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Biomedical subjects

B K Lee

Publications and source records attributed to B K Lee.

At least 127 records · Page 7Linked to original sources
PubMed1982

Ecotropic murine leukemia virus DNA content of normal and lymphomatous tissues of BXH-2 recombinant inbred mice.

BXH-2 recombinant inbred mice spontaneously produce a B-tropic murine leukemia virus (MuLV) beginning early in life and have a high incidence of non-T-cell lymphomas. These traits are not characteristic of the progenitor strains (C57BL/6J and C3H/HeJ) or of 11 other BXH recombinant inbred strains. Since B-tropic virus expression may be causally related to the high incidence of lymphoma in this strain, we have analyzed the ecotropic MuLV DNA content of both normal and lymphomatous tissues of BXH-2 mice. Southern analysis and hybridization with an ecotropic MuLV DNA-specific probe showed that DNA of normal BXH-2 tissues contained both parental N-tropic MuLV proviruses but lacked endogenous B-tropic MuLV DNA sequences. In addition, none of 116 F1 hybrid mice derived from male BXH-2 mice spontaneously produced ecotropic MuLV early in life. These results suggest that the B-tropic virus is horizontally transmitted in BXH-2 mice. Southern analysis of DNA from tumor tissues of 12 BXH-2 mice showed that amplification of ecotropic-specific DNA sequences had occurred in lymphomatous tissues of 3 mice and suggested that these tumors were monoclonal. The number of newly acquired proviruses, which appeared to be structurally nondefective and integrated at different sites, varied from one to three copies. Since lymphomatous tissues from only 3 of 12 mice examined carried additional detectable ecotropic proviruses, these results suggest that amplification of ecotropic MuLV DNA sequences is not required for maintenance of transformation in BXH-2 lymphomas.

Age Factors↗
PubMed1982

Organization, distribution, and stability of endogenous ecotropic murine leukemia virus DNA sequences in chromosomes of Mus musculus.

The endogenous ecotropic murine leukemia virus DNA content and integration sites were characterized for 54 inbred strains and substrains of mice by restriction enzyme digestion, Southern blotting, and hybridization with an ecotropic murine leukemia virus DNA-specific probe. More than 75% of these strains carried endogenous ecotropic proviruses which were located in at least 29 distinct integration sites in chromosomes of Mus musculus. Fourteen of these proviruses have been assigned specific locus designations. Most, but not all, of the endogenous ecotropic proviruses were structurally indistinguishable by this analysis from the prototype AKR ecotropic virus, and the distribution of these proviruses followed known relationships among the inbred strains and substrains of mice. These results suggest that, in general, viral DNA integration preceded the establishment of inbred mouse strains and that these integrations are relatively stable.

Animals↗
PubMed1982

Occupational lead exposure of storage battery workers in Korea.

Two hundred and thirty-four lead workers employed in a storage battery factory in Korea were examined for lead in blood (PbB) and urine (PbU). delta-aminolaevulinic acid in urine (ALAU), coproporphyrin in urine (CPU), and haemoglobin. The dose-response relationship between PbB and ALAU suggested that a PbB below 50-60 micrograms/dl is a proper practical limit of biological monitoring for lead workers. The inter-relationship between PbB and ALAU or PbU was better explained by a segmental straight function than by a curvilinear function. Inclusion of data from workers whose PbB was below 30-40 micrograms/dl, if they comprise a relatively large proportion of the whole, seems to have a role as a dummy effect on the overall regression function causing the curvilinear trend. At a given blood lead concentration, the ALAU of lead workers increased with an increase in the duration of exposure. This could be explained by the chronic effect of lead on haem precursors. Semi-quantitative measurement of CPU still played an important part in the screening of lead workers due to its simplicity, showing high sensitivity (97.8%) in detecting lead workers with PbB of 60 micrograms/dl or over.

Adult↗
PubMed1981

Dilute (d) coat colour mutation of DBA/2J mice is associated with the site of integration of an ecotropic MuLV genome.

