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Biomedical subjects

C H Hsieh

Publications and source records attributed to C H Hsieh.

At least 55 records · Page 3Linked to original sources
PubMed1996

Clinical efficacy of prostate-specific antigen testing in patients with prostate disease.

Prostate-specific antigen (PSA) has become the most commonly used marker for the detection of prostatic adenocarcinoma (PCa) in recent years. To understand the clinical value of PSA testing in patients with prostate disease, the preoperative serum PSA values of 562 patients who underwent prostatic surgery from April 1993 to December 1995 were correlated with histologic findings in samples taken during surgery. Histopathologic findings revealed 93 cases of PCa and 469 cases of benign prostatic hyperplasia (BPH). Of the 220 patients with a serum PSA level within the normal range (0-4 ng/mL), PCa was diagnosed in six (2.7%) cases. However, among the 342 patients (61%) who had serum PSA > 4.0 ng/mL, BPH was diagnosed in 225 (75%) patients. With a PSA cutoff value of 4.0 ng/mL, the sensitivity, specificity and positive predictive value of PSA in distinguishing PCa from BPH were 94%, 45% and 25%, respectively. Raising the cutoff value to 10 ng/mL enhanced the specificity (76%) and positive predictive value (42%) with a slight compromise in sensitivity (85%). Of the 469 patients with BPH, 255 (54%) had a serum PSA > 4.0 ng/mL and 107 (24%) had a serum PSA > 10.0 ng/mL. Prostate volume, histologically documented prostatic inflammation and history of urinary retention prior to PSA determination may partly explain the abnormal elevation of serum PSA in patients with BPH. Our data confirmed the sensitivity of PSA in the detection of PCa in a country with a low incidence of PCa. However, a considerable proportion of patients with BPH had elevated serum PSA levels caused by factors unrelated to malignancy. Raising the cutoff value of PSA or employing adjunct parameters derived from PSA determination may be helpful in improving the diagnostic efficacy of PSA.

Aged↗
PubMed1996

Hemorrhage in intracranial epidermoid cyst.

A case of intracranial epidermoid cyst with intracystic hemorrhage is reported. A 63-year-old woman sustained a head injury after a fall; obtundation and ataxia were noted later. Computed tomography revealed a heterogeneous hyperdense lesion in the posterior and middle cranial fossas. Magnetic resonance imaging showed a lesion with increased signal intensity both on T1 and T2 weighted images. Two craniotomies revealed an intracranial epidermoid cyst with about 6 mL of clotted blood. Pathologic study showed hemosiderin-laden macrophages and neovascularity in the cystic wall granulation tissue, which indicated rupture of the cystic wall with intracystic hemorrhage, which later correlated with the diagnostic image findings. The patient tolerated the two operations well and her postoperative course was smooth. She was discharged in good health without obvious neurologic deficits.

Brain Diseases↗
PubMed1995

Mass spectrometric analysis of rat liver cytosolic glutathione S-transferases: modifications are limited to N-terminal processing.

Cytosolic glutathione S-transferases (GSTs) from rat livers were purified using an S-hexylglutathione affinity column. The GST subunits were resolved by reverse-phase HPLC and their molecular masses were determined by electrospray mass spectrometry. The major hepatic GSTs detected were subunits 1, 1', 2, 3 and 4, with molecular mass of 25,520, 25,473, 25,188, 25,782 and 25,571 Da respectively. Subunits 6, 7 and 10 are minor components, with molecular mass of 25,551, 23,308 and 25,211 Da respectively. Alternatively, the hepatic GSTs were purified using a glutathione affinity column. Subunits 1, 1', 2, 8 and 10 were eluted from this column with GSSG, the oxidized form of glutathione. Subunit 8 has a molecular mass of 25,553 Da. The remaining proteins on the glutathione affinity column were removed with glutathione and S-hexylglutathione. Subunits 2, 3, 4 and 6 could be detected in the eluate. We could not detect any significant difference in molecular mass between GSTs isolated from male and female rat livers. Cytosolic GSTs were isolated from livers of buthionine sulphoximine-treated female rats for MS analysis. The molecular masses obtained were identical to those determined for the controls.

