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Biomedical subjects

Y Kim

Publications and source records attributed to Y Kim.

At least 649 records · Page 36Linked to original sources
PubMed1994

A 20 nucleotide upstream element is essential for the nopaline synthase (nos) promoter activity.

The nopaline synthase (nos) promoter is expressed in a wide range of plant cell types and regulated by various developmental and environmental factors. The nos upstream control region essential for this regulation was studied by means of synthetic oligomers using transient and stable transformation systems. Insertion of a 20 nucleotide sequence containing two hexamer motifs and a spacer region into deletion mutants lacking the upstream control region was essential for promoter activity. Mutation of one or more nucleotides of either hexamer sequence significantly altered the strength of expression of the nos promoter. Point mutations within the spacer region also strongly influenced promoter strength. Insertion of multiple copies of the 20 nucleotide sequence into the nonfunctional deletion mutants proportionally increased the promoter activity. These results suggest that this twenty nucleotide sequence is essential for the nos promoter to function. Substitution of the nos element with the ocs or 35S as-1 which contain similar hexamer motifs restored not only promoter activity but also responses to wounding, auxin, methyl jasmonate, and salicylic acid.

Amino Acid Oxidoreductases↗
PubMed1994

Antineutrophil cytoplasmic autoantibody-positive crescentic glomerulonephritis as a complication of treatment with propylthiouracil in children.

Propylthiouracil, which is commonly used in the treatment of hyperthyroidism, has been associated in adults with antineutrophil cytoplasmic autoantibody, a serologic marker of vasculitis. Severe renal disease has not been reported as a complication of therapy with this drug. We report severe antineutrophil cytoplasmic autoantibody-positive vasculitis in children receiving propylthiouracil, as well as rapidly progressive crescentic glomerulonephritis after administration of this drug.

Adolescent↗
PubMed1994

Subinguinal microsurgical varicocelectomy: a technical critique and statistical analysis of semen and pregnancy data.

A total of 606 modified subinguinal microscopic varicocelectomies was performed on 466 outpatients using local anesthesia and sedation. The patients selected for these procedures were infertile for at least 12 months and had at least 1 semen parameter below threshold level: less than 20 million per ml., less than 50% motility or less than 40% normal morphological forms. The lymphatics, spermatic artery and vas were preserved, whereas all refluxive veins were transected or obliterated. Postoperative complications were limited to transient epididymal discomfort in 5.5% of the patients, ecchymosis at the wound site in 3.4% and wound inflammation in 2.4%. There was only 1 permanent hydrocele. The palpable recurrence rate was 0.82% per procedure. The median values for each semen parameter were compared preoperatively and postoperatively by the Wilcoxon signed rank test. The differences in the median values were significant for all parameters. As an alternative statistical model, the average preoperative semen value was subtracted from the average postoperative semen value for each parameter. The median differences were 10.8 million sperm per ml. for sperm density, 13.9% for motility and 3.8% for normal morphological forms. These differences were significantly greater than zero by the Wilcoxon signed rank test. The intra-quartile ranges for these differences suggested that postoperatively more than 75% of the patients had a difference of greater than zero for sperm density and per cent motility, and 63% had a difference of greater than zero for normal morphology. The 1-year pregnancy rate was 35.6% for 186 varicocelectomy patients compared to 15.8% for 19 medically treated men with varicocele. The difference between the true 1-year pregnancy rates was 19.8% and the 95% confidence intervals estimated bounds of 1.91 to 37.5%. These data suggest that outpatient subinguinal microscopic varicocelectomy has minimal morbidity and recurrence, and may be beneficial for select patients.

Adult↗
PubMed1994

Recurrence of steroid-resistant nephrotic syndrome in kidney transplants is associated with increased acute renal failure and acute rejection.

We performed 73 kidney transplants in 51 patients with steroid-resistant nephrotic syndrome (SRNS) with focal segmental glomerular sclerosis (FSG) ages 18.4 +/- 12.8 (mean +/- SD) years. Recurrence of SRNS, defined by rapid onset of proteinuria, hypoalbuminemia and/or > 95% epithelial cell foot process effacement with or without the presence of FSG, occurred in 26 grafts in 16 patients. Acute renal failure (ARF) occurred in 16 of 26 (61.5%) grafts with recurrence versus 7 of 47 (14.9%) grafts without recurrence (P < 0.0001). ARF occurred in 4 of 9 (44.4%) living-related donor (LRD) recipients with recurrence and 3 of 21 (12.5%) LRD recipients without recurrence (NS). ARF in cadaver donor (CAD) recipients with recurrence was 12 of 17 (70.5%) versus 4 of 23 (17.4%) without recurrence (P < 0.0001). ARF was also higher in LRD or CAD with recurrence than in a control group of non-SRNS patients matched for age, sex and time of transplantation. Graft survival at one year was lower in patients with recurrence and ARF [4 of 16 (25%)] compared to patients with recurrence and no ARF [9 of 11 (82%), P < 0.01]. There was no difference in graft survival in patients without recurrence who did or did not have ARF. One or more acute rejection episodes occurred in all 16 patients with ARF and recurrence, in all 7 patients with ARF without recurrence, and in 7 of 10 patients with recurrence without ARF compared with only 11 of 40 (28%) of patients with neither recurrence nor ARF (P < 0.0001, < 0.001 and < 0.04, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1994

Effects of matrix glycation on mesangial cell adhesion, spreading and proliferation.

