Biomedical subjects

C S Hsu

Publications and source records attributed to C S Hsu.

At least 19 recordsLinked to original sources

PubMed2002

Effect of enantiomeric excess on surface structures and phase sequences in free-standing liquid-crystal films.

We present differential optical reflectivity and null transmission ellipsometry data from several mixtures of MHPBC enantiomers. From this data, we have determined the chiral smectic phase sequence as a function of enantiomeric excess. The data suggest a change in the structure of the smectic-C(*)(alpha) phase and the surface tilt state as the enantiomeric excess is reduced. The results also show that the intermediate phases, smectic C(*)(FI2), smectic C(*)(FI1), and smectic C(*)(alpha), disappear sequentially on reducing the net chirality.

Journal Article↗

PubMed2001

Heterotrimeric G-protein and signal transduction in the nematode-trapping fungus Arthrobotrys dactyloides.

The fungus Arthrobotrys dactyloides produces specialized constricting rings to trap and then consume nematodes. The signal transduction pathway involved in the nematode-trapping process was examined. Mastoparan, an activator of G-protein, had a stimulatory effect on the inflation of ring cells, whereas a G-protein inhibitor, pertussis toxin, prevented ring-cell expansion. The 40-kDa G alpha of heterotrimeric G-proteins was specifically ADP-ribosylated by pertussis toxin. Using an antibody specific to the 35-kDa subunit G beta, we showed that immunogold-labeled G beta was more concentrated in ring cells than in the hyphae. In the absence of nematodes, the rings could be inflated by either pressurizing the culture in a syringe, raising intracellular Ca2+ concentrations, or adding warm water. We used these methods to reveal differences in responses to antagonists. The results support a model in which the pressure exerted by a nematode on the ring activates G-proteins in the ring cells. The activation leads to an increase in cytoplasmic Ca2+, activation of calmodulin, and finally the opening of water channels. The ring cells expand to constrict the ring and thus immobilize the nematode.

ADP-Ribosylation Factors↗

PubMed2001

Sacral parasite conjoined twin.

BACKGROUND: A variant of conjoined twins is one in which one twin is incomplete. CASE: A female infant was born vaginally at 40 weeks' gestation to a healthy primipara. No important abnormalities were noted during prenatal examinations. The infant was fully developed in all external aspects except for a parasitic body conjoined with her sacrococcygeal region. Separated by operation 2 weeks after birth, the parasite contained lower limbs, adipose tissue, muscles, and a bowel sac. Over 4 years of observation, no abnormalities have been found since the operation. CONCLUSION: Obstetricians should be aware of the existence of a parasite twin during prenatal examinations and of the importance of the differential diagnosis of parasite and teratoma, a neoplasm with malignant potential.

Diagnosis, Differential↗

PubMed2001

Mutational analysis of the Arabidopsis RPS2 disease resistance gene and the corresponding pseudomonas syringae avrRpt2 avirulence gene.

Plants have evolved a large number of disease resistance genes that encode proteins containing conserved structural motifs that function to recognize pathogen signals and to initiate defense responses. The Arabidopsis RPS2 gene encodes a protein representative of the nucleotide-binding site-leucine-rich repeat (NBS-LRR) class of plant resistance proteins. RPS2 specifically recognizes Pseudomonas syringae pv. tomato strains expressing the avrRpt2 gene and initiates defense responses to bacteria carrying avrRpt2, including a hypersensitive cell death response (HR). We present an in planta mutagenesis experiment that resulted in the isolation of a series of rps2 and avrRpt2 alleles that disrupt the RPS2-avrRpt2 gene-for-gene interaction. Seven novel avrRpt2 alleles incapable of eliciting an RPS2-dependent HR all encode proteins with lesions in the C-terminal portion of AvrRpt2 previously shown to be sufficient for RPS2 recognition. Ten novel rps2 alleles were characterized with mutations in the NBS and the LRR. Several of these alleles code for point mutations in motifs that are conserved among NBS-LRR resistance genes, including the third LRR, which suggests the importance of these motifs for resistance gene function.

