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Biomedical subjects

Y Yajima

Publications and source records attributed to Y Yajima.

At least 145 records · Page 8Linked to original sources
PubMed1985

The stimulatory and inhibitory guanine nucleotide-binding proteins of adenylate cyclase in erythrocytes from patients with pseudohypoparathyroidism type I.

Both the inhibitory and stimulatory guanine nucleotide-binding proteins of the adenylate cyclase complex were measured in erythrocyte membranes from patients with pseudohypoparathyroidism (PHP). The inhibitory guanine nucleotide-binding protein (Ni) of adenylate cyclase was measured by incorporation of [32P]ADP-ribose from [32P]NAD into the 39K subunit of Ni catalyzed by pertussis toxin. The ADP-ribosyltransferase activity of the toxin was expressed through incubation with dithiothreitol and erythrocyte membranes. Erythrocytes from 12 patients with PHP type I (PHP-I) had Ni values similar to those of 9 normal subjects and 2 patients with pseudopseudohypoparathyroidism. In 6 PHP-I patients, decreased activity of the stimulatory guanine nucleotide-binding protein (Ns) of adenylate cyclase, as determined by reconstitution of adenylate cyclase in the Ns-deficient membranes of cyc-S49 cells, corresponded with the reduced degree of ADP-ribosylation of the 42K subunit of Ns catalyzed by cholera toxin. These data suggest that the defect of Ns results in reduced stimulation of adenylate cyclase in some PHP-I patients, and that enhanced inhibition of the enzyme due to an increase in the 39K subunit of Ni does not account for the biochemical lesion in PHP-I patients.

Adenosine Diphosphate Ribose↗
PubMed1985

Endotoxemia in liver diseases: detection by a quantitative assay using chromogenic substrate with perchloric acid pretreatment.

With a quantitative blood endotoxin assay using a chromogenic substrate with a perchloric acid pretreatment (PCA-LCT), endotoxemia in various liver diseases was studied. With PCA-LCT, recovery of added endotoxin in human plasma was nearly 90%, as evidenced by an intra- and inter-assay coefficients of variation of 5.7% and 11%, respectively. Because the recovery of endotoxin was not affected in severely icteric plasmas, PCA-LCT proved to be applicable to patients with liver diseases where various degree of jaundice exist. In none of the plasmas from patients with chronic hepatitis, acute hepatitis without hepatic failure or liver cirrhosis without ascites did the endotoxin level exceed the normal range of less than 5 pg/ml. With the presence of ascites, however, endotoxemia became detectable, but at low levels and not in all cases. At the stage of hepatic failure complicated with renal failure or disseminated intravascular coagulation, endotoxemia was more frequent and endotoxin concentration greater. It is uncertain, at present, whether endotoxemia itself is deteriorating factor in hepatic failure or is merely concomitant phenomenon resulting from Kupffer cell failure.

Ascites↗
PubMed1984

[The measurement of N-protein activity in plasma membranes: the comparison of assay methods by reconstitution of cyc- membranes and cholera toxin-catalyzed ADP ribosylation].

