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S Kim

Publications and source records attributed to S Kim.

At least 1,333 records · Page 74Linked to original sources
PubMed1986

Rho-dependent transcription termination of a bacterial operon is antagonized by an extrachromosomal gene product.

The psu gene product of "phasmid" (phage-plasmid) P4 acts as a transcription antitermination factor in trans and in cis, respectively, within the morphogenic operons of its P2 phage helper during lytic viral development and on P4 itself during the establishment stage of its alternative mode of propagation as a plasmid. Here we show that psu also antagonizes activity of the Escherichia coli transcription termination factor rho at the terminator of the trp operon. Such a finding provides to our knowledge the first direct evidence for antitermination activity at a known rho-dependent site by the psu gene product. It also reveals an example of an extrachromosomal gene product that acts on specific sites of three different genomes to regulate expression of unlinked families of genes.

Coliphages↗
PubMed1986

Multiple control elements in the TRP1 promoter of Saccharomyces cerevisiae.

The TRP1 promoter generates two groups of mRNAs, transcript I and transcript II. The difference in size between the largest and smallest mRNAs is about 200 base pairs. A series of one-sided and internal deletions were constructed in vitro throughout the TRP1 promoter, and the effect of each deletion on transcription was assessed by Northern blotting. We showed that 395 base pairs of the TRP1 promoter were sufficient for the normal transcription of all RNAs and that the promoter contained two control domains. The control domain for transcript I consisted of one positive element and one negative element, while the control domain for transcript II contained two positive elements. The negative element, mapped between -293 and -318, expression of transcript I. Two regions of transcript I. Two regions (-280 to -236 and -235 to -209) were required for accurate initiation of transcript I. Each region contained sequences homologous to known consensus sequences of the TATA box.

Aldose-Ketose Isomerases↗
PubMed1986

Efficient expression of the Saccharomyces cerevisiae PGK gene depends on an upstream activation sequence but does not require TATA sequences.

The Saccharomyces cerevisiae PGK (phosphoglycerate kinase) gene encodes one of the most abundant mRNA and protein species in the cell. To identify the promoter sequences required for the efficient expression of PGK, we undertook a detailed internal deletion analysis of the 5' noncoding region of the gene. Our analysis revealed that PGK has an upstream activation sequence (UASPGK) located between 402 and 479 nucleotides upstream from the initiating ATG sequence which is required for full transcriptional activity. Deletion of this sequence caused a marked reduction in the levels of PGK transcription. We showed that PGK has no requirement for TATA sequences; deletion of one or both potential TATA sequences had no effect on either the levels of PGK expression or the accuracy of transcription initiation. We also showed that the UASPGK functions as efficiently when in the inverted orientation and that it can enhance transcription when placed upstream of a TRP1-IFN fusion gene comprising the promoter of TRP1 fused to the coding region of human interferon alpha-2.

Base Sequence↗
PubMed1986

The influence of 5-hydroxytryptamine (serotonin) on blood flow in the dog pulp.

The effect of intra-arterial injection of 5-hydroxytryptamine (5-HT) on pulpal blood flow of the dog was determined using the 15-micron radioisotope-labeled microsphere injection method. Pulpal blood flow was significantly reduced following the 5-HT injection. This decrease in blood flow appeared to be due to vasoconstriction as determined by an increase in pulpal vascular hindrance. However, our findings do not preclude the possibility that blood flow was reduced as a result of passive compression of venules produced by vasodilation in a low-compliance environment.

Animals↗
PubMed1986

The development of an improved murine iontophoresis reactivation model for the study of HSV-1 latency.