Alleles↗

PubMed2001

Soy isoflavone supplementation in postmenopausal women. Effects on plasma lipids, antioxidant enzyme activities and bone density.

OBJECTIVE: To investigate isoflavone supplementation on plasma lipids, erythrocyte antioxidant enzyme activities and bone mineral density in postmenopausal women. STUDY DESIGN: Thirty-seven postmenopausal women were given 150 mg/d of isoflavone supplements twice daily for six months. Blood was sampled before and after supplementation, at three and six months. RESULTS: There were no significant differences in plasma total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride concentrations or erythrocyte antioxidant enzyme activities after three and six months of supplementation when compared with the baseline. No significant changes were noted in calcaneus bone mineral density after supplementing isoflavones for six months. CONCLUSION: The antioxidant effect of isoflavones in normal postmenopausal women is not obvious, and supplementation with isoflavone alone may not have a hypocholesterolemic effect. Since the duration of this study was too short with respect to bone density, longer studies are needed to clarify the bone-sparing effect of isoflavone supplementation.

Adult↗

PubMed2000

Temporary hearing impairment after general anesthesia--a case report.

The incidence of hearing impairment after anesthesia is rare. We report a case who received left total knee and hip replacement and developed severe hearing impairment of the left ear after general anesthesia. Examination of the left ear by an otolaryngologist showed that there was no noticeable abnormality. The hearing acuity recovered gradually and returned to normal 3 days later. The use of nitrous oxide during anesthesia was incriminated as the possible cause.

Anesthesia, General↗

PubMed1999

Low dose ketamine and midazolam as supplements for spinal anesthesia.

BACKGROUND: Low dose ketamine and midazolam together were used as supplements during spinal anesthesia to provide analgesia for insertion of spinal needle and intraoperative sedation. METHODS: Two regimens of drug combination (ketamine 0.5 mg/kg and midazolam 0.05 mg/kg in group I, n = 30; ketamine 0.5 mg/kg and midazolam 0.1 mg/kg in group II, n = 30) were administered intravenously before proceeding lumbar puncture. RESULTS: Systolic and diastolic arterial blood pressure, heart rate, and arterial oxygen saturation did not change significantly before and after the administration of drugs. Most patients in both groups showed good analgesic response to the lumbar puncture. The medications induced a brief unconsciousness (4.1 min in group I; 8.5 min in group II). The time from drug administration to recovery of mental orientation was 8.8 min in group I and 15.1 min in group II. The regimens also provided intraoperative sedation. Patients in group II appeared to be more depressed than group I in the first 30 min. None of the patients had significant respiratory disturbance, involuntary movement, or recall to spinal puncture. There were 7 patients in group I and 4 patients in group II who experienced dreaming. CONCLUSIONS: The use of low dose ketamine together with midazolam as supplement for spinal anesthesia is helpful in anesthetic practice.

Adolescent↗

PubMed1999

[The role of nurse anesthetist in Taiwan (questionnaire report)].

BACKGROUND: Anesthesia as a specialty was introduced to Taiwan for over 40 years. In early days, there were quite a number of nurse anesthetists who were trained to share the heavy burden of anesthetic work. However, due to the increasing demand for better anesthetic quality, the role of nurse anesthetists is open to discussion. METHODS: Questionnaires were sent to anesthesiologists working in medical centers, regional hospitals, and district hospitals. We hoped to find out the present working condition of nurse anesthetists and what their future role would be. RESULTS: Over one-half of the questionnaires collected agree that nurse anesthetists should not conduct anesthesia by their own, and that they should only help prepare patients and drugs for anesthesia. CONCLUSIONS: Anesthesia as a highly specialized field of medicine should be conducted by qualified and well trained anesthesiologists only. Training for nurse anesthetists should be confined to preparation of drugs and care of patients only.

Anesthesiology↗

PubMed1997

Effects of various chemical sterilization methods on the crosslinking and enzymatic degradation characteristics of an epoxy-fixed biological tissue.

