Central effects of pituitary adenylate cyclase activating polypeptide (PACAP) on gastric motility and emptying in rats

Pituitary adenylate cyclase activating polypeptide (PACAP) is a new member of the secretin-glucagon-vasoactive intestinal peptide (VIP) peptide family. PACAP is widely distributed not only in the mammalian brain but also in the gastrointestinal tract. Here, we investigated the effects of central and peripheral administrations of PACAP on gastric motility and gastric emptying in rats. We found that the intracerebroventricular or intracisternal injection of PACAP increased gastric motility in a dose-dependent manner. The intracisternal injection of PACAP delayed gastric emptying. These central effects of PACAP on gastric motility and emptying were blocked by bilateral vagotomy. In contrast, intravenous administration of PACAP decreased gastric motility and delayed gastric emptying. The peripheral inhibitory effect was unaffected by bilateral vagotomy, adrenalectomy, phentolamine, and propranolol. We investigated the effect of PACAP38 on blood glucose levels (BGL) at the same doses as those used in the gastric motility and emptying studies in urethane-anesthetized rats. The intravenous but not intracerebroventricular injection of PACAP38 (1-8 nmol/rat) produced a significant increase in the BGL. We conclude that PACAP has opposite central and peripheral effects on gastric motility, ie, central PACAP activates the vagal pathway in the central nervous system to increase gastric motility, whereas peripheral PACAP inhibits gastric motility via an unknown pathway. The delay in gastric emptying after the central administration of PACAP might be due to the lack of coordinated gastropyloroduodenal contraction, whereas that after the peripheral administration might be due to the inhibition of gastric contraction, and this effect may be related to the hyperglycemic action of PACAP.

Contribution of peripheral chemoreception to the depression of the hypoxic ventilatory response during halothane anesthesia in cats

BACKGROUND

The effects of inhalational anesthetics on the hypoxic ventilatory response are complex. This study was designed to determine the contribution of peripheral chemoreception to the depression of hypoxic ventilatory response seen with halothane anesthesia.

METHODS

Cats were anesthetized with pentobarbital sodium and alpha-chloralose and artificially ventilated. Respiratory output was evaluated by phasic inspiratory activity of the phrenic nerve. In 12 cats, this activity was measured during inhalation of an hypoxic gas mixture with halothane, 0, 0.1, and 0.8%, with intact or denervated carotid bodies. In 10 cats, a carotid body was isolated from the systemic circulation and perfused with hypoxic Krebs-Ringer solution equilibrated with halothane, 0, 0.1, and 0.8%.

RESULTS

The hypoxic ventilatory response was depressed in a dose-dependent manner during halothane anesthesia. In carotid body perfusion studies, the response was significantly depressed only with halothane, 0.80%.

CONCLUSION

The hypoxic ventilatory response is depressed by a high dose of halothane through a peripheral effect at the carotid body.

Antibacterial temporary filling materials: the effect of adding various ratios of Ag-Zn-Zeolite

The effect of a new type of antibacterial temporary filling material was evaluated. Ag-Zn-Zeolite (Bactekiller, Kanebo, Japan) and SiO2 filler were incorporated into urethane acrylate monomer paste in amounts of 5/55, 10/50, 20/40 and 30/30 wt%, respectively. The present study was designed to use a dye penetration test to measure direct inhibition of bacterial growth of four oral bacteria (Streptococcus mutans, Streptococcus mitis, Streptococcus salivarius, Streptococcus sanguis). The amounts of silver and zinc ions released from these materials were measured by atomic absorption spectrophotometry. The results indicated that the occurrence of marginal leakage was low in all of these materials. These materials exhibited prominent in-vitro antibacterial activity against S. mutans and S. mitis. The Ag-Zn-Zeolite in these materials was able to release very small but detectable amounts of Ag and Zn even 4 weeks after the immersion started. The larger the amounts of Ag-Zn-Zeolite that were incorporated, the greater the release of silver and zinc. However, it appears that increasing antibacterial activity is not promoted by the higher ratio of Ag-Zn-Zeolite.

