Biomedical subjects
Publications and source records attributed to W S Kim.
The radiologic findings of plasma cell granuloma involving the left tracheobronchial angle in a child are described. The left lung volume was decreased on chest radiograph, and CT scan showed an intraluminal mass.
We report a rare case of cystic intrapulmonary lymphangioma involving the left lung, which presented with pneumothorax and respiratory distress in a 6-month-old infant. Chest radiographs showed a multicystic lesion in the left lung mimicking the features of congenital cystic adenomatoid malformation of the lung. The lesion appeared on high-resolution CT (HRCT) as a multiseptate, air-filled cystic lesion in the left hilar area. Associated HRCT findings were thickening of interlobular septa and bronchovascular bundles in the left lung and the presence of peripheral pulmonary vessels within cystic lesions in the apex of the left lung. HRCT findings correlated well with histopathologic findings. We suggest that these associated findings may be helpful in distinguishing this condition from other cystic lung diseases and that this entity should be included in the differential diagnosis of multicystic lung lesions.
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A series of novel cephalosporin compounds which have 3-[(aminopyrimidiniumyl)thio]methyl substituents was synthesized. They show high antimicrobial activity against various bacterial species including Pseudomonas aeruginosa. Structure-activity relationships with various thiopyrimidines, thiopyrimidiniums, bicyclic thiotriazolopyrimidiniums, and bicyclic thioimidazolopyrimidiniums as 3'-substituents were also studied; cephalosporins with quarternized pyrimidinium moieties have better antimicrobial activities than neuteral pyrimidine cephalosporins, and stabilization of the positive charge on the pyrimidinium moieties is essential for better activity. According to semiempirical PM3 calculations, amino and alkylthio substituents on the pyrimidinium rings play a major role in charge stabilization and delocalization.
Castleman disease is a relatively rare disorder affecting young adults. We present the CT and ultrasonographic findings of Castleman disease in two children. In one patient with hyaline-vascular type disease, CT showed a well-enhancing mass in the right paratracheal area. In a second patient with plasma cell type disease, there was a solid, homogeneous mass in the retroperitoneal space which was poorly enhancing. Ultrasound showed a uniform hypoechogenic mass in both cases.
MR findings of a patient with hemolytic uremic syndrome involving the CNS are described. Abnormal high signal intensity on T2-weighted images combined with swelling in the lentiform nucleus, posterior limb of internal capsule, external capsule bilaterally, and left extreme capsule was shown on initial MR; a small low signal intensity in the left putamen on T1- and T2-weighted images and generalized atrophy in the area of high signal intensity on previous T2-weighted images was shown on follow-up MR. These findings indicate infarct with focal hemorrhage, which is one of the histopathological features of CNS complication in hemolytic uremic syndrome.
Six cases of undifferentiated embryonal sarcoma (UES) were reviewed to determine their characteristic features on ultrasonography (US) (n = 5) and computed tomography (CT) (n = 6). US demonstrated a single large, echogenic mass with some anechoic spaces. Contrast-enhanced CT scan revealed a well-demarcated low-attenuation mass with hyperdense septations of variable shape and thickness. Discrepancy of internal architecture on US and CT was one of the important characteristics of UES. CT numbers were 25-47 HU in low-attenuation areas. Enhancing peripheral rim was found in four cases and some solid portions at the periphery or adjacent to the septa were found in all cases. Two patients who had follow-up US and CT without treatment showed enhancing solid portions, changing to hypodense as the tumor grew. When compared with the pathologic findings, US showed a more accurate representation of internal architecture than did CT. Familiarity with these US and CT findings of UES of the liver will be helpful in the differential diagnosis of primary hepatic tumors in childhood.
We tested the efficacy of a new approach for the tissue-engineered growth of cartilage developed in our laboratory in repairing surgically created bone defects in the craniums of rats. Large cranial defects were created bilaterally in the frontoparietotemporal bones of athymic nude rats (n = 10). There was gross evidence of new cartilage in 8 of 10 experimental defects that had been filled with a synthetic biocompatible, biodegradable polymer template that had been seeded in vitro with freshly isolated chondrocytes. The control defects, filled with either nothing at all or a polymer template without chondrocytes, showed no evidence of cartilaginous repair (0 of 10). Statistical analysis using McNemar's test with pooled samples showed significant differences between the two groups (p < 0.05). Prior reports concerning the biologic repair of bony defects involved stimulation of adjacent mesenchymal tissue and resulted in ingrowth of new bone. To our knowledge, this is the first report of structural cartilaginous repair of a bony defect with matrix secreted by implanted chondrocytes.
