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J K Chang

Publications and source records attributed to J K Chang.

At least 55 records · Page 3Linked to original sources
PubMed1998

Analysis of responses to adrenomedullin-(13-52) in the pulmonary vascular bed of rats.

The effects of human adrenomedullin-(13-52) [hADM-(13-52)] were investigated in the rat pulmonary vascular bed and in isolated rings from the rat pulmonary artery (PA). Under conditions of controlled blood flow and constant left atrial pressure when tone was increased with U-46619, injection of hADM-(13-52) produced dose-related decreases in lobar arterial pressure. Pulmonary vasodilator responses in the intact rat and vasorelaxant responses to hADM-(13-52) in rat PA rings were inhibited by NG-nitro-L-arginine methyl ester (L-NAME) and L-N5-(1-iminoethyl)-ornithine hydrochloride (L-NIO). Vasorelaxant responses to hADM-(13-52) were also inhibited by methylene blue, endothelium removal, hADM-(26-52), and iberiotoxin, whereas meclofenamate, calcitonin gene-related peptide-(8-37) [CGRP-(8-37)], glibenclamide, and apamin were without effect. Because vasorelaxant responses to NS-1619, a large-conductance Ca(2+)-activated K+ channel agonist, were not altered by L-NAME and vasorelaxant responses to acetylcholine and CGRP were not altered by hADM-(26-52), the present data suggest that ADM-(13-52) acts on a receptor in the pulmonary vascular bed that is coupled to endothelial nitric oxide release. These data suggest that this nitric oxide release may lead to guanosine 3',5'-cyclic monophosphate-dependent K+ channel activation, which produces a pulmonary vasorelaxant response through hyperpolarization of vascular smooth muscle cells. The present data suggest that ADM-(13-52) modulates receptor-mediated, but not voltage-dependent, pulmonary vascular contraction by influencing Ca2+ influx. These results suggest that the ADM fragment, hADM-(13-52), acts as an endothelium-dependent vasodilator agent in the pulmonary vascular bed of the rat.

Adrenomedullin↗
PubMed1998

Effects of ketorolac on bone repair: A radiographic study in modeled demineralized bone matrix grafted rabbits.

The effects of ketorolac on bone repair were studied radiographically. The effects of methylprednisolone were also compared. Demineralized bone matrix was grafted into the fractured gap of rabbit's ulna as an experimental bone repair model. The rabbits received ketorolac 2 or 4 mg/kg body weight daily for 6 weeks after transplantation. Serial radiographic studies were performed 2, 4, and 6 weeks after transplantation. Mineralization of grafts and bone union were evaluated as the parameters of bone repair. Comparing the bone repair among groups at individual time points, ketorolac-treated groups showed no statistical differences as compared with the control group in either mineralization or bone union, whereas methylprednisolone significantly suppressed both parameters. However, comparing the mineralization during the healing process in each group, the control group and the group treated with ketorolac 2 mg/kg showed a significant increase during the period from the 2nd to the 4th week of medication, whereas both the group treated with ketorolac 4 mg/kg and the methylprednisolone-treated group showed no significant increase during this period. This poor mineralization of grafted bone in repair process affected by ketorolac suggests that 4 mg/kg of ketorolac might delay the endochondral ossification process during the period from the 2nd to the 4th week of fracture healing.

Animals↗
PubMed1998

Gender-biased activity of the novel prolactin releasing peptides: comparison with thyrotropin releasing hormone reveals only pharmacologic effects.

The prolactin- (PRL) releasing activities of the newly described PRL-releasing peptides (PrRPs) were compared to that of thyrotropin-releasing hormone (TRH) in dispersed, rat anterior pituitary cell cultures. A dose-related stimulation of PRL release by TRH was observed in cells harvested from both intact male and random cycle female pituitary donors. The minimum effective dose of TRH ranged from 1 to 10 nM. Neither PrRP-20 nor PrRP-31 significantly altered PRL secretion in cells from male donors even at doses as high as 1 microM. In cells harvested from females, only the highest doses of PrRP-20 and PrRP-31 tested (0.1 and 1.0 microM) significantly stimulated PRL secretion. The PRL-releasing action of TRH was observed already at 15 min of incubation, whereas those of PrRP-20 and PrRP-31 appeared only after 1 and 2 h of incubation, and the magnitude of PRL release in the presence of 1 microM PrRPs was significantly less than that of a similar dose of TRH. These data do not suggest a physiologically relevant role for the PrRPs in the neuroendocrine regulation of PRL secretion in intact male and nonlactating, random-cycle female rats.