The relationship between the assay values of the activities of the stimulatory guanine nucleotide-binding regulatory component (N-protein) of adenylate cyclase by two different methods: reconstitution of plasma membranes of cyc- S49 cells and ADP ribosylation catalyzed by cholera toxin, have not been fully elucidated yet. In the present study, the reconstitution and ADP ribosylation assay methods were utilized, and the relationship between the assay values of the N-protein activities of the erythrocyte membranes from normal subjects and patients with pseudohypoparathyroidism type I (PHP-I) measured by the two methods was investigated. When Lubrol extracts of human erythrocyte membranes were reconstituted with cyc- membranes, the rate of cyclic AMP synthesis reached a constant rate after incubation of 80 minutes at 30 degrees C. This reaction depended on the concentrations of cyc- membranes and Lubrol extracts of the erythrocyte membranes. N-protein activity in the erythrocyte membranes of normal subjects and PHP-I patients assayed by reconstitution of cyc- membranes (mean +/- SD, expressed by % of pooled standard preparation) was 100.1 +/- 13.5 (n = 29) and 82.3 +/- 28.0 (n = 19) respectively. The cholera toxin-catalyzed transfer of [32P]ADP ribose from [32P]NAD to the 42,000-dalton peptide subunit of human erythrocyte N-protein reached a plateau after incubation of 10 minutes at 30 degrees C. This reaction depended on the concentrations of cholera toxin, NAD, and the erythrocyte membranes. N-protein activity in the erythrocyte membranes from normal subjects and PHP-I patients assayed by cholera toxin-catalyzed ADP ribosylation (pmol/mg of protein) was 1.33 +/- 0.20 (n = 7) and 1.15 +/- 0.43 (n = 5) respectively. The correlation between assay values of erythrocyte N-protein activity in PHP-I patients by reconstitution of cyc- membranes (X, % of pooled standard) and cholera toxin-catalyzed ADP ribosylation (Y, % of pooled standard) was recognized as a linear regression: Y = 0.77X + 16.8 (r = 0.981, P less than 0.001). It is thus concluded that the activity of N-protein in human erythrocyte membrane can be assayed by the ADP ribosylation method more simply than by the method of reconstitution of cyc- membranes, with highly close correlation between the values determined by these two methods.

Adenosine Diphosphate↗
PubMed1984

The effects of epidermal growth factor on cell proliferation and prolactin production by GH3 rat pituitary cells.

The effects of epidermal growth factor (EGF) were studied in rat pituitary tumor cells, GH3, grown in serum-supplemented and serum-free chemically defined media. EGF (1 nM) increased the cell number to 132% of the control cultured in the defined medium during a 6-day incubation period, while it decreased the cell number to 60% of the control in the serum-supplemented medium. EGF altered the morphology of the cells grown in the defined medium more markedly to an elongated conformation than that of cells grown in the serum-supplemented medium. EGF also stimulated prolactin (PRL) production by culture in the presence or absence of serum. The effects of the cell density of GH3 on the action of EGF were shown to appear in two ways. The mitogenic influence of EGF was more effective on, and more responsive to, high-density cells, whereas the stimulatory action on PRL production was less effective on high-density cells. However, the inhibitory effects on cellular growth appeared independently of cell densities. The results obtained with 125I-EGF binding experiments indicated that the number of binding sites, affinity, and internalization of EGF receptors were similar in either serum-supplemented or serum-free culture. At low cell density, the number of available 125I-EGF binding sites per cell was larger than at high cell density. These results suggested that there was no apparent correlation between EGF binding and its differing effects on the growth of GH3 cultured in the serum-supplemented and the defined medium.

Animals↗
PubMed1984

Localization of aldose reductase in the human eye.

The presence of the enzyme aldose reductase is increasingly being linked to diabetic complications. The distribution of this enzyme in human cornea, lens, retina, and optic nerve has been studied using specific antibodies against purified human placental aldose reductase raised in both rabbit and goat. The antisera from both animals gave equal, specific reactions. In frozen sections of ocular tissues, significant aldose reductase localization was reproducibly demonstrated in the endothelium and epithelium of the cornea and in the basal cell layers of the conjunctiva. In the lens, staining was observed in the epithelium and superficial lens fibers. In retinal sections, the presence of aldose reductase was demonstrated in the Mueller's cells, especially near the inner limiting membrane. It was also found in some ganglion and cone cells. In the optic nerve, positive staining was observed in the axon. All other cells of the tissues examined revealed only weak, nonspecific staining.

Adult↗
PubMed1983

Identification of motoneurons in the nucleus ambiguus by antidromic stimulation of the superior and the recurrent laryngeal nerves in rats.

Motoneurons in the nucleus ambiguus (NA) for the superior and the recurrent laryngeal nerves were identified by antidromic stimulation of these nerves in rats anesthesized with urethane. Two subpopulations of NA motoneurons were distinguished in the ventrolateral medullary region: (1) NA motoneurons from which antidromically evoked action potentials by stimulation of the superior laryngeal nerve were recorded were found in the ventral formation; and (2) neurons activated antidromically by stimulation of the recurrent laryngeal nerve were in the dorsal formation of NA. These findings are in good agreement with previous morphological studies.

