Regulation of peripheral-type benzodiazepine receptors in cultured astrocytes by monoamine and amino acid neurotransmitters

Exposure of primary cultured astrocytes for 3 days to 1 μM of either dopamine, serotonin or norepinephrine resulted in upregulation (25–34% increase in B_max) of the peripheral-type benzodiazepine receptors (PBRs) labeled with [³H]Ro5-4864. A similar treatment with γ-aminobutyric acid [GABA] caused a 2-fold increase in the affinity (K_d) of [³H]Ro5-4864. The monoamines tested and GABA had no effect on the binding parameters of [³H]PK 11195, another selective PBR ligand. The present study indicates that Ro5-4864 binding sites are susceptible to regulation by specific neurotransmitters and provides further evidence for the distinction between Ro5-4864 and PK 11195 binding sites of the PBRs in cultured astrocytes.     

Administration of Half-Dose Theophylline Together with Ketotifen to Asthmatic Children—A Double-Blind, Placebo-Controlled Study

Administration of theophylline to asthmatic children is frequently associated with an adverse influence on their behavior. The efficacy and behavioral effects of the administration of high-dose theophylline (T) and ketotifen (K) in various combinations were evaluated prospectively in a double-blind, placebo controlled study in 55 children with moderately severe perennial asthma. During a baseline period of 2 weeks, theophylline (serum level of 10-20 μg/ml) was administered to all the children. After this period the patients were randomly allocated into four comparable groups. The children were treated during a 12-week period with: T + K-Placebo (T group); T + K (T + K group); half-dose T + K (T/ 2 + K group); or placebo of both T and K (P group). During the 12-week treatment period, as compared to the baseline period, only the three groups of children who received active therapy (T + P, T + K, T/2 + K) showed a similar reduction in the number of days with asthmatic symptomatology, improvement of the total asthmatic symptoms score, and increased PEFR. The behavioral activity of the children (assessed by the Conner's rating scale) improved significantly only in the groups receiving placebo or T/2 + K. The results of this study suggest that a combination therapy of half the recommended therapeutic dose of theophylline with ketotifen can be clinically as effective as therapy with a full dose of theophylline, but with significantly less adverse behavioral effects.     

Immediate root canal disinfection with ultraviolet light: an ex vivo feasibility study.

OBJECTIVE: The study was designed to test application of ultraviolet light to root canal walls, as a mean of complementary immediate disinfection after the use of sodium hypochlorite. STUDY DESIGN: Root canals were infected ex vivo with Enterococcus faecalis for 48 hours. Non-attached bacteria were washed away, and the remaining attached bacteria were subjected to disinfection, with 5% sodium hypochlorite alone or followed by exposure to ultraviolet light (254 nm, 300 mJ/cm(2)). Root canals were then tested for remaining viable bacteria. Canals were obturated and tested again after 14 days. RESULTS: Sodium hypochlorite alone achieved negative cultures in only 47% of the cases, but 96% was achieved with sodium hypochlorite followed by ultraviolet light (P < .001). This status was also maintained after 14 days. CONCLUSIONS: Illumination of root canals with ultraviolet light may be an effective supplementary means to achieve immediate disinfection of infected root canals.     

Inhibition of plaque formation, rosette formation and phagocytosis by alpha globulin

The immunosuppressive effect of an alpha globulin fraction isolated from normal human plasma is described.

The administration of this material to rats suppressed both the primary and secondary antibody responses against sheep erythrocytes. Alpha globulin also depressed the ability of mice spleen cells to confer immunity to irradiated isologous recipients.

The in vitro addition of alpha globulin to mouse peritoneal leucocytes (MPL) and whole human blood caused a significant reduction of their phagocytic activity against bacteria.

The mode of action of alpha globulin in relation to its immunosuppressive activity is discussed.

     

Familial thyroglossal duct cyst

Thyroglossal duct cysts are common congenital abnormalities or developmental field defects, usually detected in early childhood. Despite their frequent occurrence, familial patterns are rare. We report on two new families with thyroglossal duct cysts. In the first family three siblings were involved, while in the second one, father and son were affected. This trait may be autosomal recessive or possibly multifactorial, as the first family would indicate, and also autosomal dominant, as the second family would suggest.     

