Biomedical subjects

M H Kim

Publications and source records attributed to M H Kim.

At least 181 records · Page 10Linked to original sources

PubMed1998

Biliary stricture caused by blunt abdominal trauma: clinical and radiologic features in five patients.

PURPOSE: To evaluate the clinical and radiologic features of biliary stricture after blunt abdominal trauma and to report the results of endoscopic stent placement. MATERIALS AND METHODS: Medical records and radiologic findings were reviewed in five patients with biliary stricture after blunt abdominal trauma. The level, length, and contour of the strictures were analyzed with endoscopic retrograde cholangiopancreatography (ERCP). Computed tomographic (CT) scans were also reviewed to determine the presence of biliary dilatation, configuration of the injured bile duct, and ancillary abdominal findings. Results from endoscopic stent placement were evaluated in all patients. RESULTS: Stricture occurred in the suprapancreatic portion of the common bile duct in four patients and in the intrapancreatic portion in one patient. At ERCP, the stricture contour was concentric and smooth in three patients, eccentric and smooth in one, and abruptly terminated in one. CT showed abrupt narrowing of the common bile duct with dilatation of the proximal portion in all patients. Endoscopic stent placement was successful in all patients. CONCLUSION: Patients with biliary stricture after blunt abdominal trauma exhibit a delayed onset of symptoms. A correct diagnosis may be difficult on the basis of findings from CT or ERCP alone without a clinical history or evidence of contusions at other sites.

Abdominal Injuries↗

PubMed1998

Inhibitory effect of calyculin A, a Ser/Thr protein phosphatase type I inhibitor, on renin secretion.

We have recently shown that several putative selective inhibitors of Ca2+-calmodulin-dependent myosin light chain kinase (MLCK), such as ML-9 [1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine], reversibly stimulate renin secretion [C. S. Park, S.-H. Chang, H. S. Lee, S.-H. Kim, J. W. Chang, and C. D. Hong. Am. J. Physiol. 271 (Cell Physiol. 40): C242-C247, 1996]. We hypothesized that Ca2+ inhibits renin secretion, via phosphorylation of 20-kDa myosin light chain (MLC20), by activating MLCK. In the present studies, we have investigated the types of protein phosphatase (PP) involved in the control of renin secretion through inhibition of MLC dephosphorylation using inhibitors of various types of serine/threonine-specific protein phosphatases. Cyclosporin A, a putative inhibitor of PP type 2 (calcineurin), was without effect. Calyculin A and okadaic acid, putative selective inhibitors of both PP type 1 (PP1) and type 2A (PP2A), significantly inhibited renin secretion under control conditions. Calyculin A had inhibitory effects at least 10-fold more potent than okadaic acid, suggesting that PP1, rather than PP2A, is involved in the control of renin secretion. Furthermore, calyculin A blocked the reversal of renin secretion preinhibited by raised intracellular Ca2+ concentrations in a concentration-dependent manner. Calyculin A (10(-6) M) significantly inhibited renin secretion stimulated by lowering intracellular Ca2+ concentrations and blocked the stimulatory effect of ML-9 on renin secretion. Taking all of these results into consideration, we hypothesize that dephosphorylation of MLC20 by Ca2+-independent PP1 stimulates renin secretion, whereas phosphorylation of MLC20 by Ca2+-calmodulin-dependent MLCK inhibits it. This hypothesized regulatory model of renin secretion predicts that the rate of renin secretion at a given time is determined by the ratio of phosphorylated to dephosphorylated MLC20, which is, in turn, determined by the dynamic balance between activity of MLCK and MLC phosphatase.

Animals↗

PubMed1998

MR cholangiopancreatography of pancreaticobiliary diseases: comparing single-shot RARE and multislice HASTE sequences.