Our aim was to assess whether endotoxemia impairs the ability of the diaphragm to extract O2 and whether this defect leads to a greater dependence of O2 uptake on O2 delivery. In two groups of anesthetized mechanically ventilated dogs, the left hemidiaphragm was vascularly isolated. Diaphragmatic blood flow and cardiac output (CO) were measured simultaneously in all animals. Saline (S group) or Escherichia coli endotoxin (100 mg; E group) was infused intravenously over 60 min. In both groups, CO was reduced in stages by controlled hemorrhage, and systemic and diaphragmatic O2 deliveries and consumptions were measured at each stage to construct the O2 delivery-O2 consumption relationships. In the S group, the average systemic O2 delivery below which O2 uptake became supply dependent was 7.2 ml.kg-1.min-1. At this O2 delivery, systemic O2 extraction ratio (ER) averaged 67.9%, whereas the maximum O2 ER was 91.3%. Critical diaphragmatic O2 delivery and critical and maximum diaphragmatic O2 ER, by comparison, averaged 9.0 ml.kg-1.min-1, 65%, and 81.9%, respectively. Endotoxin infusion raised critical systemic O2 delivery to 16.7 ml.kg-1.min-1 (P < 0.05) and reduced critical and maximum systemic O2 ER to 55.5 and 77% (P < 0.05), respectively. Similarly, critical diaphragmatic O2 delivery in the E group increased to 14.8 ml.kg-1.min-1 (P < 0.05), whereas critical and maximum O2 ER declined to 51.8 and 72.8%, respectively (P < 0.05). Thus, endotoxemia impairs diaphragmatic O2 extraction. This, in turn, leads to a greater dependence of diaphragmatic O2 uptake on O2 delivery.
Many peptide hormones and neuropeptides are produced from larger, inactive precursors through endoproteolysis at sites usually marked by paired basic residues (primarily Lys-Arg and Arg-Arg), or occasionally by a monobasic residue (primarily Arg). Based upon data concerning processing of prorenin and its mutants around the native Lys-Arg cleavage site expressed in mouse pituitary AtT-20 cells, we present the following sequence rules that govern mono-arginyl cleavages: (a) a basic residue at the fourth (position -4) or the sixth (position -6) residue upstream of the cleavage site is required, (b) at position -4, Arg is more favorable than Lys, and (c) at position 1, a hydrophobic aliphatic residue is not suitable. These rules are compatible with those proposed by comparison of precursor sequences around mono-arginyl cleavage sites. We also provide evidence that precursor cleavages at mono-arginyl and dibasic sites can be catalyzed by the same Kex2-like processing endoprotease, PC1/PC3.
We used the polymerase chain reaction to identify a mouse testis cDNA that represented another member of a growing class of mammalian endoproteases involved in the processing of precursor proteins. This cDNA encoded a 655-residue protein, designated PC4, containing a bacterial subtilisin-like catalytic domain closely related to those of the recently characterized precursor-processing endoproteases, furin, PC1/PC3, PC2, and Kex2. Within this domain, the amino acid sequence of PC4 was 70, 58, 55, and 45% identical with those of mouse furin, mouse PC1/PC3, mouse PC2, and yeast Kex2, respectively. Northern blot analysis indicated that the PC4 mRNA was detectable only in the testes after the 20th day of postnatal development. Moreover, this message was mainly expressed in the round spermatids. These data suggest that PC4 represents a prime candidate for a precursor-processing endoprotease in the testicular germ cells and that its gene expression is regulated during spermatogenesis.
As an extension of the projection-data-based cardiac cycle extraction that we developed previously (W. S. Kim, K. J. Jung, K. D. Lee, J. B. Ra, and Z. H. Cho, "Proceedings, Seventh Annual Meeting of the Society of Magnetic Resonance in Medicine, 1988," p. 958; W. S. Kim, C. W. Mun, D. J. Kim, and Z. H. Cho, Magn. Reson. Med. 13, 25, 1990), a new technique with which one can extract the cardiac cycle by flow-based projection data measurements is described. Because the method uses flow-dependent projection data, it is possible to obtain the cardiac cycle even from regions such as the head, which has virtually no geometrically varying parts, unlike the cardiac region. The signal-to-noise of this flow (such as blood and CSF) based projection data acquisition is further enhanced by the use of the static sample signal suppression technique developed for angiography (J. H. Kim and Z. H. Cho, Magn. Reson. Med. 14, 554, 1990).
A case of inflammatory pseudotumor of the lung in a 6-year-old boy is presented. The respiratory illness presented as a mycoplasma pneumonia and there had been a similar episode of mycoplasma pneumonia one and a half years previously. Computed tomography revealed a large, calcified right posterior mediastinal mass and exploratory thoracotomy revealed a large posterior mediastinal mass that had an endobronchial component and grew exophytically from the lung. The present case suggests that inflammatory pseudotumor of the lung can manifest as a mediastinal mass and could be associated with mycoplasma pneumonia infection.