We examined the effects of in vitro nonenzymatic glycosylation (NEG) of the extracellular matrix (ECM) on various aspects of the adhesive interaction between the ECM and human kidney mesangial (HKM) cells, and also on the ability of HKM cells to spread and proliferate. Isolated type IV collagen (tIV) or intact complexes of glomerular basement membrane and mesangial matrix (GBM/MM) were used as substrates following control incubation or modest glycation. We observed that HKM cells adhered less effectively to glycated tIV at early time intervals and were delayed in attaining maximal levels of adhesion compared to cells interacting with control tIV. The nature of the adhesive interaction was also different since antibodies which blocked the function of beta 1-containing integrins more effectively inhibited adhesion between HKM cells and glycated tIV than cells and control tIV. HKM cells interacting with glycated tIV also demonstrated less cell surface microspike and ruffle formation at five minutes after plating, less extensive spreading throughout the examined time intervals (> or = 90 min after plating), and slightly increased cell numbers 5 to 10 days after plating when compared to cells interacting with control tIV. However, increased cell numbers were not observed when HKM cells were grown on glycated GBM/MM. Similar changes in response to glycated substrate were observed when HKM cells were grown in either 5 or 25 mM glucose. In conclusion, relatively modest glycation of the ECM alone was sufficient to result in specific changes in HKM cell behavior in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Glomerular distribution of type IV collagen in diabetes by high resolution quantitative immunochemistry.

We examined type IV collagen distribution and density in human diabetic kidneys by quantitative immunogold electron microscopy. We studied normal kidney transplant donors and "slow-track" and "fast-track" insulin dependent diabetic (IDDM) patients. The "slow-track" patients had IDDM for > or = 20 years and mesangial volume fraction (VvMes/glom) of < or = 0.32. The "fast-track" patients had IDDM for < or = 20 years and VvMes/glom > or = 0.37. Renal biopsies were embedded in Lowicryl, reacted with polyclonal anti-type IV collagen (in the distribution of the classical alpha 1(IV) and alpha 2(IV) collagen chains) and monoclonal anti-alpha 4(IV) collagen chain antibody followed by gold conjugated secondary antibody. We found, by morphometric techniques, a decrease in the immunogold densities of anti-type IV collagen in the subendothelial zone of the GBM in the "fast-track" IDDM patients. There was a trend towards a decrease in mesangial matrix (MM) particle density in the "fast-track" (P = 0.07) but not in the "slow-track" patients. However, because of the marked increase in MM in the "fast-track" patients, the per glomerulus estimated quantity of these antigens in MM was increased. In contrast, the density of alpha 4(IV) collagen chain was increased in the epithelial zone of the GBM in the "fast-track" IDDM patients. It is not known whether these changes in glomerular type IV collagen represent markers of advanced diabetic lesions or whether these changes might be detected earlier in diabetic patients destined for the later development of serious lesions.

Adolescent↗
PubMed1994

Role of elevated alpha-fetoprotein in prenatal diagnosis of junctional epidermolysis bullosa and pyloric atresia.

A case of junctional epidermolysis bullosa, Herlitz variant, and pyloric atresia in a 33 weeks' gestation male infant is reported. The second trimester amniotic fluid exhibited elevated concentrations of alpha-fetoprotein and presence of acetylcholinesterase; however, the fetus appeared anatomically normal by multiple high-resolution ultrasound examinations. This case, as well as others previously reported, shows that serious fetal skin disease should be considered as part of the differential diagnosis whenever persistent elevation of alpha-fetoprotein and presence of acetylcholinesterase are found in the amniotic fluid of a fetus that appears anatomically normal by ultrasound. Prenatal diagnosis may be established by fetal skin biopsy and extensive prenatal counseling should be offered to families on the basis of the prognosis and severity of this disease.

Acetylcholinesterase↗
PubMed1994

Cryobiology of the face fly and house fly (Diptera: Muscidae).

