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Biomedical subjects

J Kim

Publications and source records attributed to J Kim.

At least 1,117 records · Page 62Linked to original sources
PubMed1988

Facilitation of Hb S polymerization by the substitution of Glu for Gln at beta 121.

In an effort to clarify the role of Glu-beta 121 of Hb S molecules in polymerization, we studied the solubility and kinetics of polymerization of various mixtures of deoxyhemoglobins S (Glu-beta 6----Val) and D Los Angeles (Glu-beta 121----Gln). It is known that patients with Hb S-D Los Angeles have a relatively severe clinical course. Mixtures of Hb S and Hb D Los Angeles polymerized after a distinct delay time, the length of which depended on the initial hemoglobin concentration and the fraction of Hb S in the mixture. There was a linear relationship between the logarithmic plot of delay time and initial hemoglobin concentration. The line for a 1:1 mixture of Hb S and Hb D Los Angeles shifted to the right of that for deoxy-Hb S by 0.08. This shift is much smaller than the shift of 0.32 for 1:1 AS mixtures. From these data, the probability factor for nucleation of S-D Los Angeles hybrid hemoglobin was calculated to be 1.16, which is higher than that of Hb S (1.0) and AS hybrid hemoglobin (0.5). The degree of co-polymerization of Hb D Los Angeles in S-D Los Angeles mixtures was similar to that of Hb A in AS mixtures. The critical concentration for the polymerization of Hb D Los Angeles was between that of Hb A and Hb Machida, which has the same amino acid substitution (Glu----Gln) at the beta 6 position. These results suggest that the protein interaction of Hb S molecules during nucleation involves at least two steps. First, the Val-beta 6 of a Hb S molecule interacts hydrophobically with the Phe-beta 85 and the Leu-beta 88 of an adjacent Hb S molecule. In the second step, Glu-beta 121 weakens the interaction with His-beta 116 and Pro-alpha 114. The substitution of Glu-beta 121----Gln may strengthen this second reaction and facilitate nucleation as well as polymerization.

Glutamates↗
PubMed1988

Cloning and analysis of a yeast genomic DNA sequence capable of directing gene transcription in Escherichia coli as well as in yeast.

A DNA fragment was isolated from yeast genomic sequences by its ability to direct the transcription of promoterless CmR (cat) gene in Escherichia coli and in yeast. Nucleotide sequencing and primer extension analysis showed that yeast DNA contains sets of consensus sequences pertaining to prokaryotic and yeast-type promoter elements. It was designated as yeast- and E. coli-type promoter (YEP1). Typical E. coli-type promoter elements are found at appropriate positions: TATTTT from -12 to -7 and TTGTCC from -35 to -30 with their spacing of 17 bp from the single mRNA start point determined by the primer extension. Analysis of cat transcripts from yeast cells showed that the YEP1 caused multiple transcription initiations at more than 20 different points that are spaced over a 100-bp region. The DNA is composed of A + T-rich sequences and putative TATA-like sequences are found at several places upstream from the transcription start points. Deletion analysis showed that a 276-bp sequence between -872 and -596 from the initiating ATG codon was required for the maximal promoter activity in yeast but not in E. coli.

Base Sequence↗
PubMed1988

The mechanisms of action of E. coli endonuclease III and T4 UV endonuclease (endonuclease V) at AP sites.

Treatment of DNA containing AP sites with either T4 UV endonuclease or with E. coli endonuclease III followed by a human class II AP endonuclease releases a putative beta-elimination product. This result suggests that both the T4 endonuclease and E. coli endonuclease III class I AP endonucleases catalyze phosphodiester bond cleavage via a lyase- rather than a hydrolase mechanism. Indeed, we have not detected a class I AP endonuclease which hydrolytically catalyzes phosphodiester bond cleavage. Whereas these enzymes use a lyase-like rather than a hydrolytic mechanism, they nonetheless catalyze phosphodiester bond cleavage. We suggest that the term endonuclease can be properly applied to them.

Bacterial Proteins↗
PubMed1988

The MAL63 gene of Saccharomyces encodes a cysteine-zinc finger protein.

Inducible maltose fermentation by Saccharomyces carlesbergensis requires the product of the MAL63 gene of the MAL6 locus. It has been suggested that this gene product is an activator protein controlling the expression of the structural genes encoding the maltose fermentative enzymes perhaps by binding to DNA sequences upstream of these genes. We report the sequence of the MAL63 gene. A single open reading frame is seen capable of encoding a protein of 470 amino acid residues. The deduced sequence of this protein indicates that it is a cysteine-zinc finger protein supporting the hypothesis that the MAL63 gene product is a DNA binding protein.