Pleuropulmonary paragonimiasis is a disease caused by lung flukes characterized by migration of a juvenile worm in the early stage and by formation of cysts around the worm later on. The purpose of this study was to describe the radiologic manifestations of pleuropulmonary paragonimiasis, with special emphasis on the worm cyst and worm migration track. We retrospectively studied 71 patients who had evidence of pleuropulmonary paragonimiasis on chest radiographs (n = 71) and CT scans (n = 17). The diagnosis was based on the detection of eggs or on positive antibody tests. On chest radiographs, 59 patients (83%) had pulmonary lesions and 43 patients (61%) had pleural lesions. Pulmonary findings included patchy air-space consolidation (n = 37) with or without cystic changes; ring shadows (n = 16); and peripheral linear opacities (n = 29), which were more prominent in patients with pleural effusion. Twelve patients (17%) had bilateral pleural effusions or pneumothoraces. On CT scans, round low-attenuation cystic lesions (5-15 mm), filled either with fluid (n = 5) or gas (n = 5), were characteristically seen within the consolidation. Peripheral linear opacities seen on radiographs were suggestive of worm migration tracks on CT scans. CT may reveal an intracystic worm. Although the findings vary depending on the stage of the disease, findings on chest radiographs are usually typical of paragonimiasis. CT provides more specific information about the worm cyst and the worm migration track.
Cases of hospital acquired pneumonia occurring during the 1st 12 months of Medico-Surgical ICU (Intensive care unit, MSICU) in operation were evaluated retrospectively to determine its incidence, common causative pathogens, outcome and radiological patterns with the new hospital setting providing a unique relatively aseptic environment. Among the 920 admitted patients, 73 episodes of nosocomial pneumonia on 63 patients were identified and the incidence rate was 7%. The most common pathogens were Pseudomonas. Staphylococcus, Serratia, and Enterobacter in the order of frequency of occurrence, and the gram-negative pathogens comprised 70%. Nosocomial pneumonia was more common after use of antibiotics due to such pathogens as Enterobacter, Acinetobacter, and Candida which caused poor outcome. Enterobacter had the greatest tendency to be related with poor outcome and Serratia the least. Overall mortality was 25%. Bronchopneumonia was the most common type of pneumonia caused by any pathogen except Acinetobacter which caused a mixed type of nosocomial pneumonia.
We have recently demonstrated, by protein and cDNA sequence analyses, that prorenin converting enzyme (PRECE) in the ICR mouse submandibular gland is identical to the epidermal growth factor-binding protein (EGF-BP) type B, the mGK-13 gene product identified in Balb/c mouse. However, in the course of cDNA cloning, we noticed the presence of the other cDNA type highly homologous but not identical to the PRECE cDNA. The sequence of the newly identified cDNA was identical to that of the pSGP-2 cDNA cloned from NMRI mice, which also encodes EGF-BP type B different at 9 out of 261 amino acids from the mGK-13 product. Although this difference has been explained by strain polymorphism, our results indicate that these two proteins are distinct gene products. The product of the newly identified cDNA also had a prorenin converting activity. Thus, the products of both cDNAs identified in previous and present studies are involved in maturation of two bioactive polypeptides, renin and EGF.
Mouse submandibular gland prorenin-converting enzyme (PRECE) consists of the two polypeptide chains of 17 and 10 kDa and cleaves mouse Ren-2 prorenin at a dibasic site to yield mature renin. Western blot analysis using an antiserum against this enzyme gave rise to multiple bands in mouse submandibular glands, suggesting that PRECE is a member of a protease family. Partial amino acid sequence analysis of purified PRECE and cloning and sequence analyses of its cDNA indicated that it is identical to the mGK-13 gene product, epidermal growth factor-binding protein type B, which is a member of the glandular kallikrein family and is involved in maturation of epidermal growth factor. Conditioned medium from Chinese hamster ovary cells transfected with an expression plasmid for PRECE had prorenin converting activity. These results indicate that PRECE is involved in the maturation of two bioactive polypeptides expressed in mouse submandibular glands, Ren-2 renin and epidermal growth factor.
Many peptide hormones are produced from larger precursors by endoproteolysis at pairs of basic amino acids (e.g. Lys-Arg and Arg-Arg) within the regulated secretory pathway in endocrine cells. However, many other secretory and membrane proteins appear to be produced from precursors through cleavage at multiple, rather than paired, basic residues within the constitutive secretory pathway in non-endocrine cells. By surveying various precursors processed constitutively, we noticed that most of them have the consensus sequence, Arg-X-Lys/Arg-Arg (RXK/RR), at the cleavage site. When expressed in endocrine and non-endocrine cells, a precursor with the RXKR sequence was cleaved in both types of cells, whereas that with the Lys-Arg pair was cleaved only in the endocrine cells. When the RXKR precursor was coexpressed with furin and PC3, both of which are mammalian homologues of the yeast precursor-processing endoprotease Kex2, in non-endocrine cells, enhancement of the precursor cleavage by furin but not by PC3 was observed. By contrast, when the Lys-Arg precursor was coexpressed with the two mammalian proteases in endocrine cells with no endogenous processing activity at dibasic sites, it was cleaved only by PC3. These results indicate that the basic pair and the RXK/RR sequence are the signals for precursor cleavages catalyzed by PC3 within the regulated secretory pathway and by furin within the constitutive pathway, respectively.