Due to the nature of bioprostheses, which are mainly biological tissues that cannot be sterilized with heat or irradiation, the sterilization method by choice is generally liquid chemicals. It is known that a number of liquid chemicals can have rapid germicidal effect and can be used to sterilize bioprostheses. The study was to evaluate the effects of various chemical sterilization methods on the crosslinking and enzymatic degradation characteristics of an epoxy-fixed biological tissue. The chemical sterilants employed were: a 70% ethanol solution (EtOH), a 2% epoxy compound + 20% ethanol solution (EX-810), a 2% propylene oxide + 20% ethanol solution (PO), and a 0.625% glutaraldehyde + 20% ethanol + 0.2% polysorbate solution (GA). Both masking and crosslinking of the free amino groups within the epoxy-fixed tissue were observed subsequent to sterilization with GA or EX-810. This improved the resistance of the GA or EX-810 sterilized tissues against collagenase degradation as compared to its nonsterilized counterpart. However, subsequent to sterilization with PO, only masking of the free amino groups within the epoxy-fixed tissue was noted. The inhibition of the collagenase degradation by masking of the free amino groups was traded off by the more random molecular packing of the PO sterilized sample due to the introduction of the side branches. Sterilization of the epoxy-fixed tissue with EtOH may increase its denaturation temperature and tensile strength, while neither masking nor crosslinking of free amino groups within the tissue took place. The resistance to degradation of the EtOH sterilized tissue, however, did not improve as compared to its nonsterilized counterpart.

Bioprosthesis↗

PubMed1997

Degradation potential of biological tissues fixed with various fixatives: an in vitro study.

The purpose of this study was to investigate the in vitro degradation potential of porcine pericardia fixed with various aldehyde or epoxy compound (EC) fixatives, using bacterial collagenase and pronase. The fixatives investigated were formaldehyde (FA), glutaraldehyde (GA), monofunctional EC (EX-131), and multifunctional ECs (EX-810, EX-313, and EX-512). Fresh porcine pericardium was used as a control. The test samples were well immersed in a 20-U/mL collagenase solution or a 10-U/mL pronase solution and incubated at 37 degrees C at pH 7.5 for 24 h. The extent of degradation of each test sample was determined by measuring its increment in free amino group content and changes in collagen structure, denaturation temperature, and tensile stress after degradation. In general, the extent of tissue degradation with pronase was more notable than with collagenase. As observed with fresh tissue, the EX-131 EC fixed tissue radically disintegrated after either collagenase or pronase degradation, whereas the other test samples remained intact. The reason for this may reside in the more random molecular packing of the EX-131 EC-fixed tissue, which led to some loss in its helical integrity. This made penetration of enzymes into biological tissue easier. Of the multifunctional EC test groups, tissues fixed with tetrafunctional EC (EX-521) or trifunctional EC (EX-313) had relatively better resistance to degradation than those fixed with bifunctional EC (EX-810). The extent of degradation for the EX-313 or EX-512 EC fixed tissues was similar to that observed for the FA- or GA-fixed tissues. The results of this study indicated that the biological tissue fixed with monofunctional EC (EX-131) cannot resist bacterial collagenase or pronase degradation. However, resistance to degradation of the multifunctional EC (EX-313 or EX-152)-fixed tissues was comparable to that of the aldehyde (FA or GA)-fixed tissues. Therefore, of various EC fixatives, the EC with a greater number of functional groups should be chosen for tissue fixation to increase its resistance to enzymatic degradation.

Amino Acids↗

PubMed1997

Fixation of various porcine arteries with an epoxy compound.

