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Biomedical subjects

S Naruse

Publications and source records attributed to S Naruse.

At least 199 records · Page 11Linked to original sources
PubMed1988

The relationship between blood gastrin levels and gastric secretion in conscious dogs.

1. In conscious dogs with gastric fistulae and Heidenhain pouches, acid and pepsin secretion, immunoreactive plasma pancreatic polypeptide (PP) and gastrin were measured following intravenously administered pentagastrin, cholinomimetics, and intragastric administration of milk. 2. Pentagastrin did not raise endogenous plasma gastrin. There was a significant positive dose-response relationship between pentagastrin and acid and fistula pepsin secretions, but not between plasma gastrin of endogenous origin and gastric secretion. 3. Carbachol raised plasma gastrin immunoreactivity; but in no instance was there a significant relationship between gastric secretion and plasma gastrin immunoreactivity. Gastric acid secretion faded, but plasma gastrin concentrations did not. 4. PP plasma immunoreactivity was elevated by methacholine and carbachol. Its levels correlated significantly with gastric acid secretion. Pentagastrin did not raise PP and its levels did not, therefore, correlate with gastric acid secretion. 5. Intragastric milk raised plasma gastrin immunoreactivity, but the acid secretion per pg of plasma gastrin was much smaller than with the cholinomimetics. Ganglionic blocking agents depressed both plasma gastrin and acid and pepsin secretion. 6. The results suggest that cholinomimetics sensitize parietal cells to the stimulating action of gastrin.

Animals↗
PubMed1988

The effect of cholecystokinin-related peptides on periodic pancreatic secretion in fasting dogs.

1. The effect of cholecystokinin octapeptide (CCK-8) and pentagastrin on periodic pancreatic secretion was studied in fasting conscious dogs. 2. Both CCK-8 and pentagastrin, in small doses, prolonged the interval of periodic pancreatic secretion. Periodicity was disrupted by large doses of CCK-8 and pentagastrin. 3. CCK-8, at the dose which did not disrupt the cycle, raised the peak and the valley-to-valley means, but not the valley mean, of protein secretion in one cycle. Except at large doses, pentagastrin failed to increase the peak and valley mean, but increased mean, valley-to-valley protein secretion. Large doses of both pentagastrin and CCK-8 increased protein secretion at the valley. 4. The peak of periodic pancreatic protein secretion was about half the observed maximum protein response to CCK-8. 5. Atropine reduced pancreatic fluid and protein responses to small doses of CCK-8 to the levels of valleys. At large doses, however, both responses were augmented by atropine. Hexamethonium reduced the responses to any dose of CCK-8 to valley levels or less. Volume and protein responses to pentagastrin following atropine or hexamethonium were of similar magnitude to those at valleys. 6. It is concluded that CCK-8 and pentagastrin stimulate pancreatic enzyme secretion directly by acting on acinar cells and indirectly by modifying cholinergic ganglionic activities which control periodic secretion in conscious dogs.

Animals↗
PubMed1988

Postprandial celiac and superior mesenteric blood flows in conscious dogs.

Celiac and superior mesenteric arterial blood flows were measured simultaneously in conscious beagle dogs. The responses to food were completely different between the two arteries. Celiac flow increased quickly to 180-200% of the control 2 min after food but started to decline rapidly to preprandial levels, though greater than 90% of food was still in the stomach. It remained at preprandial levels over the next 1-6 h. Superior mesenteric flow increased gradually in 20-50 min (peak: 230%) and remained above the control levels for 3-6 h. The celiac response was inhibited by vagal block, hexamethonium, and gastric mucosal anesthesia by oxethazaine but not by atropine, phenoxybenzamine, or propranolol. Postprandial superior mesenteric hyperemia was blocked by mucosal anesthesia and was reduced by atropine by 80%. Ganglionic or adrenergic blockades were without effect. It is concluded that the celiac peak response to food is mediated by a nonadrenergic, noncholinergic vagal reflex in conscious dogs. Extrinsic nerves probably play little part in the postprandial increase of superior mesenteric flow.

Animals↗
PubMed1988

Age changes in secretory function of male and female rat parotid glands in response to methoxamine and pilocarpine.

