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Biomedical subjects

K Shima

Publications and source records attributed to K Shima.

At least 343 records · Page 19Linked to original sources
PubMed1987

Complete evaluation of the cardiovascular lesions in 24 patients with Takayasu's aortitis using four-image, intravenous digital subtraction angiography.

We studied the entire distribution of cardiovascular lesions with the use of intravenous digital subtraction angiography (DSA) in 24 patients having Takayasu's aortitis. The aorta, its branches, pulmonary vessels, and left ventricle were assessed by neck (anteroposterior), abdominal (anteroposterior), and chest (right and left anterior oblique) images. DSA showed multiple arterial lesions (n = 24) including proximal renal artery stenoses (n = 4), pulmonary arterial stenoses (n = 4), inferior-superior mesenteric arterial anastomoses (n = 3), brachiocephalic arterial aneurysms (n = 2), aortic root aneurysm (n = 1), diffuse left ventricular hypokinesis (n = 1), subclavian steal phenomenon (n = 1), and right aortic arch (n = 1). The incidence of total occlusion was highest in the right subclavian artery (n = 12). Average percent luminal stenosis (mean +/- S.D.) over the aorta and its branches tended to be smaller in patients with prior corticosteroid therapy (17.3 +/- 14.6%) than in those without (22.0 +/- 9.8%), but the difference was not significant. DSA (four-series) was useful in assessing the whole disease spectrum and often revealed subclinical lesions in this disease.

Adolescent↗
PubMed1987

Failure of human insulin to influence endogenous basal insulin secretion in mild diabetics.

In evaluating the possibility of self-regulation of insulin secretion in man, human insulin may be more appropriate as an inhibitor to be considered than insulins from other species because the differences in the structure of the hormones might play some part in this conflicting proposal. The present study was carried out to examine whether human insulin per se can exert a feedback effect on the insulin secretion of B-cell in mild diabetics under physiologic condition. Fifteen mild diabetics were given a two-hour infusion of human insulin at a constant rate of 40 mU/m/min after a priming dose of 160 mU/m/min for the first two minutes. The plasma glucose in nine of these patients were maintained at their basal level of 92.8 +/- 3.7 mg/dL (Group A) with a glucose clamp technique (the coefficient of variation = 5.0 +/- 0.8% during the clamp), while that in the remaining six patients were intentionally altered, within physiologic range, from 114.5 +/- 8.4 mg/dL to 83.8 +/- 4.9 mg/dL (Group B). During insulin infusion the plasma immunoreactive insulin (IRI) level were well-maintained at about 50 microU/mL level in both groups, whereas the C-peptide reactivity (CPR) in group B decreased from 1.28 +/- 0.15 ng/mL to 0.59 +/- 0.14 ng/mL in parallel to the change of plasma glucose, in contrast to the relatively stable CPR level of 0.92 +/- 0.08 ng/mL in group A.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Effect of exercise training on insulin and glucagon release from perfused rat pancreas.

The effect of physical training on insulin and glucagon release in perfused rat pancreas was examined in the spontaneously exercised group running in a wheel cage an average of 1.4 km/day for 3 weeks and in the sedentary control group kept in the cage whose rotatory wheel was fixed on purpose. Pancreatic immunoreactive insulin (IRI) responses to glucose and arginine were reduced by 28% and 47.8% respectively in trained rats compared with untrained rats, while IRI content of the pancreas was similar in these two groups. The demonstrated decrease in insulin secretion of the beta-cell of the trained rats, in response to the glucose and arginine stimulations, may be functional in nature. On the other hand, neither pancreatic glucagon immunoreactivity (GI) response to glucose and arginine nor GI content of the pancreas was modified by exercise training. These results demonstrate that exercise training reduces IRI responses to glucose as well as to arginine stimulations, but does not modify any secretory response of pancreatic GI.

Animals↗
PubMed1987

Identification and localization of glucagon-like peptide-1 and its receptor in rat brain.

