Biomedical subjects

J K Chang

Publications and source records attributed to J K Chang.

At least 73 records · Page 4Linked to original sources

PubMed1995

Substance P binding in normal neonatal foreskin.

The distribution of binding sites for NTE-biotinyl-[Arg3]-substance P (SPB) was demonstrated in neonatal foreskin using a conjugate of streptavidin with horseradish peroxidase. The observed binding is reversible, and may be abrogated by either the non-peptide substance P receptor antagonist, CP-96,345, or by unlabelled substance P. The generalized epidermal distribution and focal dermal localization of SPB binding suggest that although NK-1 receptors are abundant in human neonatal foreskin, neuromodulatory mechanisms may play a significant role in epidermal physiology.

Binding Sites↗

PubMed1995

Comparative affinities of human adrenomedullin for 125I-labelled human alpha calcitonin gene related peptide ([125I]hCGRP alpha) and 125I-labelled Bolton-Hunter rat amylin ([125I]BHrAMY) specific binding sites in the rat brain.

Adrenomedullin (ADM) is a recently identified peptide that shows some homology (approximately 25%) with calcitonin gene related peptide (CGRP) and is now considered to be a new member of this peptide family. Because it shares biological effects with CGRP, we evaluated the possible affinity of human adrenomedullin (hADM) for 125I-labelled human CGRP alpha ([125I]hCGRP alpha) binding sites in the rat brain. Moreover, we evaluated the potential existence of cross-reactivity for 125I-labelled Bolton-Hunter rat amylin ([125I]BHrAMY), another member of this peptide family. In all brain areas investigated, hADM only competed with relatively low affinities for both [125I]hCGRP alpha and [125I]BHrAMY binding sites, with IC50 values generally in the high nanomolar-low micromolar range, the lowest affinity being observed for [125I]BHrAMY binding sites. Interestingly, the lowest affinities of hADM against both radioligands were detected in the nucleus accumbens and ventral striatum. These areas are known to be enriched with atypical CGRP - salmon calcitonin - amylin sensitive sites. It thus appears that hADM is unlikely to bind to this atypical site. Moreover, hADM demonstrated limited affinity for either [125I]hCGRP alpha or [125I]BHrAMY binding sites in the rat brain. This suggests that the potential biological effects of ADM in the brain could be mediated through a different class of receptors with higher affinity for this newly isolated peptide.

Adrenomedullin↗

PubMed1995

Pulmonary vasodilation to adrenomedullin: a novel peptide in humans.

The present study investigates the effects of human adrenomedullin (ADM) on the pulmonary vascular bed of isolated, blood-perfused rat lung. Because pulmonary blood flow and left atrial pressure were constant, changes in pulmonary arterial pressure directly reflect changes in pulmonary vascular resistance. Under conditions of resting (low) pulmonary vasomotor tone, intra-arterial bolus injections of ADM-(1-52) and two truncated sequences of ADM-(1-52) [ADM-(1-12) and ADM-(13-52)] did not alter pulmonary arterial pressure. When pulmonary vasomotor tone was increased by U-46619, a thromboxane A2 mimic, intra-arterial bolus injections of ADM-(1-52) and ADM-(13-52) at similar doses produced similar, dose-dependent reductions in pulmonary arterial pressure. On a molar basis, ADM-(1-52) had greater pulmonary vasodilator activity than isoproterenol. In contrast, ADM-(1-12) had no activity. When pulmonary vasomotor tone was actively increased to the same level using KCl, the pulmonary vasodilator activity of ADM-(13-52) was decreased 10-fold. The present data demonstrate that ADM-(1-52) dilates the pulmonary vascular bed and suggest that the pulmonary vasodilator activity of ADM is greater on pulmonary blood vessels preconstricted through a receptor-dependent mechanism. Because meclofenamate, nitro-L-arginine methyl ester, methysergide, BW A-1433U83, U-37883A, and calcitonin gene-related peptide [CGRP-(8-37)], a CGRP-receptor antagonist, did not alter the pulmonary vasodilator response to ADM-(1-52), the present data suggest that ADM dilates the pulmonary vascular bed independently of cyclooxygenase products, endothelium-derived relaxation factor, serotoninergic receptors, adenosine1 purinoreceptors, ATP-dependent potassium channels, and CGRP receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1995

Axenization of Entamoeba histolytica, a Korean strain YS-27.

