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Biomedical subjects

D S Kang

Publications and source records attributed to D S Kang.

At least 19 recordsLinked to original sources
PubMed2001

Optimizing of gadolinium-enhanced MR angiography by manipulation of acquisition and scan delay times.

An optimized protocol for achieving high-quality contrast-enhanced MR angiography (CE MRA) was designed and evaluated. Time-intensity curves of the test bolus and main bolus were compared in 11 volunteers. To identify the acquisition zone sensitive to venous overprojection, sequential filling phantoms which consisted of 12 test tubes were developed and scanned. Using the parameters of the time-intensity curve which were consistent between the test and main boluses and the parameters of the sensitive acquisition zone in the pulse sequences, the protocol for calculation of scan delay time and acquisition time was optimized. The new protocol was verified by comparison of lower extremity CE MRAs acquired by traditional (scan delay time = peak enhancement time minus injection duration/2 + acquisition time/2; n = 12) and new (n = 23) protocols. The arterial and venous enhancing times of the time-intensity curves of the test and main boluses were statistically consistent (p < 0.01). The length of the sensitive acquisition zone was one-half the acquisition duration. With the parameters identified in the time-intensity curve and pulse sequence analyses, a new protocol was developed. For validation, the new protocol was able to study the smaller arteries such as the distal tibial arteries and branches of the femoral and iliac arteries (p < 0.01). Using the optimized protocol, higher-quality images were obtained than those acquired by traditional methods.

Adult↗
PubMed2001

Prevalence of malocclusion among Latino adolescents.

Although numerous studies have documented malocclusion in various ethnic groups in the United States, the prevalence of malocclusion in the Latino population is not well known. The Latino population may be the largest minority group in the United States by the year 2004. This study analyzes the occlusion of 507 Latino adolescents between the ages of 12 and 18 years. More than 93% of the subjects demonstrated some form of malocclusion. The distribution of malocclusion patterns is presented and contrasted with data published for other ethnic groups. Information about the prevalence and types of malocclusion in the Latino population should be of interest to general dental practitioners and specialists.

Adolescent↗
PubMed2000

The human B1 bradykinin receptor exhibits high ligand-independent, constitutive activity. Roles of residues in the fourth intracellular and third transmembrane domains.

The B1 bradykinin (BK) receptor (B1R) is a seven-transmembrane domain, G protein-coupled receptor that is induced by injury and important in inflammation and nociception. Here, we show that the human B1R exhibits a high level of ligand-independent, constitutive activity. Constitutive activity was identified by the increase in basal cellular phosphoinositide hydrolysis as a function of the density of the receptors in transiently transfected HEK293 cells. Several B1R peptide antagonists were neutral antagonists or very weakly efficacious inverse agonists. Constitutive B1R activity was further increased by alanine mutation of Asn(121) in the third transmembrane domain of the receptor (B1A(121)). This mutant resembled the agonist-preferred receptor state since it also exhibited increased agonist affinity and decreased agonist responsiveness. A dramatic loss of constitutive activity occurred when the fourth intracellular C-terminal domain (IC-IV) of the human B2 BK receptor subtype (B2R), which exhibits minimal constitutive activity, was substituted in either B1R or B1A(121) to make B1(B2ICIV) and B1(B2ICIV)A(121), respectively. Activity was partially recovered by subsequent alanine mutation of a cluster of two serines and two threonines in IC-IV of either B1(B2ICIV) or B1(B2ICIV)A(121), a cluster that is important for B2R desensitization. The ligand-independent, constitutive activity of B1R therefore depends on epitopes in both transmembrane and intracellular domains. We propose that the activity is primarily due to the lack of critical epitopes in IC-IV that regulate such activity.

Amino Acid Sequence↗
PubMed2000

Osteoma cutis coexisting with cutis laxa-like pseudoxanthoma elasticum.

Pseudoxanthoma elasticum (PXE) is a heritable disorder of elastic fibers characterized by yellowish, coalescing papules on the loose and wrinkled flexural area. There have been no reports of osteoma cutis associated with PXE. A 17-year-old Korean girl presented cutis laxa-like marked wrinkling on the flexural area, and a skin biopsy specimen revealed multiple foci of ossification with irregularly clumped, basophilic-stained elastic fibers in the reticular dermis and calcium deposits along the elastic fibers. Ultrasonographic evaluation showed multiple tiny osteomas diffusely scattered along the entire abdominal wall, axillae, and medial aspect of the upper arms. We report the first case of osteoma cutis coexisting with cutis laxa-like PXE.

Adolescent↗
PubMed2000

Segmental and subsegmental pulmonary arteries: evaluation with electron-beam versus spiral CT.