Afferent Pathways↗
PubMed1983

Ambiguous motoneurons discharging synchronously with ultrasonic vocalization in rats.

Unit discharges associated with ultrasonic vocalization were recorded from the rat medullary region including the nucleus ambiguous (NA). Three types of units were distinguished: ultrasound-related (US), expiration (EXP) and inspiration (INSP) units. Both US and EXP units discharged with tonic bursts mostly prior to ultrasounds. US units were silent during respiration while EXP units discharged synchronously with expiration. During ultrasonic vocalization INSP units suppressed their discharges which were otherwise synchronized with inspiration. Histological examination revealed that US and EXP units were recorded from the ventral division of the NA and the adjacent medullary region where the NA contained large cells and the adjacent region consisted of small cells. These results suggest that both US and EXP units are NA motoneurons responsible for ultrasound emission. EXP units were always supplied with respiratory afferents while US units were not.

Animals↗
PubMed1983

The effects of hypothalamic extracts and TRH on the growth and hormone production of GH3 cells in culture.

Hypothalamic factors were tested for their effects on the production of hormones and the growth of GH3 cells, cloned rat pituitary cells producing prolactin (Prl) and growth hormone (GH). Hypothalamic extracts (HE) (0.05 mg/ml) and TRH (0.3 microM) stimulated the synthesis of Prl to levels of 306% and 360%, respectively, of the control culture in a medium containing 0.5% foetal bovine serum (FBS) during a 24 h incubation. They did not affect the rate of GH production. The thymidine uptake was suppressed to 57% and 46% of the control by the addition of HE and TRH, respectively. They also inhibited the growth of GH3 to 70% and 74% of the control culture during an 8-day incubation period. On the other hand, LRH affected neither the rate of hormone production nor the thymidine uptake. Somatostatin suppressed the synthesis of Prl and GH, but it did not affect the incorporation of thymidine into the cells. The gel filtration studies of HE revealed that the inhibitory effects of HE on the thymidine uptake were dependent on two substances, TRH and an unknown factor(s) of high molecular nature. The relationship between hormone synthesis and DNA synthesis will be discussed on the basis of the TRH-induced effects on Prl production and DNA synthesis in GH3 cells.

Animals↗
PubMed1983

Ultrasonographical diagnosis of fatty liver: significance of the liver-kidney contrast.

In order to investigate the reliability of ultrasonography in the diagnosis of fatty liver, retrospective evaluation was made of abdominal echograms in 45 patients with various diffuse liver diseases who underwent liver biopsy within 2 weeks after the ultrasound study. Instead of the well-recognized but subjective diagnostic criterion, i.e. the bright liver pattern, liver-kidney contrast is proposed as a new criterion. The liver-kidney contrast is based on the brightness of the liver in comparison to the renal parenchyma where fatty change seldom occurs. Combination of this liver-kidney contrast with two other well-known ultrasonographical findings of fatty liver, vascular blurring and deep attenuation, enables us to grade fatty change semiquantitatively. When fatty change of over 30% in the hepatic lobule was adopted as the definition of fatty liver, the satisfaction of both liver-kidney contrast and vascular blurring presented an ultrasound diagnostic criterion for fatty liver, with sensitivity of 83%, specificity of 100%, and an accuracy of 96%.

Abdominal Muscles↗
PubMed1983

A case of idiopathic fatty liver detectable only by ultrasonography.

A 40-year-old man was diagnosed as fatty liver according to our ultrasonographical criteria for fatty liver, i.e., liver-kidney contrast in the ultrasound mass screening of the liver, biliary tract and pancreas. He lacked any signs or symptoms, nor any known causes of fatty liver, i.e., obesity, diabetes, hyperlipidemia, ingestion of alcohol or drugs. Liver biopsy of this patient revealed fatty change of about 50% of the hepatic lobules. It has been difficult to suspect the presence of latent fatty liver which lacked both the abnormality in the liver function test and hepatomegaly, and even impossible when it lacked any risk factors. In the future as the ultrasonography becomes more generally used as a primary screening examination, "idiopathic latent fatty liver", like this patient, will be more frequently found and this, in turn, will contribute to the progress of the epidemiology and etiology of fatty liver.

Adult↗