Resorbable calcium phosphate bone substitute

Bacteroides fragilis strains isolated from different sources, i.e. 1 strain (AA1) from an aquatic environment, 1 strain from normal flora (118310) and the type strain (ATCC 25285) originally isolated from clinical material, were analysed for both cell envelope proteins composition and surviving under oxidative stress starvation. All strains examined showed a similar survival response when cultured in drinking water with a ten-fold decrease in viable counts per day during the 7 days of analysis. The outer membrane protein (OMP) profiles of all strains were quite similar during the stress period as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). However, the periplasmic proteins of the strain 118310 showed two protein bands at 48 and 58 kDa, respectively, that were absent in the strains AA1 and ATCC 25285 during the incubation period in potable water. Whole cells and periplasmic 35S-labelled proteins from bacteria cultured in drinking water showed a significant increase in proteins at 16, 18, 24, 26, 35, 48, and 58 kDa and 18, 22, 24, 48, 58, and 70 kDa, respectively, in all strains when compared to cells grown in BHI-PRAS media as detected by autoradiography following SDS-PAGE. These data suggest that B. fragilis may have a synthesis mechanism that allows them to adapt to adverse environments.     

Electrophysiological properties of cultured neonatal rat dorsal horn neurons containing GABA and met-enkephalin-like immunoreactivity

We have developed a culture of neurons dissociated from the most superficial laminae of the neonatal rat spinal cord dorsal horn (DH). By using the perforated patch-clamp technique, we distinguished four types of neurons based on their firing properties in response to intracellular injection of 900 ms lasting current pulses. Type 1 neurons were characterized by a tonic firing. Type 2 neurons displayed marked spike accommodation and fired brief (<500 ms) bursts of action potentials, whereas type 3 neurons fired a single spike. Type 4 neurons exhibited different types of firing patterns, but all of them possessed a time-dependent inwardly rectifying current activated by membrane hyperpolarization. Met-enkephalin-like immunoreactivity (met-ENK-LI) and glutamic acid decarboxylase-like immunoreactivity (GAD-LI) were colocalized in 42% of the neurons (n = 59), which were previously identified electrophysiologically. Type 1-4 neurons represented respectively 4, 64, 20, and 12% of the population of neurons colocalizing met-ENK-LI and GAD-LI. We conclude that the electrophysiological properties of DH neurons present in our cultures are similar to those described in acute slice or hemisected spinal cord preparations and that met-ENK-LI and GABA-LI are preferentially colocalized in type 2 neurons.     

Use of a multileaf collimator for the production of intensity-modulated beams

The continuous release of nitric oxide (NO) from the constitutive, endothelial isoform of nitric oxide synthase (e-NOS) serves mainly to keep the vasculature in a continuous state of active vasodilation. Although it has been suggested that NO production from e-NOS might also be affected by hemorrhagic shock (HS), this relationship is still controversial. Therefore, the roles of NO in the pathophysiology in hemorrhagic shock were reviewed. According to the previous reports, NO might play an important role in the pathophysioliogy of HS. In the early phase of HS, it may be possible that NO delivered from e-NOS serves a cytoprotective function in preventing shock-induced organ injury. This opinion suggests that endothelial NO production has a significant modulatory effect on vascular tone during hemorrhage, and that inhibition of NO production permits greater vasconstrictor influences leading to organ injury. NO production in the late phases of HS has an adverse effect on survival rate in the HS model. Moreover, the findings from an animal study of prolonged periods of HS suggest that excessive NO formation, including those produced from i-NOS, induces vascular hypoactivity and they have suggested that NOS inhibitors may improve the therapeutic outcome for patients suffering from HS. Therefore, it may be suggested that NO might play a biphasic role, cytoprotective during the early phase and cytotoxic late in HS.     

Acylated ascorbate stimulates collagen synthesis in cultured human foreskin fibroblasts at lower doses than does ascorbic acid

Acylated derivatives of ascorbic acid were found to be active in a number of biochemical and physiological processes. In the present study we investigated the effects of 6-O-palmitoyl ascorbate on collagen synthesis by cultured foreskin human fibroblasts. Our observations indicate a marked stimulatory effect on collagen synthesis by 6-O-palmitoyl ascorbate in the concentration range of 5-20 microM, while the synthesis stimulated by ascorbic acid was maximal at concentrations of 20-100 microM. Cells treated with 10 microM palmitoyl ascorbate for 36 h exhibited a production of collagen threefold greater than those in the presence of 10 microM ascorbic acid, and it was about the same as in cells treated with 100 microM ascorbic acid. By 48 h differences were not significant. Acylated ascorbate impaired vitality of the treated fibroblasts at concentrations exceeding 20 microM in media supplemented with 0.5% FCS. However, most of the cytotoxic effect was neutralized by FCS at a concentration of 10%. The resistance of acylated ascorbate against oxidative degradation as well as the role of free radicals in the modulation of collagen synthesis by ascorbic acid and by its derivatives is discussed.     

