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Biomedical subjects

J K Lim

Publications and source records attributed to J K Lim.

At least 73 records · Page 4Linked to original sources
PubMed1980

Site specificity of mutations arising in dysgenic hybrids of Drosophila melanogaster.

Mutations arising in dysgenic hybrids of Drosophila melanogaster were collected in the zeste-white region of the X chromosome. A preponderance of the mutations affected the zw1 locus; many of these were asociated with structural abnormalities including inversions, deficiencies, and insertions in the 3A3-4 region of the polytene chromosome map. The extreme sensitivity of the zw1 locus to the mutator activity of dysgenic hybrids contrasted with the apparent insensitivity of the zw2 locus. Other loci in the zeste-white region were weakly sensitive to the mutator activity. Insertions of two and six bands were seen between bands 3A4 and 3A6 in the chromosomes of one of the zw1 mutant stocks examined. Another insertion was detected at position 2F4-5 in a different stock. Many of the mutant chromosome were evidently unstable, as judged by secondary breakage in other parts of the X chromosome. The cytogenetic data are consistent with the idea that mutations arising in dysgenic hybrids are caused by transposable elements which insert preferentially at certain sites on the chromosomes.

Animals↗
PubMed1979

Beneficial effects of methionine and histidine in aspirin solutions on gastric mucosal damage in rats.

Amino acids methionine and histidine, which are soluble in propylene glycol, were investigated for their purported beneficial effects on aspirin-induced gastric mucosal damage in the rat. The pathognomonic changes observed microscopically in the fundic region of the stomach of animals administered daily doses (100 mg/kg), for up to 15 days, of aspirin solutions (0.36 M) in propylene glycol incorporated with the amino acids were compared with those of animals given equivalent quantities of aspirin in an aqueous suspension combined with an aluminum hydroxide antacid. A "delayed" onset of aspirin-induced cellular damage due to the presence of amino acids, analogous to that associated with the use of antacids, was found as determined partly by differences in the staining ability of injured cells with hematoxylin and eosin.

Animals↗
PubMed1979

Amino acid effect on aspirin stability in propylene glycol.

Temperature stability studies were conducted on 0.36 M (6.5% W/V) aspirin solutions including either 0.02 M L-methionine or 0.02 M histidine in propylene glycol. Aspirin was determined spectrophoto-fluorometrically as salicylic acid content at 412 nm. A 0.36 M aspirin in polyethylene glycol 400 solution was studied concurrently. Aspirin degradation rate constants, k, obtained from semilogarithmic plots of percent drug remaining versus time at 30-70 +/- 0.5 degrees were used for preparing Arrhenius plots. Good correlation was seen between predicted aspirin stability and experimental k25 degrees values. L-Methionine and histidine markedly reduced aspirin stability.

Amino Acids↗
PubMed1979

Site-specific instability in Drosophila melanogaster: the origin of the mutation and cytogenetic evidence for site specificity.

During a study of delayed mutations, an unstable X chromosome (Uc) was detected. Spontaneous X-linked recessive lethal mutations were detected in 34 of 993 sperm sampled from 50 males carrying this chromosome. All but three of the 34 lethals originated as clusters in three of the 50 males Cytogenetic and complementation analyses revealed 14 intrachromosomal rearrangements: ten inversions, two reverse repeats, one deficiency and one transposition. Eight of the 14 rearrangements have one break in the 6F1-2 doublet and two rearrangements have a break in 6F1-5 of the X chromosome. The remaining four rearrangements have in addition to the aberrations a lethal point mutation between 6F1 and 6F5. Though each of the lethal lines was established from a single lethal-bearing female, chromosome polymorphism is evident in 17 of the 18 lines having rearrangements, with certain aberrations recurring in several lines. The lethal mutations revert frequently to the nonlethal state, and cytological evidence indicates that more than one mutational event may occur at the unstable locus of the chromosome during one generation. Two lethal lines had more than one type of chromosome rearrangement sharing a common breakpoint. These observations are consistent with the view that the instability of the Uc lines is caused by a transposable element capable of site-specific chromosome breaks and perpetual generation of mutations. The mutagenic and genetic properties of transposable elements can be related to the two-mutation theory of KNUDSON (1971) for cancer initiation.

Animals↗
PubMed1979

A simple ultrasound method to characterize in vitro plaque inhibition activity.

A method employing ultrasound vibration for evaluating in vitro plaque derived from Streptococcus mutans was developed. It successfully detected small changes in the cohesive/adhesive characteristics of deposits briefly exposed to several antibacterials and "antiadherents". Increased structural fragility and diminished plaque growth were generally associated with the antibacterials.

Adhesiveness↗
PubMed1978

Nitroglycerin stability in polyethylene glycol 400 and povidone solutions.

