Sphingoid bases are taken up by Escherichia coli and Staphylococcus aureus and induce ultrastructural damage.

Sphingoid bases found in the outer layers of the skin exhibit antimicrobial activity against gram-positive and gram-negative bacteria. We investigated the uptake of several sphingoid bases by Escherichia coli and Staphylococcus aureus, and assessed subsequent ultrastructural damage. E. coli and S. aureus were incubated with D-sphingosine, dihydrosphingosine, or phytosphingosine at ten times their MIC for 0.5 and 4 h, respectively, to kill 50% of viable bacteria. Treated bacterial cells were immediately prepared for SEM, TEM, and analyzed for lipid content by QTLC. E. coli and S. aureus treated with sphingoid bases were distorted and their surfaces were concave and rugate. Significant differences were observed in the visual surface area relative to controls for both E. coli and S. aureus when treated with dihydrosphingosine and sphingosine (p < 0.0001) but not phytosphingosine. While sphingoid base-treated S. aureus exhibited disruption and loss of cell wall and membrane, E. coli cytoplasmic membranes appeared intact and the outer envelope uncompromised. Both E. coli and S. aureus cells contained unique internal inclusion bodies, likely associated with cell death. QTLC demonstrated extensive uptake of sphingoid bases by the bacteria. Hence, sphingoid bases induce both extracellular and intracellular damage and cause intracellular inclusions that may reflect lipid uptake.

Effects of keratinocyte and hepatocyte growth factor in vivo: implications for retrovirus-mediated gene transfer to liver.

We have previously shown that intravenous administration of keratinocyte growth factor (KGF) induces hepatocyte proliferation, allowing for efficient and noninvasive in vivo gene transfer with high-titer retroviral vectors in mice. The distinctive periportal distribution of transduced cells led us to investigate the ability of virus-sized particles to perfuse the liver adequately after growth factor treatment. We found that perfusion was adequate, and that transduction was limited to the periportal region because only those cells were stimulated to divide. Cells in this region also showed increased expression of Ram-1, the receptor for the murine Moloney leukemia virus (MoMLV) amphotropic envelope, after KGF treatment. In further studies we found that recombinant hepatocyte growth factor (HGF) induces a different population of hepatocytes to divide and upregulate Ram-1. The differential pattern of induction suggested that combining KGF and HGF would improve gene transfer efficiency further. Indeed, simultaneous delivery of both growth factors leads to an overall increase in the number of proliferating cells. Importantly, when coupled with MoMLV delivery, efficiency of gene transfer increased. These results confirm the utility of growth factors for noninvasive hepatic gene transfer in mice, and demonstrate how experiments to define the mechanism of transduction can be taken advantage of to develop improved gene transfer protocols.

Social anxiety and peer relations among adolescents: testing a psychobiological model.

This study tested hypotheses derived from Trower and Gilbert's (1989) model of social anxiety. Participants were 1,179 students (594 males and 585 females) in grades 6, 7, 8, 9, and 11. Participants completed the Social Anxiety Scale for Adolescents and a sociometric nomination task. Nominations from the following behavioral descriptors: most cooperative, class leader, fights the most, and easiest to push around, were used to classify students into four peer nomination groups (i.e., cooperative, friendly dominant, hostile dominant, and submissive). Results indicated that students classified as submissive reported greater social anxiety than those classified as cooperative, friendly dominant, and hostile dominant. Implications of these results for further study of the Trower and Gilbert (1989) model of social anxiety are discussed.

Usher's syndrome type IC: clinical studies and fine-mapping the disease locus.

Usher's syndrome type I is a heterogeneous group of diseases characterized by severe to profound sensorineural hearing loss, absent vestibular function, and progressive pigmentary retinopathy. Other identifying clinical features have not been documented. In this study, we examined olfactory acuity, plasma levels of polyunsaturated fatty acids and sarcosine, and cilia ultrastructure in a homogeneous cohort of patients with Usher's syndrome type IC. The normal age-dependent decline in olfactory acuity was observed, and normal plasma levels of polyunsaturated fatty acids and sarcosine were found. However, the incidence of compound cilia in biopsies from the inferior turbinate was significantly higher than that reported in control populations. By reconstructing haplotypes in affected persons. D11S902 and D11S1310 were identified as flanking markers over an interval that contains a candidate gene, KCNC1. No mutations in the coding sequence of this gene could be demonstrated in affected persons.

Oral bacterial attachment to titanium surfaces: a scanning electron microscopy study.

Despite the wide use of dental implants, the understanding of the mechanism(s) of bacterial attachment to implant surfaces and of the factors that affect such attachment is limited. In this study, the attachment of oral bacteria--including Streptococcus sanguis, Actinomyces viscosus, and Porphyromonas gingivalis--to titanium (Ti) discs with different surface morphology (smooth, grooved, or rough) was examined by scanning electron microscopy (SEM). The most bacterial attachment was observed on the rough BSA-coated Ti surfaces. The smooth surfaces promoted poor attachment for S. sanguis and A. viscosus. However, P. gingivalis attached equally well to both the smooth and grooved coated Ti surfaces, based on direct cell quantitation and examination with SEM. Cell-surface fimbriae (which may play a role in adhesion) of both A. viscosus and P. gingivalis observed were associated with the Ti surfaces. Ti implant surface characteristics appeared to influence oral bacterial attachment in vitro. The in vitro attachment system has proven its usefulness for future bacterial attachment studies with model implant surfaces.

Carrageenan-induced inclusions in mammary myoepithelial cells.