OBJECTIVE: In this study, we compared the single-shot rapid acquisition with relaxation enhancement (RARE) sequence with the multislice half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence to assess the ability of each technique to show various pancreaticobiliary diseases using MR cholangiopancreatography. SUBJECTS AND METHODS: MR cholangiopancreatography was performed using both the single-shot RARE and the multislice HASTE pulse sequences in 80 consecutive subjects in whom we had proof of a range of diagnoses. The study population included healthy subjects (n = 9), patients with benign lesions (n = 41), and patients with malignant lesions (n = 30). We analyzed each image using the following criteria: the cause of the lesions, the image quality (i.e., the amount of artifact and the sharpness of anatomic structures such as the right and left hepatic ducts, the extrahepatic bile duct, and the main pancreatic duct), and the reviewers' preference of images. The images were evaluated independently by two radiologists who were unaware of the results of the other cholangiopancreatographic sequence and of the diagnosis. RESULTS: Artifacts were less prominent in images that were obtained using the single-shot RARE sequence (p = .0192); however, the sharpness of anatomic structures was the same using either sequence (p = .1673). For images that were obtained using the single-shot RARE technique, the sensitivity, specificity, and accuracy in distinguishing malignant from other abnormalities were 83%, 78%, and 80%, respectively; for the multislice HASTE technique, these values were 77%, 72%, and 74%, respectively (p > .05). Disease-specific accuracy in determining the correct diagnosis was 54% and 59%, respectively (p > .05). In patients in whom all the ducts needed to be defined, the single-shot RARE technique was preferred to the multislice HASTE technique (p < .01). CONCLUSION: The single-shot RARE technique shows fewer artifacts and is preferred to the multislice HASTE technique. However, both techniques show the same degree of sharpness of anatomic structures, both are able to reveal malignant diseases, and both provide enough information to determine a specific diagnosis.

Adult↗

PubMed1998

Loss of heterozygosity on chromosome XP22.2-p22.13 and Xq26.1-q27.1 in human breast carcinomas.

In an attempt to investigate the X chromosome harboring putative tumor suppressor genes (TSGs) in sporadic breast carcinoma, we performed loss of heterozygosity (LOH) studies on 23 breast carcinomas using 15 polymorphic markers covering the whole X chromosomes. Matched DNA extracted from tumor samples and corresponding normal tissues were analyzed by polymerase chain reactions (PCR) using microsatellite markers. In 10 cases (43.5%), LOH was detected for at least 1 of the 15 polymorphic markers of the X chromosome tested. Four cases carried a LOH at Xp, and three cases LOH on Xp and Xq. Three cases carried a LOH Xq. Percentage of LOH was relatively high in DXS987 (26.7%), DXS999(30.0%), HPRT(21.4%), DXS1062(23.1%) loci. Common regions of deletions were found on Xp22.2-p22.13 (30% of LOH) measuring about 4.5Mb and Xq26.1-q27.1 (23.1% of LOH) measuring 10 Mb. The deleted allele was an active copy of the X chromosome. The results indicate the TSGs on the X chromosome are involved in breast cancer.

Adenocarcinoma↗

PubMed1998

Surgical options of hypertensive intracerebral hematoma: stereotactic endoscopic removal versus stereotactic catheter drainage.

The authors analyzed the difference between two surgical procedures, stereotactic endoscopic removal (SER) and stereotactic catheter drainage (SCD), in 18 patients of ganglionic intracerebral hematoma (ICH). Ten patients underwent SCD and eight SER within 24 hours of insult. The mean age was 53.3 (33-81) years and male to female ratio was 11:7. The mean volume of hematoma was 34.4 (23-105) ml. All patients had major neurological deficits without signs of transtentorial herniation. Mean follow-up was 8 (6-10) months. Under local anesthesia, Otzuki's cannula was placed through a burr hole. ICH was removed with suction and forceps under endoscopic guidance. Hemostasis was performed with Nd-YAG laser. For SCD, we used silicone catheter and urokinase. The hematoma was drained in 3-5 days in SER, whereas 7-10 days in SCD. Postoperative rebleeding occurred in one case of SER. Mortality rate was 13% in SER, 10% in SCD. The patients who gained most from these treatments were those who had been admitted with an impaired level of consciousness. The whole procedure can be done under direct vision in SER, so SER might replace SCD with similar mortality.

Adult↗

PubMed1998

Cerebral vasoreactivity by transcranial Doppler in carbon disulfide poisoning cases in Korea.