The existence and distribution of glucagon-like peptide-1 (GLP-1) and its receptor in rat brain in relation to that of glucagon were examined. The concentration of GLP-1 immunoreactivity (GLP-1-IR), measured by a specific and sensitive RIA established in this study with anti GLP-1 serum (LMT-01), was found to be highest in the thalamus-hypothalamus, followed by the medulla oblongata. The distribution of glucagon-like immunoreactivity was similar to that of GLP-1-IR. However, appreciable glucagon immunoreactivity was detected only in the thalamus-hypothalamus. Gel filtration analysis showed the presence of GLP-1-IR of various molecular weights in the extract of thalamus-hypothalamus including that eluted at the same position as synthetic GLP-1 (1-37); moreover, HPLC analysis also confirmed the presence of GLP-1-IR, eluted at the exact position as synthetic GLP-1 (1-37). The distribution of receptors for GLP-1 corresponded with that of GLP-1-IR in the rat brain, except in the pituitary gland. The distribution of these receptors was also similar to that of glucagon receptors. The thalamus-hypothalamus, pituitary gland, and medulla oblongata were rich in GLP-1 and glucagon-binding sites. The binding affinities of GLP-1 and glucagon were in the nanomolar range [disocciation constant Kd approximately equal to 4 nM]. The presence of specific, high affinity receptors for GLP-1 was confirmed by demonstrating that GLP-1 stimulated cAMP formation in the thalamus-hypothalamus and the pituitary gland. The concentration of GLP-1 required for half-maximal stimulation of cAMP formation in these regions was about 1 nM. These results suggest that GLP-1 may be synthesized in certain parts of the brain and play a role as a neurosignal transmitter.

Animals↗
PubMed1987

Twenty-four hour secretory pattern of growth hormone in hyperprolactinemic women with pituitary microadenoma.

The 24-h secretory pattern of GH was evaluated in normal women (n = 4) and hyperprolactinemic-amenorrheic women with pituitary microadenoma (n=6). Serum GH concentrations significantly differed according to the time of day, and there were nocturnal rises in normal women and hyperprolactinemic women. However, episodic fluctuations in serum GH levels were almost absent during the day time in hyperprolactinemic women, and the mean 24-h GH concentration was significantly lower in these women than in normal women. Thus, GH secretion was diminished in hyperprolactinemic women with pituitary microadenoma, though a nocturnal increase in GH secretion continued.

Adenoma↗
PubMed1987

Correlation of regional insulin and glucagon content in canine pancreas and a possible interaction of A and B cells.

Canine pancreases divided into 8 anatomical subportions were examined for their regional insulin and glucagon content. Insulin content in the pancreas was gradually increased in the left lobe to about twice as much as that in the uncinatus, while glucagon content was increased steeply in the left lobe to 16 times as much as that of the uncinatus. Although hormonal content differs according to the anatomical area, a statistically significant positive correlation of mean regional insulin and glucagon content was observed (r = 0.994, p less than 0.001). A constant ratio of these two hormones suggests the functional coupling of A and B cells within the islets or in a given pancreatic subportion.

Animals↗
PubMed1987

Release of glucagon-like peptide 1 immunoreactivity from the perfused rat pancreas.

A reliable radioimmunoassay for glucagon-like peptide 1 (GLP-1) was developed with a detection limit of 12 pmol/l, which enabled us to detect the subtle change in concentrations of this peptide in the perfusate from the perfused rat pancreas. With this RIA, GLP-1 immunoreactivity (GLP-1 IR) was found to be secreted synchronously with glucagon immunoreactivity upon arginine stimulation from the perfused rat pancreas. Gel chromatographic analysis showed the presence of GLP-1 IR in the pancreatic extract which is eluted at the same position as synthetic GLP-1 (1-37). Moreover HPLC analysis confirmed the presence of GLP-1 IR, which eluted at exactly the same position as synthetic GLP-1, in the perfusate from pancreas perfusion upon stimulation of arginine. These results suggest that the pancreas stores and secrets GLP-1 IR concomitantly with glucagon as one of the cleavage products of their common precursor.

