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C J Hsu

Publications and source records attributed to C J Hsu.

At least 37 records · Page 2Linked to original sources
PubMed1994

Effects of tumor necrosis factor-alpha on glucose and albumin production in primary cultures of rat hepatocytes.

Tumor necrosis factor-alpha (TNF) is known to alter significantly in vivo hepatic glucose and albumin metabolism. However, it remains unclear whether the observed effects represent direct actions of this factor or secondary responses due to the recruitment of other mediator systems. The present study was designed to investigate direct actions of TNF on glucose and albumin production in primary cultures of rat hepatocytes. Addition of TNF to the culture medium resulted in a 45% to 50% reduction in glucose production from a control level of 239 +/- 15 nmol/plate.h. This effect was reversed by addition of anti-TNF monoclonal antibody. In glycogen-depleted cells, short-term (5-hour) incubation with TNF did not affect hepatocyte albumin secretion, which was 8.13 +/- 0.29 microgram/plate.h. However, in cells exposed to insulin or in non-glycogen-depleted cells, addition of TNF resulted in a 10% to 25% reduction in albumin production. These findings indicate that TNF exerts direct inhibitory effects on hepatocyte glucose and albumin production, but the effects on the latter process are modest. A notable aspect of the findings is that the albumin effects are insulin or glucose substrate-dependent, which may have implications regarding liver function during nutritional support in critical illness.

Albumins↗
PubMed1994

Activities of carbonic anhydrase in the cochleae of guinea pigs with early experimental endolymphatic hydrops.

Normal auditory function depends on maintenance of the unique ion composition in the endolymph. Carbonic anhydrase in the inner ear has been suggested to play an important role in maintaining the ion concentration and regulating fluids of the inner ear. Cochlear dysfunction may indicate changes in the biochemical components and osmotic pressure of the inner ear fluids as well as inadequate generation of intracellular metabolic energy. Dysfunction of the inner ear was investigated in the early stages of endolymphatic hydrops. Normal adult albino guinea pigs were operated on to obliterate the endolymphatic ducts and sacs of the right ears to induce endolymphatic hydrops. The auditory function of experimental guinea pigs was assessed according to the difference between the preoperative and postoperative hearing thresholds of the auditory brainstem response (ABR). Vibratome sections of the hydropic cochlea (right) and control cochlea (left) were stained histochemically for the activities of carbonic anhydrase in this study. Decreased activity of this enzyme was not shown consistently in the stria vascularis and organ of Corti of the hydropic cochlea in the early stage of endolymphatic hydrops whereas auditory dysfunction in the hydropic ear was noted from the ABR threshold for the experimental animals with 2 months survival. The results of the present study suggest that further investigation concerning the role of carbonic anhydrase in the cochlear auditory function is necessary.

Animals↗
PubMed1993

Factors affecting secretory protein production in primary cultures of rat hepatocytes.

Previous studies suggest that protein synthesis in the liver may be influenced by alterations in hepatic proteolysis and gluconeogenesis. Since proteolysis and gluconeogenesis are accelerated in acute stress states (especially when associated with nutrient deprivation), these alterations may substantially affect hepatic protein synthesis, the integrity of which is important for host survival. In the present study, we have investigated albumin secretion and glucose production in primary cultures of rat hepatocytes in response to nutrient-limiting conditions, including amino acid depletion, proteolysis inhibition, and augmented gluconeogenesis. In nonlimiting nutrient culture medium containing 10 times the normal plasma amino acid concentrations, hepatocytes produced 8.05 +/- 1.62 micrograms/plate-hr of albumin. Short-term (5 hr) inhibition of cellular protein degradation with the lysosomal protease inhibitor leupeptin did not influence albumin production, but caused a profound reduction (17-41%) when amino acid supply was reduced to the physiologic range (1.5-0.5 times, respectively). This indicates the need for active proteolysis for the maintenance of secretory protein production during nutrient limitation. Similarly, leupeptin inhibited glucose production by 22-30% at physiologic (1.5 times and 0.5 times, respectively) amino acid concentrations. Additionally, hepatocyte glucose production could be augmented 168% by epinephrine (2 microM) in 10 times medium, but this response was markedly depressed by leupeptin. Similar catecholamine-mediated effects, but of a smaller magnitude, were noted at lower medium amino acid concentrations. These findings indicate that hepatocyte albumin and glucose production are associated with the common factor of active cellular proteolysis, probably through the regulation of amino acid supply. However, protein synthesis exhibits a higher priority, since stimulated hepatocyte glucose production did not substantially alter albumin secretion.

