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Biomedical subjects

H Seo

Publications and source records attributed to H Seo.

At least 235 records · Page 13Linked to original sources
PubMed1990

Pro-opiomelanocortin gene expression in silent corticotroph-cell adenoma and Cushing's disease.

The silent corticotroph-cell adenoma (SCCA) is characterized by the presence of immunoreactive adrenocorticotropic hormone (ACTH) in the tumor tissue in patients without symptoms of Cushing's disease. To elucidate the pathophysiology of SCCA, the expression of pro-opiomelanocortin (a ACTH precursor) genes was studied in a patient with SCCA and in three patients with Cushing's disease. Pro-opiomelanocortin messenger ribonucleic acid (mRNA) was found in the SCCA tissue to a greater degree than in the adenomas of the patients with Cushing's disease. Northern blot analysis revealed that the size of pro-opiomelanocortin mRNA present in the SCCA tissue was indistinguishable from that in the adenomas associated with Cushing's disease. A ribonuclease mapping study indicated that there were no point mutations in the coding sequence of pro-opiomelanocortin mRNA present in the SCCA tissue. Because of the presence of pro-opiomelanocortin mRNA and immunoreactive ACTH in the adenoma tissue, it is proposed that translation of the mRNA and subsequent accumulation of ACTH precursor occurred in the SCCA. Thus, the absence of Cushing's disease symptoms in this SCCA could not be caused by abnormality in the coding sequence of the pro-opiomelanocortin gene or in ribonucleic acid processing. The occurrence of abnormality at or after the translational steps was strongly suggested.

Adenoma↗
PubMed1990

Prolactin gene expression in human growth hormone-secreting pituitary adenomas.

To elucidate the mechanism of hyperprolactinemia often observed in patients with growth hormone (GH)-secreting pituitary adenomas, the presence of immunoreactive prolactin (ir-PRL) and prolactin (PRL) messenger ribonucleic acid (mRNA) in the tumor tissue was examined by immunohistochemistry and cytoplasmic dot hybridization. Hyperprolactinemia was observed in three of 18 patients with GH-secreting adenoma. The tumor tissue was demonstrated to contain ir-PRL in nine patients and PRL mRNA in 13. The presence of ir-PRL in the tumor tissue was always associated with positive PRL mRNA, indicating production of PRL in GH-secreting tumors. Among the three patients with hyperprolactinemia, both ir-PRL and PRL mRNA was revealed in the tumor tissue of one, PRL mRNA but not ir-PRL was detected in the adenoma tissue of another, and neither PRL mRNA nor ir-PRL was found in the tumor tissue of the third. The association of hyperprolactinemia with the presence of both ir-PRL and PRL mRNA or PRL mRNA alone is indicative of PRL production and secretion. However, the absence of ir-PRL and PRL mRNA in the tumor tissue may indicate that hyperprolactinemia is caused by the suppression of PRL inhibitory factor due to hypothalamic dysfunction by the tumor mass. Thus, the study of PRL gene expression and immunohistochemistry in GH-secreting adenomas is valuable to understanding the pathophysiology of pituitary tumors.

Adenoma↗
PubMed1990

Determination of the molecular nature and cellular localization of Thy-1 in human renal tissue.

The molecular nature and cellular localization of Thy-1 antigen in human renal tissue were studied. Strong immunohistochemical staining was observed in frozen sections of human kidney using monoclonal anti-human Thy-1 antibody; this reaction was almost completely abolished by pretreating the kidney section with phosphatidyl inositol (PI)-specific phospholipase C (PI-PLC). Immunohistochemical analysis revealed that the Thy-1 antigen is localized on the proximal tubular epithelial cells and the Bowman's capsule of the glomerulus. Northern blot analysis of renal mRNA using a cloned human Thy-1 gene revealed the presence of human Thy-1 mRNA of a similar size to the one in human brain. When a human kidney cDNA library was screened with the same probe, a cDNA of human Thy-1 was isolated. Moreover, human Thy-1 protein with a molecular weight (MW) of 21,000 was detected in renal tissue by gel electrophoresis and Western blot analysis using monoclonal anti-human Thy-1 antibody. These data demonstrate for the first time the production of human Thy-1 as a PI-anchored protein with a unique cellular location in human renal tissue.

Adult↗
PubMed1990

[A case of pseudoinfarct of the liver (Zahn's infarct)].