Amino Acid Sequence↗
PubMed1988

Characterization of ischemia-induced loss of epithelial polarity.

Total renal ischemia for various time intervals (0-50 min) resulted in the rapid and duration-dependent redistribution of polarized membrane lipids and proteins in renal proximal tubule cells. Following only 15 min of ischemia, apical membrane enrichment of NaK-ATPase, normally a basolateral membrane (BLM) enzyme, had increased (1.6 +/- 0.6 vs. 2.9 +/- 1.2, P less than 0.01). In vivo histochemical localization of NaK-ATPase showed reaction product throughout the apical microvillar region. PTH-stimulatable adenylate cyclase, another BLM protein, was also found in ischemic but not control apical membrane fractions. One dimensional SDS-PAGE showed four bands, present in control BLM and ischemic apical membranes, which could not be found in control apical membrane fractions. Immunohistochemical localization of leucine aminopeptidase (LAP) showed the enzyme was limited to the apical domain in control cells. Following ischemic injury (50 min), LAP staining could be seen within the cell and along the BLM. Following 24 hr of reperfusion, the BLM distribution of LAP was further enhanced. With cellular recovery from ischemic injury (5 days), LAP was again only visualized in the apical membrane. Duration-dependent alterations in apical and BLM lipids were also observed. Apical sphingomyelin and phosphatidylserine and the cholesterol-to-phospholipid ratio decreased rapidly while apical phosphatidylcholine and phosphatidylinositol increased. Taken together, these results indicate renal ischemia causes rapid duration-dependent reversible loss of surface membrane polarity in proximal tubule cells.

Adenylyl Cyclases↗
PubMed1988

Pseudallescheria boydii brain abscess. Complication of an intravenous catheter.

An adult patient survived a brain abscess with Pseudallescheria boydii. She received intraventricular miconazole, 20 mg every 72 hours (minimal inhibitory concentration = 0.4 microgram/ml), and surgery. The abscess resulted from an infected central venous catheter (Port-A-Cath) and steroid therapy. Miconazole caused a ventriculitis. There are 12 reported cases of P. boydii brain abscesses from 1965 to 1985 with only two survivors.

Adult↗
PubMed1988

Proportion and location of spinal neurons receiving ventral root afferent inputs in the cat.

Spinal neurons receiving ventral root afferent inputs were investigated in anesthetized and paralyzed cats. We were concerned with the afferent fibers in the ventral root that travel distally and then enter the spinal cord through the dorsal root. The questions to be answered included the proportion and distribution of spinal neurons receiving ventral root afferent inputs and their peripheral input characteristics. The 1.7 ventral root was cut near the spinal cord and the distal stump was stimulated while making a systematic search for neurons in the entire gray matter of the ipsilateral spinal cord that responded to the stimulation. The following conclusions were made: (i) the afferent fibers in the cat ventral root enter the spinal cord through the dorsal root and evoke a variety of responses (excitation, inhibition, or mixed) in a large proportion of spinal neurons (about 20%): (ii) these responses seem to be mediated largely by spinal mechanisms: (iii) spinal neurons receiving ventral root afferent inputs are situated in a wide region of the ventral spinal cord: (iv) ventral root fibers in a single root enter the spinal cord and exert their responses over a large region of the spinal cord (at least two spinal segments rostrally and caudally): (v) some of the spinal neurons that responded to ventral root stimulation were found to be ascending tract cells, suggesting that ventral root afferent inputs can reach supraspinal structures: (vi) ventral root afferent fibers converge onto spinal neurons that have a variety of peripheral receptive field characteristics: and (vii) with some exceptions, most neurons receiving ventral root inputs were excited best by mechanical and/or thermal noxious stimuli applied to the periphery.

Afferent Pathways↗
PubMed1988

Studies with a monoclonal antibody to the beta subunit of the receptor with high affinity for immunoglobulin E.