Amino Acids↗
PubMed1993

The high jugular bulb: report of five cases and a review of the literature.

The jugular bulb varies widely in position and dimensions. A high jugular bulb is not an uncommon finding in temporal bones. Besides our five cases with different clinical manifestations, we review 52 cases diagnosed clinically and published previously in the English literature. The high jugular bulb occurs more often on the right temporal bone. Certain pathologic conditions, such as an abnormal bone formation, an aberrant sinusojugular system, or decreased pneumatization of the mastoid bone, may predispose an individual to its occurrence. Most people with this anatomical variation remain asymptomatic. However, various otologic problems and symptoms may be attributed to this condition. A high resolution computed tomography scan is the most convenient diagnostic tool at present. Law projection plain mastoid radiography may reveal a high jugular bulb in certain cases, providing a preoperative warning to an otologic surgeon. An exploratory tympanotomy is not suggested for those with a high jugular bulb with a conductive hearing loss, while jugular vein ligation has been reported to have good results in alleviating intractable pulsatile tinnitus. For most asymptomatic patients, regular long-term follow-up is recommended.

Adolescent↗
PubMed1993

Chronic mastoiditis mimicking recurrence of nasopharyngeal carcinoma: report of a case.

A nasopharyngeal mass with cranial neuropathies usually indicates an advanced neoplastic process. We present a case of nasopharyngeal carcinoma diagnosed and treated 38 years ago. A nasopharyngeal mass recurred with cranial neuropathies and concurrent otologic infection in June, 1990. Repeated nasopharyngeal biopsies were negative with respect to tumors. Suspecting direct extension of the otologic infection, modified radical mastoidectomy was performed. The nasopharyngeal mass resolved after the surgical intervention. Spread of otologic infection from the temporal bone to the nasopharynx may be more common than was previously thought. Clinicians should modify diagnostic approaches in patients with a nasopharyngeal mass and concurrent otologic disease.

Chronic Disease↗
PubMed1993

Reduced Na(+)-K(+)-ATPase activities in the cochleae of guinea pigs with experimental endolymphatic hydrops.

Normal auditory function depends on the maintenance of the unique ion composition in the endolymph. The Na(+)-K(+)-ATPase in the lateral wall of the cochlear duct has been suggested to play an important role in maintaining the endolymphatic ion concentration and in generating a positive endocochlear potential. Cochlear dysfunction may indicate changes in the biochemical components and osmotic pressure of the inner ear fluids as well as inadequate generation of intracellular metabolic energy. Dysfunction of the stria vascularis and spiral prominence was investigated in the early stages of endolymphatic hydrops. Vibratome sections of hydropic and normal cochleae were stained histochemically for Na(+)-K(+)-ATPase activity in this study. Decreased activity of this enzyme was shown in the stria vascularis and spiral prominence of the hydropic cochlea in the early stage of endolymphatic hydrops. The results coincide with those of studies of electrophysiologic changes in cochlear function in hydropic animals by others. The results of the present study provide further information concerning a possible deficit in ion transport activity and decreased enzymatic activity in the cochlea.

Animals↗
PubMed1992

Effects of insulin on total RNA, poly(A)+ RNA, and mRNA in primary cultures of rat hepatocytes.

The purpose of this study was to examine mechanisms involved in the regulation of protein synthesis in primary cultures of rat hepatocytes. Hepatocytes were maintained in a chemically defined serum-free medium in the presence or absence of insulin. The rate of protein synthesis in hepatocytes deprived of insulin between days 2 and 5 of culture was reduced to 67% of the rate observed in insulin-maintained controls. The decrease in protein synthetic rate was accompanied by a proportional fall in the content of both total RNA and poly(A)+RNA, suggesting that the capacity for protein synthesis was reduced in the absence of insulin. Both total RNA and poly(A)+ RNA contents and the protein synthetic rate were returned to control values after 3 days of insulin resupplementation. In addition, the effect of insulin on the expression of specific mRNAs was assessed by in vitro translation of total RNA followed by two-dimensional gel analysis of radiolabeled translation products. Only 13 of the greater than 150 spots discernible on the two-dimensional gels were altered in response to insulin. The mRNAs that were altered include examples of repression and stimulation of expression in response to insulin deprivation. Thus, in isolated rat hepatocytes, insulin regulates the capacity of both overall protein synthesis as well as the capacity for the synthesis of specific proteins.

Animals↗
PubMed1992

Changes in activity of cytochrome oxidase in the cochleae of guinea pigs with experimental endolymphatic hydrops.

