Effects of bone types, particle sizes, and gamma irradiation doses in feline demineralized freeze-dried bone allograft.

BACKGROUND AND AIM: Fracture cases significantly increase recently, demanding high quality of bone graft materials. This research aimed to evaluate the effects of bone types, particle sizes, and gamma irradiation doses on morphological performance and cell viability of feline demineralized freeze-dried bone allograft (DFDBA) through an in vitro study. MATERIALS AND METHODS: Feline DFDBA derived from feline cortical and cancellous long bones was processed into four different sizes: Group A (larger than 1000 µm), B (841-1000 µm), C (420-840 µm), and D (250-419 µm) for each type of bones. The materials were then irradiated with two doses of gamma rays, 15 and 25 kGy, resulting in 16 variants of feline DFDBA. The surfaces of each material were then observed with the scanning electron microscope (SEM). The in vitro evaluation of feline DFDBA was then performed using 3-(4,5-dimethythiazol-2)-2,5-diphenyltetrazolium bromide (MTT) assay with calf pulmonary artery endothelial cells. RESULTS: The MTT assay results showed that the lowest inhibition rate (14.67±9.17 %) achieved by feline DFDBA in Group A derived from cortical bones irradiated with 15 kGy. Group D generally showed high inhibition rate in both cancellous and cortical bones, irradiated with either 15 or 25 kGy. The SEM results showed that cancellous and cortical bones have numerous macropores and micropores structure in 170× and 3000×, respectively. CONCLUSION: The material derived from cortical bones in Group A (larger than 1000 µm in particle size) irradiated with 15 kGy is the best candidate for further development due to its abundance of micropores structure and ability in preserving the living cells.

The Inflammatory and Foreign Body Reaction of Polymethyl Methacrylate Glaucoma Drainage Device in the Rabbit Eye.

Purpose: To assess the safety and tissue response of a polymethyl methacrylate (PMMA) glaucoma drainage device (GDD) in the rabbit eye. Methods: Specially constructed PMMA GDD devices were implanted into rabbit eyes and evaluated histopathologically following euthanasia on days 5, 30, and 60 after implantation surgery. Hematoxylin-eosin, Masson's trichrome, and periodic acid-Schiff were used to stain tissue specimens dissected from the surgical site. Inflammatory cell count and capsule thickness measurements were performed. Results: Three rabbits were sacrificed on day 5, 3 on day 30, and 4 on day 60. Macrophage and lymphocyte counts increased from day 5 to day 30 then decreased (P = 0.0000) with greater counts seen in the superior regions. At day 30, a fibrous capsule had formed around the plate area. Fibroblast counts increased significantly between day 5 to day 30 and again to day 60 (P = 0.001) with greatest numbers anteriorly. The inferior capsule thickness at day 60 was 243 µm (standard deviation, 120; 95% confidence interval: 53-433). The superior capsule thickness was 388 µm (standard deviation, 136; 95% confidence interval: 172-604). No adverse reactions were seen. Conclusions: Histopathologically, the inflammatory response toward this PMMA glaucoma drainage device was comparable to other reported GDDs. No accentuated response or adverse event was seen suggesting that PMMA may be useful as a GDD material. Translational Relevance: An affordable, locally built GDD is needed in Indonesia because of the high prevalence of severe glaucoma. This rabbit study is a significant step toward justifying the use of PMMA as a GDD material. PMMA is cheap and easily manufactured and sterilized in developing economies.

A Wearable Iron-Based Implant as an Intramedullary Nail in Tibial Shaft Fracture of Sheep.

A stable repaired fracture is the key factor responsible for the recovery of a damaged bone. The iron-based implant is one of the biodegradable metals that have been proven safe as a fracture fixation device. The objective of our experimental approach was to examine the potential of the iron-based implant as a biodegradable metal in tibia shaft fracture in sheep chronically. The samples used for this experiment were iron-based and stainless steel implants. Each had a diameter of 5 mm. These samples were analyzed through 3 phases which are material characterization, in vitro and in vivo examination. The samples were examined using a scanning electron microscope with energy dispersive spectrometer and X-ray diffraction. Based on the analysis carried out, the samples contained 90,02% and 60,81% Fe for iron-based implant and stainless implant, respectively. Both implants maintained high viability when being in contact with calf pulmonary artery endothelial cells, indicating that both implants had a minimum response to the cell in a hemocytometer and methyl tetrazolium (MTT) assay. The systemic effect of the implants was observed using hematology and blood chemistry examination. Data collection also shows that both implants also had a minimum response to the erythrocytes, leucocytes, blood chemistry, and blood mineral during the period of observation. Therefore, it could be concluded that the iron-based implant is tolerable for a period of 9 months. It also has the potential to be used as a biodegradable orthopedic implant.

Characterization of the gene encoding the 16S rRNA of Enterobacter sakazakii and development of a species-specific PCR method.

The gene encoding the 16S rRNA of Enterobacter (E.) sakazakii (ATCC 29544, plus four strains isolated from powdered infant formula) was studied, and the sequence compared with those of other Enterobacteriaceae in aspects of genetic variability. Sequence differences between E. sakazakii and other Enterobacteriaceae within the hypervariable regions V1, V2, and V3, respectively, were used to develop two PCR methods for E. sakazakii. PCR1 employed a primer pair located in V1/V2, while PCR2 utilized a primer pair located in V1/V3, respectively. The two PCR methods were tested against a set of 57 E. sakazakii and 148 non-E. sakazakii isolates. PCR1 gave an amplicon with a size of 406 bp and resulted in 100% positive results for E. sakazakii, but also detected Citrobacter koseri/amalonaticus and all nine tested Salmonella enterica serovars. In contrast, PCR2 (amplicon size of 952 bp) gave positive results only for E. sakazakii, thus allowing specific identification of this species.

Enterobacteriaceae in dehydrated powdered infant formula manufactured in Indonesia and Malaysia.

To determine the occurrence of Salmonella and Shigella in infant formula from Southeast Asia, 74 packages of dehydrated powdered infant follow-on formula (recommended age, > 4 months) from five different manufacturers, four from Indonesia and one from Malaysia, were analyzed. None of the 25-g test portions yielded Salmonella or Shigella. However, further identification of colonies growing on selective media used for Salmonella and Shigella detection revealed the frequent occurrence of several other Enterobacteriaceae species. A total of 35 samples (47%) were positive for Enterobacteriaceae. Ten samples (13.5%) from two Indonesian manufacturers yielded Enterobacter sakazakii. Other Enterobacteriaceae isolated included Pantoea spp. (n = 12), Escherichia hermanii (n = 10), Enterobacter cloacae (n = 8), Klebsiella pneumoniae subsp. pneumoniae (n = 3), Citrobacter spp. (n = 2), Serratia spp. (n = 2), and Escherichia coli (n = 2). To our knowledge, this is the first report to describe the contamination of dehydrated powdered infant formula from Indonesia with E. sakazakii and several other Enterobacteriaceae that could be opportunistic pathogens. Improper preparation and conservation of these products could result in a health risk for infants in Indonesia.