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Biomedical subjects

C Y Hong

Publications and source records attributed to C Y Hong.

At least 145 records · Page 8Linked to original sources
PubMed1990

Effects of endothelin and vasopressin on portal pressure of rats.

Endothelin is a vasoconstrictor peptide which has recently been isolated and sequenced from the vascular endothelial cells. It was reported to increase blood pressure in vivo and produce a prolonged contraction with a slow onset in vitro. The purpose of this study was to investigate whether endothelin can lower the portal pressure as another endogenous vasoconstriction peptidevasopressin (AVP) can. Heart rate, systemic blood pressure, portal pressure, and portal vein blood flow were measured. Effects of endothelin on these parameters were compared with those of AVP. Endothelin 10(-10) mol/Kg significantly decreased all of the parameters mentioned. At the higher dose (5 x 10(-10) mol/Kg), however, the portal pressure and blood pressure were increased and portal vein blood flow was unchanged. On the other hand, AVP decreased the portal pressure and portal vein blood flow but elevated the systemic blood pressure. In vitro experiments revealed that endothelin contracted both tail artery and portal vein of rat and vasopressin contracted only tail artery. We concluded that although both are endogenous vasoconstricting peptides, endothelin and AVP affect differently on arterial and venous vascular beds as well as on portal pressure.

Animals↗
PubMed1990

Intracavernosal metaraminol for treatment of intraoperative penile erection.

Four patients developed penile erection when regional anaesthesia was induced with spinal block. In another patient, penile erection developed during fentanyl-induced general anaesthesia. Injection of metaraminol into corpus cavernosum successfully achieved detumescence in all these patients. The dose of metaraminol ranged from 10 to 25 micrograms, much less than that required for the treatment of vasodilator-induced priapism. Intracavernosal injection of metaraminol is a simple, effective and safe method for immediate relief of intraoperative penile erection. It is most useful when urogenital operation would be delayed by penile tumescence.

Adult↗
PubMed1990

Prevalence of mottled enamel after 12 years of water fluoridation in Chung-hsing New Village.

The prevalence of mottled enamel (dental fluorosis) was investigated among children, aged 6 to 15 years, in Chung-hsing New Village and in Tsao-tun Village. The drinking water in Chung-hsing New Village has been fluoridated for 12 years at a level of 0.6 ppm, while the drinking water in Tsao-tun contains a negligible level of 0.08 ppm. The degree of mottled enamel was assessed by using Dean's Index and the Community Fluorosis Index (CFI), the latter being derived from Dean's Index for the purpose of comparison. In Dean's Index, 6 classes based on the severity of the mottling, are identified: normal, questionable, very mild, mild, moderate, and severe. The results showed that children in Chung-hsing had whiter teeth than those in Tsao-tun Village. In the fluoridated group, 5.8% of children fell into the "very mild" mottling category, as compared to 0.9% in Taso-tun, the control area. For the "mild" class, the rate was 1.9% for Chung-hsing New Village and 0.4% for Tsao-tun. With only one exception in Tsao-tun, none of the children in the two groups showed mottling in the "moderate" or "severe" classes. The Community Fluorosis Index (CFI) was 0.15 for the Chung-hsing group, indicating that the occurrence of mottled enamel is very low when compared with data from fluoridation programs in other countries. It is concluded that in Taiwan, a 0.6 ppm fluoride concentration in drinking water, which has previously been reported to be effective in prevention of dental caries, is associated with only negligible mottling of enamel. Even when mottling does occur, the degree is very mild and only small chalky spots can be seen on the teeth.

Adolescent↗
PubMed1990

Histologic reactions to a newly developed calcium phosphate cement implanted in the periapical and periodontal tissues.

A newly developed calcium phosphate cement (CPC), basically composed of tetracalcium phosphate, Ca4(PO4)2O and dicalcium phosphate dihydrate, CaHPO4.2H2O or anhydrous calcium phosphate, CaHPO4, was tested in this study. When combined with water, the cement hardens and produces hydroxylapatite resembling the principal mineral of teeth and bones. Therefore, the CPC should be highly compatible with the body. However, before its clinical application in dentistry, the biocompatibility of CPC in the potential environments of implantation needs confirmation. Eight monkeys were used in our study to test the material in the periapical and marginal periodontal regions. Surgically created periodontal defects were implanted with CPC and hydroxylapatite (HA) (Calcitite 4060). In another application, CPC was pushed into the periapical areas via overfilling of the root canals. Sargenti N2 served as the control material in the periapical test. Generally, only a limited inflammatory response to CPC was found after 6 weeks of implantation in the periodontal area. In the 16-week specimens, the adverse reaction was negligible, and bone regeneration was marked and directly surrounding the CPC. The bone formation activity and biocompatibility in general were found to be even better in the periapical region. The results suggest that the CPC may have a good potential in future clinical applications, although many issues remain to be investigated.

Animals↗
PubMed1989

The inhibitory effect of gossypol on human sperm motility: relationship with time, temperature and concentration.