PURPOSE: To compare contrast agent-enhanced spiral and electron-beam computed tomography (CT) for the analysis of segmental and subsegmental pulmonary arteries. MATERIALS AND METHODS: CT angiography of the pulmonary arteries was performed in 56 patients to rule out pulmonary embolism. Electron-beam CT was performed in 28 patients. The other 28 patients underwent spiral CT with comparable scanning protocols. The depiction of segmental and subsegmental arteries was analyzed by three independent readers. The contrast enhancement in the main pulmonary artery was measured in each patient. RESULTS: Analysis was performed in 1,120 segmental and 2, 240 subsegmental arteries. One segmental (RA7, P =.010) and two subsegmental (LA7b, P =.029; RA6a+b, P =.038) arteries in paracardiac and basal segments of the lung were depicted significantly better with electron-beam CT. There was no statistically significant difference between electron-beam and spiral CT in the total number of analyzable peripheral arteries depicted. The mean contrast enhancement in the main pulmonary artery was 362 HU in electron-beam CT studies versus 248 HU in spiral CT studies. CONCLUSION: Detailed visualization of peripheral pulmonary arteries is well within the scope of advanced CT techniques. Electron-beam CT has minor advantages in analyzing paracardiac arteries, probably because of reduction of motion artifacts and higher contrast enhancement. Further studies are needed to establish whether electron-beam CT allows a more confident diagnosis of emboli in these vessels.

Adult↗
PubMed1999

Common blue naevus with satellite lesions: possible perivascular dissemination resulting in a clinical resemblance to malignant melanoma.

We report a case of common blue naevus with polymorphous guttate and linear satellite lesions, thereby mimicking peripherally spreading malignant melanoma. Histopathologic examination showed that the naevus cells are clustered around blood vessels in the primary as well as satellite lesions, suggestive of spreading of the naevus cells along the perivascular space. Such biological behaviour resulting in a clinical manifestation of a malignant melanoma-like lesion is a rarity in common blue naevus, a benign cutaneous disorder that is devoid of a malignant potential, and has not been described before.

Adult↗
PubMed1999

Septic arthritis versus transient synovitis at MR imaging: preliminary assessment with signal intensity alterations in bone marrow.

PURPOSE: To find any differential magnetic resonance (MR) imaging findings between septic arthritis and transient synovitis in pediatric patients. MATERIALS AND METHODS: The MR imaging findings in nine pediatric patients with septic arthritis and 14 with transient synovitis were retrospectively studied. The diagnoses were made by means of joint aspiration with bacteriologic study, arthrotomy, and clinical evaluation. MR imaging findings were analyzed with emphasis on the grade of joint effusion and alterations in signal intensity in the soft tissue and bone marrow of the affected hip joint. RESULTS: Signal intensity alterations in bone marrow (i.e., low signal intensity on fat-suppressed gadolinium-enhanced T1-weighted spin-echo images and high signal intensity on fat-suppressed T2-weighted fast spin-echo images) were seen in eight of nine patients with septic arthritis. These signal intensity alterations consisted of mild juxtaarticular changes in six patients without osteomyelitis and extensive changes in the femoral head and neck in two patients with coexistent osteomyelitis. Signal intensity alterations in bone marrow were not seen in the 14 patients with transient synovitis. CONCLUSION: Signal intensity alterations in the bone marrow of the affected hip joint are useful in the differentiation of septic arthritis from transient synovitis.

Adolescent↗
PubMed1999

Regulation of type I collagen and interstitial collagenase mRNA expression in human dermal fibroblasts by colchicine and D-penicillamine.

Sclerosis is a disease process in which idiopathic hardening occurs in the skin and/or internal organs as a result of the accumulation of type I collagen, induced mainly by transforming growth factor-beta. Colchicine and D-penicillamine are widely used for its treatment. Their effects are known to be due to post-translational down-regulation of type I collagen synthesis, with colchicine also up-regulating interstitial collagenase. To determine whether or not they have any pre-translational effect on type I collagen and MMP-1, and also to observe their effects on the action of TGF-beta, cultured neonatal foreskin fibroblasts were treated with colchicine and D-penicillamine, singly and together. The amount of type I collagen and MMP-1 mRNA were quantitated by Northern blot hybridization. Colchicine suppresses the basal level of type I collagen mRNA but minimally stimulates the mRNA expression of MMP-1, whereas D-penicillamine does not have any significant effects on either. Colchicine was also able to significantly suppress the TGF-beta-induced up-regulation of type I collagen mRNA expression.