Animals↗
PubMed1987

Gonadotropin binding sites in human ovarian follicles and corpora lutea during the menstrual cycle.

Gonadotropin binding sites were localized by autoradiography after incubation of human ovarian sections with 125I-labeled gonadotropins. The binding sites for 125I-labeled human follicle-stimulating hormone (125I-hFSH) were identified in the granulosa cells and in the newly formed corpora lutea. The 125I-labeled human luteinizing hormone (125I-hLH) binding to the thecal cells increased during follicular maturation, and a dramatic increase was preferentially observed in the granulosa cells of the large preovulatory follicle. In the corpora lutea, the binding of 125I-hLH increased from the early luteal phase and decreased toward the late luteal phase. The changes in 3 beta-hydroxysteroid dehydrogenase activity in the corpora lutea corresponded to the 125I-hLH binding. Thus, the changes in gonadotropin binding sites in the follicles and corpora lutea during the menstrual cycle may help in some important way to regulate human ovarian function.

3-Hydroxysteroid Dehydrogenases↗
PubMed1986

Beta-endorphin in the human gallbladder.

The presence of beta-endorphin-like immunoreactivity (beta-END-LI) in human gallbladder and its release were examined by means of radioimmunochemical measurements and immunohistochemical stainings. beta-END-LI was detected in the gallbladder (27.2 +/- 3.2 ng/g wet weight, mean +/- S.E.). The immunoreactivity in beta-END-LI extracted from the gallbladder was similar to that of synthetic beta-END, judging from the result of its inhibition curve parallel to that of the synthetic substance in the radioimmunoassay (RIA) system. On gel-filtration chromatography of a gallbladder extract, two components of beta-END-LI were found; one eluted on a position of beta-lipotropin (beta-LPH) and another on a position of synthetic beta-END. Specific beta-END-LI positive cells were detectable in metaplastic mucous glands. When human gallbladder mucosa was perfused with a solution of 10(-8) M or 10(-6) M cholecystokinin octapeptide (CCK-8), the release of beta-END-LI from mucosa into the perfusate increased 2-3 fold. These results indicate that beta-END-LI present in human gallbladder is released by the direct action of CCK-8 on the gallbladder mucosa and suggest that it may have a physiological or pathophysiological role.

Chromatography, Gel↗
PubMed1986

Firing properties of two types of nucleus raphe dorsalis neurons during the sleep-waking cycle and their responses to sensory stimuli.

Spontaneous activity of the nucleus raphe dorsalis (NRD) neurons during the sleep-waking cycle and effects of sensory stimuli upon NRD neurons were studied in cats. Seventy-one neurons recorded within the NRD were classified into two groups with the use of the coefficient of variation of firing intervals during waking (W): 41 regularly firing (clock-like) and 30 irregularly firing (non-clock-like) neurons. The majority of clock-like and one-third of non-clock-like neurons showed a decrease in their firing rate during slow-wave sleep (SWS) compared with W. All neurons of both types displayed their lowest level of activity during paradoxical sleep. During the late phase of SWS, many clock-like neurons reduced their firing prior to the occurrence of pontogeniculo-occipital waves, whereas non-clock-like neurons did not show such a specific property. Clock-like neurons were totally unresponsive to nociceptive and non-nociceptive somesthetic stimuli, while about half of the non-clock-like neurons were driven by these stimuli. Half of the clock-like and one-third of the non-clock-like neurons were driven by click stimulation, and the majority of them showed an excitatory response. Some of the clock-like and non-clock-like neurons exhibited inhibitory and excitatory response to flash stimulation, respectively. The results of this experiment show that two types of neurons do exist in the NRD and suggest that they play a functionally different role in the brain.

Acoustic Stimulation↗