Cochlear dysfunction may indicate inadequate generation of intracellular metabolic energy which is necessary for the regulation of the transport of ions and fluid as well as production of electro-energy in the cochlea. Changes in cochlear function in the early stages of endolymphatic hydrops attributed to dysfunction of the sensory hair cells and stria vascularis were investigated. The main source of metabolic energy, produced by intracellular respiration, is located in the stria vascularis and sensory hair cells. Since cytochrome oxidase is one of the most important respiratory enzymes, vibratome sections of hydropic and normal cochleae were stained cytochemically for cytochrome oxidase activity in this study. Decreased activity of this enzyme was consistently shown in the normal-appearing outer hair cells and stria vascularis, as well as the degenerated hair cells and stria vascularis, of the higher turns of the hydropic cochlea. The results coincide with those in other studies of electrophysiologic changes in cochlear function in hydropic animals. A decrease in the activity of respiratory enzymes was noted before the destruction of the cellular structures. The activity of cytochrome oxidase may serve as a useful indicator for demonstrating the functional status of cochlear hair cells and stria vascularis.

Animals↗
PubMed1991

Nuclear calcium gradients in cultured rat hepatocytes.

Ca2+ concentrations ([Ca2+]) in cytosol and nucleus in fura-2-loaded cultured rat hepatocytes were determined by three-dimensional (3-D) optical-sectioning microscopy. After determining the empirical 3-D point spread function of the fluorescence microscope-coupled digital video imaging system, contaminating light arising from optical planes above and below the plane of interest was removed by deconvolution using the nearest-neighboring approach (NNA) algorithm. Although deconvolution resulted in substantial improvement in accuracy of fluorescence intensity determinations in single-wavelength excitation images as well as sharper delineation of boundaries between cellular compartments, the complicated mathematical process did not significantly enhance the precision of [Ca2+] values derived from ratiometric (ratio of dual-wavelength excitation) images. In resting hepatocytes, cytosolic Ca2+ (210 +/- 15 nM) was 1.6- to 2-fold higher than nuclear Ca2+ (128 +/- 12 nM). This difference in Ca2+ between the two compartments was detected both in raw ratiometric images and in those processed with NNA algorithm. Addition of arginine vasopressin or epidermal growth factor resulted in significant increases (2- to 3-fold) in both cytosolic and nuclear Ca2+; however, the nuclear-to-cytosolic Ca2+ gradient was preserved in hepatocytes stimulated with mitogens. We conclude that the hepatocyte nuclear membrane contains Ca2+ permeability barriers and Ca2+ transport mechanisms that may be hormonally sensitive. We postulate that the increase in nuclear Ca2+ may be important in regulation of cell proliferation induced by mitogens, possibly by activating Ca(2+)-dependent endonucleases, nuclear calmodulin, or nuclear protein kinase C.

Algorithms↗
PubMed1991

Ultrastructural study of cytochemical localization of carbonic anhydrase in the inner ear.

Vibratome sections were stained for cytochemical localization of carbonic anhydrase (CA) activity in vestibular neuro-epithelium, spiral ligament and spiral limbus. The new finding is the localization of reaction products in the interdental cells of the spiral limbus, Claudius' cells, mesothelial cells of the lower border of spiral ligament, vestibular sensory cells and perilymphatic cells, which have not earlier been proved to have CA activity. The interdental cells showed the products only on the basolateral infoldings. Claudius' cells showed prominent products in the microvilli. In the vestibular sensory cells, the products were present only in the stereocilia and cuticular areas. The perilymphatic fibrocytes under the vestibular sensory epithelium, like the fibrocytes of the spiral ligament, revealed diffuse products throughout the whole cell. In the vestibular supporting cells and transitional cells, the reaction products were localized diffusely in the cytosol, but not in the secretory granules. In the long cell projections of the transitional cells, type II fibrocytes at spiral prominence, mesothelial cells at the uppermost region of the spiral ligament and Borghesan's zone, the localization of the reaction products was the same as that of the basolateral infoldings of the vestibular dark cells and marginal cells of stria vascularis shown previously.

Animals↗
PubMed1988

Gonadotropins increase concentrations of immunoreactive insulin-like growth factor-I in porcine follicular fluid in vivo.