Cells, Cultured↗
PubMed1998

Surveillance for asthma--United States, 1960-1995.

PROBLEM/CONDITION: Asthma is one of the most common chronic diseases in the United States, and it has increased in importance during the preceding 20 years. Despite its importance, no comprehensive surveillance system has been established that measures asthma trends at the state or local level. REPORTING PERIOD: This report summarizes and reviews national data for specific end-points: self-reported asthma prevalence (1980-1994), asthma office visits (1975-1995), asthma emergency room visits (1992-1995), asthma hospitalizations (1979-1994), and asthma deaths (1960-1995). DESCRIPTION OF SYSTEM: The National Center for Health Statistics (NCHS) annually conducts the National Health Interview Survey, which asks about self-reported asthma in a subset of the sample. NCHS collects physician office visit data with the National Ambulatory Medical Care Survey, emergency room visit data with the National Hospital Ambulatory Medical Care Survey, and hospitalization data with the National Hospital Discharge Survey. NCHS also collects mortality data annually from each state and produces computerized files from these data. We used these datasets to determine self-reported asthma prevalence, asthma office visits, asthma emergency room visits, asthma hospitalizations, and asthma deaths nationwide and in four geographic regions of the United States (i.e., Northeast, Midwest, South, and West). RESULTS: We found an increase in self-reported asthma prevalence rates and asthma death rates in recent years both nationally and regionally. Asthma hospitalization rates have increased in some regions and decreased in others. At the state level, only death data are available for asthma; death rates varied substantially among states within the same region. INTERPRETATION: Both asthma prevalence rates and asthma death rates are increasing nationally. Available surveillance information are inadequate for fully assessing asthma trends at the state or local level. Implementation of better state and local surveillance can increase understanding of this disease and contribute to more effective treatment and prevention strategies.

Adolescent↗
PubMed1997

Cl- secretion induced by 5-hydroxytryptamine and calcitonin gene-related peptide in rat tracheal epithelia.

The effects of 5-hydroxytryptamine (5-HT) and calcitonin gene-related peptide (CGRP), which are colocalized in nerve terminals in the airway, on Cl- secretion in rat tracheal epithelia were tested. Short-circuit current (Isc) was measured after rat tracheal epithelial monolayers were cultured on porous filters. In rat tracheal monolayers 5-HT and CGRP increased Isc upon addition to the serosal compartment, in a dose-dependent manner with EC50 values at 5 micromol/l and 5 nmol/l, respectively. The responses were dependent on the presence of Cl- in the bathing solution and were inhibited by 100 micromol/l bumetanide. When 5-HT or CGRP was added after the administration of forskolin, the responses were not observed. 5-HT and CGRP increased the intracellular cAMP concentration. Low-Ca2+ buffer (0.1 mmol/l) and pretreatment with BAPTA/AM (10 micromol/l), thapsigargin (1 micromol/l) or indomethacin (10 micromol/l) did not affect the responses to 5-HT and CGRP. The 5-HT-induced response was not inhibited by 5-HT2 and/or 5-HT4 antagonists. These results indicate that in the rat tracheal epithelia 5-HT and CGRP increase Cl- secretion by an increase in intracellular cAMP concentration via direct activation of basolateral receptors, and that the response to 5-HT is not mediated via 5-HT4 receptors.

Animals↗
PubMed1996

Plastic bronchitis.

Plastic bronchitis is generally associated with some type of pulmonary disease and improves either spontaneously or with medical therapy. We present a case of plastic bronchitis with no known cause. The patients' symptoms were not responsive to medical therapy but were relieved after right middle lobectomy.

Adolescent↗
PubMed1993

Crystal structure of human annexin I at 2.5 A resolution.

cDNA coding for N-terminally truncated human annexin I, a member of the family of Ca(2+)-dependent phospholipid binding proteins, has been cloned and expressed in Escherichia coli. The expressed protein is biologically active, and has been purified and crystallized in space group P2(1)2(1)2(1) with cell dimensions a = 139.36 A, b = 67.50 A, and c = 42.11 A. The crystal structure has been determined by molecular replacement at 3.0 A resolution using the annexin V core structure as the search model. The average backbone deviation between these two structures is 2.34 A. The structure has been refined to an R-factor of 17.7% at 2.5 A resolution. Six calcium sites have been identified in the annexin I structure. Each is located in the loop region of the helix-loop-helix motif. Two of the six calcium sites in annexin I are not occupied in the annexin V structure. The superpositions of the corresponding loop regions in the four domains show that the calcium binding loops in annexin I can be divided into two classes: type II and type III. Both classes are different from the well-known EF-hand motif (type I).

Amino Acid Sequence↗