Animals↗
PubMed1995

Solvent effect on phosphatidylcholine headgroup dynamics as revealed by the energetics and dynamics of two gel-state bilayer headgroup structures at subzero temperatures.

The packing and dynamics of lipid bilayers at the phosphocholine headgroup region within the temperature range of -40 to -110 degrees C have been investigated by solid-state nuclear magnetic resonance (NMR) measurements of selectively deuterium-labeled H2O/dimyristoylphosphatidylcholine (DMPC) bilayers. Two coexisting signals with 2H NMR quadrupolar, splittings of 36.1 and 9.3 (or smaller) kHz were detected from the -CD3 of choline methyl group. These two signals have been assigned to two coexisting gel-state headgroup structures with fast rotational motion of -CD3 and -N(CD3)3 group, respectively, with a threefold symmetry. The largest quadrupolar splitting of the NMR signal detected from the -CD2 of C alpha and C beta methylene segment was found to be 115.2 kHz, which is 10% lower than its static value of 128.2 kHz. Thus, there are extensive motions of the entire choline group of gel-state phosphatidylcholine bilayers even at a subzero temperature of -110 degrees C. These results strongly support the previous suggestion (E. J. Dufourc, C. Mayer, J. Stohrer, G. Althoff, and G. Kothe, 1992, Biophys. J. 61:42-57) that 31P chemical shift tensor elements of DMPC determined under similar conditions are not the rigid static values. The free energy difference between the two gel-state headgroup structures was determined to be 26.3 +/- 0.9 kJ/mol for fully hydrated bilayers. Furthermore, two structures with similar free energy difference were also detected for "frozen" phosphorylcholine chloride solution in a control experiment, leading to the conclusion that the two structures may be governed solely by the energetics of fully hydrated phosphocholine headgroup. The intermolecular interactions among lipids, however, stabilize the static headgroup structure as evidenced by the apparently lower free energy difference between the two structures for partially hydrated lipid bilayers. Evidence is also presented to suggest that one of the headgroup structures with trimethylammonium group rotation, which is not compatible with the static headgroup structure in crystals, is due to the dielectric relaxation of the slowly reorienting inter bilayer water molecules near the physical edge of membrane surface. Finally, a molecular model of the hydration-induced conformational changes at the torsion angle a5 of the O-C-CN+ bond is proposed to explain the two detected coexisting headgroup structures. These results emphasize the important role of the trimethylammonium group in monitoring the structure and dynamics of the lipid headgroup.

Deuterium↗
PubMed1995

Molecular order and hydration property of amine group in phosphatidylethanolamine and its N-methyl derivatives at subzero temperatures.

