitro and in planta.     

Influence of feeding regime on timing of parturition in beef cattle and the relationship of vaginal temperature to parturition

The timing of parturition was recorded for a total of 56 beef cattle (Japanese Black × Holstein Friesian) on different dietary treatments. The rate of calving during daylight hours in cows night‐fed (18.00 hours) with a roughage diet was significantly higher than that in cows night‐fed with a high concentrate diet (79.2% vs 38.5%, P < 0.05). Subsequently, the vaginal temperature (VT) of these cows was analyzed using a cosinor method. When the feeding schedule was changed from twice daily (08.30 and 15.30 hours) to night feeding, the periodicity, the acrophase and the bathyphase, which were the parameters of the cosine curve, were unstable from the first day of night feeding until after day 6 (P < 0.05). Prior to parturition, the midline‐estimating statistic of rhythm (MESOR) and the amplitude for the cows that were fed a high‐roughage diet at night and that calved at night‐time were lower and larger, respectively, than that for the other treatments (P < 0.01). Based on these results, the time of parturition in most of the beef cows was influenced by feeding time and diet composition. Those cows that calved at night‐time in spite of night feeding had lower vaginal temperatures.     

Diazepam potentiates the positive inotropic effects of histamine and forskolin in guinea-pig papillary muscles

There have been diverse reports on the effects of diazepam on cardiac contractility. The purpose of this study was to examine whether diazepam modifies the inotropic response elicited by histamine on an isolated guinea-pig papillary muscle. The responses of electrically driven papillary muscle to histamine and cyclic AMP-related inotropic agents were recorded in the absence and in the presence of diazepam. Histamine and forskolin, which directly stimulate adenylate cyclase, significantly increased the contractile force in the papillary muscle in a concentration-dependent manner. A histaminergic H₂-receptor antagonist, cimetidine, but not a H₁-receptor antagonist, diphenhydramine, at 10 μ M produced a rightward shift in the concentration-response curve for histamine. Diazepam (10 μ M ) shifted the concentration-response curve for histamine and forskolin to the left by 1.8 and 1.6 times, respectively. Neither a central type (fulmazenil) nor a peripheral type (PK11195) of benzodiazepine receptor antagonist modified the effect of diazepam on the histaminergic-evoked contraction. Phosphodiesterase blockade by 3-isobutyl-1-methylxanthine shifted the concentration-dependent curve for histamine to the left. A combination of 3-isobutyl-1-methylxanthine also produced a leftward shift of the curve. However, there was no significant difference between the 3-isobutyl-1-methylxanthine only group and the combination group. These results indicate that diazepam potentiates the positive inotropic effect produced by histamine, probably mediated via an increase in cyclic AMP levels induced by histamine.     

Quantitative structure-activity studies of substituted benzyl chrysanthemates: 7. Relationship between induction of repetitive discharges and effects on the action potential

The effects of substituted benzyl (1R)-trans-chrysanthemates and related compounds on the action potential of the crayfish giant axon were investigated using an intracellular microelectrode. The effects are broadly classified into three types: deceleration of the falling-phase of the action potential (type A), elevation of the depolarizing after-potential (type B), and the combination type (type C). The potency of the type A compounds to decelerate the rate of the falling-phase was determined in terms of the concentration required for reducing the rate to a specified degree. This potency was shown to correlate with the potency to induce repetitive discharges in the cockroach central nerve cord in terms of minimum effective concentration, which was determined previously. The potency of the types B and C compounds to elevate the after-potential was, however, not related directly with the cockroach nerve repetitive activity. The elevation of the after-potential is one of the critical factors but other effects such as a depolarization of the resting potential may be involved in determining the repetitive activity.     

Rapid and simple mutation screening of G(M1) gangliosidosis in Shiba dogs by direct amplification of deoxyribonucleic acid from various forms of canine whole-blood specimens.

This report describes a rapid and simple method for mutation screening of G(M1) gangliosidosis in Shiba dogs by direct amplification of DNA from canine whole-blood specimens using a novel polymerase chain reaction (PCR) reagent cocktail, which can eliminate the DNA extraction process and amplify the genomic DNA directly from human or murine whole blood. The strategy of this mutation screening is based on the identification of a nucleotide deletion by restriction enzyme analysis, coupled with the direct PCR amplification. The target sequence of the canine beta-galactosidase gene could be amplified directly from various forms of canine whole-blood specimens, including anticoagulated blood, blood stored frozen for 1 year, dried blood held in filter paper for 1 year at room temperature, and dry powder of blood stripped from Giemsa-stained blood films, which had been prepared 10 years earlier, resulting in the determination of genotypes in all the specimens. This method simplified the molecular diagnosis and carrier screening of G(M1) gangliosidosis in Shiba dogs, making it simple to examine specimens from the large, widely distributed population of these dogs.     

Growing situation of afforested trees and damage to lower-story trees caused by felling in multi-storied forest management in Peninsular Malaysia

The growing condition of afforestation trees and damage to lower-story trees caused by felling and hauling of upper-story trees in a multi-storied forest in Peninsular Malaysia was surveyed. Seventy months have passed since the planting ofAcacia mangium upperstory trees, which have grown 233 m³/ha in volume. The growth ofShorea leprosula thirty-five months after planting of lower-story trees have reached 5.54 m in height. However, as the ratio of height to basal diameter exceeds 100:1, trees are tapering to a considerable degree. A backhoe was installed in order to fell the upper-story trees. From the results of logging, the damage ratio estimation of the lower-story trees was simulated by using the Monte Carlo method. The damage ratio differed considerably depending on planting patterns, height of upper-story trees and felling skills. The results of this survey proved that the felling and hauling of upper-story trees would be technically feasible in the future, except when one row upper-story trees and one row lower-story trees method were employed.     

Sodium bicarbonate protects uranium-induced acute nephrotoxicity through uranium-decorporation by urinary alkalinization in rats

To evaluate the effectiveness of sodium bicarbonate (SB) in removing uranium and protecting animals from uranium toxicity, we intramuscularly administered 1 mg/kg of uranyl nitrate to 8-wk-old male SD rats, and 20 min after administration of uranyl nitrate, the animals were given a single oral administration of SB at 0.1, 0.3 or 1 g/kg. The SB treatment at a dose of 0.3 g/kg or more raised the pH of the rats’ urine until 4 h after treatment, and it significantly reduced the uranium amounts in the kidneys at 1 day after treatment. In another experiment, rats were intramuscularly administered 1 mg/kg of uranyl nitrate, and 20 min later, the animals were treated with sodium bicarbonate (0.1 or 1 g/kg). The rats were autopsied at 1, 3 and 7 days after uranium treatment. High-dose SB resulted in a significant increase in urinary uranium excretion in the first 24 h and a reduction of uranium deposition in the kidneys and femurs, and it also significantly suppressed uranium-induced renal toxicity, as shown by both histopathology and clinical chemistry at 3 days after uranium treatment. Low-dose SB did not show such marked effects. Our findings demonstrated that the uranium decorporation effect of sodium bicarbonate was observed at the dosage showing urine alkalinization in rats and that decorporation effect of sodium bicarbonate might be beneficial if it is administered immediately after incorporation of soluble uranium.