[Regional cerebral oxygen saturation as a monitor of cerebral oxygenation and perfusion during deep hypothermic circulatory arrest and selective cerebral perfusion]

In order to evaluate cerebral oxygenation and perfusion during deep hypothermic circulatory arrest (DHCA) and selective cerebral perfusion (SCP), continuous measurement of regional cerebral oxygen saturation (rSO2) by near-infrared spectroscopy (NIRS) was performed. Two patients undergoing aortic arch surgery performed under DHCA and SCP were studied. 1) Circulatory arrest produced a continuous decrease in rSO2. Introduction of SCP increased rSO2 to even above the pre-circulatory arrest level (reperfusion hyperoxia). 2) During SCP, changes in rSO2 correlated well with the naso-pharyngeal temperature, SCP flow rate, and level of carbon-dioxide insufflation to SCP. 3) These changes in rSO2 paralleled with those of jugular venous hemoglobin saturation (SjO2) measured simultaneously, although SjO2 frequently exhibited artifacts. We conclude that rSO2 measurement may be a non-invasive and continuous measure in the evaluation of cerebral oxygenation and perfusion during DHCA and SCP.

The inhibitory influence of pulmonary vagal afferents on respiratory distress induced by airway occlusion in halothane-anesthetized cats

Although the sensation of dyspnea is common, the mechanisms underlying the sensation have not been fully elucidated. Dyspnea, which is a subjective sensation induced by various respiratory and nonrespiratory stimuli, ranges in intensity from an awareness of difficulty in breathing to an incapacitating state of respiratory distress. It need not be an all or none concept when tolerable; however, intolerable dyspnea is often accompanied by some kind of escape response. In a previous study, we developed a new concept of minimum alveolar anesthetic concentration for airway occlusion (MAC-AOR). Using this model, we assessed the influence of pulmonary vagal afferents on respiratory distress induced by airway occlusion. Adult cats (n = 13) of both sexes weighing 2.7-5.6 kg (3.9 +/- 0.3 kg, mean +/- SE) were anesthetized with halothane and tracheally intubated. After determination of MAC-AOR, anesthesia was maintained with the highest concentration of halothane permitting the positive motor response identified by visual inspection or electromyogram (EMG) of the forearm, usually of the head or extremities. Twisting or jerking of the head was considered a positive response, but twitching or grimacing was not. A slight movement of the shoulder and/or the extremities was not considered positive, nor were coughing, swallowing and chewing, or rigidity recognized as the increase of tonic activity on the forearm EMG. The duration from the start of airway occlusion to the onset of the positive response (DOCCL) was considered as behavioral measures of the tolerable limit of respiratory distress. DOCCL was measured before (Control 1), during, and after (Control 2) lung expansion induced by the injection of the inhaled gas of 5 mL/kg or 10 mL/kg (LE5 or LE10) at functional residual capacity level. Subsequently, 6 of 13 cats received bilateral vagotomies, and the same procedure was repeated at the same concentration as stated above. Then, MAC-AOR after vagotomy was determined again. Before vagotomy, the values of DOCCL during lung expansion (238 +/- 30 s during LE5 and 288 +/- 24 s during LE10) were significantly longer than Control 1 (169 +/- 29 s) and Control 2 (154 +/- 29 s) values (P < 0.01). After vagotomy, the effect of lung expansion on DOCCL was totally abolished. MAC-AOR after vagotomy (1.4% +/- 0.1%) was significantly higher than that before vagotomy (1.1% +/- 0.1%) (P < 0.01). We have demonstrated that vagotomy abolishes the prolongation effect of the lung expansion on DOCCL and increases the value of MAC-AOR in this animal model. These results suggest that pulmonary vagal afferents play an important role in relief of respiratory distress developed during airway occlusion.

IMPLICATIONS

In anesthetized cats, we found that lung expansion reduces the tolerable limit to airway occlusion and vagotomy decreased minimum alveolar anesthetic concentration for airway occlusion, which suggests that pulmonary vagal afferents play an important role in relief of respiratory distress.

Minimum alveolar anesthetic concentrations for airway occlusion in cats: a new concept of minimum alveolar anesthetic concentration-airway occlusion response

