Biomedical subjects

C C Tseng

Publications and source records attributed to C C Tseng.

At least 145 records · Page 8Linked to original sources

PubMed1988

Microcomputer-based image analysis systems for two-dimensional electrophoresis gels.

The intent of this overview is to provide the readers, especially those who are currently conducting two-dimentional electrophoresis, a basic understanding in the construction and use of microcomputer-based systems for the analysis of protein profiles generated by two-dimensional gel electrophoresis. In addition, a microcomputer-based system, employing fixed-point operations and effective algorithms, has been evaluated. The validity of this system has been demonstrated by using the two-dimensional silver-stained gels and fluorograms derived from the rat prostate. It is concluded that the present system can be used to aid the analysis of two-dimensional electrophoresis gels. An overall consideration of hardware and software components of a computer-based system is briefly discussed.

Computer Systems↗

PubMed1987

Conformational analysis of the cholecystokinin C-terminal octapeptide: a nuclear magnetic resonance and computer-simulation approach.

The C-terminal octapeptide portion of cholecystokinin (CCK8) has well-defined biological properties which include action as a neurotransmitter and induction of gall-bladder contraction and pancreatic enzyme secretion. Many analogues of CCK8 have been prepared and tested for potency, making this an ideal model system in which to initiate evaluation of structure-function relationships. The present study uses high-resolution proton nuclear magnetic resonance (NMR) spectroscopy and energy minimization techniques to evaluate the solution (DMSO) and in vacuo conformation(s) of CCK8. The NMR results provide amide and C alpha H alpha chemical shift temperature dependencies and all phi dihedral angles and chi 1 rotamer populations. The energy minimization data located deep potential energy wells, for which all torsion angles are reported. Collectively, the data support models for CCK8 where the structures are characterized by a high degree of folding. These conformations are characterized by sharp turns, possibly stabilized by hydrogen-bonds. Taken together with pharmacologic data and somewhat similar folded structures implied from fragments of CCK8, it is suggested that both electrostatic and steric effects are needed for full biological potency.

Computer Simulation↗

PubMed1987

Nuclear magnetic resonance spectroscopic and computer-stimulated structural analyses of a heptapeptide sequence found around the N-glycosylation site of a proline-rich glycoprotein from human parotid saliva.

The proline-rich glycoprotein from human parotid saliva has a common heptapeptide sequence around four of six N-glycosylation sites (Maeda, N., H. S. Kim, E. A. Azen, and O. J. Smithies, 1985, J. Biol. Chem., 20:11123-11130). A synthetic model of the heptamer protein sequence, NH2-Q(1)-G(2)-G(3)-N(4)-Q(5)-S(6)-Q(7)-CONH2, was examined by nuclear magnetic resonance (NMR) spectroscopy and the ECEPP/2-VAO4A (Empirical Conformation Energy Program for Peptides) energy minimization computer algorithm (Scheraga, H. A., 1982, Quantum Chemistry Program Exchange, 454; Powell, M. J. D., 1964, Quantum Chemistry Program Exchange, 60). The NMR spectrum was almost completely assigned in dimethylsulfoxide-d6 (DMSO), and the amide chemical shift temperature dependence, phi dihedral angles, and chi 1 rotamer populations elucidated. These data indicated that a significant population of the heptamer could exist as a type I beta-turn [4----1 between Q(5) and G(2)] and/or a type II' beta-turn [4----1 between (Q)5 and G(2) and/or a gamma-turn [3----1 between Q(5) and G(3)] with the amino acid chi 1 torsion angles weighted toward the gauche- conformation. Starting from these three possible conformations, the ECEPP/2-VAO4A rigid geometry energy minimization program was used to find the localized predominant in vacuo structures of this heptapeptide sequence. The type II' beta-turn conformation best fits the data based on internuclear hydrogen-bonding distances, minimum potential energy considerations, and the NMR parameters.

Computer Simulation↗

PubMed1987

Relationship between ornithine decarboxylase activity and gastric damage.