The molecular order and hydration properties of the amine group in phosphatidylethanolamine and its N-methyl derivatives were studied by 2H-NMR at subzero temperatures. Three coexisting signals with 2H-NMR quadrupolar splittings of 146, 106, and 28.8 KHz were detected from the fully hydrated phosphatidylethanolamine/D2O at the lowest studied temperature of -120 degrees C by using short recycle time in the applied NMR pulse sequence. These signals have been assigned to originate from frozen D2O in the interbilayer space and the deuterated amine group, i.e., -ND, with and without threefold symmetric motions. Comparative 2H-NMR studies of phosphatidylethanolamine/D2O with different degrees of methylation over a temperature range between -40 and -120 degrees C lead to the following conclusions. First, the bond angle of -D attached to the nitrogen atom of the amine group may be determined by the 2H-NMR quadrupolar splittings, i.e., 106 and 28.8 KHz, of the two coexisting signals of the deuterated amine group and found to be 112.9 for the gel-state phosphatidylethanolamine. Second, assuming the applicability of the empirical equation for the hydrogen bond distance of N+D--O with deuteron quadrupole coupling constants and using the intermolecular hydrogen bond distance of the amine group determined in single crystals of phosphatidylethanolamine bilayers, the largest measured quadrupolar splitting (delta nu Q) of N-D in this study, i.e., 106 KHz, is close to the static value. This interpretation is also consistent with the fact that the delta nu Q value determined remains constant in the temperature range between -70 and -120 degrees C. Third, the molecular order parameter of the amine group, as calculated from the ratio of the libration-averaged and static delta nu Q value for the lipid with different degrees of methylation, suggests that the perturbation of the headgroup interaction is most significant for the final methylation step. Finally, measurement of the spectral intensity of isotropic unfrozen D2O signals in D2O/phospholipid dispersions at temperatures below the homogeneous nucleation temperature of ice formation for D2O, i.e., below -34 degrees C, suggests that the first methylation step perturbs the neighboring water most significantly. Assuming that the molecular order of the amine group and the amount of unfrozen water detected under the present experimental condition can be taken as a measure of the hydrogen-bonding ability and the extent of perturbation caused by the methyl group, respectively, the gradual methylation of the amine group perturbs the interactions of the N-methylated headgroups in a nonlinear fashion. The results provide a molecular explanation for the phase behavior of phospholipids with different degrees of methylation.

Deuterium↗
PubMed1994

Modification of glutathione S-transferase 3-3 mutants with 2-(S-glutathionyl)-3,5,6-trichloro-1,4-benzoquinone. Identification of the C-terminal tryptic fragment as part of the H-site and evidence that 2-(S-glutathionyl)-3,5,6-trichloro-1,4-benzoquinone is not specific for cysteine labelling.

A triple mutant of rat liver glutathione S-transferase 3-3 that has all three cysteine residues replaced with serine (CallS) and a quadruple mutant with a Tyr-115 to phenylalanine substitution on CallS (CallSY115F) were reacted with 2-(S-glutathionyl)-3,5,6-trichloro-1,4-benzoquinone (GS-1,4-TCBQ). The modified proteins were analysed on a triple-quadrupole mass spectrometer equipped with an electrospray ionization source. At an enzyme: GS-1,4-TCBQ ratio of 1:10, the enzymes were modified at multiple sites. Covalent attachment of a single inhibitor on to the protein was achieved by lowering the enzyme: GS-1,4-TCBQ ratio to 1:1. Results from m.s. analyses suggest that the inhibitor on the CallSY115F mutant exists as a glutathionyl dichlorobenzoquinone derivative. The modifiers of the CallS mutants are glutathionyl monochlorobenzoquinone derivatives. Therefore, GS-1,4-TCBQ reacts at a single site on CallSY115F, but probably cross-links two regions on wild-type and CallS mutant. To confirm our observation, CallS was modified with 1-chloro2,4-dinitrobenzene, which specifically labels Tyr-115, before reacting with GS-1,4-TCBQ. The inhibitor formed a glutathionyl dichlorobenzoquinone adduct on the dinitrophenyl-CallS mutant. In addition, the benzoquinone derivative on the protein can be partially removed by 1-chloro-2,4-dinitrobenzene. Peptide mapping and sequencing analysis of the GS-1,4-TCBQ-modified CallS mutant revealed that the C-terminal 16-amino-acid fragment is labelled. Molecular modelling suggests the C(5) and C(6) on the benzoquinone ring of the inhibitor interact with the oxygen atoms of Tyr-115 and Ser-209 respectively.

Amino Acid Sequence↗
PubMed1994

cDNA cloning, sequencing and in situ localization of a transcript specific to both sublingual demilune cells and parotid intercalated duct cells in mouse salivary glands.

