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Minimally invasive retrieval of incarcerated flexible intramedullary reamer

Low TH, Loke YH, Chiu CK

Eur J Orthop Surg Traumatol, 2012 Nov;22 Suppl 1:113-5.
PMID: 26662760 DOI: 10.1007/s00590-012-0995-y

Reaming is an integral step of long bone nailing and is associated with low complication rate. We report a case of a flexible reamer that was broken and incarcerated in the femoral canal during a femoral canal reaming. The reamer was used without a ball-tipped guide wire, and thus, the routine extraction using the guide wire was not possible. The incarcerated reamer was successfully extracted after medullary decompression with small drilling corticotomies adjacent to the reamer head. This case report serves as a reminder of the importance of using the ball-tipped guide wire with a flexible reamer. It also describes a simple and minimally invasive technique of removing an incarcerated flexible reamer.
Appraisal of latex glove proteins in the induction of sensitivity to multiple latex allergens

Yeang HY, Chow KS, Yusof F, Arif SA, Chew NP, Loke YH

J Investig Allergol Clin Immunol, 2000 Jul-Aug;10(4):215-22.
PMID: 11039838

Six Hevea brasiliensis latex protein allergens, Hevb 1, Hev b 2, Hev b 3, Hev b 4, and two variants of Hev b 7 (7b and 7c), were purified from Hevea latex, while a seventh protein, Hev b 5, was prepared in recombinant form. The presence of these proteins in glove extracts was indicated by their respective antibodies in the serum of rabbits immunized against the extracts. The relative propensities of IgE binding to the individual latex allergens were compared using sera from latex-allergic patients. IgE recognition of Hev b 4, Hev b 7b, Hev b 5 and Hev b 2 was most frequently encountered, with 75, 61, 31 and 28%, respectively, of the patient sera reacting. Sensitivity to multiple latex proteins was common, and out of the 31 seropositive patients, 23 (74%/ ) had IgE against at least two latex allergens, while 12 (39%) had IgE specific for at least three allergens. Statistical analysis of the data suggested that many patients might have acquired sensitivity to Hev b 2, Hev b 4 and Hev b 7b from a common source. (e.g., from latex products). On the other hand, sensitivity to Hev b 5 and to Hev b 7c were interrelated. It is plausible that sensitivity to these two proteins might have been acquired from sources other than latex products (e.g., from certain foods).
Hev b 5 and Hev b 13 as allergen markers to estimate the allergenic potency of latex gloves

Yeang HY, Arif SA, Raulf-Heimsoth M, Loke YH, Sander I, Sulong SH, et al.

J Allergy Clin Immunol, 2004 Sep;114(3):593-8.
PMID: 15356563 DOI: 10.1016/j.jaci.2004.05.039

BACKGROUND:
Sensitization to natural rubber latex has been linked to proteins from medical latex gloves. Various assays to estimate the amount of residual allergenic proteins extractable from latex gloves to assess their potential exposure hazard have inherent weaknesses.

OBJECTIVE:
This investigation was aimed at developing 2-site immunoenzymetric assays and identifying appropriate protein markers to assess the allergenic potential of latex gloves.

METHODS:
The presence of 6 latex allergens--Hev b 1, 2, 3, 5, 6, and 13--was measured in a cross-section of commercial latex medical gloves by using monoclonal and polyclonal antibody-based 2-site immunoenzymetric assays. The overall allergenic potential of these gloves was assessed by IgE-inhibition assay. Stepwise multiple regression analyses were performed to identify marker allergens that best explained the variation in latex glove allergenicity.

RESULTS:
All 6 latex allergens were detected in at least some of the glove samples. Hev b 5 and Hev b 13 were identified as the marker allergens that combined best to explain the variation in the glove allergenicity. The significant multiple correlation (R=0.855) between these 2 markers and glove allergenic potency forms the basis of an assay to gauge latex glove allergenicity.

CONCLUSION:
The overall allergenic potential of latex gloves can be estimated by using Hev b 5 and Hev b 13 as indicator allergens. The correlation between glove allergenicity and the level of these allergens was maintained for low-protein gloves (<200 microg/g). This estimation of glove allergenicity was superior to that obtained by using total protein readings.
Allergen concentration in natural rubber latex

Yeang HY, Hamilton RG, Bernstein DI, Arif SA, Chow KS, Loke YH, et al.

