Porous carriers for biomedical applications based on alginate hydrogels

Macroporous scaffolds are typically utilized in tissue engineering applications to allow for the migration of cells throughout the scaffold and integration of the engineered tissue with the surrounding host tissue. A method to form macroporous beads with an interconnected pore structure from alginate has been developed by incorporating gas pockets within alginate beads, stabilizing the gas bubbles with surfactants, and subsequently removing the gas. Macroporous scaffolds could be formed from alginate with different average molecular weights (5-200 kDa) and various surfactants. The gross morphology, amount of interconnected pores, and total void volume was investigated both qualitatively and quantitatively. Importantly, macroporous alginate beads supported cell invasion in vitro and in vivo.     

A system of corticotropin releasing factor-containing amacrine cells in the rat retina

Immunohistochemical processing of Long-Evans retina wholemounts using an antiserum directed against rat, human corticotropin releasing factor revealed a group of immunoreactive amacrine cells. Two subpopulations could be distinguished based primarily on the location of their cell bodies. One subpopulation had cell bodies situated along the junction of the inner nuclear layer and the inner plexiform layer. The other subpopulation had cell bodies in the ganglion cell layer. The latter was judged to be displaced amacrine cells since double-label experiments indicated that the pattern of corticotropin releasing factor-like immunoreactive staining in the ganglion cell layer did not coincide with that of ganglion cells labeled retrogradely with fluorogold. Corticotropin releasing factor-like immunoreactive amacrine cells on either side of the inner plexiform layer emitted processes which ramified extensively in sublamina 5 and, to a lesser degree, in sublamina 4. A minority of these cells also sent a single process to ramify in sublamina 1. Throughout the retina, corticotropin releasing factor-like immunoreactive cells were distributed relatively evenly, with a tendency to peak in the superior temporal region. Despite the anatomical classification into two subpopulations, it is proposed that the corticotropin releasing factor-like immunoreactive cells are functionally one system, influencing preferentially synaptic interactions associated with the inner half of the inner plexiform layer. The results of this study provide anatomical basis for further investigations of corticotropin releasing factor as a putative peptidergic neurotransmitter in the retina.     

Incidence and case-fatality rates resulting from the 1998 enterovirus 71 outbreak in Taiwan

In 1998, an epidemic of hand-foot-and-mouth disease and herpangina caused by enterovirus 71 occurred in Taiwan, leaving many fatalities and severely handicapped survivors in its wake. The reasons this rather common pathogen would cause such a large-scale epidemic remain unknown. A seroepidemiological survey to elucidate the epidemiological characteristics of this outbreak, including its incidence and case-fatality rates was undertaken. Microneutralization tests for antibodies against enterovirus 71 were used to screen four collections of serum samples: 1) 202 specimens taken from individuals > or = 4 years old in 1994; 2) 245 specimens collected from individuals of all ages in 1997; 3) 1,258 specimens collected from individuals of all ages in 1999; and 4) sera samples from a birth cohort of 81 children who had yearly blood samples taken from 1988-98. After the maternal antibody had declined, the seropositive rates began to increase with age. Approximately half of all children aged 6 years or older were enterovirus 71 seropositive. Significantly higher seropositive rates were noted in 1999 than in 1997, in children aged 0.5-3 years. The incidence of enterovirus 71 infection during the epidemic was estimated to be 13-22%, with the higher rates in younger children. The case-fatality rate was highest (96.96 per 100,000) in infants aged 6-11 months, and declined in older children. The results showed that enterovirus 71 is endemic in Taiwan. The apparent lack of large-scale enterovirus 71 activity in the 3 years before 1998 might have been the prelude to the epidemic's appearance in 1998, and might suggest that enterovirus 71 infection will reappear every few years. The lack of a protective antibody in younger children may account for the high incidence and case-fatality rate in this age group.     

Comparing the effectiveness of home visiting paraprofessionals and mental health professionals delivering a postpartum depression preventive intervention: a cluster-randomized non-inferiority clinical trial