A cDNA clone derived from mouse sublingual gland was isolated from lambda-phage cDNA library. Northern blot hybridization indicated that the transcript from which it was derived was approx. 700 nucleotides in length. This mRNA encoded a protein of about 20 kDa, as determined by hybrid selection and cell-free translation. Conceptual translation of the cDNA clones showed that p20 is 170 amino acids in length. The putative protein is hydrophobic in nature, is neither a mucin-like protein nor does its amino acid sequence or composition resemble the other known mouse proteins. However, the amino acid sequence of p20 suggests that it may be from a gene or gene family homologous to rat common salivary protein 1. The p20 mRNA also appears to share a non-random degree of sequence homology with the cysteine-rich domains of bovine and porcine submandibular mucins. The p20 mRNA is abundant in the mouse sublingual gland, and its expression is approx. nine times greater than in the parotid gland. In situ hybridizations localized the p20 mRNA exclusively in the demilune cells of the sublingual gland and in the intercalated duct cells of the parotid gland. It is detectable in the neonatal and adult submandibular gland at very low levels, but is absent from liver, heart, brain, thymus, spleen, lens and lacrimal glands.

Amino Acid Sequence↗
PubMed1994

Abdominal pregnancy--report of two cases and review of literature.

Ectopic pregnancy is one of the major complications of pregnancy. The abdominal pregnancy is a comparatively rare type of ectopic gestation with a high fetal and maternal morbidity and mortality. Although abdominal pregnancy had been well documented, it still remains a serious dilemma for most clinicians in the contemporary obstetric practice because of the difficulties in early diagnosis and proper management. We reported two cases of early abdominal pregnancy with accurate preoperative diagnosis followed by immediate surgical intervention and total removal of the placental tissue. The important concepts of management with this uncommon but ominous condition are discussed, including the predisposing risk factors, clinical features, diagnostic difficulties, appropriate surgery and management of the placenta.

Adult↗
PubMed1992

Stability studies of topical carbonic anhydrase inhibitor 6-hydroxyethoxy-2-benzothiazole sulfonamide.

A new carbonic anhydrase inhibitor, 6-hydroxyethoxy-2-benzothiazole sulfonamide (6-hydroxyethyoxyzolamide), was studied to determine its stability in aqueous solution from pH 2.9 to 9.2 at a constant ionic strength of 0.15 M. This newly synthesized derivative of ethoxyzolamide has demonstrated clinical efficacy for use as an ophthalmic drug to lower intraocular pressure. Drug solution in sealed ampules was placed in a constant temperature over either at two temperatures (75 and 85 +/- 0.2 degrees C) or four temperatures (75, 80, 85, and 90 +/- 0.2 degrees C). Samples were analyzed by known HPLC methods. The results indicated that 6-hydroxyethoxyzolamide is most stable at pH 4 to 5.5. The aqueous drug solutions at pH 7.0 and 8.0 were, nevertheless, sufficiently stable, based on extrapolation of kinetic data at high temperatures using the experimentally determined Arrhenius equation. The degradation compound was identified by spectral analysis to have a hydroxyl group substituting for the original -SO2NH2 group.

Administration, Topical↗
PubMed1991

Phenylarsine oxide inhibits insulin-dependent glucose transport activity in rat soleus muscles.

Phenylarsine oxide (PAO) is known to block insulin-stimulated glucose transport activity in 3T3 L1 adipocytes at a post-receptor step. Herein, we demonstrate that, at right concentration, PAO also inhibits insulin activation of glucose uptake in rat soleus muscles but does not affect basal level of uptake. In control experiments, insulin stimulation of 2-deoxy-D-glucose uptake is about 400% of that of the control level. After PAO treatment, the stimulation reduces to 150% of the control. Since the intracellular level of ATP remains unchanged after PAO treatment, when measured by phosphorus-31 nmr spectroscopy, this inhibition is not due to depletion of ATP pool size. Moreover, PAO does not affect autophosphorylation of the insulin receptors purified from rat soleus muscles, implying that the PAO blockage of insulin-dependent glucose uptake in soleus muscles also may be post-receptor.