The stability of solutions of nitroglycerin in several common pharmaceutical solvents and compounds used as tablet excipients was investigated using a UV spectrophoto metric assay. Included in the study were povidone (I), polyethylene glycol 400 (II), and solvents such as absolute alcohol, propylene glycol, and glycerol. At the elevatted temperatures of the accelerated stability studies, only II demonstrated a considerable adverse effect on the stability of the nitroglycerin solution. It is postulated that a "reaction compound" was formed between nitroglycerin and II which regenerated nitroglycerin depending on hydrolysis conditions. Based on the Arrhenius equation and with initial rates of up to 6 hr of degradation, the predicted stability for a II solution of nitroglycerin in terms of its 10% decomposition at 25 degrees was approximately 7 days.

Chemical Phenomena↗
PubMed1978

A comparative study of the effect of oxantel-pyrantel suspension and mebendazole in mixed infections with Ascaris and Trichuris.

A comparative trial was carried out in 4 orphanges in Seoul, to compare the anthelminthic efficacy of oxantel-pyrantel suspension and mebendazole tablets against mixed infections of Ascaris lumbricoides and Trichuris trichiura. 40 patients were divided into 4 groups and received oxantel-pyrantel suspension at 15 or 20mg/kg once only or on 2 consecutive days. Another group of 20 patients was treated with 100mg of mebendazole twice a day for 3 days. Both drugs achieved a 100% cure rate for Ascaris infections. Against Trichuris infections, the average cure rate and egg reduction rate of oxantel-pyrantel treated groups was 87.5% and 92.3% respectively, and that for mebendazole was 65% and 89.1%. There were no side-effects. The results of the present study suggest that oxantel-pyrantel is more effective in the treatment of mixed infections of Ascaris and Trichuris, and was more acceptable to the patients, than mebendazole.

Ascariasis↗
PubMed1978

Anthelminthic effect of oxantel and oxantel-pyrantel in intestinal nematode infections.

704 patients with intestinal nematode infestation were treated with oxantel and oxantel-pyrantel in either liquid or tablet form, at doses from 10 to 25mg/kg. All were given the drug or drugs as a single dose. In 699 patients with trichuriasis cure rates between 64 and 93% were obtained and there were egg reduction rates of between 90 and 100%. The best results were obtained using oxantel, either alone or in combination with pyrantel, at 15 to 20mg/kg. Only 2 of 152 patients with ascariasis were not cured after a single dose of pyrantel (given as oxantel-pyrantel) of 10, 15 or 20mg/kg, and both these patients were from the group given the lowest dose. Only mild side-effects were noted. The combination, oxantel-pyrantel is a safe and effective treatment for multiple intestinal nematode infection.

Adolescent↗
PubMed1976

Causes for removal of the eye: a study of 890 eyes.

This study is a review of 890 cases of eye enucleations performed over a period of 22 years. The major cause for enucleations was trauma, accounting for 39.7% of the eyes enucleated. Chronic inflammatory diseases accounted for 22.1%, glaucoma for 11.5% and tumours for 9.2% in this group. Retinal diseases were responsible for 5.5% of the eyes; vascular occlusion for 5%; and miscellaneous causes for the remaining 7%. Injuries were everyday tools and small flying missiles caused most of the trauma. Previously planned surgical operations accounted for 15% of the enucleations. Forty-eight of these eyes had epithelial or fibrous downgrowths resulting from inflammation, secondary glaucoma, and phthisis bulbi. A more careful selection of cases and better surgical techniques might significantly lower these statistics. Also, vascular occlusion should be given a high level of suspicion in all intractable cases of glaucoma of unexplained etiology. As a general rule, enucleations should not be performed because of the suspected presence of sympathetic ophthalmia.

Adolescent↗
PubMed1975

Intestinal pH as a factor in selection of animal models for bioavailability testing.

Previous in situ studies showed that intestinal drug absorption is strongly influenced by intestinal pH. Three animal species considered for bioavailability testing were studied in situ to determine intestinal pH. Results from the rat and dog correlated well with results in humans, while results from the rabbit did not. The rabbit appears to be a poor candidate for attempted animal-human bioavailability correlations.

Animals↗
PubMed1975

Complementation analysis of methyl methane-sulfonate-induced recessive lethal mutations in the zeste-white region of the X chromosome of Drosophila melanogaster.

Recessive lethan mutations in the 3A1 to 3C2 region of the X-chromosome of Drosophila melanogaster were detected in 113 of 33,544 sperm treated by feeding 5 mM methyl methanesulfonate in 1% sucrose for 22 hours. Seven of the 113 lethans were sterile, leaving 106 for analysis by complementation tests. With only one exception, these mutants were found to have lesions restricted to single loci. One of these single-site mutations was in qt, 2 in tko, 18 in zw-1, 12 in zw-8, 6 in zw-4, 3 in zw-10, 3 in zw-13, 21 in zw-2, 7 in zw-3, 5 in zw-6, 6 in zw-12, 1 in zw-7, 12 in zw-5, 5 in zw-11, and 3 in zw-9. One of the lethals, m69, was non-complementary to two adjacent loci, zw-2 and zw-3, possible indicating a deletion encompassing two loci. The results confirm that there are at least 15 recessive lethal loci in the region and are consistent with the hypothesis of LIM and SYNDER (1968 and 1974) that inability of monofunctional alkylating chemicals to induce deletion associated mutations is a characteristic of the compounds.

Animals↗