In the present communication, YS-27, a Korean strain of Entamoeba histolytica is described for the isolation and establishment of axenic cultivation. E. histolytica, designated as strain "YS-27", was isolated from the pus of a hepatic abscess obtained from a 72 year old inpatient of August 10, 1969. Specimens, were obtained by needle aspiration, inoculated immediately and weekly cultured in a modified diphasic medium at 37 degrees C. Strain YS-27 had been maintained for more than 15 years by weekly subculture until February, 1985. These cultures were transferred to a monoxenic TTY-SB medium seeded with a trypanosomatid of the genus Crithidia. Penicillin G, 2 to 10 x 10(3) International units and Streptomycin, 2 to 10 mg per 100 ml, were added to the cultures to eliminate the bacteria. After more than one year later, these two organisms were well maintained by transfer every 3 or 4 days until January, 1986 at 37 degrees C in TTY-SB medium in the absence of other microorganisms. These monoxenic cultures were then transferred to TYI-S-33 medium. Strain YS-27 alone had not been growing at the time of transfer, but when overlaid with Crithidia at intervals of 3 to 4 days, strain YS-27 propagated well. The Crithidia died out several weeks later after several passages. Beginning in April, 1986, strain YS-27, was successfully established in axenic culture in TYI-S-33 medium and has been maintained in continuous culture and multiplied well to present.

Aged↗

PubMed1995

Duplication of the extracranial internal carotid artery.

We describe a case of duplication of the left internal carotid artery from a point 1 cm distal to the origin to the proximal petrous segment where the vessel reunites. Duplication and fenestration of the internal carotid artery are discussed. A review of embryologic development is presented. Identification of these entities is important, especially in patients who require surgical intervention involving the internal carotid artery.

Angiography, Digital Subtraction↗

PubMed1995

Antiinflammatory drug effects on bone repair and remodeling in rabbits.

Ketorolac and methylprednisolone effects on bone repair were studied. Demineralized bone matrix was used to graft the defects of rabbits' ulnae. Twenty-seven rabbits were divided into 4 groups: Group A (control group; no drug treatment), Group B (treated with ketorolac 2 mg/kg body weight daily), Group C (treated with ketorolac 4 mg/kg body weight daily), and Group D (treated with methylprednisolone 1 mg/kg body weight weekly). Drug treatment was continued for 6 weeks. The biomechanical results indicated methylprednisolone significantly deteriorated the mechanical properties of the grafted ulnae and the contralateral intact ulnae, although the effects were more pronounced in the grafted side. In Group B, there was minimum effect of ketorolac on the bone properties. In Group C, ketorolac significantly decreased the torsional stiffness and energy absorption of the grafted ulnae and also decreased the maximum torque in the intact and the grafted bones. It was concluded that the inhibitory effect of ketorolac on bone repair was dose dependent. In comparing the effects of ketorolac and methylprednisolone, the latter is more pronounced on torsional stiffness, but the effects on maximum torque and energy absorption were similar to ketorolac. The mechanism of the effects of ketorolac needs additional investigation.

Animals↗

PubMed1995

Arthroscopic debridement for osteoarthritis of the knee: a seven years follow-up study.

We reviewed 32 knees with osteoarthritis of the knee treated by either arthroscopic debridement in association with drilling the subchondral bone or arthroscopic debridement alone and followed for 2.5 to 11 years. Eighteen knees had arthroscopic debridement and drilling the subchondral bone, and 14 knees had arthroscopic debridement alone. In the group treated with arthroscopic debridement and drilling the subchondral bone, 55.6% had good to excellent results, 22.2% had fair results, and 22.2% had poor results. In the group that had arthroscopic debridement alone, 57.2% had good to excellent results, 35.7% had fair results, and 7.1% had poor results. There was better relief of pain in the group with arthroscopic debridement alone.

Adult↗

PubMed1994

An adrenomedullin fragment retains the systemic vasodepressor activity of rat adrenomedullin.

The present study was undertaken to investigate the effects of human adrenomedullin, a newly discovered peptide present in normal human plasma, as well as a fragment of adrenomedullin, on systemic hemodynamics in the anesthetized rat. Intravenous (i.v.) bolus injections of rat adrenomedullin, rat adrenomedullin-(11-50), human adrenomedullin-(13-52) decreased mean systemic arterial pressure in a dose-dependent manner. Since rat adrenomedullin and human adrenomedullin did not decrease cardiac output, the decreases in systemic arterial pressure reflect dose-dependent reductions in systemic vascular resistance. The systemic vasodepressor responses to similar doses of the adrenomedullin fragments studied and to their respective parent adrenomedullin peptides were similar. The present data demonstrate that the entire adrenomedullin molecule is not required for full systemic vasodilator activity in vivo suggesting that rat adrenomedullin-(11-50) or a structurally similar peptide, if formed endogenously, could mediate the hemodynamic properties of adrenomedullin in vivo. Since rat adrenomedullin had significantly greater systemic vasodilator activity than human adrenomedullin at similar doses in the rat, the present data suggest that adrenomedullin has greater systemic vasodilator activity in its native species and that limited changes in the peptide's sequence confer markedly different vascular activity in vivo.

