Injection molding of vertebral fixed cage implant

A vertebral cage is a hollow medical device which is used in spine surgery. By implanting the cage into the spine column, it is possible to restore disc and relieve pressure on the nerve roots. Most cages have been made of titanium alloys but they detract the biocompatibility. Currently PEEK (polyether ether ketone) is applied to various implants because it has good properties like heat resistance, chemical resistance, strength, and especially biocompatibility. A new shape of vertebral cage is designed and injection molding of PEEK is considered for production. Before injection molding of the cage, it is needed to evaluate process conditions and properties of the final product. Variables affecting the shrinkage of the cage are considered, e.g., injection time, packing pressure, mold temperature, and melt temperature. By using the numerical simulation program, MOLDFLOW, several cases are studied. Data files obtained by MOLDFLOW analysis are used for stress analysis with ABAQUS, and shrinkage and residual stress fields are predicted. With these results, optimum process conditions are determined.     

Acid-sensitivity and physical properties of polymethylmethacrylate and polyurethane films containing polymeric styryl dye

Solution-cast films of polymethylmethacrylate (PMMA) and polyurethane (PU) containing polymeric styryl dye up to 5% by weight were prepared to investigate their acid-sensitivity and mechanical and thermal properties. Original red samples due to styryl dye turned out yellow very rapidly as they were exposed to acid vapor of hydrochloric acid or p-toluenesulfonic acid. According to UV/VIS spectroscopic measurements, characteristic peak intensities near 430 nm and 520 nm increased or decreased relatively with exposed amounts of acid, respectively. Both PMMA and PU samples showed uniform color distribution due to a good miscibility between polymer and dye which can be evidenced by measurements of glass transition temperature. No significant difference in acid-sensitivity was found between PU and PMMA except relative absorbance. However, dependence of their mechanical properties on dye content was somewhat different with PU or PMMA. In case of PMMA, modulus and breaking stress increased up to about 50% with increasing dye content, whereas those of PU samples showed only slight increase. It was ascribed to whether the matrix polymer was in the glassy or rubbery state.     

Antimicrobial resistance, virulence-associated genes, and pulsed-field gel electrophoresis profiles of Salmonella enterica subsp. enterica serovar Typhimurium isolated from piglets with diarrhea in Korea

Salmonella enterica subsp. enterica serovar Typhimurium was isolated from diarrheic piglets in 2 periods, 2000-2001 (n = 25) and 2005-2006 (n = 17). To compare the characteristics of the isolates collected during the 2 periods, all isolates were tested for antimicrobial resistance, the presence of virulence genes, and pulsed-field gel electrophoresis (PFGE) patterns. All 42 isolates were resistant to at least 1 of the 20 antimicrobials tested, and 39 (93%) were resistant to 2 or more antimicrobials. One isolate was resistant to 12 antimicrobials. Profiles of antimicrobial resistance revealed 20 resistance types. Several isolates were also resistant to quinolones and expanded-spectrum cephalosporins. Ten isolates (24%) were resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline (ACSSuT); only one isolate had been isolated in 2000-2001, indicating that this type of resistance has rapidly disseminated. Polymerase chain reaction (PCR) assays revealed that all the isolates carried invA. Among the 25 strains isolated in 2000-2001, all carried the sipA, sopA, sopD, sopE2, and ssaR genes, and 96% carried sopB and sifA. Among the 17 strains isolated in 2005-2006, all carried sifA, and approximately 90% carried sipA, sopA, sopB, sopD, sopE2, and ssaR. However, only 6 (14%) of the 42 isolates carried spvC. By PFGE analysis, all 42 strains were classified into 4 major clusters, basically by collection period. The genetic similarity according to PFGE suggests that the strains isolated from diarrheic piglets of this region within the same period may be closely related.     

Differential effects of treadmill exercise on calretinin immunoreactivity in type 2 diabetic rats in early and chronic diabetic stages

In this study, we investigated the effects of treadmill exercise on calretinin (CR), a marker of early postmitotic neurons, immunoreactivity in the dentate gyrus (DG) of Zucker diabetic fatty (ZDF) rats, before or after diabetes onset, and Zucker lean control (ZLC) rats. For this study, 6-week-old ZLC and prediabetic ZDF rats, and 22-week-old ZLC and ZDF rats were exercised on the treadmill. Sedentary ZLC and ZDF rats of the same age were used as exercise experiment controls. The exercised prediabetic ZDF rats did not show diabetes onset, while the sedentary prediabetic ZDF rats showed significantly increased blood glucose levels. The exercised diabetic ZDF rats exhibited a decrease in their blood glucose levels compared to the sedentary diabetic ZDF rats, but the levels were still above 20 mmol/l. ZLC rats of both ages were in the normoglycemic range. CR immunoreactivity was detected throughout the DG, including the subgranular zone and the polymorphic layer. Diabetic rats exhibited a significant decrease in the number of CR-immunoreactive cells and fibers in the DG. Exercise in the prediabetic ZDF rats significantly increased the number of CR-immunoreactive cells and fibers in the subgranular zone of the DG. In the ZLC and ZDF rats of chronic diabetic phase, exercise increased CR-immunoreactive neurons in the hilar region. These results suggest that diabetes significantly reduces the number of postmitotic CR-immunoreactive neurons and the intensity of immunoreactivity and that exercise increases these CR-related parameters in a diabetic stage-dependent manner.     