We reported a case of pseudoinfarct (Zahn's infarct) of the liver caused by the inflammatory pseudotumor. A dense segmental staining in the area of Zahn's infarct, which was thought to be characteristic finding, was found on the hepatic angiography. This finding was supposed to be consistent with sinusoidal hyperemia according to the pathological finding.

Adult↗
PubMed1989

[Ultrasonographic diagnosis of mild fatty infiltration of the liver with the difference between liver and kidney echolevels].

At the same dynamic range (DR) a constant difference of echolevels was found between two materials with different acoustic impedance in any gain-setting by the phantom study. Our retrospective study in which we compared the difference between liver-kidney echolevels with the US-findings of fatty liver indicated that the difference over 10 in echoleveled by our equipment with 3.5 MHz phased array sector scan and 42 dB DR had a possibility of the fatty infiltration of the live. In our prospective study of 1452 abdominal US-studies we found 93 cases (6.5%) with the difference over 10 in echolevel. In all these patients the difference of liver-spleen CT-numbers and liver-kidney echolevels was compared. Although the liver CT-number is normally higher than the spleen, 75 of 93 patients showed the lower liver CT-number than that of the spleen, indicating fatty infiltration of the liver. The abnormal difference of echolevels were independent from the severity of fatty infiltration. Concerning the US-findings, "bright liver" (77.4%) and "masking sign" (66.7%) were more sensitive than "vascular blurring" (44.1%) and "deep attenuation" (44.1%). But for the severe fatty infiltration with the difference over -20 H.U. between liver-spleen CT numbers, the last two findings seemed very credible. The abnormal difference between liver-kidney echolevels was most sensitive (80.7%), especially in mild cases with 0 to -19 H.U. (53 in 75 cases), and very objective than the other US-findings.

Fatty Liver↗
PubMed1989

A kinetic study on secretion and elimination of endogenous thyrotropin in the thyrotropin-releasing hormone test.

Serum thyrotropin (TSH) concentrations in normal young men were measured by a high-sensitivity immunoradiometric assay before and after intravenous administration of 500 micrograms of TSH-releasing hormone (TRH). A kinetic model was applied to evaluate the secretion rate both before (V0) and after (V0 + V* at maximum rate) the administration of TRH, the elimination constant (K), the latent time (L) between TRH administration and start of the stimulated secretion, and the total amount of TSH (T) released in response to TRH. V0, V* and T varied widely from individual to individual, but correlated well with TSH before TRH administration (r = 0.93, 0.80 and 0.87, respectively). A few minutes (1.89 +/- 1.30 min) after the administration of TRH, the secretion of TSH (0.025 +/- 0.016 microU/min ml) was stimulated, and the total release over about 1 h was 12.5 +/- 5.6 microU/ml. Serum TSH was maximum at 31.5 +/- 5.7 min. The half-time of disappearance of TSH was 42 +/- 9 min. These data confirm that the stimulated secretion continues for more than 30 min, and that the pituitary releases 43.2 +/- 22.9 mU of TSH (assuming the distribution volume of TSH is 5.8% of body weight) in response to TRH, an amount which correlates closely (r = 0.91) with TSH before TRH administration.

Adult↗
PubMed1989

The ontogeny of growth hormone in the human fetal pituitary.

To examine the ontogeny of growth hormone synthesis and secretion in human fetus, growth hormone messenger ribonucleic acid was measured in 11 pituitaries from fetuses of 16 to 27 weeks of gestation by hybridization of cytosol ribonucleic acid with complementary deoxyribonucleic acid labeled with phosphate 32. Pituitary growth hormone content and serum growth hormone, thyroxine, and cortisol concentrations were assessed by radioimmunoassay. Growth hormone messenger ribonucleic acid content in the fetal pituitary increased from the early midtrimester, reaching a level 15.3 times higher at 27 weeks of gestation than the value at 16 weeks. However, growth hormone content in the pituitary showed no evident change during 16 to 21 weeks of gestation and started to increase after 22 weeks. Serum concentration of growth hormone was variable but always greater than 50 ng/ml, and the maximal level was observed at 20 weeks of gestation (141 ng/ml). Although serum thyroxine concentration in the fetuses showed no correlation with pituitary growth hormone content or serum growth hormone concentration, serum concentration of cortisol was correlated positively with growth hormone content in the fetal pituitary. These results suggest that the maturation of the growth hormone synthesis and secretion system in the fetal pituitary occurs after 22 weeks of gestation and that cortisol may play some role in the ontogenesis of growth hormone.