Hypertonic NaCl increases the activity of gastric mucosal ornithine decarboxylase (ODC). Intragastric administration of concentrated NaCl solution also induces ulcers in the glandular gastric mucosa. The relationship between ODC activity and gastric mucosal damage and the significance of ODC increases in hypertonic NaCl-treated rats are unknown. Rats were fasted 24 h before being given 1.0 ml of 3.4 M NaCl, 120 mM aspirin in 100 mM HCl or 50% ethanol intragastrically. The oxyntic gland mucosa was removed and assayed for ODC and in some experiments DNA, RNA, and protein content. DNA, RNA, and protein content were decreased by 3.4 M NaCl, and these decreases were much greater if ODC was inhibited by pretreatment with alpha-difluoromethylornithine (DFMO). Both aspirin and 3.4 M NaCl induced ODC activity 6 h later. However, DFMO increased the lesion index only in NaCl-treated rats. Although ethanol produced damage, it had no effect on ODC levels, and DFMO did not alter the severity of ethanol lesions. When different concentrations (0.4, 0.8, 1.6, 2.5, and 3.4 M) of NaCl were administered, ODC activities were increased 6 h later in rats receiving 1.6, 2.5, and 3.4 M NaCl but not lower concentrations. Gross lesions appeared in response to the 2.5 M dose and increased with increasing NaCl concentration. However, microscopic damage of the gastric mucosa occurred at all the concentrations tested. These data show that 1) ODC activation is not necessarily produced by damage, 2) in the case of NaCl, increasing damage increases ODC, and 3) ODC appears to have a role in the prevention of a recovery to damage caused by NaCl.

Animals↗

PubMed1987

Hormonal effects on development of the secretory apparatus of chief cells.

We used light microscopy, transmission electron microscopy, and stereological point-counting methods to investigate the response of rat gastric chief cells to corticosterone and thyroxine during postnatal development. Administration of corticosterone or thyroxine to normal animals in the first two postnatal weeks increased relative numbers of chief cells in the fundic mucosa but did not change the absolute number of total cells in each gland. The chief cells displayed more rough endoplasmic reticulum, zymogen granules, and Golgi saccules in corticosterone- or thyroxine-injected rats than in normal control rats. When rats were either adrenalectomized or made hypothyroid using propylthiouracil, the number of chief cells dramatically decreased. Ultrastructural studies of chief cells from adrenalectomized or hypothyroid rats showed retarded differentiation as indicated by increased free ribosomes, less rough endoplasmic reticulum, fewer zymogen granules, and poorly developed Golgi apparatuses. In adrenalectomized animals, thyroxine replacement alone failed to induce the histological maturation of chief cells, but addition of corticosterone stimulated chief cell differentiation. In hypothyroid animals, either thyroxine or corticosterone replacement restored the differentiation of chief cells to normal levels. Our data indicate that 1) corticosterone is necessary for gastric chief cell maturation during postnatal development, 2) a decrease or loss in either corticosterone and/or thyroxine results in retarded chief cell differentiation and functional activity, and 3) the effect of thyroxine on chief cell development is secondary to an accompanying increase in serum corticosterone.

Adrenalectomy↗

PubMed1987

Hormonal effects on development of the secretory apparatus of parietal cells.

The effect of corticosterone and thyroxine on the development of parietal cells was studied in 20-day-old rats. Either corticosterone or thyroxine injection significantly increased the amount of mitochondria, tubulovesicles, and intracellular canaliculi in normal rat pup parietal cells. However, the ultrastructure of parietal cells did not change when rats were adrenalectomized or made hypothyroid by propylthiouracil (PTU) during the first week of life. Corticosterone had the same effect in hypothyroid rats as in normal rats, increasing the volume fraction of mitochondria and the surface density of tubulovesicles and intracellular canaliculi in the parietal cell. However, thyroxine failed to do so in adrenalectomized animals. When 20-day-old adrenalectomized or hypothyroid rats were challenged with secretagogues, there was no increase in maximal acid output over the basal secretory rate, while normal rats showed a 40-50% increase. We conclude that 1) normal parietal cells respond to additional thyroxine or corticosterone with increases in volume fraction of mitochondria and surface density of tubulovesicles and intracellular canaliculi; 2) the dramatic decreases in acid secretion observed in adrenalectomized or PTU-treated rats are not explained by the morphology of parietal cells that remains normal; 3) the effect of thyroxine on the development of acid secretion is mediated by corticosterone; and 4) unlike chief cells the morphological development of parietal cells does not appear to depend on corticosterone or thyroxine after postnatal day 7.