Epidemiological survey for Brucella in wildlife and stray dogs, a cat and rodents captured on farms

Brucella infections in wildlife originate either from contact with infected livestock or from a natural sustainable reservoir in wildlife populations. As South Korea has set a goal of brucellosis eradication by 2013, it is necessary to determine the prevalence of Brucella in wildlife and wild rodents. This information will play an important role in the control of brucellosis. Because of the absence of prominent clinical signs, direct and indirect laboratory tests are essential for diagnosing brucellosis. In this study, tissue and blood samples were taken from wild animals, abandoned dogs, a cat and wild rodents, and they were tested for Brucella or Brucella-specific antibodies by isolation, PCR and serology. Results showed that 18.6% (33/177) of blood samples were positive by PCR, and 5.7% (11/194) were positive by C-ELISA. However, none of these samples yielded culturable bacteria. Of the tissue samples, 9.7% (8/82) were positive by PCR. Brucella was isolated from only one tissue culture from a Chinese water deer carcass. This Brucella species was identified as Brucella abortus biovar 1 by biotyping, 16S rRNA PCR and the Bruce-ladder PCR assay. In this study, we reported the prevalence of Brucella in wildlife, dogs, a cat and rodents by using serological and molecular methods, and we report the first isolation of B. abortus in wild Chinese water deer in South Korea.     

Localization of Insulin‐Like Growth Factor‐I (IGF‐I) and IGF‐I Receptor (IGF‐IR) in Equine Testes

The insulin‐like growth factor‐I (IGF‐I) is a key regulator of reproductive functions. IGF‐I actions are primarily mediated by IGF‐IR. The main objective of this research was to evaluate the presence of IGF‐I and IGF‐I Receptor (IGF‐IR) in stallion testicular tissue. The hypotheses of this study were (i) IGF‐I and IGF‐IR are present in stallion testicular cells including Leydig, Sertoli, and developing germ cells, and (ii) the immunolabelling of IGF‐I and IGF‐IR varies with age. Testicular tissues from groups of 4 stallions in different developmental ages were used. Rabbit anti‐human polyclonal antibodies against IGF‐I and IGF‐IR were used as primary antibodies for immunohistochemistry and Western blot. At the pre‐pubertal and pubertal stages, IGF‐I immunolabelling was present in spermatogonia and Leydig cells. At post‐pubertal, adult and aged stages, immunolabelling of IGF‐I was observed in spermatogenic cells (spermatogonia, spermatocyte, spermatid, and spermatozoa) and Leydig cells. Immunolabelling of IGF‐IR was observed in spermatogonia and Leydig cells at the pre‐pubertal stage. The immunolabelling becomes stronger as the age of animals advance through the post‐pubertal stage. Strong immunolabelling of IGF‐IR was observed in spermatogonia and Leydig cells at post‐puberty, adult and aged stallions; and faint labelling was seen in spermatocytes at these ages. Immunolabelling of IGF‐I and IGF‐IR was not observed in Sertoli cells. In conclusion, IGF‐I is localized in equine spermatogenic and Leydig cells, and IGF‐IR is present in spermatogonia, spermatocytes and Leydig cells, suggesting that the IGF‐I may be involved in equine spermatogenesis and Leydig cell function as a paracrine/autocrine factor.     

Influenza virus neuraminidase inhibitory activity of phlorotannins from the edible brown alga Ecklonia cava

Influenza A virus infections continue to pose a major threat to humans and several animal species. Neuraminidase (NA) is one of the most promising targets for the development of drugs against influenza viruses because of its critical role in the viral life cycle. During the course of a search for NA inhibitors from edible natural sources, we found that the ethyl acetate layer of ethanol extracts of Ecklonia cava showed extremely high NA-inhibitory activity (72.1% inhibition at 30 μg/mL). Bioactivity-guided fractionation of the ethyl acetate layer yielded five phlorotannins, identified as phloroglucinol (1), eckol (2), 7-phloroeckol (3), phlorofucofuroeckol (4), and dieckol (5). The inhibitory activities of these compounds (1-5) against NAs from group-1 (A/Bervig_Mission/1/18 [H1N1], A/PR/8/34 [H1N1]) and group-2 (A/Hong Kong/8/68 [H3N2], A/Chicken/Korea/MS96/96 [H9N2]) influenza A were evaluated to determine potencies and kinetic behavior. Analyses using various in vitro influenza A virus NA assays showed that all five phlorotannin derivatives were selective NA inhibitors. Of the phlorotannins, phlorofucofuroeckol (4) exhibited the most potent inhibitory activities toward group-1 NAs (IC?? values, 4.5 and 14.7 μM), whereas dieckol (5) potently inhibited group-2 NAs. Kinetic analyses indicated that compounds 1-5 were all noncompetitive. Notably, these noncompetitive inhibitors synergized with oseltamivir to enhance the NA-inhibitory effects of oseltamivir.     

Efficacy of fipronil, amitraz and (S)-methoprene combination spot-on for dogs against adult dog fleas (Ctenocephalides canis, Curtis, 1826)

A novel spot-on formulation combining fipronil, amitraz and (S)-methoprene (CERTIFECT?, Merial Limited, GA, USA) was evaluated in adult Beagle dogs in a study to determine its adulticidal efficacy against the dog flea (Ctenocephalides canis, Curtis, 1826). Sixteen dogs were randomly allocated to treatment groups: 8 dogs served as untreated controls, and 8 dogs were treated once. Treatment consisted of applying a new combination formulation to deliver at least 6.7mg fipronil/kg body weight (bw), 8.0mg amitraz/kg bw, and 6.0mg (S)-methoprene/kg bw. The combination was designed to enhance the efficacy against ticks of the original fipronil/(S)-methoprene combination. Each dog was infested with 100 adult unfed dog fleas within 24h prior to treatment and then at weekly intervals for 8 weeks after treatment. At 24h after treatment or after each subsequent infestation, each dog was combed thoroughly to remove live fleas to be counted. A single treatment with CERTIFECT provided excellent knock-down of fleas within 24h after treatment and controlled re-infestations for up to 7 weeks (efficacy ≥96.5%, p<0.05).