Animals↗
PubMed1998

Giant cervical epidural veins after craniectomy for head trauma.

Markedly dilated cervical epidural veins and right upper extremity weakness developed in a 43-year-old man 4 months after contralateral craniectomy for head trauma. After cranioplasty, his symptoms improved markedly and the size of the veins returned to normal. These findings suggest that enlarged cervical epidural veins may occur without an underlying vascular lesion and that upper extremity weakness may occasionally be attributable to spinal cord venous stasis.

Adult↗
PubMed1998

Technetium-99m(V)-DMSA and gallium-67 in the assessment of bone and joint infection.

UNLABELLED: The aim of our study was to investigate the diagnostic value of scans with 99mTc(V)-dimercaptosuccinic acid (DMSA) to localize bone and joint infection compared with scans using 67Ga. METHODS: Thirty-six patients referred for investigation of bone and joint infection were studied. In all patients, a bone scan was obtained initially. Subsequently, comparative scans with 99mTc(V)-DMSA and 67Ga were performed 1 wk apart. Microbiological findings, pathologic findings and/or clinical follow-up (until symptoms disappeared) were considered to be proof of the presence of bone and joint infection. RESULTS: Technetium-99m (V)-DMSA showed greater sensitivity and accuracy than 67Ga in the assessment of bone and joint infection, although the difference was not statistically significant. CONCLUSION: In comparison with a 67Ga scan, a 99mTc(V)-DMSA scan, in combination with a bone scan, is a reliable way to diagnose bone and joint infection. Both tracers were useful in the diagnosis of bone and joint infection.

Adult↗
PubMed1997

Cells lacking CIP1/WAF1 genes exhibit preferential sensitivity to cisplatin and nitrogen mustard.

We have previously shown that p53 disruption sensitizes certain cancer cell types to cisplatin (CDDP) (Fan et al., 1995). In the present study we investigated the role of the p53 downstream effector, p21CIP1/WAF1 (p21), in this sensitization. Studies were performed in human colon cancer HCT-116 cells and murine embryonic fibroblasts (MEF) with intact versus disrupted p21 genes. For comparison, HCT-116 cells lacking p53 function were also prepared through stable transfection with the human papillomavirus type-16 E6 gene. HCT-116/E6 cells were found to be more sensitive than control transfectants to CDDP and another DNA crosslinking agent, nitrogen mustard (HN2). HCT-116 cells with disrupted p21 genes also exhibited greater CDDP and HN2-sensitivity than parental HCT-116 cells. In contrast, the clonogenic survival of HCT-116 cells exposed to ionizing radiation, adriamycin, taxol or vincristine was not affected by p53 or p21 disruption. Sensitization of HCT-116/p21-/- cells to CDDP and HN2 was not limited to the HCT-116 cell background since MEF from p21 knockout mice were also more sensitive to these DNA crosslinking agents. Investigations into a possible cause of this enhanced sensitivity revealed that HCT-116 cells lacking p53 or p21 function exhibited a reduced ability to repair cisplatin-damaged CAT-reporter plasmids transfected into the cells. In addition, we found that HCT-116/p21-/- cells were much more susceptible to HN2-induced cell cycle delay than parental cells. Our results suggest that p21 disruption preferentially sensitizes at least some cell types to DNA crosslinking agents.

Animals↗
PubMed1997

Diuretic and antinatriuretic responses produced by the endogenous opioid-like peptide, nociceptin (orphanin FQ).

