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Bioactivity and mechanical stability of Ti-6Al-4V implants superplastically embedded with hydroxyapatite in rats

Mohd Khalid H, Jauhari I, Mohamad Wali HA, Abdulrazzaq Mahmod S

Biomed Mater, 2017 01 25;12(1):015019.
PMID: 28120816 DOI: 10.1088/1748-605X/aa4f8b

In this in vivo study, Sprague Dawley (SD) rats were used to investigate the bioactivity as well as the microstructural and mechanical properties of Ti-6Al-4V samples embedded with hydroxyapatite (HA) using two different coating methods-superplastic embedment (SPE) and superplastic deformation (SPD). The HA layer thickness for the SPE and SPD samples increased from 249.1 ± 0.6 nm to 874.8 ± 13.7 nm, and from 206.1 ± 5.8 nm to 1162.7 ± 7.9 nm respectively, after 12 weeks of implantation. The SPD sample exhibited much faster growth of newly formed HA compared to SPE. The growth of the newly formed HA was strongly dependent on the degree of HA crystallinity in the initial HA layer. After 12 weeks of implantation, the surface hardness value of the SPE and SPD samples decreased from 661 ± 0.4 HV to 586 ± 1.3 HV and from 585 ± 6.6 HV to 425 ± 86.9 HV respectively. The decrease in surface hardness values was due to the newly formed HA layer that was more porous than the initial HA layer. However, the values were still higher than the substrate surface hardness of 321 ± 28.8 HV. Wear test results suggest that the original HA layers for both samples were still strongly intact, and to a certain extent the newly grown HA layers also were strongly bound with the original HA layers. This study confirms the bioactivity and mechanical stability of the HA layer on both samples in vivo.
Oral ketamine induced pathological changes of the urinary tract in a rat model

Rajandram R, Yap NY, Ong TA, Mun KS, Mohamad Wali HA, Hasan MS, et al.

Malays J Pathol, 2017 Apr;39(1):47-53.
PMID: 28413205 MyJurnal

INTRODUCTION: In recent years, prolonged ketamine abuse has been reported to cause urinary tract damage. However, there is little information on the pathological effects of ketamine from oral administration. We aimed to study the effects of oral ketamine on the urinary tract and the reversibility of these changes after cessation of ketamine intake.
METHODS: Rats were fed with illicit (a concoction of street ketamine) ketamine in doses of 100 (N=12), or 300 mg/kg (N=12) for four weeks. Half of the rats were sacrificed after the 4-week feeding for necropsy. The remaining rats were taken off ketamine for 8 weeks to allow for any potential recovery of pathological changes before being sacrificed for necropsy. Histopathological examination was performed on the kidney and urinary bladder.
RESULTS: Submucosal bladder inflammation was seen in 67% of the rats fed with 300 mg/kg illicit ketamine. No bladder inflammation was observed in the control and 100 mg/kg illicit ketamine groups. Renal changes, such as interstitial nephritis and papillary necrosis, were observed in rats given illicit ketamine. After ketamine cessation, no inflammation was observed in the bladder of all rats. However, renal inflammation remained in 60% of the rats given illicit ketamine. No dose-effect relationship was established between oral ketamine and changes in the kidneys.
CONCLUSION: Oral ketamine caused pathological changes in the urinary tract, similar to that described in exposure to parenteral ketamine. The changes in the urinary bladder were reversible after short-term exposure.
Fulltext Genetic characterization of commensal Escherichia coli isolated from laboratory rodents

Loong SK, Mahfodz NH, Che Mat Seri NA, Mohamad Wali HA, Abd Gani SA, Wong PF, et al.

Springerplus, 2016;5(1):1035.
PMID: 27462483 DOI: 10.1186/s40064-016-2745-9

Escherichia coli, a commensal in the intestines of vertebrates, is capable of colonizing many different hosts and the environment. Commensal E. coli strains are believed to be the precursor of pathogenic strains by means of acquisition of antimicrobial resistant and virulence genes. Laboratory rodents are inherently susceptible to numerous known infectious agents, which could transfer virulence determinants to commensal E. coli. Hence, in this study, the genetic structure of commensal E. coli found in laboratory rodents and their antimicrobial resistance profiles were investigated.
A New Bioactive Fibrin Formulation Provided Superior Cartilage Regeneration in a Caprine Model

Vardar E, Nam HY, Vythilingam G, Tan HL, Mohamad Wali HA, Engelhardt EM, et al.

Int J Mol Sci, 2023 Nov 29;24(23).
PMID: 38069268 DOI: 10.3390/ijms242316945

The effective and long-term treatment of cartilage defects is an unmet need among patients worldwide. In the past, several synthetic and natural biomaterials have been designed to support functional articular cartilage formation. However, they have mostly failed to enhance the terminal stage of chondrogenic differentiation, leading to scar tissue formation after the operation. Growth factors substantially regulate cartilage regeneration by acting on receptors to trigger intracellular signaling and cell recruitment for tissue regeneration. In this study, we investigated the effect of recombinant insulin-like growth factor 1 (rIGF-1), loaded in fibrin microbeads (FibIGF1), on cartilage regeneration. rIGF-1-loaded fibrin microbeads were injected into full-thickness cartilage defects in the knees of goats. The stability, integration, and quality of tissue repair were evaluated at 1 and 6 months by gross morphology, histology, and collagen type II staining. The in vivo results showed that compared to plain fibrin samples, particularly at 6 months, FibIGF1 improved the functional cartilage formation, confirmed through gross morphology, histology, and collagen type II immunostaining. FibIGF1 could be a promising candidate for cartilage repair in the clinic.
Fulltext Isolation of Streptococcus cuniculi from corneal lesion in laboratory-raised mice

Tiong V, Loong SK, Mohamad Wali HA, Tan KK, Jee PF, Lim FS, et al.

J Vet Med Sci, 2021 Mar 05;83(2):280-284.
PMID: 33441499 DOI: 10.1292/jvms.20-0070

Corneal lesions appearing as white mass beneath intact epithelium, with ocular discharge in one mouse, was observed in a batch of laboratory-raised BALB/c mice (n=9 of 56). The affected mice remained active, well-groomed and had normal appetite. Isolates recovered from swab cultures of the external and internal contents of the eye had partial 16S rRNA gene sequence of 99.1% similarity to Streptococcus cuniculi. No previous report of S. cuniculi infection in laboratory rodents has been presented. The isolate was susceptible to all antibiotics tested. We suggest S. cuniculi is an opportunistic bacteria in laboratory mice but are uncertain of its source. Our findings revealed that S. cuniculi is able to colonize laboratory mice and should be considered when mice present with eye lesion or ocular discharge.