The abnormalities of cerebral vasoreactivity were evaluated in CS2 poisoning cases. In 34 retired workers with CS2 poisoning (case group) and 20 healthy individuals (control group), blood flow velocities were measured in the middle cerebral arteries (MCA) by transcranial Doppler. Compared with the control group, the case group showed lower mean values of blood flow velocities and pulsatile indices. The differences in CO2 reactivities of both groups were remarkable (1.10-2.19% decrease/mmHg CO2 for cases and 3.35-5.08 for controls). Multiple regression analyses were conducted to adjust the effect of age, sex, and exposure level (non-low-high exposure) to CO2 reactivity and pulsatile index. The exposure level was statistically significant in the regression model for CO2 reactivity of both MCA and for pulsatile index of the right MCA. Our study noted a decrease of CO2 reactivity and pulsatile index of cerebral vessels related with CS2 exposure. These findings suggested that CS2 exposure could lead to a decrease of cerebral vasoreactivities by the atherosclerotic change of cerebral vessels.

Adult↗

PubMed1998

Evaluation of risk from space radiation with high-energy heavy ion beams.

The most challenging radiation in space consists of fully ionized atomic elements with high energy for which only the few lowest energy ions can be stopped in shielding materials. The health risk from exposure to these ions and their secondary radiations generated in shield materials is poorly understood since there are few human data and a systematic study in relevant animal model systems has not been made. The accuracy of risk prediction is described as the major limiting factor in the management of space radiation risk. The expected impact of systematic studies is examined using the limited available biological data and models. Given the limitations of current predictions, models must be developed that are able to incorporate the required fundamental scientific data into accurate risk estimates. The important radiation components that can be provided for laboratory testing are identified. The use of ground-based accelerator beams to simulate space radiation is explained and quantitative scientific constraints on such facilities are derived. Three facilities, one each in the United States, in Germany and in Japan, currently have the partial capability to satisfy these constraints. A facility has been proposed using the Brookhaven National Laboratory Booster Synchrotron in the United States; in conjuction with other on-site accelerators, it will be able to provide the full range of heavy ion beams and energies required.

Aerospace Medicine↗

PubMed1998

Regulation of renin secretion through reversible phosphorylation of myosin by myosin light chain kinase and protein phosphatase type 1.

Possible involvement of reversible phosphorylation and dephosphorylation of myosin light chain (MLC) by myosin light chain kinase (MLCK) and protein phosphatases (PPases), respectively, in the Ca++-calmodulin-dependent inhibition of renin secretion was investigated with the use of putative MLCK inhibitor ML-7 [1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine] and PPase type1 (PPase-1) and type 2A (PPase-2A) inhibitor calyculin A. ML-7 (1 x 10(-)6 to 3 x 10(-)5 M) increased renin secretion in vitro from rat renal cortical slices under "resting" conditions in a concentration-dependent manner with maximal 2.5-fold stimulation. Furthermore, Ca++-induced inhibition of renin secretion in depolarizing K+-rich Krebs-Ringer bicarbonate not only was prevented completely but also reversed by ML-7 in a concentration-dependent and reversible manner. On the other hand, calyculin A (3 x 10(-)6 M) blocked both effects of ML-7 on stimulation and reversal of renin secretion independently of intracellular Ca++ concentrations. Such antagonistic effects of ML-7 and calyculin A on renin secretion most likely resulted from their respective effects on the level of MLC phosphorylation: ML-7 stimulates renin secretion by decreasing phosphorylation of MLC through its inhibition of MLCK, whereas calyculin A inhibits secretion by increasing phosphorylation of MLC through its inhibition of PPase-1. By inference from these results, MLC may be the target protein involved in regulation of the renin secretory process by Ca++: Ca++-calmodulin phosphorylates MLC via activating MLCK and thereby inhibits renin secretion, whereas dephosphorylation of phosphorylated MLC by PPase-1 reverses the inhibited secretion. We therefore conclude that reversible phosphorylation of MLC may be an important biochemical step determining the rate of renin secretion from the juxtaglomerular cell.

Animals↗

PubMed1998

Treatment of total hyphema with relatively low-dose tissue plasminogen activator.