Clin Exp Allergy, 2006 Aug;36(8):1078-86.
PMID: 16911364 DOI: 10.1111/j.1365-2222.2006.02531.x

BACKGROUND:
Hevea brasiliensis latex serum is commonly used as the in vivo and in vitro reference antigen for latex allergy diagnosis as it contains the full complement of latex allergens.

OBJECTIVE:
This study quantifies the concentrations of the significant allergens in latex serum and examines its suitability as an antigen source in latex allergy diagnosis and immunotherapy.

METHODS:
The serum phase was extracted from centrifuged latex that was repeatedly freeze-thawed or glycerinated. Quantitation of latex allergens was performed by two-site immunoenzymetric assays. The abundance of RNA transcripts of the latex allergens was estimated from the number of their clones in an Expressed Sequence Tags library.

RESULTS:
The latex allergens, Hev b 1, 2, 3, 4, 5, 6, 7 and 13, were detected in freeze-thawed and glycerinated latex serum at levels ranging from 75 (Hev b 6) to 0.06 nmol/mg total proteins (Hev b 4). Hev b 6 content in the latex was up to a thousand times higher than the other seven latex allergens, depending on source and/or preparation procedure. Allergen concentration was reflected in the abundance of mRNA transcripts. When used as the antigen, latex serum may bias the outcome of latex allergy diagnostic tests towards sensitization to Hev b 6. Tests that make use of latex serum may fail to detect latex-specific IgE reactivity in subjects who are sensitized only to allergens that are present at low concentrations.

CONCLUSION:
Latex allergy diagnostics and immunotherapy that use whole latex serum as the antigen source may not be optimal because of the marked imbalance of its constituent allergens.
Isolation and characterization of the early nodule-specific protein homologue (Hev b 13), an allergenic lipolytic esterase from Hevea brasiliensis latex

Arif SA, Hamilton RG, Yusof F, Chew NP, Loke YH, Nimkar S, et al.

J Biol Chem, 2004 Jun 04;279(23):23933-41.
PMID: 15024009

Recurring reports of a highly allergenic 42-46-kDa protein in Hevea brasiliensis latex appeared to have been resolved with the discovery of a 43-kDa allergenic latex protein that was a homologue to patatin. However, the low to moderate prevalence of sensitization to the protein, designated Hev b 7, among latex-allergic patients could not adequately explain the frequent observations of the 42-46-kDa allergen. This led to the hypothesis that another, more allergenic protein of a similar molecular mass existed in Hevea latex. We report the isolation and purification of a 42.98-kDa latex glycoprotein showing homology to the early nodule-specific protein (ENSP) of the legumes Medicago sativa, Medicago truncatula, and Glycine max. The protein is allergenic, being recognized by immunoglobulin E (IgE) in sera from latex-allergic patients. The IgE epitope resides on the carbohydrate moiety of the protein, and the presence of a similar carbohydrate component on potato tuber patatin enables the latter to inhibit IgE binding to the ENSP homologue. The cDNA encoding the ENSP homologue was isolated by reverse transcription-PCR and cloned. The protein predicted from the cDNA sequence has 391 amino acids, the first 26 of which constitute a putative signal peptide. The deduced molecular mass of the mature protein is 40.40 kDa, while its isoelectric point is estimated at 5.0. The discrepancy between the predicted and observed molecular mass might be due to glycosylation, for which three N-sites on the protein are predicted. The purified protein showed lipase and esterase activities and may be involved in plant defense.
Fulltext Cocoa Butter: Evolution from Natural Food Ingredient to Pharmaceutical Excipient and Drug Delivery System

Loke YH, Phang HC, Mohamad N, Kee PE, Chew YL, Lee SK, et al.