Nociceptin (orphanin FQ) is a novel peptide isolated from brain tissue that has an amino acid sequence most similar to that of the endogenous opioid peptide dynorphin A. Aside from this similarity, the association of nociceptin to the endogenous opioid peptide systems and the functional importance of this new peptide in vivo are not completely known. Here we report that nociceptin is physiologically active in vivo and produces marked changes in the renal excretion of water and sodium. In conscious Sprague-Dawley rats, intravenous infusion of nociceptin produced a profound increase in urine flow rate and decrease in urinary sodium excretion. In further studies, intracerebroventricular (i.c.v.) injection of nociceptin into conscious rats produced a concurrent diuresis (dose-dependent) and antinatriuresis. The magnitude and pattern of the central nociceptin-induced water diuresis was similar to that produced by i.c.v. dynorphin A. Whereas i.c.v. pretreatment with the selective kappa-opioid receptor antagonist, nor-binaltorphimine, completely prevented the renal responses produced by dynorphin A, this antagonist did not alter the diuresis or antinatriuresis produced by central nociceptin. Thus, these results indicate that in conscious rats, nociceptin produces a selective water diuresis via a central nervous system mechanism independent of kappa-opioid receptors. Together, these observations suggest that endogenous nociceptin may be a novel peptide involved in the central control of water balance and ultimately in the regulation of arterial blood pressure. In the future, analogues of nociceptin may prove to be the first clinically useful water diuretics for patients with water-retaining diseases.

Animals↗
PubMed1997

Nociceptin: an endogenous agonist for central opioid like1 (ORL1) receptors possesses systemic vasorelaxant properties.

The purpose of the present study was to investigate the effects of nociceptin on peripheral arterial rings from the cat. When feline renal, mesenteric, carotid and femoral rings with intact endothelium were precontracted with phenylephrine (100 nanomolar), nociceptin (3 x 10(-11)-3 x 10(-6) M) decreased tension in a concentration-dependent manner. The present data suggest nociceptin possesses biologic activity outside the CNS and may contribute to the regulation of systemic blood pressure and regional blood flow.

Animals↗
PubMed1997

Moving actuator type total artificial heart with reverse position of the aortic and pulmonary conduits.

Adequate intrathoracic anatomical compatibility is one of the most important considerations in designing a fully implantable total artificial heart (TAH). We have recently developed an innovative concept of reverse positioning of the aortic and pulmonary conduits to facilitate anatomical compatibility of the moving actuator type TAH. The pulmonary conduit of this TAH is designed to be located posterior to the aortic conduit, which results in a substantial reduction in the anteroposterior diameter of this heart, as well as the virtual elimination of the compression of the low pressure pulmonary conduit. In ovine orthotopic implantation experiments with this model of the TAH, we consecutively achieved 3 day survival in 1 sheep and 2 day survival in another. To the best of our knowledge, these were the first significant short-term survival cases in the orthotopic implantation of electric TAHs in sheep.

Animals↗
PubMed1997

The long-term effects of pregnancy and bromocriptine treatment on prolactinomas--the value of radiologic studies.

OBJECTIVE: To evaluate the long-term effects of pregnancy and bromocriptine treatment on prolactin-secreting pituitary tumors in women undergoing infertility treatment for prolactinomas. METHODS: The records of 17 patients with prolactinomas were reviewed. Data regarding age, prepregnancy baseline and postpartum serum prolactin levels, and radiologic studies including CT or MRI were assessed. 16 patients were treated with bromocriptine before achieving pregnancy. Bromocriptine therapy was resumed after delivery for the duration of 1 to 14 years. RESULTS: 45% of pregnancies did not affect the size of prolactinomas, 27% of pregnancies showed a decrease in size of prolactinomas or radiologic evidence of resolution of the tumor and 27% of pregnancies demonstrated radiologic increase in the size of prolactinomas. CONCLUSIONS: It is safe for patients with prolactinomas to achieve pregnancy following bromocriptine treatment. Pregnancy may lead to a slight decrease in the size of prolactinomas, increase in size, no change, and in some cases, complete resolution. There were no visual field changes during the pregnancies. Pregnancy and long-term bromocriptine treatment may be helpful in reduction of the size of the tumor.