Adrenomedullin↗

PubMed1994

An adrenomedullin (ADM) fragment retains the systemic vasodilator activity of human ADM.

The present study was undertaken to investigate the effects of human ADM, a newly discovered peptide present in normal human plasma, as well as a fragment of human ADM, human ADM13-52, on systemic hemodynamics in the anesthetized cat. Intravenous (i.v.) bolus injections of human ADM and human ADM13-52 decreased systemic arterial pressure (SAP) in a dose-dependent manner. Since neither peptide altered cardiac output, the decreases in SAP reflect reductions in systemic vascular resistance. The systemic vasodilator responses to the same doses of human ADM and human ADM13-52 in the cat were similar. The present study demonstrates the systemic vasodilator activity of ADM is conserved across species. The present data suggest that human ADM13-52 or a peptide structurally similar to it may mediate the hemodynamic properties of ADM in vivo in man. Since cardiac output and heart rate were not altered during the marked systemic vasodepressor response to ADM, activation of the ADM vasodilator mechanism may represent a therapeutic alternative in the clinical management of hypertensive diseases.

Adrenomedullin↗

PubMed1994

Prodepin: a new product of the adrenomedullin (ADM) gene has systemic vasodilator activity.

The purpose of the present study was to investigate the effects of products of the ADM gene other than ADM on systemic hemodynamics in the anesthetized rat, rabbit, piglet, cat and dog. Bolus intravenous (i.v.) injections of rat proADM22-41 (3-30 micrograms) significantly decreased systemic arterial pressure (SAP) and systemic vascular resistance in the anesthetized rat. Unlike ADM, rat proADM22-41 markedly increased cardiac output in the rat. Bolus i.v. injections of human proADM22-41 up to 500 micrograms had not effect in all species studied and rat proADM22-41 had no effect in species other than the rat. The present data suggest that rat proADM22-41 is a novel product of the ADM gene other than ADM and possesses marked systemic vasodilator activity. The present data also suggest that the hemodynamic activity of this peptide is species specific.

Adrenomedullin↗

PubMed1994

Adrenomedullin dilates the pulmonary vascular bed in vivo.

The present study was undertaken to investigate the effects of adrenomedullin (ADM), a newly discovered peptide in normal human plasma, in the pulmonary and systemic vascular bed of the intact cat. Because pulmonary blood flow and left atrial pressure were held constant, changes in lobar arterial pressure directly reflected changes in pulmonary vascular resistance. Under conditions of resting (low) pulmonary vasomotor tone, intralobar arterial bolus injections of ADM-(1-52) and two truncated ADM sequences, ADM-(13-52) and ADM-(1-12), had little effect on baseline lobar arterial pressure. In contrast, when pulmonary vasomotor tone was actively increased by intralobar arterial infusion of U-46619, intralobar arterial bolus injections of ADM-(1-52) (10-3,000 ng) and ADM-(13-52) (10-3,000 ng) decreased lobar arterial pressure in a dose-dependent manner, whereas only the highest doses of ADM-(1-52) and ADM-(13-52) (1,000-3,000 ng) mildly decreased systemic arterial pressure. Under the same experimental conditions, injections of ADM-(1-12) had no effect on lobar arterial and systemic arterial pressures. The present data suggest that ADM-(13-52) or a similar ADM fragment is responsible for the marked pulmonary vasodilator activity of ADM-(1-52) in vivo.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1994

Lower tibial osteotomy for osteoarthritis of the ankle.