Face flies, Musca autumnalis De Geer, have a circumpolar distribution and overwinter as adults in reproductive diapause. House flies, Musca domestica L., have a cosmopolitan distribution and overwinter in northern latitudes in animal confinement quarters. We compared supercooling points with low temperature tolerances, as measured by bioassays, in all developmental stages of both species. There was no correlation between supercooling points and the ability to survive subzero temperatures. Rapid cold hardening was induced in adults of both species by a 2-h acclimation period at 0 degrees C. Hemolymph melting points were measured osmometrically in diapausing and reproductive face flies. Freezing point depressions differed between diapausing and reproductive flies and between reproductive flies given a 2-h pre-exposure to 0 degrees C and unexposed flies. Our data suggest that a -8 to 8 degrees C range with a mean close to 0 degrees C is necessary for successful face fly overwintering. House fly overwintering sites must offer microhabitats that remain above -5 degrees C with sufficient time above 10 degrees C to allow larval, pupal, and ovarian development.

Acclimatization↗
PubMed1994

Evaluation of a combined two- and three-dimensional compression method using human visual characteristics to yield high-quality 10:1 compression of cranial computed tomography scans.

RATIONALE AND OBJECTIVES: The compression of cranial computed tomography scans was improved by using independent intra- and interframe compression techniques. METHODS: For intraframe compression, an image was decomposed into four subimages, one subimage was chosen as a reference subimage, and three of the subimages were predicted from the reference subimage. The prediction error was encoded with a classified vector quantizer (CVQ) based on human visual perception characteristics. Interframe redundancy is exploited by a displacement estimated interslice (DEI) algorithm that encodes the differences between reference subimages from adjacent slices. This combined DEI/CVQ method was subjectively evaluated by 13 radiologists under a blinded protocol, and was compared to the CVQ method alone, the DEI method alone, the original images, and to a standard intraframe discrete cosine transform (DCT) compression method. RESULTS: Only the combined DEI/CVQ method at 10:1 compression was not scored significantly different from the original images. At 15:1 compression, the DEI/CVQ method was scored significantly better than the 10:1 DCT and any other 15:1 compression methods. CONCLUSIONS: Compressed image quality is enhanced by exploiting inter- and intraframe redundancy, and by modeling some characteristics of human visual perception. The DEI/CVQ method is well-suited for progressive transmission, and thus, holds potential in teleradiology as well as picture archiving and communications systems.

Analysis of Variance↗
PubMed1994

Isolation and characterization of cDNAs encoding the vacuolar H(+)-pyrophosphatase of Beta vulgaris.

The H(+)-pyrophosphatase (V-PPase) of plant vacuolar membranes catalyzes the electrogenic translocation of H+ from the cytosol to vacuole lumen and, in parallel with the vacuolar H(+)-ATPase located in the same membrane, establishes the inside-acid, inside-positive H(+)-electrochemical potential difference responsible for energizing the H(+)-coupled transport of solutes into the vacuole. The results of previous investigations suggest that the gene encoding the substrate-binding subunit of the V-PPase is present in a single copy in the genome of Arabidopsis thaliana (V. Sarafian, Y. Kim, R.J. Poole, P.A. Rea [1992] Proc Natl Acad Sci USA 89: 1775-1779), but it is not known whether the situation in Arabidopsis is typical of most vascular plants. With the objective of assessing the general applicability of this finding and acquiring sequence data for structure-function analyses of the enzyme from Beta vulgaris, we have sought to isolate cDNAs encoding the V-PPase from this organism by screening a Beta cDNA library constructed in lambda ZAP with the Arabidopsis cDNA insert (AVP) encoding the V-PPase. The results of these investigations demonstrate that at least two genes encode the V-PPase in Beta. Restriction and sequence analyses of the cDNAs from Beta reveal two classes, designated BVP1 and BVP2. BVP1 and BVP2 encode closely related but distinct polypeptides with computed masses of 80,550 and 80,000 D, respectively, exhibiting 88% identity with each other and 89% identity with the corresponding polypeptide from Arabidopsis. The nucleotide sequences of BVP1 and BVP2, on the other hand, are 70% identical within their coding regions but less than 28 and 53% identical within their respective 5' and 3' noncoding regions. Southern analyses of Beta genomic DNA confirm that two genes encode the V-PPase, and northern analyses of polyadenylated RNA isolated from a range of tissue types and probed with RNAs transcribed from the 3' noncoding sequences of BVP1 or BVP2 indicate that both genes are expressed in the intact plant. On the basis of these findings and the recent demonstration of then sufficiency of the substrate-binding polypeptide, alone, for all of the known catalytic functions of the V-PPase (E.J. Kim, R.-G. Zhen, P.A. Rea [1994] Proc Natl Acad Sci USA [91:6128-6132]), the two cDNA species isolated from Beta are concluded to encode variant, possibly isoforms, of the enzyme.