Saliva secreted in response to methoxamine and pilocarpine was collected from the cannulated ducts of both parotid glands of male and female rats at weekly age intervals from three to 10 weeks, and at 3.5, 8, and 15 months of age. It was analyzed for the concentrations of protein, potassium, calcium, inorganic phosphate, and for amylase activity. The type of protein were determined electrophoretically, and an amino acid analysis of the total protein was also carried out. The wet weights of the glands increased substantially up to eight weeks of age, then reached almost plateau values, and finally tended to decrease at 15 months of age in both sexes. The salivary volumes secreted in response to methoxamine and pilocarpine were positively correlated with the parotid gland weights in both sexes. The concentrations of protein, potassium, and inorganic phosphate were inversely related to the salivary flow rates only at relatively low rates of flow. The amylase activity was positively correlated with the concentration of protein, independent of the nature of the stimulus, age, and sex. With methoxamine as a stimulus, the amylase activity was positively correlated with the concentration of calcium, independent of age and sex. The types of protein and amino acid concentrations were independent of the nature of the stimulus, age, and sex up to 15 months of age. However, in parotid saliva of several rats at 8 and 15 months of age, unusual proteins were observed electrophoretically, independent of the nature of the stimulus and sex.

Aging↗
PubMed1988

In vivo 31P MRS in new antineoplastic agents evaluation on experimental tumor models.

Two new antineoplastic agents, a nitrosourea and a DNA-bis-intercalator have been studied in vivo by 31P magnetic resonance spectroscopy on a rat glioma and Walker carcinoma. On rat glioma, spectra are modified when the tumor is treated by the nitrosourea, showing the depletion of high-energy phosphates. On Walker carcinoma both drugs delay the tumor evolution to necrosis, showing important levels of high-energy phosphates on NMR spectra. There appears to be a great dependence upon energy metabolism during chemotherapy, depending on the nature and physiology of the observed tumor.

Animals↗
PubMed1987

Corelease of PHI and VIP by vagal stimulation in the dog.

Electrical vagal stimulation increased immunoreactive peptide histidine isoleucine (IR-PHI) and vasoactive intestinal polypeptide (IR-VIP) levels in the portal plasma in anesthetized dogs, depending on the stimulation frequency. Atropine failed to suppress the vagal release of IR-PHI and IR-VIP, whereas hexamethonium abolished the increase of both peptide immunoreactivities. Gel filtration profiles of IR-PHI and IR-VIP in the portal plasma obtained during vagal stimulation revealed major peaks of IR-PHI and IR-VIP eluting in the same positions as synthetic PHI-27 and VIP-28, respectively. These data demonstrate that PHI and VIP are coreleased by vagal stimulation via a nicotinic ganglionic mechanism. An additional peak of larger molecular weight IR-PHI was observed in gel filtration of the portal plasma obtained under higher frequency vagal stimulation, when measured by the N-terminal-specific PHI antiserum. The presence of this larger form of IR-PHI together with a PHI-27-like component was also demonstrated in tissue extracts of the entire length of the gastrointestine, particularly in higher concentration in the stomach. The structure and the physiological significance of this larger form of IR-PHI remains to be elucidated.

Animals↗
PubMed1986

Helodermin has a VIP-like effect upon canine blood flow.

The effect of helodermin on vascular physiology was studied in anesthetized dogs using a synthetic replicate of helodermin and helodermin related peptides. Intraarterial infusion of helodermin caused a dose-dependent increase in femoral blood flow. Helodermin was 16 times less potent than VIP and 5 times more potent than PHM (human PHI). The helodermin effect lasted significantly longer; the half-life of the helodermin effect was 6.5 times longer than VIP. Synthetic helodermin (Hd) N-terminal fragment Hd(1-27)NH2 retained substantial activity similar to the full helodermin molecule but the prolonged effect was lost. Hd(7-35) and Hd(22-35) were inactive in this system. Intravenous injection of synthetic helodermin produced prolonged systemic hypotension and tachycardia; and, similar to VIP, it increased the common carotid arterial blood flow while those of the superior mesenteric and femoral arteries were decreased. The results demonstrate the VIP-like vasodilating activity and cardiovascular effects of helodermin in anesthetized dogs.

Animals↗
PubMed1986

Significance of proton relaxation time measurement in brain edema, cerebral infarction and brain tumors.