The clinical results of biological vascular grafts have been unsatisfactory. The poor results of these vascular grafts may be attributed to the fixatives, aldehydes, used in fixing tissues. In an attempt to overcome this problem, a new fixative, epoxy compound, has recently been used to fix biological vascular grafts. The study was undertaken to investigate the crosslinking characteristics, fixation index and denaturation temperature, of various porcine arteries fixed with an epoxy compound. The porcine arteries investigated in the study were the common carotid artery, internal thoracic artery, abdominal aorta, and saphenous artery. In addition, the effects of sonication on the porcine arteries before fixation on their crosslinking characteristics were analyzed. The fresh and glutaraldehyde-fixed arteries were used as controls. It was noted that glycine, proline, and alanine were the most abundant amino acids found in the porcine internal thoracic artery. In the amino acid analysis, it was observed that the amino acids in the porcine arteries reacted with epoxy compound or glutaraldehyde were lysine, hydroxylysine, histidine, and arginine. Of these amino acids, lysine was the most reactive. In general, the fixed arteries were relatively stiffer than their fresh counterparts. The fixation indices and denaturation temperatures of various porcine arteries were comparable throughout the entire fixation process. The amounts of free amino groups of the sonicated arteries were significantly lower than those of their unsonicated counterparts (p < 0.05). It is speculated that the diminishing free amino groups of the sonicated arteries may be attributed to the removal of the destroyed cell debris and adherent proteins of the arteries after sonication. However, it was learned that sonication on the porcine arteries before fixation did not seem to affect their fixation indices and denaturation temperatures. The results obtained in this study may help one in selecting the raw materials for developing a small-diameter biological vascular graft

Analysis of Variance↗

PubMed1997

Dibutyryl cAMP prevents increased vascular permeability caused by air embolism in isolated rat lungs.

BACKGROUND AND HYPOTHESIS: Venous gas bubbles are routinely detected in astronauts undergoing extravehicular activities at lower suit pressure. Venous air embolism increases the pulmonary arterial pressure and the vascular permeability leading to acute lung injury. In the present study we evaluated the protective effect of dibutyryl cAMP, aminophylline, and pentoxifylline on the pulmonary vasculatures after air embolism. METHOD: In isolated and perfused rat lungs, we induced air embolism by introducing air bubbles into the pulmonary artery. We measured the pulmonary arterial pressures and capillary pressure. Vascular permeability was determined by measuring the filtration coefficient (Kf) and the protein concentration in the lung lavage fluid. RESULTS: Air infusion caused pulmonary hypertension and increased vascular permeability, resulting in pulmonary edema. The Kf (in g.min-1.cm H2O-1.100 g-1) increased from 0.44 +/- 0.05 at baseline to 2.98 +/- 0.47 after air infusion. Pretreatment with DBcAMP prevented the increase in Kf (0.63 +/- 0.09) caused by air embolism without altering the hemodynamics. Aminophylline and pentoxifylline did not prevent lung injury induced by air embolism. Although aminophylline did not alter the response of pulmonary arterial pressure to air infusion, it elevated the capillary pressure to 5.1 +/- 0.4 mmHg, which was significantly greater than that in the lung receiving air infusion alone. CONCLUSION: Our results suggest that DBcAMP prevents the increase in vascular permeability caused air embolism. The ineffectiveness of aminophylline and pentoxifylline on the prevention of air embolism-induced lung injury remains for further investigation.

Aerospace Medicine↗

PubMed1997

[The shear bond strength of porcelain and base metal alloys for metal-ceramic crown (VI)].

The popularity of base metal alloy for porcelain fused to a metal crown and bridges has increased recently because of lower price, superior yield strength and modulus of elasticity (rigidity). The use of these alloys give them the potential advantage of thinner coping with less material and the required rigidity for long-span fixed partial dentures. The addition of beryllium to base metal alloys increases fluidity and improves casting fit. Beryllium also controls surface oxidation and bonding strength. Oxidation heat treatment of the metal is used to remove entrapped air, eliminate organic material and form the metal oxidized layer. The bonding agent and gold bonding agent also affect the bonding strength between porcelain and metal alloys. Four commercially available ceramic base alloys (two alloys contain beryllium element, another two do not) are studied. The purposes of this investigation are to test the shear bond strength between porcelain and metal alloy under different conditions (oxidized layer removed or not, gold bonding agent and uniseal bonding agent used in combination, separately or not at all). The following results were obtained: 1. Whether the oxidized layer was removed or not did not have a significant effect on the bond strength of porcelain (p > 0.05). 2. When different metal alloys was used, Wiron 88 alloy showed significantly the best bond strength of all alloys tested (p < 0.05). 3. When different bonding agent were used, the combination of bonding agent and gold bonding agent showed the best bond strength of all bonding agents tested. It showed a significantly higher bonding strength than opaque layer and gold bonding agent. 4. Vita porcelain powder showed a significantly higher bond strength than did Unibond porcelain (p < 0.05). 5. When opaque layer was used and when no bonding agent was used, the porcelain powder significantly affected the bond strength (p < 0.0001). The Vita porcelain showed a significantly higher bond strength than did Unibond porcelain. Wiron 88 alloy showed significantly the high bond strength than Rexillium III alloy (p < 0.05). 6. When bonding agent was used, the porcelain powder and alloy significantly affected bond strength. The Vita porcelian showed a significantly higher bond strength than did Unibond porcelain. Wiron 88 alloy showed significantly the best bond strength than other alloys Wiron (p < 0.05). 7. When bonding agent and gold bonding agent were used, the porcelain powder significantly affected the bond strength (p < 0.05). The Vita porcelain showed a significantly higher bond strength than did Unibond porcelain (p < 0.05). 8. When gold bonding agent was used, there was not any bond strength between metal and powder.