Fetal Blood↗
PubMed1989

Potentiation of atrial natriuretic peptide-stimulated cyclic guanosine monophosphate formation by glucocorticoids in cultured rat renal cells.

1. The effect of steroid hormones on atrial natriuretic peptide (ANP)-stimulated cyclic guanosine monophosphate (cyclic GMP) formation was studied in cultured rat renal cells. 2. ANP increased cyclic GMP formation in a dose-dependent manner, while cyclic AMP was not changed by ANP. 3. Steroid hormones did not affect basal cyclic GMP levels in cultured rat renal cells. 4. Dexamethasone at 10(-8) M increased ANP (human and rat ANP)-stimulated cyclic GMP dose-dependently in cultured rat renal cells. Cortisol, corticosterone and aldosterone at a concentration of 10(-7) M also potentiated ANP-stimulated cyclic GMP formation, although triiodothyronine, oestradiol and testosterone were ineffective. Potentiation of ANP action by these steroids seems to parallel glucocorticoid activity. 5. Dexamethasone did not affect cyclic GMP formation stimulated by sodium nitroprusside which stimulates soluble guanylate cyclase in the cytosol. Therefore, the potentiating action of dexamethasone may be mediated through the action on particulate guanylate cyclase at the plasma membrane. 6. It is suggested that the diuretic action of glucocorticoids may, at least in part, be mediated through the potentiating effect of glucocorticoids on cyclic GMP response to ANP.

Animals↗
PubMed1989

Sequence of the variant thyroxine-binding globulin of Australian aborigines. Only one of two amino acid replacements is responsible for its altered properties.

A form of thyroxine-binding globulin (TBG) with reduced affinity for hormone and increased susceptibility to heat and acid denaturation has been identified in Australian Aborigines (TBG-A). Results of heat denaturation of TBG established that the TBGA allele is X linked and has a frequency of 50.9% in Western Australian Aborigines. The sequence of an isolated TBGA allele differed at two positions from that of the normal TBG allele (TBGC). One substitution was in codon 191, ACA (threonine) rather than GCA (alanine), and the other was in codon 283, TTT (phenylalanine) instead of TTG (leucine). These nucleotide substitutions resulted in the loss of sites for the enzymes Bgl 1 and Tth 111 II, respectively. The nucleotide substitutions in the TBG-A allele was confirmed by digestion of genomic DNA segments amplified using the polymerase chain reaction. The Bgl 1 and Tth 111 II sites were absent in the genes of two Aboriginal men expressing TBG-A and were present in those of three Aboriginal and six Caucasian males expressing TBG-C. The TBG gene of a seventh Caucasian male possessed the Bgl 1 site but had lost the Tth 111 II site; sequencing of this allele revealed only the substitution in codon 283 identical to that in the TBGA allele. As the biochemical properties of TBGPhe-283 expressed by this individual were indistinguishable from normal TBGLeu-283, we believe that the abnormal properties of TBG-A are due to substitution of alanine for threonine at residue 191.

Adolescent↗
PubMed1989

Studies on the role of glycosylation for human corticosteroid-binding globulin: comparison with that for thyroxine-binding globulin.

The role of glycosylation on the secretion and the stability of human corticosteroid binding globulin (CBG) was studied. Cells of the human hepatoma line were labeled by [35S]methionine in presence of or absence of tunicamycin (TM). Media or cells were harvested at 0, 3, 6, and 20 h after the addition of excess unlabeled methionine. Media and cell lysates were incubated with anti-CBG serum and immune complexes were precipitated with Staphylococcus aureus protein A (Pansorbin). Immunoprecipitates were analyzed by fluorography after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoprecipitation of T4-binding globulin (TBG) was also carried out with anti-TBG serum. Fluorographic analysis revealed three forms of CBG: CBG1, a glycosylated, mature, and secretory form with apparent mol wt of 70 K; CBG2, a glycosylated precursor which due to incomplete carbohydrate processing has an apparent mol wt of 54 K; and CBG3, a nonglycosylated form consisting of the 40 K core protein. In absence of TM, CBG1 was observed in media and CBG2 was detected in cell lysates. The proportion of CBG1 increased during the chase, whereas that of CBG2 decreased, indicating that CBG was secreted after processing of the oligosaccharides on CBG2. In presence of TM, CBG3 was found both in media and cell lysates. The sum of CBG3 in the medium and the cell lysate decreased during the chase, whereas that of CBG1 and CBG2 remained unchanged. Similar to CBG, TBG1 (mature form, 60 K) and TBG2 (partially processed glycosylated form, 54 K) were observed in media and cell lysates, respectively, in absence of TM. However, TBG3 (nonglycosylated, 44 K) was not detected in medium. These results indicate that glycosylation is not a key factor for the secretion of CBG but is important for its stability. On the other hand the glycosylation is indispensable for the secretion of TBG.

