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Biomedical subjects

J K Lim

Publications and source records attributed to J K Lim.

86 records · Page 5Linked to original sources
PubMedDate not supplied

Site-specific instability in Drosophila melanogaster: evidence for transposition of destabilizing element.

In this study, we show that at least one lethal mutation at the 3F-4A region of the X chromosome can generate an array of chromosome rearrangements, all with one chromosome break in the 3F-4A region. The mutation at 3F-4A (secondary mutation) was detected in an X chromosome carrying a reverse mutation of an unstable lethal mutation, which was mapped in the 6F1-2 doublet (primary mutation). The primary lethal mutation at 6F1-2 had occurred in an unstable chromosome (Uc) described previously (LIM 1979). Prior to reversion, the fF1-2 doublet was normal and stable, as was the 3F-4A region in the X chromosome carrying the primary lethal mutation. The disappearance of the instability having a set of genetic properties at one region (6F1-2) accompanied by its appearance elsewhere in the chromosome (3F-4A) implies that a transposition of the destabilizing element took place. The mutant at 3F-4A and other secondary mutants exhibited all but one (reinversion of an inversion to the normal sequence) of the eight properties of the primary lethal mutations. These observations support the view that a transposable destabilizing element is responsible for the hypermutability observed in the unstable chromosome and its derivatives.

Animals↗
PubMedDate not supplied

Some toxicological aspects of sttanous fluoride after ingestion as a clear precipitatefree solution compared to sodium fluoride.

Weanling rats were administered 20, 380, and 20,000 ppm F as clear precipitatefree SnF2 solutions. Equivalent ppm F as NaF solution was similarly administered for comparison. The rats were autopsied at the end of the study for histological examination of kidney, liver, and incisors. The pathognomonic manifestations were correlated with the plasma F levels.

Administration, Oral↗
PubMedDate not supplied

Microencapsulation with carrageenan-locust bean gum mixture in a multiphase emulsification technique for sustained drug release.

A multiphase emulsification technique was modified in this process of micro-encapsulating gentamicin sulphate, thus avoiding the necessity for a surfactant in preparing the secondary emulsion for a W/O/W emulsion. Various proportions of iota-carrageenan (i-C) and locus bean gum (LBG) were investigated for the W/O/W emulsion after forming the primary W/O emulsion with sorbitan trioleate, Span 85. Upon removal of the oil phase (chloroform) from the W/O/W emulsion by heating (60-65 degrees C), microcapsules or 'W/W' particles containing drug dissolved in sodium hyaluronate were spontaneously formed. These were dispersed in a solution of a mixture of 5-10 per cent w/v polyvinyl alcohol, PVA (average MW 50,000-106,000; 98 per cent hydrolysed) and 3 per cent v/v polyethylene glycol 200 (PEG 200), and dried to form the hydrogel film casts. Our in vitro experiments in isotonic phosphate buffer solution (pH 7.4) at 37 degrees C, showed that the release of gentamicin sulphate was dependent on concentration of LBG, and concentration or molecular weight of PVA. With the exception of PVA hydrogel matrix preparations containing 20 per cent w/v LBG, all other formulations showed a significant initial 'burst' release of drug within 6 h. The drug-containing microcapsules in the PVA hydrogel film with 20 per cent w/v LBG, exhibited an almost zero-order release of drug up to 140 h. It is postulated that an effective barrier or high-density membrane enveloping the microcapsules was formed between i-C and LBG because of their unique molecular configurations. This phenomenon, together with the possible adsorption of i-C molecules at the transient oil and outer aqueous phase interface, presumably eliminated the need for a permanent oil phase and/or an O/W surfactant normally required for preparing W/O/W emulsions.

Biocompatible Materials↗
PubMedDate not supplied

Physeal injury in a lightning strike survivor.

Electrical injuries resulting in physeal injury in children are an uncommon but well-recognized clinical entity. Almost all these injuries are sustained from man-made electrical sources. To date, there have been no published cases of growth arrest after lightning strike. The authors report the case of a 12-year-old girl who survived a lightning strike 2 years ago and who presented with asymmetric growth arrest in both legs. The authors discuss the pathophysiology of lightning strike and consider the evidence for direct electrical injury versus ischemic insult to the physis as explanations for the cause of the growth arrest observed in this patient.

Child↗