The purpose of this study is to investigate the efficacy of tissue plasminogen activator (tPA) in the treatment of total hyphema following ocular trauma or intraocular surgery. Three patients (3 eyes) representing unresolved total hyphema for more than 5 days and uncontrolled high intraocular pressure received intracameral injections of 10 microgram of recombinant tPA. Intracameral tPA injection resulted in complete resolution of hyphema in all 3 eyes. Resolution occurred mostly within 24 to 48 hours after injection. Possible side effects of tPA injection, such as increased intraocular pressure and corneal edema, were not observed. However, 1 eye had vitreous hemorrhage after repeated injections of tPA. Intracameral injection of tPA seems to be a safe and effective method for the treatment of unresolved total hyphema. However, repeated intracameral tPA injections may cause unwanted complications such as vitreous hemorrhage.

Adult↗

PubMed1997

Isolation of ALU1-P gene encoding a protein with aluminum tolerance activity from Arthrobacter viscosus.

We isolated a DNA fragment (ALU1-P) encoding a protein with an activity of aluminum tolerance from an Al tolerant soil microorganism, Arthrobacter viscosus. This microorganism was isolated from acidic tea field soils. The cloned DNA is composed of 1090 nucleotides, which has one open-reading frame without any stop codon. However, when the DNA fragment was transferred into Escherichia coli, a microorganism susceptible to Al toxicity, it endowed E. coli with Al tolerance. The deduced amino acid sequence of the DNA showed 65% identity with the protein of YbaX gene in Escherichia coli, and 51.1% identity with YB91 Haein hypothetical protein of HI1191 gene in Haemophilus influenzae. The ALU1-P gene in the expression vector produced a protein of 192 amino acids deriving a molecular weight of 21.3 kDa by using the stop codon in vector. The ALU1-P gene is a new one that has the characteristic of Al tolerance.

Aluminum↗

PubMed1997

Developmental expression analysis of the 1731 retrotransposon reveals an enhancement of Gag-Pol frameshifting in males of Drosophila melanogaster.

Extensive analyses of Drosophila melanogaster retrotransposon transcriptions in cultured cells or during development have been reported, but little is known about their translation during the development of the fly. Analysis of the translational products of the 1731 Drosophila melanogaster retrotransposon in Kc Drosophila cultured cells has been reported, showing the existence of primary products (Gag and Pol) and of processed polypeptides of various sizes. Study of 1731 retrotransposon expression at both levels of transcription and translation during the development of Drosophila melanogaster, is presented. 1731 transcripts were detected by in situ hybridization and 1731 proteins were detected by immunostaining and immunoblotting in embryos and in adult gonads. 1731 transcripts and proteins were detected in the mesoderm and central nervous system during embryonic development, in nurse cells and follicle cells in adult ovaries and in primary spermatocytes in adult testes. Moreover, Western blot analysis of the 1731 proteins with anti-Gag or anti-Pol antibodies in gonads revealed that the 1731 mRNA could be translated differentially according to the expressing tissue: essentially, ovarian translation and/or processing of 1731 products is different from that operating in testes, where the Gag-Pol fusion polyprotein is the most prominent product. Our results indicate that expression of the 1731 mobile element is regulated not only at the transcriptional level but also at the translational level, and that this regulation is different in the two sexes.

Animals↗

PubMed1997

Intravascular ultrasound assessment of the prevalence and causes of angiographic "haziness" following high-pressure coronary stenting.

Haziness at sites of balloon angioplasty is believed to represent plaque fractures or platelet deposition. The etiology of haziness adjacent to coronary stents remains uncertain. This study examines the prevalence and etiology of "peri-stent" haziness following high-pressure deployment. Consecutive patients undergoing coronary stenting and intravascular ultrasound imaging were included. Haziness was defined as nonhomogeneous contrast density and/or indistinct vessel borders by consensus of 2 observers. Patients were excluded if angiography revealed an obvious cause of haziness (thrombus, dissection). Matched control segments without haziness were selected for comparison. The most diseased site within the reference segment was identified by ultrasound. Lumen and plaque areas, percent plaque area, and plaque echo density were assessed. Haziness was identified within 31 segments in 30 patients (15% of 201 angiograms examined). At hazy sites, ultrasound revealed a large percent plaque area in 15, dissections in 14, and near-normal findings in 2 segments. In the absence of dissection, percent plaque area and lumen area step-down from the stent to the diseased reference were greater than controls (percent plaque area 64 +/- 12% vs 56 +/- 10%, p = 0.04 and lumen step-down 35 +/- 20% vs 13 +/- 25%, p = 0.006). With dissections, percent plaque area and lumen step-down were not different from controls (p = 0.13 and 0.30, respectively), but underlying plaques were more frequently echolucent (64% vs 23%, p = 0.02). Thus, in this study, peri-stent haziness was evident in 15% of patients after high-pressure coronary stent deployment. Etiologies identified by intravascular ultrasound included unrecognized reference plaque and angiographically occult dissections.