The purpose of this investigation was to characterize the ultrastructural changes that occur in mammary myoepithelial cells (MMEC) following exposure in tissue culture to low concentrations of lambda-carrageenan, a sulfated polysaccharide commonly used as a food additive. MMEC were obtained from reduction mammoplasty, grown in tissue culture, exposed for varying durations to low concentrations (0.0014%-0.0001%) of lambda-carrageenan, and examined by transmission electron microscopy, following staining for acid phosphatase and for aryl sulfatase. Carrageenan appeared to enter the cells by membrane-associated endocytic vesicles and accumulate in endosomes and lysosomes. Unusual lamellar inclusions were identified within lysosomes of the MMEC, and lysosomal vacuolation arose in association with the inclusions. The observed changes appeared to lead to destruction of the MMEC by release of proteolytic enzymes from the distorted lysosomes, similar to the process observed in lysosomal storage diseases.

Social Anxiety Scale for Adolescents: normative data and further evidence of construct validity.

Replicates and extends prior work with the Social Anxiety Scale for Adolescents (SAS-A) by providing psychometric data, further evidence of construct validity, and large-sample based normative data. Participants were 2,937 students (1,431 boys and 1,506 girls) in Grades 6, 7, 8, 9, and 11. Students completed the SAS-A, the Revised Children's Manifest Anxiety Scale (RCMAS), and the Children's Depression Inventory (CDI). Results replicated a three-factor structure for the SAS-A, with good internal consistencies for its subscales. Normative data were subdivided by sex and grade group. Construct validity included replication of prior relations with general anxiety (RCMAS) and depressive symptomatology (CDI). Implications of these results for further use and norming of the SAS-A are discussed.

The role of social anxiety in adolescent peer relations: differences among sociometric status groups and rejected subgroups.

Examined the relation between sociometric nominations and social anxiety in adolescence. Participants were 973 students (473 boys and 500 girls) in Grades 6, 7, 8, and 9. Students completed the Social Anxiety Scale for Adolescents and a sociometric nomination task that included the following behavioral descriptors: liked most, liked least, starts fights the most, best sense of humor, class leader, easiest to push around, and most cooperative. Sociometric nominations were used to classify students into standard sociometric status groups (i.e., popular, average, rejected, neglected, and controversial) as well as into rejected subgroups (aggressive rejected and submissive rejected). Results indicated that students classified as rejected and neglected reported more social anxiety than those classified as average, popular, or controversial. In addition, submissive rejected students reported significantly more social anxiety than did aggressive rejected or average students. Implications of these results for assessment and treatment of adolescents with peer problems are discussed.

Effect of immunological differences on rat aortic valve allograft calcification.

Calcification may be a cause of allograft valve degeneration. To determine whether immunological differences between donor and recipient affect the degree of calcification that occurs, adult Lewis rats received aortic valve allografts transplanted heterotopically into the abdominal aorta. All valves were transplanted immediately after harvest. The valves were not exposed to antibiotics or albumin before insertion. Valve donors were of the Lewis (syngeneic), F344 (weakly allogeneic, RT1 compatible, non-RT1 incompatible), LBN F1 (moderately allogeneic, one haplotype identical, one haplotype incompatible at the RT1 and non-RT1 loci), and Brown Norway (strongly allogeneic, RT1 and non-RT1 incompatible) strains. Valves were harvested 3-12 weeks following transplantation. Scanning electron microscopy and energy dispersion x-ray microanalysis were performed on one leaflet of each valve to evaluate calcium content. Calcium content expressed in counts (mean +/- standard error) according to donor strain were: Lewis, 1642 +/- 233; F344, 4853 +/- 1412; LBN F1, 4714 +/- 823; and Brown Norway, 4358 +/- 835. Significant differences (p less than 0.05) existed between valves from Lewis donors and those from each other strain. No differences among the other strains were statistically significant. It is concluded that syngeneic valve allografts calcify less than allogeneic grafts. However, the degree of allogenicity did not influence the magnitude of calcification.

Effects of calcium channel blockers on calcium uptake in rat aortic valve allografts.

BACKGROUND: The life span of human aortic valve allografts is finite, and many fail because of cusp rupture or calcification. Subcellular changes occurring in aortic valves in response to transplantation include the uptake of calcium. This study uses a heterotropic rat aortic valve transplant model to determine whether the calcium channel blockers diltiazem and verapamil might attenuate leaflet calcification. METHODS AND RESULTS: The 60 rats studied were divided into the following groups: 1) control: valves from normal, unoperated F1 generation of Lewis and Brown Norway cross (LBNF1) rats; 2) control: valves from syngeneic transplant combinations (Lewis/Lewis); 3) control: valves from allogeneic transplant combinations (LBNF1/Lewis, donor/recipient); 4) experimental: valves from allogeneic strain combinations treated with 30 mg/kg per day diltiazem; 5) experimental: valves from allogeneic strain combinations treated with 30 mg/kg per day verapamil. Drugs or saline (controls) were administered with osmotic pumps placed subcutaneously 2 days before transplantation. Animals were killed 3 weeks later, and the valves were harvested and prepared for calcium analysis. Energy-dispersive x-ray microanalysis was used to measure the calcium in a section of one leaflet from each valve studied. Paired t tests showed that allograft valves treated with diltiazem or verapamil contained significantly less calcium than allograft controls treated with saline (p < 0.001). When all five groups were subjected to one-way ANOVA, the valves in the allograft control group contained significantly more calcium than all other groups. All other groups were not different from each other. CONCLUSIONS: The calcium channel blockers verapamil and diltiazem were effective in preventing early calcification that occurs in aortic valves after transplantation. Thus, these agents might play a role in prolonging the life of human aortic valve allografts.