Minimum alveolar anesthetic concentration (MAC) is defined as an end-tidal concentration of inhaled anesthetic required to prevent purposeful movement (positive motor response) in 50% of subjects to somatic noxious stimuli. Although MAC for visceral noxious stimuli has not been well investigated, airway occlusion can be a noxious respiratory stimulus that can induce a visceral sensation of choking. In this study, MAC for airway occlusion (MAC-AOR) was determined during halothane, isoflurane, and sevoflurane anesthesia and compared with the MAC values for somatic noxious stimuli such as toe pinch (MAC-pinch) or tetanic stimulus (MAC-tetanus) in cats. Thirty-four adult cats were used. In 24 cats, the motor responses to three different stimuli (toe pinch, tetanic stimulus, and airway occlusion for 6 min) were observed during inhaled anesthesia and rated as positive or negative. The concentration of an inhaled anesthetic was changed in steps of 0.1%-0.2 vol% until the bracketing procedure (i.e., the highest concentration of inhaled anesthetic permitting a positive motor response and the lowest concentration preventing the response were determined) was completed. In 10 cats, the effect of anesthetic duration on MAC-AOR was also investigated. Each mean MAC (MAC-pinch, MAC-AOR, and MAC-tetanus, respectively) was as follows: halothane 0.99, 1.13, and 1.46; isoflurane 1.50, 1.65, and 2.22; and sevoflurane 3.07, 3.38, and 3.95. The first and last MAC-AOR values determined during 6-h halothane anesthesia were 1.10 and 1.11, respectively. In conclusion, airway occlusion can be a noxious stimulus and can induce an all-or-none type of motor response, depending on the depth of inhalational anesthesia in cats. This phenomenon can permit the introduction a new concept of MAC-AOR.

IMPLICATIONS

Airway occlusion can be a noxious visceral stimulus and induce all-or-none type of motor response in cats, depending on the depth of inhalational anesthesia. This permits the introduction of a new concept of minimum alveolar anesthetic concentration airway occlusion response.

Central administration of PACAP stimulates gastric secretion mediated through the vagal pathway in anesthetized rats

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide that was originally isolated from ovine hypothalamic tissue. The peptide has two amidated forms, PACAP38 and PACAP27. In this study, we examined the effects of centrally administered PACAP38 and PACAP27 on gastric secretion in anesthetized rats. Centrally administered PACAP stimulated gastric acid and pepsin secretion in a dose-dependent manner. PACAP38 was 1.5-2 times more potent than PACAP27 on gastric secretion. By contrast, intravenously administered PACAP38 had no effect on basal or pentagastrin-stimulated gastric secretion. PACAP6-38, a PACAP antagonist, by itself at high doses also stimulated gastric and pepsin secretion, but at lower doses had no effect. Centrally administered PACAP6-38 at a dose that had no effect on gastric secretion, atropine pretreatment, or vagotomy pretreatment, suppressed the stimulatory effect of PACAP38. It is concluded that centrally administered PACAP may have a regulatory effect on gastric secretion through PACAP receptors and the vagal pathway.

Functional evaluation of flail hip joint after periacetabular resection of the pelvis

Five patients subjected to flail hip joint after resection of primary bone tumor of the pelvis involving acetabular region were examined with respect to function. When a thick portion of the supraacetabular pelvic neck was left in place, the operated legs functioned well regardless of whether the head of the femur was placed anterior or posterior to the iliac wing. In a patient who had only a thin portion of the iliac wing left in place and in those who underwent total excision of the ilium or hemiresection of the pelvis, the function of operated legs was poorer than with a thick portion of the supraacetabular pelvic neck left in place, but still more than 50% of leg function remained. Although flail hip joint results in a larger leg-length discrepancy than do other techniques, it enables favorable healing of the operative wound. Therefore, this method should be considered for women or sedentary patients with primary bone tumor of the pelvis involving acetabular region.

Heat shock protein 70 messenger RNA reflects the severity of ischemia/hypoxia-reperfusion injury in the perfused rat liver

OBJECTIVES

To determine whether ischemia-reperfusion and hypoxia-reoxygenation cause cellular damages and stress responses in an isolated perfused rat liver model. To determine whether the increased synthesis of stress protein messenger RNA reflects cellular injury.

DESIGN

Prospective, controlled study.

SETTING

Institutional laboratories.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

Isolated rat livers with cell free perfusion were exposed to various periods of ischemia-reperfusion or hypoxia-reoxygenation.

MEASUREMENTS AND MAIN RESULTS

We measured hepatic oxygen consumption and alanine aminotransferase leakage from liver during perfusion. We analyzed the gene expression of heat shock protein 70, a major stress protein, of the liver by Northern blotting after perfusion. The expression of heat shock protein 70 messenger RNA augmented as the reperfusion period increased. The expression level after graded ischemia or hypoxia significantly correlated with the calculated hepatic oxygen debt (r2 = .737; p < .001; n = 21), or with the accumulated alanine aminotransferase leakage from the liver (r2 = .509; p < .001; n = 21).

CONCLUSIONS

These results suggest that the accumulation of heat shock protein 70 messenger RNA reflects the severity of ischemia-reperfusion and hypoxia-reoxygenation injuries, and that a stress response in reperfusion can be triggered without formed elements of blood.

