PubMed Health⌕ Search

Biomedical subjects

I Abrahams

Publications and source records attributed to I Abrahams.

17 recordsLinked to original sources
PubMed2004

Study on the role of 5-fluorouracil in the polymerization of butylcyanoacrylate during the formation of nanoparticles.

The possible involvement of 5-fluorouracil (5FU) in the initiation process of the polymerization of n-butylcyanoacrylate monomer during nanoparticle formation was investigated. 5FU in acidic solution (pH 2-3) may interfere in the initiation process through its amino groups via the formation of zwitterions. The proposed zwitterionic mechanism of initiation was supported by the molecular weight profiles of the polymer, determined by gel permeation chromatography, and the covalent linkage of the cytostatic to the main polymer chain. H NMR analyses clearly demonstrated that a significant fraction of 5FU was covalently bonded to the poly(butylcyanoacrylate) chains through its amino groups preferentially through one of the two nitrogen atoms. In vitro release study performed shows that the investigated 5FU-loaded PBCN are suitable for sustaining delivery of 5FU.

Antimetabolites, Antineoplastic↗
PubMed2003

Poly(butylcyanoacrylate) nanoparticles for topical delivery of 5-fluorouracil.

Poly(butylcyanoacrylate) nanoparticles (PBCN) as a drug carrier of 5-fluorouracil (5FU) intended for topical treatment of skin lesia were investigated. The presence of 5FU (as saline solution, pH 10-11) in the polymerization medium affected the polymerization as well as the nanoparticle formation by influencing the initiation of the polymerization reaction. 5FU acted as an initiator in the anionic polymerization of n-butylcyanoacrylate monomer through its nucleophilic nitrogen centers. The results obtained by GPC, 1H NMR, and X-ray diffraction allude to a possible mechanism of cytostatic immobilization in the polymer matrix, with evidence for both free and bound forms of the drug.

Administration, Topical↗
PubMed2001

Investigation of thermal parameters and crytallisation in a ternary CaO-Na2O-P2O5-based glass system.

This paper presents the results of a study of the thermal properties of a range of phosphate-based glasses in the system CaO-Na2O-P2O5. The glasses had a fixed P2O5 content of 45 mol% and the CaO:Na2O ratio was varied. The glasses were produced and ground and their thermal properties measured using a Setaram differential thermal analyser (DTA). Initial data showed that for the high Na2O containing glass, NaPO3 forms and a second unidentified phase that is probably calcium rich. In the middle compositional region, multiple phases precipitated out and were identified as NaPO3 and Na4Ca(PO3)6. For the high CaO content glasses, Na4Ca(PO3)6 was the only phase formed. Further studies were carried out to examine whether the phases were bulk or surface nucleating, by grinding the samples to different particle sizes. From this data, it is evident that the NaPO3 forms via a bulk nucleation mechanism and that Na4Ca(PO3)6 forms via surface nucleation. The factors controlling this precipitation process are discussed and ionic radius as a controlling factor is hypothesised.

Calcium Compounds↗
PubMed2001

Investigation of the solubility and ion release in the glass system K2O-Na2O-CaO-P2O5.

Glasses from the quaternary glass system K2O-Na2O-CaO-P2O5 were produced by standard glass forming techniques. The compositions were limited by fixing the P2O5 at 45 mol%, fixing the CaO content at either 20, 24 or 28 mol%. The K2O and Na2O made up the residual varying from 0 to 25 mol% K2O. General trends showed that with increasing CaO content, the glasses showed a decrease in solubility as expected. For a single system of fixed CaO content, with increasing K2O content, there was an increase in solubility. This was seen at all three CaO contents. All the glasses showed an initial increase in pH followed by a gradual decrease with time and this was accounted for by the initial release of Na+ ions into solution. For the ion release curves, for all fixed CaO contents, the glass with 0 mol% K2O showed the lowest Ca2+ release. This was accounted for as being due to the low solubility compared to the K2O containing glasses. The Na+ release appeared anomalous, as it was higher than all the K2O containing glasses. Even though the glasses with 0 mol% K2O showed the lowest solubility, the amount of Na+ contained in the glass was high, hence the high levels of release.

Glass↗
PubMed2000

Development of soluble glasses for biomedical use Part I: in vitro solubility measurement.

In this study soluble glasses have been developed for biomedical applications containing P2O5 as a network former and CaO and Na2O as modifiers. This study shows that as expected, the glasses have an inverse exponential relationship between solubility and CaO content. Furthermore, there is evidence for compositional related non-linearity in the dissolution of the glasses with time. This is thought to be due to either layer formation on the glass surface hindering ion diffusion, ion exchange process or change of ionic strength of the solution. Bioactivity of these glasses is indicated by the formation of a brushite precipitate, a precursor to apatite formation. Further evidence for bioactivity is also presented in the second part of this paper.

Journal Article↗
PubMed1999

Porphyria cutanea tarda occurring in a patient with renal failure, systemic lupus erythematosus and chronic hepatitis C infection treated with hemodialysis.

The diagnosis and management of porphyria cutanea tarda (PCT) is complicated when it occurs in the context of renal failure, chronic hemodialysis, and anemia. We report a case of a woman who presented with painful acral blisters and hyperpigmentation. Her medical history included systemic lupus erythematosus, chronic hepatitis C infection, and renal failure necessitating chronic hemodialysis with a baseline anemia. A highly elevated serum porphyrin level led to the diagnosis of PCT. Treatment with small repeated phlebotomies and concomitant administration of erythropoietin was effective in managing her PCT.

Adult↗
PubMed1994

Giant cell lichenoid dermatitis: a possible manifestation of sarcoidosis.

Giant cell lichenoid dermatitis is a recently described dermatosis thought to be an unusual lichenoid drug eruption. It is characterized by a generalized, pruritic, papulosquamous eruption sparing palms, soles, face and mucous membranes. Histopathologic findings include areas of epidermal hyperplasia and atrophy with focal vacuolar alteration of the basal layer, exocytosis and cytoid body formation. The dermis contains a band-like, mononuclear cell infiltrate at the dermoepidermal junction with admixed eosinophils, plasma cells and large multinucleate cells. The histologic differential diagnosis includes infectious processes, sarcoidosis, lichen nitidus, lupus erythematosus and lichen planus. We report 3 patients with giant cell lichenoid dermatitis, one of whom was subsequently diagnosed as having sarcoidosis. Because giant cell lichenoid dermatitis may resemble sarcoidosis both clinically and histologically, and because cutaneous sarcoid is often associated with systemic involvement, the diagnosis of sarcoid should be strongly considered in patients with giant cell lichenoid dermatitis.

Aged↗
PubMed1987

EXAFS studies of metallothionein.

Extended x-ray absorption fine structure (EXAFS) has been used to investigate the metal environment in a number of metallothioneins (MT). In all cases, the primary coordination sphere consists of sulphur atoms. In some cases, evidence for cluster formation is obtained.

Animals↗