Adenosine Triphosphate↗
PubMed1991

The sequence-directed bent DNA detected in the replication origin of Chlamydomonas reinhardtii chloroplast DNA is important for the replication function.

We demonstrated that the 1055 bp restriction fragment containing OriA, a chloroplast DNA replication origin of Chlamydomonas reinhardtii, has electrophoretic anomalies characteristic of bent DNA. A tandem dimer of the region was constructed. Quantitative measurement of the relative gel mobility of a set of permuted fragments was used to extrapolate the approximate position of the bent DNA segment. By analyzing the gel mobility of short, sequenced fragments of the bent DNA region, the putative bending locus was identified. Two A4 tracts and two A5 tracts were located in the bending locus. Oligonucleotide-directed mutagenesis was then used to disrupt the A tract or the spacing between A tracts and the effect of site-specific mutation on electrophoretic mobility was analyzed. To assess the functional role of the bent DNA region, subclones containing the bending locus, mutated bending locus, and regions flanking the bending locus were constructed. Each subclone was used as template in an in vitro DNA replication system which preferentially initiated DNA replication at OriA. A 224 bp subclone with the bending locus positioned in the middle displayed the highest replication function and was sufficient to initiate DNA replication in vitro. Site-specific mutations or alterations of the A tracts resulted in decreased DNA bending and decreased DNA replication activity.

Base Sequence↗
PubMed1991

Effect of aging on phosphate metabolites of rat brain as revealed by the in vivo and in vitro 31P NMR measurements.

Changes of phosphate metabolism in brains of neonate, weaning and adult rats were compared using both in vivo and in vitro nuclear magnetic resonance spectra. Ratios of phosphocreatine/nucleoside triphosphate (PCr/NTP) were the same in neonatal brain in both in vivo and in vitro studies, but not in weaning and adult brains. This discrepancy may have resulted from extended cerebral hypoxia due to slowed freezing of the brain by the increased skull thickness and brain mass in the weaning and adult rats. Variations in in vitro extraction condition for this age-related study may lead to systematic errors in the adult rats. Nevertheless, the phosphomonoester/nucleoside triphosphate (PME/NTP) ratios in extracts of brain from neonatal rats were higher than those obtained in vivo. In addition, the glycerophosphorylethanolamine plus glycerophosphorylcholine/nucleoside triphosphate (GPE+GPC/NTP) ratios, which were not measurable in vivo, showed age-dependent increase in extracts of rat brain. Some of the phosphomonoester and phosphodiester molecules in rat brain may be undetectable in in vivo NMR analysis because of their interaction with cellular components. The total in vitro GPE and GPC concentration in brain from neonatal rat was estimated to be 0.34 mmole/g wet tissue.

Aging↗
PubMed1991

Eggs enriched in omega-3 fatty acids and alterations in lipid concentrations in plasma and lipoproteins and in blood pressure.

Effects of dietary eggs enriched with omega-3 fatty acids on lipid concentrations in plasma and lipoproteins and blood pressure were determined in 11 men and women in two groups. Group 1 consumed four omega-3 eggs per day during the first 4-wk period and four control eggs for the second 4-wk period. Group 2 ate the same number of eggs in the reverse order. Mean plasma cholesterol concentration was significantly increased by control eggs (P less than 0.01) but unchanged by omega-3 eggs. Mean plasma triglyceride concentration was decreased by omega-3 eggs but increased by control eggs. Both systolic and diastolic blood pressures were significantly lowered by omega-3 eggs in group 1 whereas only systolic pressure was significantly decreased on omega-3 eggs in group 2. The control eggs did not change blood pressure. In conclusion, the omega-3 eggs may be more healthful than the control eggs.

Adult↗
PubMed1990

A simulation study on renin and aldosterone secretions in primary aldosteronism.