Adrenalectomy↗

PubMed1986

Acid phosphatase in the rat prostate: comparison with other organs.

Properties of acid phosphatase in the rat ventral prostate were compared with those in seven other organs in adult male rats by the electrophoretic mobility in acrylamide gels, susceptibility to reactions with inhibitors, and by their response to castration and subsequent testosterone replacement. The enzyme in the spleen exhibited the highest values of Km and Vmax. These values in the prostate, the liver, and the kidney showed an intermediate level, while the lowest level was found in the heart, the lung, the adrenals, and the seminal vesicle. Upon electrophoresis, a total of six isoenzyme bands were resolved. Two major zones of activity were noted. They were the slow-moving anodal bands (isoenzymes 1,2, and 3) and the fast-moving cathodal bands (isoenzymes 4,5, and 6). The spleen possessed the highest number of isoenzymes (bands 1,2,4,5 and 6) and the prostate had three (bands 1,2, and 3). The heart contained only one (band 2). Two isoenzymes (bands 1 and 2) were found in remaining organs. Results of the effects of inhibitors showed that NaF inhibited all six isoenzymes, while L(+)tartrate inhibited mainly those in the anodal zone. D(-)tartrate and formaldehyde showed no significant inhibition to any of the isoenzymes. PCMB (para-chloromercuribenzoic acid) was found to be a specific inhibitor for isoenzyme 3. Upon castration in the hosts, the enzyme activity in the prostate, the liver, and the seminal vesicle was significantly reduced. This reduction in enzyme activity involved all isoenzymes in these three organs, but isoenzyme 3 in the prostate disappeared completely after castration. The activities of these isoenzymes were restored by testosterone replacement. These results indicate that acid phosphatase in rat tissues has multiple forms; each has its own electrophoretic mobility in acrylamide gels, sensitivity to inhibitors, and response to hormonal manipulation. Isoenzyme 3 is specific to the prostate and is uniquely sensitive to PCMB inhibition and to androgen stimulation.

Acid Phosphatase↗

PubMed1986

Does corticosterone affect gastric mucosal cell growth during development?

The effect of corticosterone on the growth of the gastric mucosa was investigated during development. The weight of the mucosa and DNA, RNA, and protein content were used as parameters of growth. The pepsinogen content of the oxyntic gland was examined as an indicator of the biological action of corticosterone on development. Corticosterone-treated animals had lower body weights than control animals on days 10-20. This difference was not seen on day 25. Corticosterone administration during the first and second postnatal weeks induced the precocious appearance of pepsinogen in the oxyntic gland mucosa and increased basal acid output. These effects disappeared by day 25. The weight of the mucosa and DNA, RNA, and protein content of the oxyntic gland and antrum increased with age, but corticosterone had no effect on any of these parameters. We conclude that the induction of precocious development of the gastric mucosa by corticosterone is not due to the stimulation of growth.

Animals↗

PubMed1986

Role of thyroxine in functional gastric development.

The role of thyroxine (T4) on the functional development of chief and parietal cells was studied in the rat. Daily injection of thyroxine (0.1 microgram/g body wt) resulted in the precocious appearance of pepsinogen in the oxyntic gland mucosa and an increase in basal acid output. Thyroxine had no effect in adrenalectomized rats. In propylthiouracil-induced hypothyroid pups, pepsinogen content and basal acid secretion were low. Corticosterone acetate (200 micrograms/g body wt) injection increased pepsinogen content and basal acid secretion in the absence of normal levels of thyroid hormones. We conclude that the effect of thyroxine on the development of chief and parietal cells is primarily due to accompanying changes in serum corticosterone.

Adrenal Glands↗

PubMed1984