Aged↗

PubMed1997

Rapid analysis for the isolation of novel genes encoding putative effectors to the position-specific regulatory element of murine Hoxa-7.

Hox genes are known to play a critical role in pattern formation during vertebrate development by being expressed at the specific time and in the specific position along the antero-posterior body axis. In order to understand the regulatory mechanism for the position-specific expression of murine Hoxa-7, yeast one-hybrid system was applied. DNA fragment conferring a position specificity to the Hoxa-7 gene was placed just upstream from the yeast CYC1 promoter and lacZ gene in a reporter. Selection of LacZ positive clones after cotransformation of the reporter and mouse embryonic cDNA library as an effector, which was designed to be expressed as fusion proteins to the GAL4 activation domain, allowed us to isolate putative factors interacting with the position-specific regulatory element of murine Hoxa-7. A total of 28 positive clones were screened from 5 x 10(5) yeast transformants. About 70% of the clones turned out to be novel and most of the candidate clones selected in this study showed a temporally restricted expression pattern during embryonic development, suggesting that this method could provide an efficient way for isolating novel genes whose expressions are temporally regulated during embryogenesis.

Animals↗

PubMed1997

The structure of the superantigen exfoliative toxin A suggests a novel regulation as a serine protease.

Exfoliative toxin A (ETA) causes staphylococcal scalded skin syndrome which is characterized by a specific intraepidermal separation of layers of the skin. The mechanism by which ETA causes skin separation is unknown although protease or superantigen activity has been implicated. The X-ray crystal structure of ETA has been solved in two crystal forms to 2.1 and 2.3 A resolution and R-factors of 17% and 19%, respectively. The structures indicate that ETA belongs to the chymotrypsin-like family of serine proteases and cleaves substrates after acidic residues. The conformation of a loop adjacent to the catalytic site is suggested to be key in regulating the proteolytic activity of ETA through controlling whether the main chain carbonyl group of Pro192 occupies the oxyanion hole. A unique amino-terminal domain containing a 15-residue amphipathic alpha helix may also be involved in protease activation through binding a specific receptor. Substitution of the active site serine residue with cysteine abolishes the ability of ETA to produce the characteristic separation of epidermal layers but not its ability to induce T cell proliferation.

Amino Acid Sequence↗

PubMed1997

Induction of male-type gonadotropin secretion by implantation of 11-ketotestosterone in female goldfish.

In goldfish, plasma gonadotropin levels increase during spawning in both males and females (GTH surge). A female-typical GTH surge induces ovulation (ovulatory surge), and a male-typical surge triggers milt production in response to sex pheromones released from ovulatory females. This study examined whether the male-typical GTH surge occurs in adult females that are implanted with 11-ketotestosterone (KT), which induces male-typical sexual behavior in adult female goldfish. When KT-implanted females were exposed to ovulatory females, a GTH surge occurred without ovulation. No GTH surge was observed when KT-females were exposed to nonovulatory females. The GTH secretion in KT-females was further characterized by exposure to 17alpha,20beta-dihydroxy-4-pregnen-3-one (17,20-P), a female sex pheromone that induces the GTH surge in males. Exposure to waterborne 17,20-P caused an elevation of GTH levels in KT-females as well as in males. The elevation of GTH levels induced by 17,20-P exposure was abolished when the KT-females were rendered anosmic. Unlike the female-typical ovulatory GTH surge that occurs in synchrony with photoperiod and peaks in the dark phase of the day, the 17,20-P-induced surge did not show a peak in the dark phase. These results indicate that the GTH surge in KT-females is a male-typical surge. Together with a previous study showing KT-induced behavioral masculinization (N. E. Stacey and M. Kobayashi, 1996, Horm. Behav. 30, 434-445), this adult gonochoristic species was shown to possess sexual plasticity of brain function in behavior and GTH secretion in response to sex steroid.