[Effects of prostaglandin E1 on transient forebrain ischemia, especially in hippocampal CA 1 regions of the gerbil]

The effects of prostaglandin E1 (PGE1) on transient forebrain ischemia were studied in the gerbil. The animals were randomly divided into six groups of 6 each according to the method of administration as follows: group 1, no administration; group 2, subcutaneous administration with 5 ml.kg-1 of physiological saline, 30 min prior to ischemia; group 3, the same method with 3 mg.kg-1 of PGE1; group 4, 3 mg.kg-1 of PGE1, during 24 hours (12 hours prior to ischemia, and 12 hours following ischemia); group 5, 3 mg.kg-1 of PGE1, during 96 hours (12 hours prior to ischemia and 84 hours following ischemia); and group 6, sham operation. They were anesthetized with isoflurane and transient forebrain ischemia was induced by occluding bilateral common carotid arteries for 5 min. The extracranial electroencephalogram (EEG) was recorded from the electrodes placed at the vertex. During the experimental procedures, temperatures at tympanic membrane and rectum were maintained at 37.0 +/- 0.2 degrees C by means of a heating mat and control of the air temperature in all groups. After 6 days of survival, they were sacrificed, and the brain tissues were fixed for the immunohistochemical and histopathological analyses. The hippocampal CA 1 regions were stained for monoclonal anti microtubule-associated protein 2 (MAP 2), and hematoxylin and eosin. In the 4th group, EEG recovery was recognized earlier than the other groups. Immunoreactivities for MAP 2 and the number of surviving pyramidal cells after ischemia in the CA 1 regions were also well maintained. These results suggest the PGE1, has protective effects against degradation of cytoskeletal proteins and delayed neuronal death in the gerbil, and it might be due to direct protective action of cell membrane in addition to its microcirculatory improvement.

Antibacterial activity of silver ions implanted in SiO2 filler on oral streptococci

OBJECTIVE

To evaluate the role of silver ions in composite resin dental materials, an in vivo investigation was conducted into the antibacterial effect of SiO2 filler implanted with silver ions on oral streptococci. METHODS. SiO2 filler samples (0.1g) were implanted with silver ions. The effect of the filler with silver ions (Ag+ filler) was tested on oral streptococci bacteria. These bacterial strains had been isolated predominantly from composite resin surfaces. The organisms tested were anaerobically cultured in 5 mL Trypticase Soy Broth containing 0.5 per cent yeast extract at 37 degrees C for 10-12 h. Each bacterial strain was adjusted to a concentration of 1 x 10(6) cells per mL with reduced transport fluid (RTF). Ag+ filler was immersed in 1 mL of RTF and anaerobically incubated 2, 6 and 12 h to study the antibacterial effect. The survival of bacteria was then estimated by culturing on TSBY agar plates. A plate with approximately 100 discrete colonies was chosen from the serial agar cultures, and the number of colonies was counted at each sampling time.

RESULTS

The Ag+ filler showed significantly more antibacterial activity than the control filler without silver ions.

SIGNIFICANCE

These results indicate that the antibacterial effect found in this study was due to the silver ions released by the Ag+ filler and that it may be useful to add this filler to composite resin dental materials for secondary caries protection.

Paraquat tolerance of transgenic Nicotiana tabacum with enhanced activities of glutathione reductase and superoxide dismutase

Transgenic tobacco with enhanced cytosolic activities of glutathione reductase and superoxide dismutase were generated by cross-fertilization. Leaves of the hybrids exhibited further increased tolerance to a O2-.-generating herbicide paraquat than those of their parents. This result indicates the efficiency of manipulating more than one gene in improving resistance of plants to photooxidative stress.

Paraquat tolerance of transgenic Nicotiana tabacum with enhanced activities of glutathione reductase and superoxide dismutase

Transgenic tobacco with enhanced cytosolic activities of glutathione reductase and superoxide dismutase were generated by cross-fertilization. Leaves of the hybrids exhibited further increased tolerance to a O2-.-generating herbicide paraquat than those of their parents. This result indicates the efficiency of manipulating more than one gene in improving resistance of plants to photooxidative stress.

The effect of glaze on restorative glass-ionomer cements: evaluation of environmental durability in lactic acid solution

The surface texture changes of three kinds of glass-ionomer cements were compared with glazed and polished cement surfaces after thermal cycling in a storage media [lactic acid solution (pH 4.0)]. The changes were measured with regard to the surface roughness, colour-change, gloss, hardness, toothbrush wear, and SEM (scanning electron microscope) observation in the laboratory. The glazed cement surface was not affected after thermal cycling in the lactic acid solution.