Crowns↗

PubMed1997

[The shear bond strength of porcelain and base metal alloys for metal-ceramic crown (VII)].

The popularity of the base metal alloys has increased in the past decade because of their lower price, high tensile strength and high elastic modulus. Several factors are critical in ensuring successful bonding: the matching of the thermal coefficients of expansion and constraction of the porcelain and metal, the metallurgic composition of the alloy and the pretreatment procedures used in preparation of the metal substructure. Two ceramic base alloys (one alloy contains beryllium, another without) were studied. The surface textures were created by 50 microns, 100 microns aluminum oxide sandblasting, carbide bur, carborundum point and disk upon two base alloys, Rexillium III and Wiron 88. The purposes of this investigation were to determine how these variations in surface texture affect the bond strength of the two ceramo-metal alloy systems. The following results were obtained: 1. Statistics revealed that bond strength was not significantly increased with surface roughness (p > 0.05). 2. The shear bond strength for variable pretreatment methods were in the following sequence: 100 microns Al2O3 sandblasting, carbide bur, 50 microns Al2O3 sandblasting, carborundum point, disk. 3. The Rexillium III alloy had a significantly higher bond strength than Wiron 88 alloy (p < 0.05). 4. The Noritake porcelain showed a significantly higher bond strength than Biobond porcelain (p < 0.05). 5. The fracture site was cohesive and adhesive mode treated with 50 microns Al2O3, 100 microns Al2O3, carbide bur. But carborundum point and disk was adhesive mode.

Crowns↗

PubMed1996

Crosslinking characteristics of porcine tendons: effects of fixation with glutaraldehyde or epoxy.

Anterior cruciate ligament (ACL) injuries, if left untreated, often produce significant disability in the athletically active population. Currently, autogenous tissue is the most commonly used substitute for ACL reconstruction because its immunogenicity is virtually nonexistent. However, the functional amount of autogenous tissue available for transplantation is limited. Additionally, this transplantation procedure may create a defect at the donor site, which can result in functional disability. To address these concerns, a prototype xenograft ligament prosthesis, epoxy-fixed porcine Achilles tendon, was developed. This study was intended to investigate the crosslinking characteristics of the epoxy-fixed porcine tendon. The fresh and glutaraldehyde-fixed porcine Achilles tendons were used as controls. Fresh porcine Achilles tendons procured from a slaughterhouse were used to fabricate the ligament prostheses. A 4% epoxy (ethylene glycol diglycidyl ether) solution or a 0.625% glutaraldehyde solution was employed to fix the porcine tendons. Samples of each group were taken out at various elapsed fixation periods. The crosslinking characteristics- denaturation temperature, moisture content, and fixation index-of each sample were then determined. In the study, it was learned that the crosslinking rate for the glutaraldehyde fixation was faster than that for the epoxy fixation. While the denaturation temperatures and the fixation indices for both studied groups were higher than for the fresh one, the denaturation temperature of the glutaraldehyde-fixed tendon was relatively higher than its epoxy-fixed counterpart. However, the fixation index and the moisture content for both studied groups were comparable. Also, it was noted that the epoxy-fixed tendon appeared more natural as compared to its glutaraldehyde-fixed counterpart. The implications of these findings for the epoxy-fixed tendon in the clinical ACL reconstruction require further investigation.