Surfactant protein D enhances phagocytosis and killing of unencapsulated phase variants of Klebsiella pneumoniae

Pulmonary surfactant protein D (SP-D) is a collagenous C-type lectin (collectin) that is secreted into the alveoli and distal airways of the lung. We have studied the interactions of SP-D and alveolar macrophages with Klebsiella pneumoniae, a common cause of nosocomial pneumonia. SP-D does not agglutinate encapsulated K. pneumoniae but selectively agglutinates spontaneous, unencapsulated phase variants, such as Klebsiella strain K50-3OF, through interactions with their lipopolysaccharides (LPS). These effects are calcium dependent and inhibited with maltose but not lactose, consistent with involvement of the SP-D carbohydrate recognition domain. Precoating of K50-3OF with SP-D enhances the phagocytosis and killing of these organisms by rat alveolar macrophages in cell culture and stimulates the production of nitric oxide by the NR-8383 rat alveolar macrophage cell line. SP-D similarly enhances the NO response to K50-3OF LPS adsorbed to Latex beads under conditions where soluble LPS or SP-D, or soluble complexes of SP-D and LPS, do not stimulate NO production. Our studies demonstrate that interactions of SP-D with exposed arrays of Klebsiella LPS on a particulate surface can enhance the host defense activities of alveolar macrophages and suggest that activation of macrophages by SP-D requires binding to microorganisms or other particulate ligands. Because unencapsulated phase variants are likely to be responsible for the initial stages of tissue invasion and infection, we speculate that SP-D-mediated agglutination and/or opsonization of K. pneumoniae is an important defense mechanism for this respiratory pathogen in otherwise healthy individuals.     

Binding of Streptococcus pyogenes to soluble and insoluble fibronectin.

The interaction of soluble and insoluble fibronectin with Streptococcus pyogenes was investigated. Soluble fibronectin bound to S. pyogenes in a dose-dependent and irreversible manner. Lipoteichoic acid competitively inhibited the binding of fibronectin to S. pyogenes but had little effect on the binding of fibronectin to staphylococci or pneumococci. The phase of growth of the streptococci had a slight effect on binding of fibronectin, with optimal binding occurring in the late log phase. S. pyogenes cells bound to fibronectin immobilized on microtiter plates in a dose-dependent and saturable manner. Both soluble fibronectin and lipoteichoic acid inhibited the binding of streptococci to immobilized fibronectin, suggesting that streptococci interact with soluble and insoluble fibronectin in a similar manner. Antibodies to fibronectin blocked the attachment of streptococci to immobilized fibronectin, whereas normal serum had no effect. Adherence of streptococci to buccal epithelial cells was inhibited by antibodies to fibronectin, but not by normal sera or by antibodies to buccal epithelial cells. The data suggest that lipoteichoic acid on the surface of S. pyogenes binds to fibronectin exposed on the host cell and that such binding mediates the attachment of streptococci to host cells.     

Therapeutic Effect of Doxycycline in Experimental Subclinical Canine Monocytic Ehrlichiosis: Evaluation of a 6-Week Course

The efficacy of doxycycline treatment (10 mg/kg of body weight every 24 h for 42 days) in eliminating Ehrlichia canis from four subclinically infected dogs was evaluated. One dog remained PCR positive, suggesting that 6 weeks of doxycycline treatment may not be sufficient to clear E. canis parasites from all subclinically infected dogs. Serology (indirect immunofluorescent antibody assay) was shown to be unreliable in assessing recovery from the carrier state, as anti-E. canis antibodies persisted after elimination of the parasite. Our findings suggest that an increase in the platelet count may be an important indicator for dogs that recover from subclinical ehrlichiosis.     

Amplification of Ehrlichial DNA from Dogs 34 Months after Infection with Ehrlichia canis

In order to determine whether dogs in the subclinical phase of canine monocytic ehrlichiosis (CME) are carriers of Ehrlichia canis and to determine the significance of persistent indirect immunofluorescent anti-E. canis antibody titers during this phase, PCR was performed with blood, bone marrow, and splenic aspirates collected 34 months postinoculation from six clinically healthy beagle dogs experimentally infected with E. canis. At least one of the three samples (spleen, bone marrow, and blood) from four of the six dogs was PCR positive. The spleens of all four of these dogs were PCR positive, and the bone marrow and blood of two of the four dogs were PCR positive. Indirect immunofluorescent-antibody titers increased progressively during the first 5 months postinfection, remained high for an additional period of more than 11 months, and declined thereafter, suggesting that the dogs were recovering from the disease. Five of the dogs remained seropositive 34 months postinfection. The data obtained in this study demonstrate for the first time that clinically healthy dogs in the subclinical phase of CME are carriers of the rickettsia. It was shown that dogs can harbor E. canis for years without developing the chronic clinical disease and that dogs can eliminate the parasite and recover from CME without medical treatment. Our findings suggest that the spleen is the organ most likely to harbor E. canis parasites during the subclinical phase and the last organ to accommodate the parasite before elimination. It was concluded that PCR of DNA extracted from splenic aspirates is a reliable method for determining the carrier state of CME.