Isolation of cDNA for a plasma membrane H(+)-ATPase from guard cells of Vicia faba L

cDNA encoding the plasma membrane H(+)-ATPase of guard cells of Vicia faba L. was isolated. The clone encoded a 105-kDa polypeptide (956 amino acids) that was 79-85% identical in terms of amino acid sequence to other plant H(+)-ATPases. High levels of mRNA explain the high H(+)-ATPase activity of these plasma membranes.

[Effects of centrally administered NPY on stress induced gastric ulcers in the rat]

We investigated the central effects of neuropeptide Y (NPY) on stress-induced gastric ulcers in water immersion rats. Intracisternally administered NPY dose-dependently aggravated, but intravenously administered NPY did not affect stress ulcers in rats. Intraperitoneal pre-treatment of atropine completely blocked the central effect of NPY, but neither pyrilamine nor cimetidine affected. Intracisternal administration of NPY aggravated stress ulcers not through histamine mediated mechanism but by parasympathetic pathway. It is suggested that centrally administered NPY acted by the inhibition on gastric motility and by the suppression on gastric mucosal blood flow rather than by the stimulation on gastric secretion in rats.

[An epidemiologic examination on the prevalence of the periodontal diseases and oral pigmentation in Yusho patients]

An epidemiologic examination was carried out to reveal the prevalence of the periodontal diseases and oral pigmentation in Yusho patients 26 years after PCB exposure. The results obtained were as follows. 1) 158 teeth of the total 284 examined teeth had the periodontal pockets deeper than 3 mm and the lower left first molar showed the highest prevalence of the periodontal pocket among the examined six index teeth. There was no definitive difference not only between sexes but also between age groups. However, 42 teeth had the periodontal pockets deeper than 4 mm. 2) Oral pigmentation was observed in 25 Yusho patients (33.8%). Chronological examination revealed that the prevalence of oral pigmentation seemed to be higher in the patients below the age of 49 than in those beyond the age of 50, but there was no definitive difference between sexes. It was of particular interest that the incidence of oral pigmentation appeared to decrease with decrease of the teeth present in number.

The effect of glaze on restorative glass-ionomer cements

The surface texture changes of three kinds of glass-ionomer cements were compared with various glazed and polished cement surfaces after the initial finishing. Method 1--the glazing agent--was used, and method 2 consisted of four different Shofu Super Snap discs. In method 3 specimens were compressed with a glass plate. The glazed and polished surfaces were used for investigating various properties such as the surface roughness, colour change, gloss, hardness, toothbrush wear, and were also subject to SEM (scanning electron microscope) observation in the laboratory. The period of 48 h after mixing was chosen for the various testing data. The smoothest surface was formed after compression with a glass plate, however, the glazing agent gave the highest gloss surface for glass-ionomer cement. The lower roughness generally observed was for glazing compared to polishing. The glazed surface is effective as a glass-ionomer cement restoration.

Decrease in Activity of Glutathione Reductase Enhances Paraquat Sensitivity in Transgenic Nicotiana tabacum

Transgenic tobacco (Nicotiana tabacum L. cv SR1) with decreased activity of glutathione reductase exhibited enhanced sensitivity to paraquat in the light as evaluated by chlorophyll destruction and electrolyte leakage from leaf discs. This result indicates the involvement of glutathione reductase in the tolerance of plants to photooxidative stress caused by the herbicide.

Adaptation to the cavity floor of the light-cured glass ionomer cement base under a composite restoration

The study attempted to assess methods of prevention of the formation of a contraction gap in a cylindrical enamel and dentine cavity. The influence has been investigated of the tensile bond strength of cement/dentine and cement/composite resin and the direct tensile strength during setting of light-cured glass-ionomer cements. The interface between composite resin/cement and cement/dentine were viewed and photographed by replica techniques under an SEM (Scanning Electron Microscope). The most noticeable finding was that an enamel and dentine cavity applicated with light- and auto-cured glass-ionomer cement generally presented with a small construction gap at the tooth restoration interface. However, the light-cured glass-ionomer base (Vitrabond) exhibited significantly better tensile bond strength to dentine and resin performance than the conventional glass-ionomer tested. This study revealed that there was no clear relationship between the adhesion to dentine and the adaptation to the dentine cavity floor.