The present study reviews the development of an effective murine iontophoresis reactivation model for the study of HSV-1 latency. In a series of experiments, Balb C mice latently infected with HSV-1 McKrae strain were iontophoresed with epinephrine X 3 days (EPI X 3/ION) or 6-hydroxydopamine X 1 day followed by topical epinephrine (6-HD ION/EPI). Reactivation and recovery of latent HSV-1 was determined by daily ocular swabs, titration, and neutralization. Additional studies determined the effect of topical ocular steroids on viral recovery rate. The results demonstrated no recovery of McKrae strain in Balb C (0%) with EPI X 3/ION, and no enhancement with topical steroids. 6-HD ION/EPI demonstrated a low recovery rate in mice (8%). However, the recovery rate was significantly increased to 50% by the addition of topical steroids to form the 6-HD ION/EPI/STEROID model, a useful experimental tool. The substitution of a clinical isolate, W strain, for McKrae strain further improved the model. The results demonstrated that, following the acute infection in mice, W strain was associated with a significantly higher (P = .001) survival rate than McKrae strain (81% vs. 52%). There was no statistically significant difference between the two strains, W vs McKrae, in Balb C mice comparing keratitis, establishment of latency (by co-cultivation), spontaneous shedding rate, or induced ocular shedding following iontophoresis. The development of an effective murine iontophoresis model offers an economical method which is uniquely suited for immunological and genetic studies of HSV-1 latency.

Administration, Topical↗
PubMed1986

[Hydromyelia combined with hydrocephalus].

A case of hydromyelia (syringomyelia) combined with hydrocephalus is presented. The patient was a 17-year-old-boy. He was a admitted to our hospital because of disturbance of fine movement of the right hand. Neurological examinations showed right hemiparesis, right upper muscle atrophy and sensory dissociation of C1-T2 dermatomes. This dissociated sensory impairment gradually deteriorated. CT scan performed 3 and 6 hours after the intrathecal injection of metrizamide revealed an intramedullary syrinx extending between C1 and T4 vertebral levels and communicating with the 4th ventricle. Ventriculo-peritoneal shunt with a multipurpose flushing device was done and at the same time continuous intracranial pressure (ICP) monitoring was done on- and off-state of shunt system. When the shunt was closed, B wave (systoric pressure: 40 mmHg) appeared frequently. When the shunt was opened, B wave disappeared and resting pressure and pulse pressure decreased. The signs and symptoms of this patient improved after placement of the V-P shunt. These results supported Gardner's hydrodynamic theory of hydromyelia (syringomyelia).

Adolescent↗
PubMed1985

In vitro biosynthesis of human renin and identification of plasma inactive renin as an activation intermediate.

The biosynthesis and post-translational modifications, including proteolytic processing and core glycosylation, of the human renin precursor have been studied in vitro in a cell-free system. For this purpose, highly enriched renin mRNA was isolated from a renin-producing juxtaglomerular cell tumor and translated in rabbit reticulocyte lysate containing [35S]methionine in the presence or absence of dog pancreas microsomal membranes. Fluorographic analysis of the radioactive translation products, immunoprecipitated and then resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, revealed that the primary translation product, preprorenin (Mr = 45,000), is initially processed to glycosylated prorenin (Mr = 47,000) during or shortly after its sequestration into the lumen of the microsomal membranes. The vectorial translocation across the membrane was confirmed by the observation that the proform was resistant to digestion with trypsin while preprorenin was sensitive. Radiosequencing and the use of prorenin-specific antibodies established the cleavage points of the pre- and profragment and showed that the in vitro precursor of human renin contains a 23-residue signal peptide and a 43-residue prosegment. The post-translational modification which, despite the removal of signal peptide, resulted in an increase in apparent Mr, reflects the glycosylation as examined using Xenopus oocytes microinjected with renin mRNA in the presence of tunicamycin, an inhibitor of protein glycosylation. Four anti-peptide antibodies which specifically recognize the NH2 terminus (Pro 1), two middle parts (Pro 2A and Pro 2B), and COOH terminus (Pro 3) of the prosegment, respectively, have been raised and used to characterize plasma prorenin. Renin precursors (pre- and prorenin) synthesized in vitro or in the kidney reacted with these antibodies (anti-Pro 1, anti-Pro 2A, anti-Pro 2B, and anti-Pro 3). However, quite unexpectedly, human plasma prorenin was recognized only by anti-Pro 3, indicating that plasma prorenin is a truncated version of intact prorenin, which lacks a large portion of the NH2 terminus of the prosegment and may represent an activation intermediate. This somewhat surprising result may lead to a better understanding of the exact roles and activation mechanisms of plasma prorenin existing in a relatively large amount.

Amino Acid Sequence↗