Animals↗

PubMed1997

Cortisol and estradiol: nongenetic factors for hyperhomocyst(e)inemia.

A low plasma homocyst(e)ine concentration in premenopausal and pregnant women compared with postmenopausal women and men suggests that steroid hormones are nongenetic factors affecting homocysteine metabolism. This hypothesis was tested by determining plasma homocyst(e)ine levels in adult male rats treated with cortisol, estradiol, or a combination of both. Mean plasma homocyst(e)ine concentrations were 3.71 +/- 0.71, 5.26 +/- 1.76, and 4.28 +/- 0.84 nmol/mL in cortisol-treated, estradiol-treated, and cortisol plus estradiol-treated groups, respectively. These values were substantially low compared with the level of 7.32 +/- 0.89 nmol/mL plasma homocyst(e)ine in the control group, indicating a significant effect of steroid hormones on homocysteine metabolism.

Amino Acids↗

PubMed1997

The gallbladder also secretes.

The gallbladder is traditionally regarded as an absorptive organ. There is increasing evidence that the gallbladder mucosa can have a secretory function. We studied a patient with primary sclerosing cholangitis whose gallbladder was excluded from his extrahepatic bile ducts by stricture formation. He was admitted into hospital because of cholecystitis and cholangitis and required separate drainage tubes into his gallbladder and common hepatic duct. This unique combination of drains afforded the opportunity to examine hepatic bile and gallbladder secretion. We analyzed samples for fluid volume, protein, electrolyte concentrations and biliary lipids. The simultaneous, yet separate, drainage from the gallbladder and the liver had a striking difference. The former was colorless to opalescent; the latter always golden brown. Hepatic bile flow was continuous but gallbladder drainage was variable in volume, intermittent, and occurred only after a meal. The gallbladder fluid had no bilirubin, bile salts, cholesterol, or phospholipids and had the ionic profile of an extracellular fluid. It was alkaline and contained abundant bicarbonate. We have shown that the gallbladder can secrete. In addition, these observations may also have important implications in the pathogenesis and prevention of gallbladder sludge and stones.

Aged↗

PubMed1997

Endoscopic retrograde cholangiopancreatography and needle-knife sphincterotomy in patients with Billroth II gastrectomy: a comparative study of the forward-viewing endoscope and the side-viewing duodenoscope.

BACKGROUND AND STUDY AIMS: A prospective, randomized study was carried out to compare the success and complication rates associated with the forward-viewing endoscope and side-viewing duodenoscope in conducting endoscopic retrograde cholangiopancreatography (ERCP) and needle-knife sphincterotomy in patients with a Billroth II gastrectomy. PATIENTS AND METHODS: The study included 45 patients with a Billroth II gastrectomy who required ERCP and endoscopic sphincterotomy (EST) for evaluation and management of pancreaticobiliary disease. The patients were randomly assigned to receive ERCP and EST with either a forward-viewing endoscope or a side-viewing duodenoscope. RESULTS: Cannulation of the papilla was successful in 68% (15 of 22) in the side-viewing duodenoscope group, and in 87% (20 of 23) in the forward-viewing endoscope group. Failures of cannulation occurred in seven patients in the side-viewing duodenoscope group, caused by jejunal perforation during insertion (n = 4), by a long afferent loop (n = 1), by a complaint of severe abdominal pain (n = 1), and by failure to enter the afferent loop (n = 1). In the forward-viewing endoscope group, failure occurred in three patients due to the long afferent loop (n = 2) and to an inability to cannulate despite identification of the papilla (n = 1). Sphincterotomy was successfully completed in eight of ten patients (80%) in the side-viewing duodenoscope group, and in ten of twelve patients (83%) in the forward-viewing endoscope group. CONCLUSIONS: For ERCP and EST in patients with Billroth II gastrectomy, the forward-viewing endoscope is as effective as the side-viewing duodenoscope, but it may be the safer of the two instruments. The forward-viewing endoscope can be recommended for ERCP and EST in patients with a Billroth II gastrectomy.

Abdominal Pain↗