Achilles Tendon↗

PubMed1996

Crosslinking characteristics of an epoxy-fixed porcine tendon: effects of pH, temperature, and fixative concentration.

Injury to the anterior cruciate ligament (ACL) often results in functional instability within the knee joint and may induce a severe articular deterioration. Clinically, these patients may require an ACL reconstruction. In an attempt to develop an improved ligament prosthesis, a prototype xenograft--an epoxy-fixed porcine Achilles tendon--was developed. The study was intended to investigate the crosslinking characteristics of the epoxy-fixed porcine tendons fixed at different pHs (4.0, 7.4, 9.0, and 10.5), temperatures (4, 25, and 37 degrees C), and fixative concentrations (1, 2, or 4%). Samples of each group were taken out at various elapsed fixation periods. The crosslinking characteristics-fixation index, denaturation temperature, and moisture content-of each sample were determined. Additionally, the stiffness of the epoxy-fixed tendons under various fixation conditions was qualitatively compared. In the study it was noted that the color of porcine Achilles tendons remained natural after epoxy fixation. With increasing pH, temperature, or fixative concentration, the fixation indices and denaturation temperatures of the epoxy-fixed tendons increased. However, the fixed porcine tendons tended to be stiffer at a higher pH, temperature, or fixative concentration. The moisture contents of the epoxy-fixed tendons were relatively lower than the fresh ones, while they were approximately the same at different pHs, temperatures, and fixative concentrations. The implications of these findings for the epoxy-fixed porcine tendons in ACL reconstruction require further investigation.

Animals↗

PubMed1996

Physical properties of a porcine internal thoracic artery fixed with an epoxy compound.

This study aimed to investigate the physical properties of a porcine internal thoracic artery fixed with an epoxy compound. Fresh and glutaraldehyde-fixed porcine arteries were used as controls. Both the epoxy-fixed and glutaraldehyde-fixed porcine arteries showed significant increases in fixation index and denaturation temperature as compared to the fresh one. Additionally, the resistance of porcine arteries against bacterial collagenase in vitro degradation increased significantly after cross-linking with the epoxy compound of glutaraldehyde. The reduction of the tensile strength of the epoxy-fixed artery after bacterial collagenase degradation was more severe than in its glutaraldehyde-fixed counterpart. Generally, with increasing pH, temperature or fixative concentration, the fixation indices and denaturation temperatures of the epoxy-fixed porcine arteries increased. The results obtained in this study may be used to optimize the fixation process for developing a small-diameter biological vascular graft fixed by an epoxy compound.

Animals↗

PubMed1996

Anionic gels as vehicles for electrically-modulated drug delivery. I. Solvent and drug transport phenomena.

PURPOSE: The purpose of this study was to elucidate the in vitro behavior of anionic gels as formulation matrices for electrically-modulated drug delivery. Agarose and combinations of agarose with other anionic polymers (carbomer 934P; xanthan gum) were selected and tested to evaluate their potential for drug delivery. METHODS: Electrical current was applied by an automatic crossover power supply to minimize the current fluctuation. Hydrocortisone was selected as the model drug in order to minimize electrostatic interference with drug transport. Syneresis and drug migration were evaluated as a function of current application time and the intensity of electrical current. RESULTS: The data show that electrical current strength and gellant content can affect both the syneresis and drug migration. A linear correlation was found between hydrocortisone loss and mass loss via the exudate. Moreover, in agarose-carbomer 934P gel systems, cumulative gel mass loss is a linear function of time at low intensities of electrical current (e.g., 0.5 mA and 1 mA). However, hydrocortisone distribution, after electrical application, is relatively asymmetric in those agarose-carbomer 934P gels (and in agarose-xanthan gum gels) in contrast to gel matrices containing only agarose. CONCLUSIONS: In this study, the use of carbomer 934P in conjunction with agarose enables the formulator to achieve zero-order release with electrical application. Increased anisotropicity of a gel system due to the application of electrical current could alter the effectiveness of a drug delivery system.

Acrylic Resins↗