Cell Line↗
PubMed1989

Expression of low density lipoprotein receptor gene in human placenta during pregnancy.

Mammalian cells require cholesterol as a structural component of plasma membranes. It is also required for placental steroid synthesis. De novo synthesis of cholesterol is limited in human placenta and cholesterol is obtained mainly from plasma low density lipoprotein (LDL). Cholesterol delivery from LDL is mediated by receptor-mediated uptake and the receptor amount is the most important factor for cellular delivery. Thus, the regulation of receptor synthesis is important for placental development and function. Since the regulation of LDL receptor gene expression has not been studied in human placenta, LDL receptor mRNA was measured in placentae of 5-40 weeks of gestation by hybridization of RNA with 32P-labeled cDNA for human LDL receptor. Two mRNA species for LDL receptor were demonstrated by Northern blot analysis. The longer mRNA [5.3 kilobases (kb)] was much more abundant than the shorter mRNA (3.7 kb). The amount of 5.3 kb mRNA was highest early in gestation and decreased during pregnancy. However, the amount of 3.7 kb mRNA did not change appreciably during gestation. Dot blot analysis of 26 placental mRNAs obtained from various stages of gestation revealed a negative correlation between LDL receptor mRNA and gestation (r = -0.76, P less than 0.001). Considering the rapid growth of the trophoblast during gestation, especially in the first and the second trimester, increased expression of the LDL receptor gene and subsequent translation are expected for efficient cholesterol uptake to provide a sufficient substrate for cell growth. Possible mechanisms for the appearance of two mRNA species for LDL receptor are also discussed.

Actins↗
PubMed1989

[Enhanced bioavailability of digoxin by gamma-cyclodextrin complexation: evaluation for sublingual and oral administrations in humans].

The inclusion complex of digoxin with gamma-cyclodextrin was prepared in a molar ratio of 1:4, and evaluated for sublingual and oral administrations in humans. In the dissolution tests of digoxin tablets, the increase in dissolution rate and decrease in acid hydrolysis were attained by gamma-cyclodextrin complexation. The serum levels of digoxin after sublingual and oral administrations to human healthy volunteers in the form of complex tablets were higher than the digoxin alone, particularly in the case of the sublingual form of gamma-cyclodextrin complex. The present data suggested that the sublingual administration of the rapid dissolving form of gamma-cyclodextrin complex may be useful for improving the bioavailability of digoxin due to the prevention of acid hydrolysis in stomach and the enhancement of drug absorption rate.

Administration, Oral↗
PubMed1989

Regulation of prolactin gene expression during early pregnancy in rats.

We have shown that administration of estrogen which increases prolactin (PRL) synthesis in the rat may be mediated by an increase in poly [adenosine diphosphate ribose (ADP-ribose)] synthesis. Present investigation was attempted to study whether poly (ADP-ribose) synthesis is involved in rat PRL gene expression during early pregnancy. Anterior pituitaries were obtained on days 0, 2, 4, 6, 8, 10 and 12 of pregnancy (group C). Another group of pregnant rats was given nicotinamide, an inhibitor of poly (ADP-ribose) synthesis twice a day intra-peritoneally from day 0 to the day of sacrifice (group N). Serum estradiol (E2) concentration was determined by radioimmunoassay. PRL mRNA was measured by cytoplasmic dot hybridization using 32P-labeled cDNA. Poly (ADP-ribose) synthesis was assessed by incubating purified nuclei with 14C-nicotinamide adenine dinucleotide. The serum concentration of E2 increased between days 2 and 4, and on day 6 it decreased to the level of day 0. It remained low until day 12. No difference in the serum E2 level was observed in groups C and N. In group C, PRL mRNA increased from day 2 and remained high until day 8. In group C, poly (ADP-ribose) synthesis increased between days 2 and 4, decreased on day 6 to the level of day 0, and thereafter gradually increased until day 10. Administration of nicotinamide abolished the increase in poly (ADP-ribose) synthesis observed in group C during early pregnancy. In group N, the increase in PRL mRNA was completely suppressed. It is suggested that the increase in PRL mRNA in early pregnancy may be mediated by increased poly (ADP-ribose) synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Plasma thyroxine-binding proteins and thyroid hormone levels in primate species; is callithricidae thyroid hormone resistant?