The single endogenous DBA/2J ectropic provirus segregated concordantly with the dilute (d) coat colour mutation on chromosome 9 in 53/53 DBA/2J-derived recombinant inbred mouse strains and all seven inbred and mutant strains tested that carry the d allele. Analysis of DNA from a spontaneous DBA/2J d revertant (d+2J) showed that these mice lack ecotropic-specific MuLV DNA sequences and suggested that the dilute mutation resulted from integration of an ecotropic provirus into the mouse genome.

Animals↗
PubMed1981

Kijanimicin (Sch 25663), a novel antibiotic produced by Actinomadura kijaniata SCC 1256. Fermentation, isolation, characterization and biological properties.

A novel antibiotic complex has been isolated form the fermentation broth of a new species of Actinomadura, A. kijaniata SCC 1256. The complex was separated form the broth by a solvent extraction procedure and consists of 1 major component, designated kijanimicin, and 3 minor components. Kijanimicin was isolated form the complex by column chromatography and/or preparative high pressure liquid chromatography. Structurally the compound is a unique, large acid enol antibiotic and possesses an unusual in vitro spectrum of activity against some Gram-positive and anaerobic microorganisms. In vivo it has also shown interesting activity against malaria.

Aminoglycosides↗
PubMed1979

Tetanus and diphtheria immunity in urban Minnesota adults.

Tetanus and diphtheria antitoxin levels were measured in 183 urban adults, using a hemagglutination technique. Protective levels (greater than 0.01 unit/mL) of tetanus antitoxin were present in more than 85% of sera from all subjects under 40 years of age and from men between 40 and 59 years old. A minority of women (36%) between 40 and 59 years of age, and of men (41%) and women (29%) over 60 years of age, were protected. Less than one quarter of the study group had protective levels (greater than 0.01 unit/mL) of diphtheria antitoxin. The results of the study suggest that a minority of middle-aged women and older adults have been appropriately immunized against diphtheria and tetanus.

Adolescent↗
PubMed1979

Biosynthetic pathway leading to gentamicin C2b.

Incubation of Micromonospora purpurea SC 1210 (NRRL 5467) with L-[methyl-14C]methionine yielded [methyl-14C]gentamicin A and methyl-14C-labeled antibiotic JI-20A in a molar radioactivity ratio of 9:2. We did not isolate methyl-14C-labeled gentamicin X2, which was expected as an intermediate based on the biosynthetic pathways proposed by others. Addition of methyl-14C-labeled antibiotic JI-20A to M. purpurea SC 1124 (NRRL 8102) yielded [methyl-14C]-gentamicin C1a and [methyl-14C]gentamicin C2b in variable molar radioactivity ratios. These data do not support the biosynthetic pathway leading to gentamicin C2b proposed by Testa and Tilley.

Fermentation↗
PubMed1979

Shear vs pressure as causative factors in skin blood flow occlusion.

An instrument was developed to measure the external pressure, shear, and pulsatile arteriolar blood flow existent at a given portion of the anatomy. Application of this device to the thenar eminence of 4 healthy subjects showed that externally applied pressure was approximately twice as effective as shear in reducing pulsatile arteriolar blood flow. The combination of pressure plus shear was found particularly effective in promoting blood flow occlusion. At a sufficiently high level of shear (roughly 100 g/cm2) the pressure necessary to produce occlusion was half that required when little shear was present.

Arterioles↗
PubMed1978

The association between Staphylococcus aureus bacteremia and bacteriuria.