The receptor with high affinity for IgE consists of a tetrameric complex of polypeptides, one of which (alpha), contains the binding site for IgE. The function of the other chains--a single beta and two disulfide-linked gamma chains--is unknown. We report the cloning of a murine hybridoma that secretes an IgG1 antibody which specifically reacts with the beta subunit. Studies with this monoclonal antibody show that the subunit stoichiometry of the receptor is unaffected by the presence or absence of bound IgE. We also found that under certain conditions where the alpha beta gamma 2 complex dissociates, beta remains attached to the dimer of gamma chains, indicating that these chains contact each other in the native receptor. In rat basophilic leukemia cells--a neoplastic line of mucosal-type mast cells--all of the beta subunits expressed by the cells appeared to be associated with the high affinity receptor. However, in at least one cell line which has no high affinity receptors--a putative rat lymphoma line--beta or beta-like polypeptides were also expressed.

Animals↗
PubMed1988

Intraventricular cryptococcal granuloma. Report of two cases.

Infection by Cryptococcus neoformans, a budding nonmycelial yeast, involves the central nervous system in 70% of patients at the time of diagnosis. Meningitis and meningoencephalitis are common manifestations of infection; solid granulomas occur but are unusual, and intraventricular granulomas are distinctly rare. Two cases of intraventricular cryptococcal granuloma are reported. The diagnosis and treatment of mass lesions due to cryptococcal infection are discussed, with special reference to intraventricular granulomas.

Brain Diseases↗
PubMed1988

Phospholipase A2 activity associated with synovial fluid cells.

High activity of phospholipase A2 (PLA2) has been detected in synovial fluids (SF) in inflammatory arthritides. Since the source(s) of SF PLA2 has not been identified, we tested PLA2 content in SF cells obtained from 11 SF. Cell sonicates were prepared at 5 X 10(6) cells/ml. In the supernatants of the sonicated SF cells (n = 11), PLA2 activity ranged from 38-755 U/ml, mean 368 +/- 243 (SD) U/ml, compared to 5-64 U/ml, mean 31 +/- 15 (SD) U/ml in sonicates of normal peripheral blood PMN (n = 5) (p less than 0.0001). Spontaneous release of PLA2 from unstimulated SF cells ranged from 26-365 U/ml, mean 131 +/- 144 (SD) U/ml (n = 5), whereas spontaneous release from peripheral blood PMN was negligible. Neither 10(-8) M FMLP nor 5 X 10(-6) M dexamethasone altered extracellular PLA2 release. To assess whether PLA2 adsorbs passively to cell membranes through hydrophobic interaction, normal peripheral PMN were incubated in crude SF (n = 7) with PLA2 ranging from 4,000-24,300 U/ml, or with purified human SF PLA2 or Naja naja PLA2. We found that soluble PLA2 adsorbed to PMN membranes in a concentration dependent fashion. PLA2 activity in sonicates of PMN incubated in crude SF ranged from 185-358 U/ml compared to controls of 21-64 U/ml. Sonicates of PMN incubated with purified human SF PLA2 (5,000-30,000 U/ml) showed progressive concentration dependent increase in PLA2 from 7 +/- 4 to 212 +/- 11 (SD) U/ml (p less than 0.001). PMN incubated with Naja naja PLA2 also showed marked increase in the content of PLA2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1988

Mechanism of caffeine repression of mitomycin C induced reversion in Salmonella typhimurium strain TA94.

Caffeine significantly repressed his- reversion of Salmonella typhimurium TA94 induced by mitomycin C (MMC). The decrease in the number of revertants with increasing concentrations of caffeine was accompanied by a decrease in cell viability. Reversion rates (revertants/viable cells) in the presence of caffeine were higher than in the absence of caffeine. The results of this study indicate that the apparent antimutagenic activity of caffeine on MMC induced reversion is due to the potentiation by caffeine of MMC-induced lethality.

Caffeine↗
PubMed1988

Pleural amyloidosis.

Pleural amyloidosis has been reported rarely, and the diagnosis of this disease by Cope needle biopsy has, to our knowledge, been reported only once previously. We report two patients in whom the diagnosis of pleural amyloidosis was made by biopsy specimens obtained in the examination of large, unilateral pleural effusions. In one patient, the diagnosis was made by Cope needle biopsy. The clinical and diagnostic significance of these cases are discussed.

Aged↗
PubMed1987

A method to isolate DNA sequences that are promoter-active in Escherichia coli and in yeast.

A method convenient for isolation of DNA sequences capable of directing gene transcription in both organisms of E. coli and yeast is described. The method is composed of sequential steps of phenotypic selection for chloramphenicol resistance, first in E. coli and then in yeast. A series of promoter-probe, shuttle plasmid vectors between yeast and E. coli were constructed and utilized in the method.

Chloramphenicol↗