To determine whether pregnant women receiving the Mothers and Babies group–based intervention exhibited greater depressive symptom reductions and fewer new cases of major depression than women receiving usual community-based services, and to examine whether groups run by paraprofessional home visitors and mental health professionals yielded similar depressive symptom reductions and prevention of major depression. Using a cluster-randomized design, 37 home visiting programs were randomized to usual home visiting, Mothers and Babies delivered via home visiting paraprofessionals, or Mothers and Babies delivered via mental health professionals. Baseline assessments were conducted prenatally with follow-up extending to 24 weeks postpartum. Eligibility criteria were ≥ 16 years old, ≤ 33 gestation upon referral, and Spanish/English speaking. Depressive symptoms at 24 weeks postpartum was the primary outcome. Eight hundred seventy-four women were enrolled. Neither intervention arm was superior to usual care in decreasing depressive symptoms across the sample (p = 0.401 home visiting paraprofessional vs. control; p = 0.430 mental health professional vs. control). Post hoc analyses suggest a positive intervention effect for women exhibiting mild depressive symptoms at baseline. We have evidence of non-inferiority, as the model-estimated mean difference in depressive symptoms between intervention arms (0.01 points, 95% CI: −0.79, 0.78) did not surpass our pre-specified margin of non-inferiority of two points. Although we did not find statistically significant differences between intervention and control arms, non-inferiority analyses found paraprofessional home visitors generated similar reductions in depressive symptoms as mental health professionals. Additionally, Mothers and Babies appears to reduce depressive symptoms among women with mild depressive symptoms when delivered by mental health professionals. This trial is registered on ClinicalTrials.gov (initial post: December 1, 2016; identifier: NCT02979444).

     

Mouse hepatitis virus nucleocapsid protein-specific cytotoxic T lymphocytes are Ld restricted and specific for the carboxy terminus.

Infection of mice with the JHM strain of mouse hepatitis virus (MHV) results in an acute encephalomyelitis associated with primary demyelination of the central nervous system. Efforts at understanding the components of the immune response in the development of chronic MHV-induced demyelination have implicated the antibody response and both the CD4+ and CD8+ T cell responses. In this report, we demonstrate that Balb/c (H-2d) mice immunized with the JHM (JHMV) strain of MHV develop a CD8+ cytotoxic T lymphocyte (CTL) response. One population of these virus-specific CTL recognize the nucleocapsid (N) protein. Recombinant vaccinia viruses expressing either the entire N protein or carboxy-terminal deletions were used to determine the number and location of the epitope(s) recognized. The CTLs were found to recognize a peptide contained within the carboxy-terminal 149 amino acids of the N protein. Analysis of infected cell lines expressing transfected major histocompatibility genes demonstrated that the anti-N protein CTLs were restricted exclusively to the Ld molecule. These data provide the first definition of a MHV-specific CTL response directed to a viral protein and suggest that the anti-N protein CTL response is one potential mechanism used by the host to clear JHMV from the central nervous system.     

β-Adrenergic receptors in rat cerebellum after neonatal X-irradiation: Effect of prolonged imipramine and lithium treatment

The actions of prolonged treatment of rats within imipramine or lithium chloride on the β-adrenergic cAMP generating system of the cerebellum were compared in normal animals and in rats degranulated by neonatal X-irradiation. Whereas in normal animals imipramine treatment is without significant effect on the cerebellar cAMP system but lowers the β-adrenoceptor density significantly, in degranulated animals the cAMP system becomes subsensitive towards norepinephrine after prolonged imipramine treatment. These data support the hypothesis that in the cerebellum imipramine acts predominantly on β-adrenoceptors located particularly on Purkinje cells. Prolonged lithium treatment exhibited no significant effects on β-receptors nor the noradrenergic cAMP generating system of normal and degranulated cerebella.     

Effect of vitamin K2 on cortical and cancellous bones in orchidectomized young rats

OBJECTIVES: The purpose of the present study was to compare the effect of vitamin K(2) on cortical and cancellous bones in orchidectomized young rats. METHODS: Forty male Sprague-Dawley rats, 6 weeks of age, were randomized by stratified weight method into four groups with 10 rats in each group: baseline controls (BLC), age-matched controls (AMC), orchidectomy (ORX), and ORX+vitamin K(2) administration (K). Vitamin K(2) (menatetrenone) was administered subcutaneously twice a week at dose of 30 mg/kg each. The experimental period was 8 weeks, and cortical and cancellous bone histomorphometry was performed on the tibial shaft and the proximal tibia, respectively. RESULTS: Cortical area (Ct Ar) and cancellous bone volume (BV/TV) were significantly greater in the AMC group than in the BLC group. Ct Ar was significantly lower in the ORX group than in the AMC group, and cancellous BV/TV was also significantly lower in the ORX group than in the AMC group as a result of significantly increased eroded surface (ES/BS). Although Ct Ar in the ORX+K group did not differ significantly from that in the ORX group, cancellous BV/TV was significantly greater in the ORX+K group than in the ORX group, but still significantly lower than in the AMC group. This protective effect of vitamin K(2) on cancellous bone was attributable to normalizing increased ES/BS. CONCLUSIONS: Vitamin K(2) appears to act more strongly on cancellous bone than on cortical bone in ORX young rats. High dose vitamin K(2) could partially prevent the reduction of cancellous bone gain by normalizing raised bone resorption in ORX young rats.     