Planta Med, 2024 Sep;90(11):824-833.
PMID: 39043195 DOI: 10.1055/a-2359-8097

For decades, cocoa butter has been extensively used in food industries, particularly in the production of chocolate confectioneries. The composition of fats within cocoa butter, such as stearic acid, palmitic acid, and oleic acid, determines its properties. Studies have indicated the existence of at least six polymorphic forms of cocoa butter, each possessing distinct characteristics and melting points. Recently, cocoa butter has garnered attention for its potential as a delivery system for pharmaceutical products. This review thoroughly explores cocoa butter, encompassing its production process, composition, properties, and polymorphism. It delves into its diverse applications across various industries including food, cosmetics, and pharmaceuticals. Additionally, the review investigates cocoa butter alternatives aiming to substitute cocoa butter and their roles in different drug delivery systems. The unique properties of cocoa butter have sparked interest in pharmaceutical industries, particularly since its introduction as a drug delivery system and excipient. This has prompted researchers and industry stakeholders to explore novel formulations and delivery methods, thereby expanding the range of options available to consumers in the pharmaceutical market.
Application of cocoa butter for formulation of fast melt tablets containing memantine hydrochloride

Loke YH, Phang HC, Gobal G, Vijayaraj Kumar P, Kee PE, Widodo RT, et al.

Drug Dev Ind Pharm, 2024 Oct;50(10):845-855.
PMID: 39418138 DOI: 10.1080/03639045.2024.2417999

INTRODUCTION: Fast melt tablets (FMTs) provide a convenient dosage form that rapidly dissolves on the tongue without the need for water. Cocoa butter serves as a suitable matrix system for FMTs formulation, facilitating rapid disintegration at body temperature.
OBJECTIVES: This study aimed to formulate FMTs using cocoa butter as a base and investigate the effect of various disintegrants and superdisintegrants on their characteristics.
METHODS: Cocoa butter-based FMTs were prepared via the fusion molding technique. Different disintegrants and superdisintegrants were added at varying concentrations and subjected to characterization. The optimal formulation was selected and incorporated with 10 mg memantine hydrochloride.
RESULTS: The optimal FMT formulation consisted of 340 mg cocoa butter, 75 mg starch, and 75 mg crospovidone, exhibiting a hardness of 17.12 ± 0.31 N and a disintegration time of 32.67 ± 0.17 s. Furthermore, FMTs demonstrated a faster release profile compared to the commercially available product, Ebixa. SEM micrographs revealed homogenous blending of individual ingredients within the cocoa butter matrix and FT-IR analysis confirmed the chemical stability of memantine hydrochloride in the formulation. The dissolution profile of F17 suggested that the drug in FMTs released faster compared to Ebixia. Memantine hydrochloride achieved 98.07% of drug release in FMTs at 10 min. Moreover, the prepared FMTs exhibited stability for at least 6 months.
CONCLUSION: The successful development of cocoa butter-based FMTs containing memantine hydrochloride highlights the potential of cocoa butter as viable alternative matrix-forming material for FMTs production. This innovative formulation offers patients a convenient alternative for medication administration.
Development of a novel direct compressible co-processed excipient and its application for formulation of Mirtazapine orally disintegrating tablets

Loke YH, Chew YL, Janakiraman AK, Lee SK, Uddin ABMH, Goh CF, et al.

Drug Dev Ind Pharm, 2024 Jan;50(1):36-44.
PMID: 38149637 DOI: 10.1080/03639045.2023.2294095

INTRODUCTION: Orally disintegrating tablets (ODTs) are designed to dissolve in the oral cavity within 3 min, providing a convenient option for patients as they can be taken without water. Direct compression is the most common method used for ODTs formulations. However, the availability of single composite excipients with desirable characteristics such as good compressibility, fast disintegration, and a good mouthfeel suitable for direct compression is limited.
OBJECTIVE: This research was proposed to develop a co-processed excipient composed of xylitol, mannitol, and microcrystalline cellulose for the formulation of ODTs.
METHODS: A total of 11 formulations of co-processed excipients with different ratios of ingredients were prepared, which were then compressed into ODTs, and their characteristics were thoroughly examined. The primary focus was on evaluating the disintegration time and hardness of the tablets, as these factors are important in ensuring the ODTs meet the desired criteria. The model drug, Mirtazapine was then incorporated into the chosen optimized formulation.
RESULTS: The results showed that the formulation comprised of 10% xylitol, 10% mannitol and 80% microcrystalline cellulose demonstrated the fastest disintegration time (1.77 ± 0.119 min) and sufficient hardness (3.521 ± 0.143 kg) compared to the other formulations. Furthermore, the drug was uniformly distributed within the tablets and fully released within 15 min.
CONCLUSION: Therefore, the developed co-processed excipients show great potential in enhancing the functionalities of ODTs, offering a promising solution to improve the overall performance and usability of ODTs in various therapeutic applications.