The inhibitory effect of gossypol acetic acid on human sperm motility was studied with a transmembrane migration method. Gossypol decreased sperm motility after it had been incubated with semen for more than 15 min. However, when sperm motility was evaluated immediately after semen had been mixed with gossypol, no inhibitory effect could be found. We consider that the sperm immobilizing potency of gossypol is much less than our previously studied sperm immobilizing agents. It is unlikely that gossypol can be developed as a vaginal spermicide. The importance of time course in the pharmacological study of sperm motility is emphasized in this study.

Gossypol↗
PubMed1989

Comparison of histological effects of different bioceramic implants on surgically created periodontal defects in monkeys.

The biological response to the resorbable and nonresorbable bone grafting materials implanted in the surgically created defects was compared in 4 Maccaca cyclopsis. Intraosseous angular defects were created on the mesial side of both upper canines and premolars by an air driven fissure bur. The root surface was planed, then hydroxylapatite (HA) and tricalcium phosphate (TCP) were inserted into the right side defects respectively. The left side canine received no implants and served as the control site. The animals were sacrificed 6 and 16 weeks after the experiment. Histologically, the two implant materials were well tolerated by the surrounding tissues and did not elicit any adverse inflammatory reaction. During the 16 weeks periods, TCP was biodegraded through phagocytosis by histiocytes and multinucleated giant cells. The residual particles were incorporated into the new bone matrix and displayed the bone growth guiding property. HA particles were dense and larger in size with low resorption rate, therefore, encapsulation by fibrous tissue was more commonly seen. Although direct bone deposition adjacent to the HA particle surface was apparently found, new bone formation was observed only at the apical portion adjacent to the host alveolar bone. These findings suggested that HA might rather play the role as a biocompatible filler. However, HA was more effective in blocking the downgrowth of the junctional epithelium. Nevertheless, these two implant materials could not hasten the healing process, because new bone formation was observed to be more distinct in the control site.

Animals↗
PubMed1989

Measurement of boar sperm motility by the trans-membrane migration method.

The conventional microscopic methods for evaluating sperm motility of domestic animals are mostly inadequate due to their subjectivity and lack of precision. Recently, a trans-membrane migration method, originally developed for the examination of human sperm motility, has substantially overcome these problems. This study investigated the applicability of the method to boar sperm motility measurement. The apparatus used was simple and consisted only of syringe plungers, poriferous membranes, and modified multi-well culture plates. It measured the proportion of sperm in the semen that moved across the membrane after incubation at 37 degrees C for 3 hr. The sperm motility as measured by this method correlated well with that measured by direct microscopic examinations. The measurement was more reliable using an 8-microns instead of a 5-microns pore-size membrane. The method was found to work equally well for the sperm motility measurement of the semen with a sperm concentration between 1.5 x 10(8)/ml and 6.0 x 10(8)/ml. The results indicate that this method is a simple, objective, quantitative, and reproducible design for the measurement of boar sperm motility.

Animals↗
PubMed1989

An improved technique for dental alloy etching with a potentiostatic device.

Since a good retention of direct bonded retainers onto abutment teeth is the primary requirement for the fabrication of etched fixed partial dentures, successful formation of a micromechanical retentive architecture on the bonding surface is one of the most important procedures. For creating such a retentive dendritic pattern on nonprecious metal, a 2-electrode electrolytic method has been used. This equipment consists of a low-voltage DC power supply and two electrodes, namely, a working and a counter one. However, the current and voltage should be monitored during the entire processing time and the etching area must be pre-estimated. A potentiostat has been used to automatically stabilize the voltage across the working electrode and reference electrode by adjusting the current, as commonly employed in electro-chemical technology. A 3-electrode corrosion device originally developed for laboratory research was adapted for dental retainer etching in this study. The results revealed that the etching of dental nonprecious metal (Ni-Cr-Be alloy) could successfully be performed by using the system with a potentiostat. Moreover, the working potential was found to be approximately 1.3 volts by taking the midpoint between the breakdown and the critical potentials for passivation on the potentiostatic anode polarization curves. The optimal exposure time has been found to be in a range of 3 to 5 minutes and 4 minutes to be ideal as determined by SEM microphotographic observation which showed a uniform dendritic pattern with regular lattice form of alternating ridges and valleys.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗
PubMed1987

An initial screening of serum lipids and fatty acid profiles of hypertensive and normotensive subjects.

Serum lipids and their acyl group profiles from a group of hypertensive patients with elevated systolic and diastolic pressure were compared with normotensive subjects of matched age, body weight and dietary habits. The level of serum triacylglycerols was elevated in the hypertensive subjects, but the cholesterol level remained normal. The acyl groups of serum triacylglycerols and cholesterylesters from hypertensive subjects indicated a higher proportion of the saturated fatty acids (16:0 and 18:0) and a lower proportion of linoleic acid (18:2) as compared to normal controls. There was no obvious change in the level and acyl group composition of serum phosphatidylcholine between the two groups. Since the hypertensive and normotensive subjects indicated similar dietary habits, the resulting differences in serum lipids reflected an abnormality in the lipolytic process in the hypertensive subjects.