Diffraction ellipsometry studies of osmotically compressed muscle fibers

Microstructural features of relaxed, skinned muscle fibers compressed with polyvinylpyrollidone were examined by optical diffraction ellipsometry. This technique is sensitive to the optical anisotropy within the muscle, including that due to intrinsic properties of the protein molecules as well as that due to the regular arrangement of proteins in the surrounding medium. The change in polarization state of light after interacting with the muscle is described by the differential field ratio (DFR) and birefringence (n). Compression of single fibers (sarcomere length = 2.6 m) with 0%–21% polyvinylpyrrolidone caused an increase of up to 23% and 31% for DFR and n, respectively. The largest increase in both parameters occurred at intermediate sarcomere lengths. Theoretical modelling of the results suggest that the average S-1 tilt angle may be reduced upon compression of the filament lattice. This is supported by experiments in which S-1 was enzymatically cleaved with -chymotrypsin. Separate experiments comparing fibers with intact membranes and skinned fibers compressed to an equivalent lattice spacing showed little difference in DFR or n.     

Blood compatibility of surfaces modified by plasma polymerization

Tubular blood-contacting polymeric materials were modified by plasma polymerization and evaluated in the baboon with respect to their capacity to induce both acute and chronic arterial thrombosis. Polymer surface composition was determined by electron spectroscopy for chemical analysis. Steady-state arterial thromboembolism was initiated by introducing tubular segments into chronic arteriovenous shunts. Rates of platelet destruction induced by the test materials were calculated from 111In-platelet survival measurements. Nine plasma polymers based on tetrafluoroethylene, hexafluoroethane, hexafluoroethane/H2, and methane, when deposited on silicone rubber, consumed platelets at rates ranging from 1.1-5.6 x 10(8) platelets/cm2-day. Since these values were near the lower detection limit for this test system, the plasma polymers were considered relatively nonthrombogenic. Acute thrombus formation was initiated by inserting expanded Teflon (Gore-Tex PTFE) vascular grafts into the shunt system. 111In-platelet deposition was measured by scintillation camera imaging over a 1-h exposure period. Standard PTFE grafts (10 cm x 4 mm i.d.) accumulated approximately 1 x 10(10) platelets over this interval. While modification of PTFE grafts with a plasma polymer based on hexafluoroethane/H2 did not alter graft surface morphology, platelet deposition was reduced by 87% as compared to the controls (p less than 0.001). We conclude that both the surface chemistry and texture of prosthetic materials influence thrombogenesis. The method of plasma polymerization may be useful for assessing the importance of these variables independently and, perhaps, for minimizing certain adverse blood-material interactions.     

Epidemiologic relationship between fluoroquinolone-resistant Salmonella enterica Serovar Choleraesuis strains isolated from humans and pigs in Taiwan (1997 to 2002)

The emergence of ciprofloxacin-resistant Salmonella enterica serovar Choleraesuis in recent years has become an important public health issue in Taiwan. The resistant strains that cause human infections are considered to be from pigs. In this study, we characterized 157 swine and 42 human Salmonella serovar Choleraesuis isolates by pulsed-field gel electrophoresis (PFGE) and drug susceptibility testing to investigate the epidemiologic relationship among the isolates. By PFGE analyses, two major clusters (clusters GA and GB) were identified. Isolates in cluster GA were of both human and swine origins, while those in cluster GB were from pigs only. Among the various genotypes identified, genotype gt-1a was the most prevalent, which was found in 71% (30 of 42) and 48% (76 of 157) of human and swine isolates, respectively. The susceptibility tests for the 106 gt-1a isolates identified 44 susceptibility profiles and showed that 73% of human isolates and 34% of swine isolates were resistant to three fluoroquinolones (ciprofloxacin, enrofloxacin, and norfloxacin). Our findings indicate that a clonal group of Salmonella serovar Choleraesuis may have been circulating in human and swine populations in Taiwan for years and that the fluoroquinolone-resistant Salmonella serovar Choleraesuis strains most likely evolved from a gt-1a clone that emerged in 2000 and that then caused widespread infections in humans and pigs. Nevertheless, it is still debatable whether those Salmonella infections in humans are caused by isolates derived from pigs, on the basis of the higher fluoroquinolone and other antimicrobial resistance percentages in human isolates than in pig isolates.