To evaluate the regulation of ovarian insulin-like growth factor-I (IGF-I) during follicular growth in vivo, we measured the concentration of this peptide in follicular fluid (FFL) of immature gilts during the induction of follicular development by pregnant mare's serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG). FFL concentrations of immunoreactive (i) IGF-I were compared with those of intrafollicular steroids and with concentrations of iIGF-I, estradiol (E2), and porcine growth hormone (GH) in serum. PMSG, administered at Time 0, induced a significant (p less than 0.01), time-dependent increase in intrafollicular iIGF-I that peaked 72 h after administration of the hormone, before the administration of hCG. During the first 72 h, the changes in ovarian iIGF-I paralleled those for progesterone and E2. After the administration of hCG at 72 h, FFL levels of E2 fell, those of iIGF-I remained constant, and progesterone rose. Serum E2 concentrations paralleled those in FFL. Since serum GH and IGF-I levels rise during spontaneous puberty in some species, these levels were also monitored. However, a significant treatment effect on serum GH and iIGF-I was not demonstrated. In summary, ovarian concentrations of iIGF-I are increased by gonadotropic hormones in vivo. The absence of concomitant changes in circulating levels of iIGF-I and GH suggests that the gonadotropin effects are exerted directly on the ovary. These results, together with more abundant data regarding secretion and action of IGF-I in cultured granulosa cells, suggest that IGF-I may function in an autocrine or paracrine fashion to amplify the actions of gonadotropins at an ovarian level.

Animals↗
PubMed1987

Ovarian epidermal growth factor-like activity. Concentrations in porcine follicular fluid during follicular enlargement.

Numerous data indicate that epidermal growth factor has important effects on cultured granulosa cells. However, most of the few attempts to detect epidermal growth factor in ovarian tissue have been unrevealing. In this study, ovarian epidermal growth factor-like activity was easily detected by a radioreceptor assay based on the A431 cell line but not by an immunoassay for mouse epidermal growth factor. The concentration of this activity in follicular fluid from small porcine ovarian follicles was higher than that in fluid from medium or large follicles or serum (p less than 0.01), but lower than that in salivary gland extracts. Receptor-active epidermal growth factor-like peptides could function as local ovarian regulators.

Animals↗
PubMed1987

Gonadotropins and estradiol stimulate immunoreactive insulin-like growth factor-I production by porcine granulosa cells in vitro.

Previous studies have established the ovarian granulosa cell as a site of insulin-like growth factor-I (IGF-I) secretion and action, suggesting an autocrine function for this peptide in the ovary. To better understand how this putative autocrine system is regulated and its interface with the classic ovarian trophic hormones FSH, LH, and estradiol (E2), we have studied the effects of these hormones on the secretion of immunoreactive IGF-I (iIGF-I) by cultured porcine granulosa cells. Immature granulosa cells were cultured under serum-free conditions which were optimized to allow maximal iIGF-I production and hormonal responsivity. Measurements of iIGF-I were made after minimizing the influence of IGF-binding proteins by either acid gel filtration or reverse phase chromatography. Since the two preparative procedures gave roughly comparable results, the more expeditious reverse phase procedure was chosen for most samples. Cycloheximide virtually eliminated measurable iIGF-I in culture, suggesting that the peptide measured was newly synthesized, and degradation of IGF-I by cultured granulosa cells was negligible. Consequently, the medium levels provided an accurate indication of cellular secretion over the collection period. Under optimal culture conditions, iIGF-I was readily measurable and responsive to treatment with ovarian trophic hormones. The iIGF-I levels in several experiments with these hormones were as follows: FSH treatment, 1.58 +/- 0.21 times the control value (n = 5 experiments); E2 treatment, 1.26 +/- 0.12 times the control value (n = 5); E2 plus FSH, 3.12 X 0.31 times the control value (n = 8); LH, 1.33 +/- 0.12 times the control value (n = 3); LH plus FSH, 1.78 +/- 0.2 times the control value (n = 1). To assess the role of cAMP in the mediation of gonadotropin effects in this system, granulosa cells were treated with a phosphodiesterase inhibitor (methylisobutylxanthine), which resulted in iIGF-I levels 1.61 +/- 0.7 times the control level. In the presence of FSH, a further stimulatory effect was demonstrated (3.76 +/- 0.29 times control). In addition, the cAMP analog 8-bromo-cAMP dramatically increased iIGF-I levels (6.3 +/- 0.72 times control). These data provide the first demonstration that gonadal iIGF-I secretion can be stimulated by the principal hormones involved in trophic regulation of the ovary. As with other gonadotropin-dependent functions of granulosa cells, this effect appears to be mediated by cAMP and enhanced by E2. This interface between circulating hormones and autocrine systems could provide an important mechanism to amplify the effects of gonadotropic hormones on a local level.