Adult↗
PubMed1996

Adrenotensin: an adrenomedullin gene product contracts pulmonary blood vessels.

The purpose of the present study was to determine the effects of adrenotensin, a newly described product of the ADM gene, on cat pulmonary arterial (PA) rings. Under resting conditions, adrenotensin increased tension of PA rings in a concentration-dependent manner. Although addition of diphenhydramine, ONO-3708, phentolamine, methysergide, atropine, and meclofenamate did not alter the contractile response to adrenotensin, removal of the endothelial cell layer significantly reduced this response. Moreover, precontraction of PA rings with adrenotensin selectively attenuated the pulmonary vasorelaxant response to ADM but not to other vasodilator substances, including isoproterenol, pinacidil, nifedipine, and adenosine. The present data suggest that adrenotensin acts in an endothelium-dependent manner to contract PA rings. Moreover, the present data suggest that adrenotensin may act in a modulatory manner to influence vasorelaxation in response to ADM, a sister proADM product.

Adrenomedullin↗
PubMed1996

Accidental penetrating cervical cord injury in a young child.

A three-year-old child presented to our emergency department with a hemiparesis five days following the accidental laceration of her neck with a piece of glass. The laceration had been thought to be superficial when she was initially evaluated. When seen again three days following the injury because of right-sided weakness, computerized tomography of her head and neck was unrevealing. However, using high resolution magnetic resonance imaging (MRI) we were able to demonstrate a C1-2 cord contusion and an injury tract leading from the surface of the neck to this site. The unusual mechanism of injury and the underlying pathophysiology of this patient's presentation are reviewed. It is important for the emergency physician to be reminded that what appears to be a superficial laceration can sometimes be more serious. MRI should be considered in the evaluation of patients who have suffered penetrating trauma if the potential for spinal cord injury exists and especially when there are signs or symptoms suggesting spinal cord dysfunction.

Accidents, Home↗
PubMed1996

A 35 amino acid fragment of leptin inhibits feeding in the rat.

Peptide fragments of the larger 167 amino acid obesity gene related peptide (OBGRP), leptin, were tested for their ability to inhibit feeding in the rat. The C-terminal fragment, OBGRP 116-167 exerted only minimal inhibition of feeding when administered into the lateral cerebroventricle. No alteration in feeding was observed following administration of OBGRP 57-92. We hypothesized that the satiety effects of leptin reside in the N-terminal region of the peptide sequence. Significant, dose-related, and reversible inhibition of food intake was observed following central administration of the 35 amino acid fragment OBGRP 22-56. These results suggest that a small, readily synthesized fragment of the 167 amino acid peptide leptin may exert physiologically relevant satiety effects in brain revealing an endocrine feedback mechanism by which the adipocyte may modulate hypothalamic function.

Amino Acid Sequence↗
PubMed1996

Personal and environmental factors in relation to adjustment of offspring of alcoholics.

The purpose of the present study was to develop a causal model that explains how personal and family characteristics influence the well-being of adult children of alcoholics (ACOAs). The causal model was developed based on family systems theory, coping theory, social learning theory, and social support theory. Eight-four ACOAs were tested in order to examine the fit of the model to the data by path analysis with LISREL VII. Results of the study suggested that the revised theoretical model presented good model fit to the data with .97 for goodness of fit index, .91 for adjusted goodness of fit index, .13 for root-mean-square residuals, and 11.94 for modification indices. Results of the study also showed that 1) ACOAs who are better able to perceive the availability of social supports tend to have lower emotional status; 2) ACOAs who are better able to perceive the availability of social supports have a tendency to have better adjustment; and 3) ACOAs who have higher emotional status have a tendency to be better adjusted in life.

Adaptation, Psychological↗
PubMed1996

[Identification and characterization of allergens of Chironomus flaviplumus adults (Chironomidae, Diptera) in mice].