High-resolution HLA-DRB typing using denaturing gradient gel electrophoresis and direct sequencing

Skeletal development of transgenic mice with a type II collagen mutation was analyzed and compared with wild-type littermates. The single base substitution in Col2a1 resulted in a glycine to serine mutation within the helical domain and corresponded to one previously identified in a patient with the lethal human chondrodysplasia, hypochondrogenesis (Horton et al. [1992] Proc. Natl. Acad. Sci. U.S.A. 89:4583-4587). Skeletal staining of embryos from 14.5 through 18.5 days of gestation demonstrated a dwarf phenotype in the transgenic embryos, most notably short limb bones and vertebral column that was first detected at 15.5 days post-coitus. In addition to the reduced length, the extent of ossification was less in the transgenic mice. The architecture of the long bone growth plate was abnormal in the transgenic tissue, in particular there was no discernible proliferative zone. There were few stacks of characteristically flattened cells and the overall length of the growth plate in the mutant embryos was reduced. At the ultrastructural level, there were fewer collagen fibrils present in the transgenic mouse cartilage compared to that of wild-type littermates. Ultrastructural localization of collagen types II, IX and XI revealed a similar pattern between the transgenic and wild-type pups, suggesting that the collagen fibrils present in the matrix of littermates with both phenotypes had a similar composition. Skeletal analysis and cartilage histochemistry indicated that effect of the type II collagen mutation was to reduce the density of the collagen fibrils within the cartilage matrix which was associated with delayed bone formation and resulted in a short-limbed phenotype.     

Interpreting the chi-square statistics reported in the many-faceted Rasch model

The different chi-square statistics reported in the many-faceted Rasch model analysis are presented and interpreted. In addition, other chi-square summary values are computed and presented for interpretation of facets. The chi-square values are useful for determining: (1) the significance of a facet in the Rasch model; (2) the significant contribution of facet main and interaction effects; (3) differences among facet elements; and (4) identifying the specific facet interaction adjustments to the subjects' calibrated logit ability measure.     

The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure in primary rat astroglia: identification of biochemical and cellular targets

This paper reports the results from in vitro experiments utilizing vital fluorescent probes and biochemical assays to examine the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and related compounds in primary rat astroglia in an effort to identify the cellular site(s) involved in toxicity. Application of 100 nM 2,3,7,8-TCDD, a strong Ah receptor agonist, resulted in altered astroglial intracellular Ca2+, a significant decrease in glutathione, a disrupted mitochondrial membrane potential, a significant decrease in glutamine synthetase immunoreactivity and eventual loss of pH maintenance. In contrast, application of 10 microM 1,2,3,4-TCDD, a weak Ah receptor agonist, had no effect on any parameters measured. These findings, coupled with the identification of the 9-10S cytosolic Ah receptor in cultured rat astroglia, are consistent with typical structure-activity relationships observed for other Ah receptor mediated responses. However, the time course of the Ca2+, as well as other responses observed in this study, suggest that the above effects may not necessarily involved the formation of the nuclear Ah receptor complex.     

Clonal expansions of B lymphocytes in old mice

The effect of age on the diversity of the murine Ig heavy chain repertoire has been studied in unimmunized C57BL/6 mice. We examined the heterogeneity of complementarity-determining region 3 (CDR3) sizes of Ig mRNA of the IgM and IgG isotypes using two VH families, VHJ558 and VHQ52, which together account for approximately 65% of the Ab repertoire. The broad and bell-shaped profiles representing the diversity of the VHJ558 family in the spleen of 2- to 6-mo-old C57BL/6 mice becomes significantly less diverse after 12 mo of age and by 18 mo of age, single CDR3 sizes that dominate the profiles can be observed in the spleens of > 85% of the mice. Readable sequences have been obtained from 40 dominant mRNA CDR3 size species indicating that they represent clonal populations of B lineage. There are no significant homologies among these sequences. Clones of B lymphocytes that express a dominant CDR3 mRNA species can also be found in the bone marrow, the mesenteric lymph nodes, and the thymus of C57BL/6 mice > 18 mo of age. Some clones of B cells can be detected in only one lymphoid compartment; others are found in two or more compartments. The splenic B cell clones in C57BL/6 mice > 18 mo of age are stable for at least 2 mo. The CDR3 mRNA species that dominate the splenic repertoire of Ig mRNA-expressing cells in vivo do not dominate the repertoire of splenic B cells activated in vitro by bacterial LPS, suggesting that they represent a modest population of B cells expressing high levels of Ig mRNA.