1-Methyl-3-isobutylxanthine↗
PubMed1987

Concomitant effects of growth hormone on secretion of insulin-like growth factor I and progesterone by cultured porcine granulosa cells.

The observation that GH deficiency delays the onset of puberty has raised the question of the effect of GH on gonadal development. In addition, recent studies in the rat have indicated that GH is able to elevate ovarian levels of immunoreactive insulin-like growth factor I (iIGF-I) in vivo and enhance FSH-induced granulosa cell differentiation in vitro. To evaluate further the possibility of direct effects of GH on ovarian function, we have studied the action of GH on the secretion of iIGF-I and progesterone by cultured porcine granulosa cells from immature follicles. The effects of GH were compared with those of estradiol (E2) and FSH, hormones previously shown to stimulate steroidogenesis and iIGF-I production in this system. GH-stimulated cultures secreted 7.8 times as much iIGF-I per cell as control cultures, while cultures treated with E2 plus FSH secreted 4.5 times as much, and the combination of all three hormones produced an additional increment. The GH-dependent immunoreactivity was localized to two peaks on gel filtration which coeluted with authentic IGF-I and with an IGF-binding protein. In contrast to the results with iIGF-I secretion, GH was a relatively ineffective stimulator of progesterone secretion, resulting in levels 2.6 times the control value, compared to levels 7.4-fold the control value in cultures treated with E2 plus FSH. However, when the three agonists were combined, a synergistic interaction was observed which resulted in progesterone values 33.3 times the control value. In parallel studies, PRL was unable to mimic the effects of GH on iIGF-I or progesterone secretion. In summary, GH has direct stimulatory actions on porcine granulosa cells. Compared to E2 and FSH, established stimulators of these cells, GH is at least comparable in effectiveness with regard to iIGF-I secretion, but less effective as a stimulator of steroidogenesis. However, GH dramatically enhances the effects of E2 and FSH on progesterone secretion. These effects of GH could be important during the onset of puberty, when GH levels in plasma are elevated.

Animals↗
PubMed1986

Relaxin affects the shape of rat myometrial cells in culture.

The shape of rat myometrial cells in culture was altered by exposure to hormones. Oxytocin (107 microU/ml) significantly decreased mean cell length and area. Treatment of oxytocin-treated cells with relaxin (1.5 micrograms/ml), isoproterenol (10 microM) or (Bu)2 cAMP (1 mM) for 15 min resulted in a significant increase in cell length and area. The effect of relaxin was time dependent, with a significant increase in cell length by 1 min and in cell area by 3 min. Relaxin elicited a concentration-dependent increase in cell length and area between 0.1 and 2 micrograms/ml. The actions of relaxin correlate in time course and concentration dependence with its effects on cAMP elevation in the presence of 0.4 microM forskolin and on changes in myosin light chain kinase kinetic parameters in these cells. Myometrial cells in culture constitute a useful model system in which to correlate physical and biochemical effects of relaxin and other hormones.

Animals↗
PubMed1986

Relaxin treatment alters the kinetic properties of myosin light chain kinase activity in rat myometrial cells in culture.

Relaxin treatment altered the kinetic properties of rat myometrial cell myosin light chain kinase (MLCK) by increasing the K50 of the enzyme for calmodulin (CaM) from 1.1 +/- 0.1 to 38 +/- 14 nM. When MLCK was assayed in the presence of 7 nM CaM to maximize the effect of the decreased affinity for CaM between control and relaxin-treated groups, a rapid concentration-dependent effect of the hormone was observed. Relaxin decreased MLCK activity significantly within 1 min. The ED50 of the effect was 0.4 microgram/ml. In addition to its effect on Ca2+-CaM-dependent activity, relaxin also decreased Ca2+-CaM-independent MLCK activity. This decrease was not attributable to a decrease in the affinity of the enzyme for myosin. There was a temporal association between the effects of relaxin on mean cell length, elevation of cAMP levels in the presence of 0.4 microM forskolin previously shown in other studies, and the alteration of MLCK activity. All three parameters were changed significantly within 1 min after exposure to relaxin. The ED50 of relaxin for cell shape changes, cAMP elevation, and effects on MLCK activity were all approximately 0.4 microgram/ml. Relaxin may act in part by a cAMP-mediated phosphorylation of MLCK, thereby decreasing its affinity for CaM. The effect on MLCK may be linked to a decrease in the phosphorylation of myosin light chains and the promotion of uterine relaxation.

Animals↗