Non-biting midges (Chironomidae, Diptera) are one of the largest insect families, which are distributed worldwidely and are found in nearly all types of inland waters. They are known to be aggressive inhalant allergens which cause allergenic diseases. In this study, the crude antigens of Chironomus flaviplumus adults which are most widely distributed in Korea were extracted, and their allergens were analyzed with the sera from experimentally sensitized mice. The mice were immunized with 1 microg or 10 microg of the crude antigens, respectively, and the specific serum IgE levels were measured by both ELISA and passive cutaneous anaphylaxis (PCA) techniques. The highest levels of both total IgE and chironomid-specific IgE were found in the mouse sera obtained after 9 weeks of the first injection with 1 mu g crude antigen. The crude antigen was separated into 16-18 protein bands on gel by SDS-PAGE. The crude extract was assessed by SDS-PAGE/immunoblot analysis. One IgE-binding band (65 kDa) was detected by developing with colorimetric substrate, and 4 IgE-binding bands (65, 52, 35 IgE-binding and 25 kDa) by developing with CSPD chemiluminescent substrate. The SDS-PAGE gel of the crude extract of chironomid adults was equally cut into 30 pieces and each of them was eluted to isolate proteins by molecular weight, and the allergenicity of each eluate was assessed by applying P-K test on rats. Proteins of 65, 35 and 15 kDa showed the highest P-K titer (x 512) which was 16 times higher than that of the crude extract (x 32). The P-K titer of 52 kDa protein was also 4 times higher (x 128) than that of the crude extract, whereas the 25 kDa protein poorly responded, which seemed not antigenic. In conclusion, the present result in mice demonstrated that adults of Chironomus flaviplumus, a predominent species in Korea, cause allergenic diseases and the main allergens are 65, 52, 35 and 15 kDa proteins, of which 65 kDa protein seems to be a main allergen.

Allergens↗
PubMed1996

Effects of compressive loading on articular cartilage repair of knee joint in rats.

Effects of compressive loading on articular cartilage repair was studied. Thirty adolescent Long-Evans rats were used as experiment animals. A full-thickness defect of cartilage was created by drilling with a k-wire, 1.2 mm in diameter, into the weight bearing area of medial femoral condyle of each of bilateral knee joints. Free movement was permitted postoperatively. One leg of each rat received normal weight bearing on knee joint as experiment leg. The contralateral leg was used as the control. The control legs were paw resected to avoid weight bearing on joint cartilages but this did not interfere with the motion of knee joints. The articular cartilage repair was estimated by macroscopic examination and microscopic examination 6 weeks after surgery. Scoring systems were used to evaluate the quantity of repaired tissue in macroscopic examination and the quality of repaired tissue in microscopic examination. The differences of articular cartilage repair affected by compressive loading was analyzed statistically by paired t-test. We concluded that the effects of compressive loading on cartilage repair was to accelerate the metaplasia of repair tissue into hyaline cartilage but not to increase the quantity of repaired tissue.

Animals↗
PubMed1995

Adrenotensin: an ADM gene product with the opposite effects of ADM.

The purpose of the present study was to investigate the effects of putative products of the ADM gene, other than ADM including, prodepin, proADM45-92 and proADM153-185 on cat pulmonary arterial (PA) rings with or without precontraction with U46619. Addition of proADM153-185 (3 x 10(-10)-10(-6) M) increased tension in a concentration-dependent manner in cat PA rings without precontraction. When vessels were precontracted with U46619, ADM(3 x 10(-10)-10(-6) M) produced a concentration-dependent vasorelaxant response, whereas proADM153-185 produced a weak concentration-dependent contractile response. Prodepin and proADM45-92 up to 10(-6)M had no activity on PA rings. Since proADM153-185, similar to ADM, would be expected to be released in free form following endopeptidase-induced cleavage, the present data suggest proADM undergoes proteolytic processing to release peptides with divergent vascular effects. Thus, the present data also suggest that proADM153-185 may represent a novel product of the ADM gene and term this putative new substance "adrenotensin".

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