Amino Acid Sequence↗
PubMed1994

Assessment of the accuracy of color Doppler flow mapping by digital image analysis.

An in vitro steady flow experiment was performed in order to test the accuracy of velocity measurements obtained through color Doppler flow mapping (CDFM). Using the American Society of Echocardiography (ASE) flow phantom, low (maximum velocity = 60 cm/sec), medium (maximum velocity = 300 cm/sec) and high (maximum velocity = 600 cm/sec) speed accelerating flow fields, in which multiple aliases were visible, were imaged. A fully automatic computer algorithm was used to unwrap the aliases and to convert the CDFM to digital velocity. Packet size and wall filter frequency on the ultrasound machine were varied and the measured velocity compared to the true velocity. The results show that the velocity obtained in this way from the CDFM is very accurate at the low and medium velocities, but for the high velocity the turbulence is too intense to obtain an accurate result. There was no marked difference between the data for different packet sizes or wall filter settings.

Algorithms↗
PubMed1994

Homologous recombination of monkey alpha-satellite repeats in an in vitro simian virus 40 replication system: possible association of recombination with DNA replication.

To study homologous recombination between repeated sequences in an in vitro simian virus 40 (SV40) replication system, we constructed a series of substrate DNAs that contain two identical fragments of monkey alpha-satellite repeats. Together with the SV40-pBR322 composite vector encoding Apr and Kmr, the DNAs also contain the Escherichia coli galactokinase gene (galK) positioned between two alpha-satellite fragments. The alpha-satellite sequence used consists of multiple units of tandem 172-bp sequences which differ by microheterogeneity. The substrate DNAs were incubated in an in vitro SV40 DNA replication system and used to transform the E. coli galK strain DH10B after digestion with DpnI. The number of E. coli galK Apr Kmr colonies which contain recombinant DNAs were determined, and their structures were analyzed. Products of equal and unequal crossovers between identical 172-bp sequences and between similar but not identical (homeologous) 172-bp sequences, respectively, were detected, although those of the equal crossover were predominant among all of the galK mutant recombinants. Similar products were also observed in the in vivo experiments with COS1 cells. The in vitro experiments showed that these recombinations were dependent on the presence of both the SV40 origin of DNA replication and SV40 large T antigen. Most of the recombinant DNAs were generated from newly synthesized DpnI-resistant DNAs. These results suggest that the homologous recombination observed in this SV40 system is associated with DNA replication and is suppressed by mismatches in heteroduplexes formed between similar but not identical sequences.

Animals↗
PubMed1994

Predictive respiratory gating: a new method to reduce motion artifacts on CT scans.

PURPOSE: To evaluate a gating system, called predictive respiratory gating (PRG), that reduces motion-induced artifacts on computed tomographic (CT) scans of patients who cannot suspend respiration. MATERIALS AND METHODS: PRG uses a respiration monitor and a new algorithm to predict when a motionless period is about to occur. It automatically starts scanning so the scan is temporally centered around the motionless period at end inspiration or end expiration. To demonstrate PRG, CT was performed on a motion phantom and a quietly breathing volunteer with and without gating. RESULTS: Scans of the phantom obtained with PRG contained less motion-induced streaking and blurring than did scans acquired without PRG. Scans of the volunteer gated at end expiration contained significantly less artifact than nongated scans (P < .03). CONCLUSION: PRG reduced motion artifact on scans of a spontaneously breathing volunteer. PRG may be able to reduce motion artifacts on scans of patients unable to suspend respiration.

Adult↗
PubMed1994

Changes in airway resistance during sleep onset.

Ventilation is lower during sleep than wakefulness. An increase in airway resistance has been proposed as the critical factor. As the change in ventilation has been shown to occur abruptly at transitions between alpha and theta electroencephalogram activity, it was of interest to determine whether the increase in airway resistance between wakefulness and sleep also occurs at these transitions. Three young healthy male subjects were run for an average of 15 sleep onsets in each of three conditions. The three conditions were 1) an esophageal balloon was put in place to allow the measurement of airway resistance, 2) in addition to an esophageal balloon the nose was occluded, and 3) there was no esophageal balloon and the nose was not occluded. Ventilation and airway resistance were measured during sleep onset and analyzed as a function of arousal state. In those conditions of the experiment in which airway resistance was affected by state, the changes, like those in ventilation, occurred at transitions between alpha and theta electroencephalogram activity. However, in the three subjects studied, the magnitude of ventilatory changes at alpha-theta transitions and the extent to which changes in ventilation were associated with changes in airway resistance differed between subjects. It was concluded that although inspiratory airway resistance is a major component affecting the state-related changes in ventilation at sleep onset, the degree of its contribution may vary over individuals.

Adult↗