We examined the proton relaxation times in vitro in various neurological diseases using experimental and clinical materials, and consequently obtained significant results for making a fundamental analysis of magnetic resonance imaging (MRI) as followings. 1) In the brain edema and cerebral infarction, T1 prolonged and T2 separated into two components, one fast and one slow. Prolongation of T1 referred to the volume of increased water in tissue. The slow component of T2 reflects both the volume and the content of increased edema fluid in tissue. 2) In the edematous brain tissue with the damaged Blood-Brain-Barrier (BBB), the slow component of T2 became shorter after the injection of Mn-EDTA. Paramagnetic ion could be used as an indicator to demonstrate the destruction of BBB in the brain. 3) After the i.v. injection of glycerol, the slow component of T2 became shorter in the edematous brain with the concomitant decrease of water content. The effects of therapeutic drug could be evaluated by the measurement of proton relaxation times. 4) Almost all tumor tissue showed a longer T1 and T2 values than the normal rat brain, and many of them showed two components in T2. It was difficult to determine the histology of tumor tissue by the relaxation time alone because of an overlap of T1 and T2 values occurred among various types of brain tumors. 5) In vivo T1 values of various brain tumor were calculated from the data of MRIs by zero-crossing method, and they were compared with the in vitro T1 values which were measured immediately after the surgical operation. Though the absolute value did not coincide with each other due to differences in magnetic field strength, the tendency of the changes was the same among all kinds of tumors. It is concluded that the fundamental analysis of proton relaxation times is essentially important not only for the study of pathophysiology in many diseases but also for the interpretation of clinical MRI.

Animals↗
PubMed1986

Radiofrequency hyperthermia with successive monitoring of its effects on tumors using NMR spectroscopy.

Radiofrequency (rf) hyperthermia was generated on rat glioma inoculated s.c. in CD Fisher rats by applying the rf pulse using the surface coil in the NMR spectrometer, and the effect was monitored successively in the same spectrometer by measuring 31P NMR spectra and 1H NMR images. In the 31P NMR spectrum at the preirradiation stage, nucleoside triphosphate peaks and a phosphomonoester peak were high and a Pi peak was low. After a rf pulse at a power of 5 W was applied continuously for 60 min, the nucleoside triphosphate peaks decreased and the Pi peak increased immediately, resulting finally in a dominant Pi peak pattern within 30 min in all 10 cases examined. These spectral changes occurred much earlier than the histological changes and lasted for at least 7 days. By the 1H NMR imaging, the necrotic region was detected as a high-intensity lesion in spin echo and inversion recovery images 2 days after the irradiation. There were no changes either in the spectrum or in 1H NMR images in any of 8 cases after irradiation with a rf pulse of less than 3 W. Thus, we could generate rf hyperthermia with the NMR spectrometer and the effects were monitored sensitively with the same spectrometer. It can be concluded that the NMR device can be used not only for diagnosis but also as a therapeutic tool.

Animals↗
PubMed1986

Evaluation of the effects of photoradiation therapy on brain tumors with in vivo P-31 MR spectroscopy.

In vivo phosphorus-31 magnetic resonance (MR) spectra were obtained by a surface coil method from rat glioma tissue inoculated subcutaneously in CD Fisher rats, and the effects of photoradiation therapy on tumors were evaluated by sequentially observing spectral changes. In the control group, the nucleoside triphosphate (NTP) and phosphomonoester peaks were large, the phosphocreatine peak was small, and the inorganic phosphate (Pi) peak was intermediate. In all eight cases in the group in which a dose of 10 mg/kg of hematoporphyrin derivatives (HpD) was given before photoirradiation, NTP peaks decreased, and the Pi peak increased remarkably within 1 hour after the 60-minute white-light irradiation. Spectral changes were observed before histologic changes were apparent. Histologic examinations 3 days after irradiation showed extensive necrosis in the tumor tissue. With preinjection of 5 mg/kg HpD, three of the eight cases showed spectrum changes after the irradiation. No spectrum changes were observed in the group with preinjection of 2.5 mg/kg. In vivo P-31 MR spectra measurements are useful not only to investigate the energy metabolism of tumor tissue in vivo but also to evaluate the effects of photoradiation therapy on tumors.

Animals↗
PubMed1985

Naloxone prevents the analgesic action of alpha-MSH in mice.

alpha-MSH (0.1, 1, 10 micrograms) was administered intracerebroventricularly and its action on pain sensitivity was investigated by the hot-plate method in mice. alpha-MSH produced dose-dependent analgesia and this analgesic effect was prevented by naloxone (1 mg/kg, s.c.). It is possible that alpha-MSH may play a role in the mechanism of pain through endogeneous opioid systems.

Analgesics↗