Body Weight↗
PubMed1987

The spermicidal potency of Coca-Cola and Pepsi-Cola.

The inhibitory effect of Old Coke, caffeine-free New Coke, New Coke, Diet Coke and Pepsi-Cola on human sperm motility was studied with a trans-membrane migration method. None of them could decrease sperm motility to less than 70% of control within one hour. A previous study which claimed a marked variation of spermicidal potencies among different formulations of Coca-Cola could not be confirmed. Even if cola has a spermicidal effect, its potency is relatively weak as compared with other well-known spermicidal agents.

Beverages↗
PubMed1987

A case of congenital factor V deficiency.

A case of Factor V deficiency, the first case in Korea, is reported in a 9-year-old boy whose plasma concentration of Factor V was 6%. He complained of easy bruisability, prolonged bleeding from the mouth after minor trauma and hemarthrosis and flexion contracture of the right knee. His parents are heterozygous (maternal Factor V concentration 52%, paternal 40%).

Child↗
PubMed1986

The inhibitory effect of some ionophores on human sperm motility.

The inhibitory effect of five ionophores, namely, A23187, nonactin, nigericin, monensin and m-chlorocarbonyl cyanide phenylhydrazone, on human sperm motility were measured with a trans-membrane migration method. The concentrations of A23187 and nigericin that decreased sperm motility to 50% of control were 20 microM (10.5 mg/l) and 8 microM (5.8 mg/l), respectively. Because these two ionophores were more potent than previously reported membrane-active sperm-immobilizing agents, we propose that ionophores could be a new category of vaginal contraceptive if a pharmaceutical preparation that is safe to be administered in vivo can be developed.

Anti-Bacterial Agents↗
PubMed1986

Effect of phosphatidylcholine, lysophosphatidylcholine, arachidonic acid and docosahexaenoic acid on the motility of human sperm.

Lysophosphatidylcholine, arachidonic acid and docosahexaenoic acid were found to have a concentration-dependent inhibitory effect on the motility of human sperm, whilst phosphatidylcholine had no effect. Seminal plasma attenuated the sperm-immobilizing potencies of these lipids. Because all of the three inhibitors of motility are hydrolytic products of phosphatidylcholine, and the catalytic enzyme, phospholipase A2, is known to be calcium dependent, it is suggested that calcium might inhibit sperm motility by activating phospholipase A2 which in turn releases lysophosphatidylcholine and free fatty acids.

Arachidonic Acids↗
PubMed1986

Calcium buffering capacity of human seminal plasma: the role of EGTA in stimulating sperm motility.

The role of EGTA in stimulating human sperm motility (reported in Lancet i: 460-461, 1984) was investigated by measuring the calcium buffering capacity of human seminal plasma. Human seminal plasma contains 9.5 +/- 1.1 mM (mean +/- SE) calcium of which 0.16 +/- 0.01 mM only exists as free Ca2+. The free Ca2+ concentration was not changed by the addition of either 1 mM CaCl2 or 1 mM EGTA. The ability of seminal plasma to bind calcium ions was determined by adding varying amounts of CaCl2. Scatchard analysis of the results indicates the presence of high amounts of high-affinity (Kd1 = 3.4 +/- 0.2 microM, Bm1 = 11.5 +/- 1.5 mM) and low-affinity (Kd2 = 0.55 +/- 0.04 mM, Bm2 = 30.4 +/- 1.7 mM) Ca2+-complexing agents. The low-affinity Ca2+-binding substance may be citrate. These results seem to suggest that human seminal plasma has a high Ca2+ buffering capacity and the stimulation of sperm motility by EGTA ought to be mediated via a mechanism other than the reduction of the free calcium concentration in semen.

Calcium↗
PubMed1985

Inhibition of the mitochondrial Mg2+-ATPase by propranolol.

The in vitro effects of propranolol, a commonly used beta-adrenergic blocker, on the membrane structure and function of rat heart mitochondria were investigated. It was found that the respiratory control and oxidative phosphorylation of the isolated mitochondria decreased concomitantly when the drug was added to the assay medium. At the concentration higher than 1.0 X 10(-4) M, propranolol significantly inhibited the State 3 respiration but had little effect on the State 4 respiration of the mitochondria. On the other hand, the drug exhibited noncompetitive inhibitions toward the Mg2+-ATPase activity of submitochondrial particles and purified enzyme preparations at the concentrations ranging from 3.0 X 10(-4) to 1.5 X 10(-3) M. The inhibitory constants of propranolol toward the enzyme activity in submitochondrial particles and in the purified preparation were estimated to be 6.7 X 10(-4) and 1.4 X 10(-3) M, respectively. However, the drug did not show significant effect on the activity of any of the enzyme complexes of the mitochondrial respiratory chain. It is thus concluded that propranolol impairs the mitochondrial respiration and oxidative phosphorylation mainly through its inhibition of the Mg2+-ATPase activity of the mitochondria. This effect of propranolol may explain, at least partly, its depression effects on the cardiac functions of the animal.

Adenosine Diphosphate↗