The relationship between Staphylococcus aureus bacteremia and bacteriuria was studied over a five year period in three hospitals. In a Veterans Administration Hospital, 59 patients with Staph, aureus bacteremia had a urine culture within 48 hours of a positive blood culture. In 16 of 59 (27 per cent), greater than 10(5) Staph. aureus was recovered from the urine in pure culture. Six of these patients had apparent primary staphylococcal urinary tract infection. Clinical and laboratory parameters in the patients with staphylococcal bacteremia and bacteriuria were compared with those in 31 patients with staphylococcal bacteremia and sterile urine cultures. The two groups differed only in the more frequent occurrence of pyuria and proteinuria in the bacteriuric patients. In two other hospitals, staphylococcal bacteriuria occurred in 7 per cent of patients with Staph. aureus bacteremia and in 13 per cent of cases of staphylococcal endocarditis. Review of autopsy records for 33 patients who died within one month of their bacteremia failed to show a correlation between bacteriuria and the presence of renal abscess. Staphylococcal bacteriuria is a frequent and unexplained concomitant of Staph. aureus bactremia.

Abscess↗
PubMed1978

Method for qualitative determination of 2-deoxystreptamine.

We have developed a qualitative method to assay for the presence of 2-deoxystreptamine in hydrolysates of crude aminoglycoside preparations using a 2-deoxystreptamine-requiring idiotrophic mutant. The assay involves (i) incubation of a 2-deoxystreptamine-requiring mutant with 1 mg of a hydrolyzed preparation from a crude unknown antibiotic mixture per ml, and (ii) examination of the resultant incubation mixture for production of antibiotic(s) by disk assay.

Anti-Bacterial Agents↗
PubMed1978

Antibiotic biosynthesis by cofermentation of blocked mutants of two Micromonospora species.

Two aminocyclitol-negative Micromonospora mutants representing two different species, M. purpurea and M. inyoensis, and blocked at different steps in the biosynthetic pathway were paired and cofermented for the synthesis of antibiotics. The two blocked mutants were incapable of producing antibiotics alone except when 2-deoxystreptamine was added. When combined they produced gentamicins A, X(2), C(1a), and C(2b), which all have an amino group at the 2' position, and gentamicin B, which has a hydroxyl group at this position instead.

Anti-Bacterial Agents↗
PubMed1978

Uptake of (methyl-14C)-sisomicin and (methyl-14C)-gentamicin into bacterial cells.

Eight sensitive strains (two Staphylococcus aureus, two Escherichia coli, two Pseudomonas aeruginosa and two Klebsiella pneumoniae) and four resistant Pseudomonas aeruginosa strains were used to study uptake of sisomicin and gentamicin by the bacterial cells. In eleven out of the twelve organisms studied employing (methyl-14C)-sisomicin and (methyl-14C)-gentamicin, uptake of the former was found higher that that of the latter. In one organism, the uptake of the two antibiotics was similar. This higher uptake of sisomicin may help explain the superior potency of the antibiotic in relation to gentamicin.

Bacteria↗
PubMed1977

Biotransformation of sisomicin to gentamicin C2b.

Sisomicin was transformed to gentamicin C(2b) by Micromonospora rhodorangea NRRL 5326. The mechanisms involved in the biotransformation are the 6'-N-methylation and the (4'-5')-reduction. The progression of the methylation was followed by the isotope technique, but the reduction reaction was not monitored.

Gentamicins↗
PubMed1976

Formation of methylated and phosphorylated metabolites during the fermentation process of verdamicin.

In an attempt to understand the biosynthetic processes leading to the formation of verdamicin (end product), we have examined the patterns of the formation of methylated and phosphorylated metabolites, which resulted from either the addition of l-[methyl-(14)C]methionine or [(32)P]KH(2)PO(4) to the fermentation. Incorporation of label from l-[methyl-(14)C]methionine into the bioactive sisomicin, verdamicin, and the chromatographically polar components increased with the progression of time. Two methylated bioinactive metabolites were found in the culture broth after removal of the methylated bioactive metabolites. In contrast to the bioactive metabolites, incorporation of the methyl-(14)C label into the two methylated bioinactive metabolites decreased with the progression of time. A phosphorylated bioinactive metabolite (nonmethylated) was also found in the culture broth, fermented in the presence of [(32)P]KH(2)PO(4). The role of the phosphorylated metabolite in the biosynthesis of the bioactive metabolites cannot yet be explained.

Aminoglycosides↗