A system dynamics modeling method was developed to predict changes in plasma renin activity (PRA), plasma aldosterone (PA) and electrolyte concentrations in response to diuretic stimulation in patients with primary aldosteronism. Its clinical validity was evaluated by comparing experimental and simulation results. In a clinical experiment, furosemide 20 mg was given by intravenous injection to 20 patients with primary aldosteronism. PRA, PA and electrolyte concentrations were measured hourly for 3 hours after administration of the drug. The computer simulation outputs were consistent with the experimentally measured values at each corresponding point of time. An analysis of model predictions indicates that the method may predict the changes in PRA, PA and electrolyte concentrations after diuretic administration in accordance with a time interval.

Aldosterone↗
PubMed1989

Deletions of bases in one strand of duplex DNA, in contrast to single-base mismatches, produce highly kinked molecules: possible relevance to the folding of single-stranded nucleic acids.

A 32-base-pair (bp) DNA duplex with deletions in one strand, and thus extra bases in the opposing strand, was ligated head-to-tail to produce linear and circular multimers. The electrophoretic mobility of the linear multimers was analyzed in polyacrylamide gels and the size of the circular DNA was determined by electron microscopy. A 1-base deletion produced a marked retardation in the mobility of the linear multimers coincident with the formation of a population of multimeric circles of a smaller average size than the deletionless 32-mer; 2-, 3-, or 4-base deletions at the same site produced proportionately greater effects. Two 1-base deletions separated by 10 bp on the same strand produced a greater reduction in mobility than a 1-base deletion, whereas two 1-base deletions spaced by 5 bp on the same strand yielded a molecule that behaved more like the deletionless DNA. We conclude that deletions of 1-4 bases at a single site on duplex DNA produce molecules that behave as if they contain sharp bends or kinks. In contrast, single mismatches in the 32-bp duplex produced no abnormality in behavior relative to normally base-paired DNA in the gel mobility and electron microscopic assays. The possible role of such structures in organizing the three-dimensional folding of single-stranded nucleic acids is considered.

Base Composition↗
PubMed1989

Spatial and temporal frequency in figure-ground organization.

Figure-ground organization of an ambiguous pattern can be manipulated by the spatial and temporal frequency content of the two regions of the pattern. Controlling for space-averaged luminance and perceived contrast, we tested patterns in which the two regions of the ambiguous pattern contained sine-wave gratings of 8, 4, 1, or 0.5 cycles per degree (cpd) undergoing on:off flicker at the rates of 0, 3.75, 7.5, or 15 Hz. For a full set of combinations of temporal frequency differences, with each spatial frequency the higher temporal frequency was seen as background for more of the viewing time. For two spatial frequency combinations, 1 and 4 cpd, and 1 and 8 cpd, tested under each of the four temporal frequencies, the lower spatial frequency region was seen as the background for more of the viewing time. When the effects of spatial and temporal frequency were set in opposition, neither was predominant in determining perceptual organization. It is suggested that figure-ground organization may parallel the sustained-transient response characteristics of the visual system.

Attention↗
PubMed1988

The terminus of SV40 DNA replication and transcription contains a sharp sequence-directed curve.

We have examined nucleosome positioning on two DNA segments containing sharp sequence-directed curvatures. A 223 bp DNA from Crithidia fasciculata was cloned into two sites in pBR325 separated by 28%. These sites were found to selectively reconstitute nucleosomes 5- to 7-fold more effectively than the adjoining straight DNA. The terminus of replication and termini of transcription of SV40 DNA are contained within a region of approximately 200 bp centrally located in a 1216 bp fragment. Visualization of this fragment by electron microscopy revealed a sharp curve of approximately 200 degrees in the terminal region. Reconstitution of histone protein with this fragment revealed a 2- to 5-fold higher probability of assembling nucleosomes in the terminal region over the adjacent DNA.

Animals↗