Thyroxine(T4)-binding to serum proteins in primates; catarrhini, prosimiae, and platyrrhini were studied by polyacrylamide gel electrophoresis T4 binding analysis. From the electrophoretic analysis, it was shown that thyroxine-binding proteins similar to human thyroxine-binding globulin (TBG) and thyroxine-binding prealbumin (TBPA) were present in catarrhini and prosimiae species, but not in platyrrhini (callithricidae and cebidae). T4-binding analysis also revealed that catarrhini and prosimiae have a high affinity T4-binding protein similar to human TBG. The association constant (Ka) for T4 of the plasma proteins in these species was approximately 2.0 X 10(10) M-1. On the other hand, it was unable to demonstrate a high affinity binding site for T4 in the plasma of platyrrhini species. Both the total and free thyroid hormone concentrations in catarrhini and prosimiae were similar to those in human. Total T4 in cebidae, one of the platyrrhini species, was extremely low. Among 8 animals examined, T4 in 6 was undetectable by radioimmunoassay and the mean T4 of the other two was 2.8 micrograms/dl. However, free thyroid hormone concentrations were similar to those in human. In callithricidae, another platyrrhini species, T4 in plasma was 6.90 +/- 2.11, which is comparable to the level in normal human subjects. However, in this species, high-affinity T4-binding protein was lacking and free thyroid hormone concentrations were extremely high (most were higher than the assay limit). Although the thyroid function of callithricidae remains to be studied, it will be interesting if callithricidae is resistant to thyroid hormone action.

Animals↗
PubMed1989

Elevation of plasma atrial natriuretic peptide in a neurosurgical patient with the syndrome of inappropriate secretion of antidiuretic hormone--case report.

The authors describe a case of subarachnoid hemorrhage with hyponatremia accompanied by elevation of plasma atrial natriuretic peptide (ANP). The early phase of hyponatremia was classified as the syndrome of inappropriate secretion of antidiuretic hormone (ADH) due to subarachnoid hemorrhage. However, in the later phase, hyponatremia and natriuresis were accompanied by suppression of ADH while plasma ANP remained elevated. The patient was effectively treated with demeclocycline and hypertonic saline. The significance of ANP in the pathophysiology of increased natriuresis is discussed.

Aged↗
PubMed1989

Cavernous angioma of the cerebellum--case report.

Computed tomography (CT) allows earlier diagnosis of intracranial cavernous angioma than was formerly possible. However, cerebellar lesions are uncommon. Cerebellar cavernous angioma with hemorrhage was diagnosed in a 54-year-old male who suddenly developed nausea and vomiting, then declined over the following week and developed ataxia and nystagmus. Blood pressure was normal, and he had no history of hypertension or hemorrhagic diathesis. Precontrast CT revealed an irregularly-shaped, hyperdense lesion in the left cerebellum and an associated hematoma. Injection of contrast medium did not significantly enhance the lesion. Vertebral angiography demonstrated only an avascular mass in the cerebellum. A semiliquid hematoma was evacuated and a vascular nodule was removed from the posterior wall of the hematoma cavity. The histopathological diagnosis was cavernous angioma. Nine sufficiently documented reports of cerebellar cavernous angioma are reviewed and the clinical and radiological features of these lesions are discussed.

Cerebellar Diseases↗
PubMed1989

Manufacture of custom CMOS LSI for an implantable multipurpose biotelemetry system.

Implantable biotelemetry systems are indispensable tools not only in animal research but also in clinical medicine as such systems enable the acquisition of otherwise unavailable physiological data. This paper describes the manufacture of custom CMOS LSI to implement an implantable biotelemetry system. The internal circuits of this system are fabricated on a single silicon chip with a size of 4 x 5 mm. This IC is designed and manufactured not only to achieve as small size and low power dissipation as possible, but also to have multiple functions. Its main functions are to select one of implanted sensors and to accomplish On-Off power switching of an implanted battery by receiving appropriate control signals and command signals from an external circuit. This system, used together with appropriate sensors, is expected to be capable of measuring and transmitting such significant parameters as pressure, pH and temperature.

Electronics↗