Ankle arthrodesis is still the treatment of choice for most disabling arthritic ankles. But in spite of its popularity, ankle arthrodesis has many disadvantages, including long immobilization, a high pseudoarthrosis rate, and load shift with increased stress on neighboring joints of ankle. Lower tibial osteotomy is one of the methods which attempts to halt ankle arthritis in the intermediate stage and trying to prevent ankle arthroadesis. From Aug. 1989, we performed 8 operations of lower tibial osteotomy in our hospital on intermediate arthritic ankle which included 4 post-traumatic ankle arthritis and 4 ankle osteoarthritis. The patient's ages ranged from 21y/o to 72y/o with an average of 41.6y/o. The mean time of followed up was 31.7 months. The patients were evaluated by the ankle functional scale preoperatively and during their followed up. The average preoperative functional score was 49.6 and the last follow up score was 88.5 which is increasing year by year. Significant improvement occurred in function and pain relief and there was improvement of ankle motion in most patients except one. Complications included late infection in 1 patient and implant failure with subsequent revision surgery due to overcorrection in 1 patient. No nonunion was noted. Although our series was small, we had encouraging short-term results. We believe lower tibial osteotomy, by pressure redistribution on the joint surface, is an alternative for the treatment of ankle osteoarthritis and may save or delay arthritic ankle from the fate of fusion.

Adult↗

PubMed1994

Surgical reconstruction for chronic lateral instability of the ankle.

Chronic lateral instability of the ankle is not uncommon due to improper management of the acute ankle sprain. From July 1987 to December 1991, 45 cases of chronic lateral ankle instability that underwent surgical treatment were followed. The patients included 28 males and 17 females with an average of 24.6 y/o. The time interval from initial injury to surgery ranged from 3 months to 5 years with an average of 9.6 months. All the patients had persistent symptoms in spite of conservative treatment for at least 2 months. The method for reconstruction of the lateral stability of the ankle was the modified Evans' method using part of peroneal brevis tendon. These cases were followed-up for average 25.1 months (range from 13 Ms to 49 Ms). According to Good, Jones & Livingston's criteria for clinical evaluation, 95.6% of the patients obtained excellent or good results. But 11.1% of patients were subjectively unsatisfied and complained of over tightness and limitation of foot inversion. The modified Evans' method has been proven to be easy and effective for reconstruction of the laterally unstable ankle, but it should be performed in the neutral flexion of ankle to prevent an over tight correction of lateral stability.

Adolescent↗

PubMed1993

The effect of adrenomedullin on the isolated heart.

A novel peptide found in human blood, adrenomedullin (ADM), has been shown to have systemic vasodepressor activity in the rat. However, the direct effects of ADM on cardiac function are unknown. Results of the present study demonstrate that ADM13-52 possesses marked systemic vasodepressor activity in the anesthetized rat. Although ADM13-52 modestly decreased peak systolic pressure (PSP) indicating mild negative inotropic activity, the present data suggest that bolus administration of ADM decreases systemic arterial pressure by dilating the systemic vasculature. The present data also suggest that only a portion of the ADM molecule is necessary to produce systemic vasodilation.

Adrenomedullin↗

PubMed1993

Restricted ability of group B streptococcal C5a-ase to inactivate C5a prepared from different animal species.

Most strains of group B streptococci (GBS) elaborate a cell surface-associated enzyme that rapidly inactivates the human complement-derived chemoattractants C5a and C5adesarg by cleaving the His-Lys bond at positions 67 and 68 in the C5a molecule. We have suggested that rapid inactivation of C5a and C5adesarg by this enzyme, called C5a-ase, can hinder the inflammatory response at sites of GBS infection. We tested the ability of GBS C5a-ase to inactivate C5a preparations from various animal species to determine the proper species for studying the role of GBS C5a-ase in the pathogenesis of GBS infections. Exposure of C5a preparations from humans, monkeys, and cows to GBS caused inhibition of C5a functional activity as measured by the ability of C5a to stimulate human polymorphonuclear leukocyte (PMN) adherence and human PMN chemotaxis. Bovine PMN chemotaxis to bovine C5a was also abolished after exposure of bovine C5a to GBS. In contrast, mouse, rat, guinea pig, rabbit, pig, and sheep C5a preparations retained full functional activity after exposure to GBS as measured by chemotaxis of human PMNs, PMNs from the same animal species, or both. These data suggest that there are structural differences between C5a proteins from different species which alter their susceptibility to GBS C5a-ase and indicate that most commonly used animal models of human GBS infection are inadequate for detection of a contribution of GBS C5a-ase to GBS virulence.

Amino Acid Sequence↗

PubMed1993

Serodiagnosis of cysticercosis by ELISA-inhibition test using monoclonal antibodies.

Monoclonal antibodies (Mabs) were produced against crude scolex extract of T. solium metacestodes, and applied to ELISA-inhibition test for improving the specificity of serodiagnosis of human cysticercosis. Four hybridomas secreting species-specific anticysticercal Mabs (Cya-1, Cya-7, Cya-28 and Cya-31) were selected. Each Mab reacted on antigenic components of 25.5 kDa (Cya-1), 28 kDa (Cya-7), 87.5 kDa (Cya-28), and 12.5 kDa (Cya-31). IFA showed that Cya-1 was located at the calcium corpuscles, and Cya-7 at the loose connective tissue of T. solium metacestode scolex. Cya-28 and Cya-31 reacted on the tegument of the scolex. By conventional ELISA, 23 out of 28 (82.1%) cysticercosis patients were found serologically positive, but 1 out of 9 (11.1%) sparganosis cases and 6 out of 31 (19.4%) paragonimiasis cases showed false positives. By ELISA-inhibition test using species-specific anti-cysticercal Mab Cya-7, 19 out of 28 (67.9%) cysticercosis cases were found serologically positive, but there were no false positives in other parasitic infections.

Animals↗

PubMed1992

Effect of endothelium-derived relaxing factor inhibition on the umbilical-placental circulation in fetal lambs in utero.

OBJECTIVE: The purpose of this study was to examine whether basal endothelium-derived relaxing factor release contributes to regulation of resting umbilical-placental vascular resistance. STUDY DESIGN: Because N omega-nitro-L-arginine selectively inhibits the synthesis of nitric oxide, a major endothelium-derived relaxing factor, we investigated the effects of N omega-nitro-L-arginine on umbilical-placental vascular resistance in 10 fetal lambs in utero. We inserted catheters and fitted an umbilical artery electromagnetic flow transducer around the common umbilical artery to measure umbilical blood flow and catheterized the left umbilical arterial hypogastric branch to allow selective umbilical-placental infusion (60 minutes) of pH-matched saline solution (control) or N omega-nitro-L-arginine. RESULTS: In seven normal fetal lambs, N omega-nitro-L-arginine increased umbilical-placental vascular resistance and arterial pressures and decreased umbilical blood flow (p less than 0.05); percentage changes from baseline were 50.8% +/- 18.3%, 40.3% +/- 8.1%, and -9.9% +/- 6.4%, respectively. In three mildly asphyxiated (compromised) fetuses, these changes were 101.4% +/- 28.7%, 31.2% +/- 4.8%, and -37.9% +/- 12.0%. CONCLUSION: These data support the hypothesis that the basal endothelium-derived relaxing factor release plays a role in regulating resting umbilical-placental vascular resistance.

Animals↗

PubMed1992

K+ channel pulmonary vasodilation in fetal lambs: role of endothelium-derived nitric oxide.

To define the role and mechanism of action of K+ channels in regulating fetal pulmonary vascular tone, we studied the hemodynamic effects of pinacidil (a K+ channel activator) and glibenclamide (a K+ channel blocker). The effects of pinacidil were compared with those of acetylcholine [an endothelium-derived relaxing factor- (EDRF) dependent pulmonary vasodilator] and 8-bromoguanosine 3',5'-cyclic monophosphate (8-bromo-cGMP, an EDRF-independent pulmonary vasodilator) before and after treatment with N omega-nitro-L-arginine [a competitive inhibitor of an EDRF, endothelium-derived nitric oxide (EDNO), synthesis], or L-arginine (the substrate for the formation of EDNO). In 14 unanesthetized fetal lambs in utero, catheters were inserted into the fetal pulmonary artery, descending aorta, left atrium, and superior vena cava to measure pressures and administer drugs. An ultrasonic flow transducer was placed around the left pulmonary artery to measure flow (QP) continuously. In eight animals, pinacidil, acetylcholine, and 8-bromo-cGMP caused similar acute maximal increases in QP of 128, 137, and 155 ml/min, respectively. After a 60-min infusion of N omega-nitro-L-arginine (2.07 +/- 0.27 mg.kg-1.min-1), the increase in QP caused by acetylcholine and pinacidil was significantly attenuated, by 84 and 68%, respectively, with only a 10% attenuation of the increase in QP caused by 8-bromo-cGMP. In six additional N omega-nitro-L-arginine-pretreated fetal lambs, infusion of L-arginine (32.2 +/- 4.3 mg.kg-1.min-1) restored the vasodilatory effects of acetylcholine and pinacidil. A 20-min infusion of glibenclamide (n = 6; 0.64 +/- 0.07 mg.kg-1.min-1) blocked the vasodilation by pinacidil but not acetylcholine.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