Influence of particulate trap oxidizers on emission of mutagenic compounds by diesel automobiles

Diesel exhaust particles are known to contain mutagenic and carcinogenic chemicals. The aim of this study was to determine whether, and to what extent, catalytic particulate trap oxidizers on light-duty diesel engines may reduce the emission of particle-associated mutagenic chemicals into the environment. Exhaust particles were collected from Mercedes Benz and Volkswagen diesel automobiles, equipped with or without the manufacturer's exhaust traps, while running on a chassis dynamometer under specified load conditions. Exhaust particles were collected from a dilution tunnel onto 20" X 20" Teflon-coated fiberglass filters. Mutagenesis tests of dichloromethane (DCM) extracts of the particles were conducted using the Ames Salmonella bacterial test system. The mutation rate was calculated in terms of histidine revertants per mile of travel during a set of standard test cycles. With both vehicles the traps produced an 87-92% reduction in the total amount of particulate material collected by the filters. There was no significant change in the specific mutagenic activity (revertants per microgram of DCM particle extract) with or without the traps. These studies support the notion that installation of exhaust traps which reduce particulate emission on diesel-powered vehicles will also reduce the emission of particle-associated mutagenic and carcinogenic materials into the environment.     

Experimental Cryptosporidium parvum infections in immunosuppressed adult mice.

Five strains of adult mice were immunosuppressed with the synthetic glucocorticosteroid dexamethasone (DEX), administered either orally or intraperitoneally. The strains of mice used were C57BL/6N, DBA/2N, CBA, C3H/HeN, and BALB/cAnN. All mice were evaluated for susceptibility to Cryptosporidium parvum after intragastric inoculation with 10(6) oocysts per mouse. The DBA/2N, CBA, C3H/HeN, and BALB/cAnN mice given 0.25 micrograms of DEX per g per day orally (the dose and route previously used to infect rats with C. parvum) failed to develop chronic infections. However, the C57BL/6N mice sustained light infections during the entire 28-day experiment. The five strains of mice were also administered DEX intraperitoneally at concentrations ranging from 62.5 to 500 micrograms/day. Only the C57BL/6N mice given DEX at 125 micrograms/day developed chronic infections which persisted over 10 weeks, suggesting that the genetic background of the mouse plays a role in determining susceptibility to cryptosporidosis following immunosuppression with DEX. We believe that the C57BL/6N mouse model will prove to be superior to other animal models for evaluating potential anticryptosporidial agents, as well as for elucidating the immunological defects that allow C. parvum to establish chronic infections, because of cost effectiveness and ease in maintenance, breeding, and handling. We also evaluated the C3H/HeJ/beige mouse (lacks natural killer cell activity) and the C57BL/6N mouse maintained on a low-protein diet to induce immunosuppression. Neither of these mice exhibited heavy cryptosporidial infections.     

Quantitative studies of Fc receptors on human monocytes: characterization by binding of homologous and heterologous monomeric IgG and soluble immune complexes of different composition

The binding of 125I-labelled monomeric human and rabbit IgG (H-IgG, R-IgG) and rabbit IgG immune complexes (IC) to monocyte-enriched human peripheral blood cells had been investigated quantitatively. Scatchard plots at 4 degrees demonstrated that R-IgG bound to the same number of Fc receptors per cell (19,000) as H-IgG, but with a lower affinity (2.4 +/- 0.9 X 10(8)/l/mol and 3.5 +/- 1.1 X 10(8)l/mol, respectively). Inhibition studies demonstrated that the two ligands could mutually inhibit each other, H-IgG having higher inhibitory efficiency versus R-IgG than the reverse. It seems likely that R-IgG reacts with the Fc receptor for the homologous IgG, although with lower affinity. Binding of soluble R-IgG anti-bovine serum albumin (BSA) IC, prepared at molar antigen:antibody (Ag:Ab) ratio of 2:1 and 12:1, showed quite different behaviour, the IC binding with association constants almost 10-fold lower than the affinity of monomeric R-IgG, but binding six- to seven-fold as many IgG molecules per cell at saturation.     

Nutrient signalling in the regulation of human muscle protein synthesis

The mammalian target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) are important nutrient- and energy-sensing and signalling proteins in skeletal muscle. AMPK activation decreases muscle protein synthesis by inhibiting mTOR signalling to regulatory proteins associated with translation initiation and elongation. On the other hand, essential amino acids (leucine in particular) and insulin stimulate mTOR signalling and protein synthesis. We hypothesized that anabolic nutrients would be sensed by both AMPK and mTOR, resulting in an acute and potent stimulation of human skeletal muscle protein synthesis via enhanced translation initiation and elongation.
We measured muscle protein synthesis and mTOR-associated upstream and downstream signalling proteins in young male subjects ( n = 14) using stable isotopic and immunoblotting techniques. Following a first muscle biopsy, subjects in the 'Nutrition' group ingested a leucine-enriched essential amino acid–carbohydrate mixture (EAC). Subjects in the Control group did not consume nutrients. A second biopsy was obtained 1 h later. Ingestion of EAC significantly increased muscle protein synthesis, modestly reduced AMPK phosphorylation, and increased Akt/PKB (protein kinase B) and mTOR phosphorylation ( P < 0.05). mTOR signalling to its downstream effectors (S6 kinase 1 (S6K1) and 4E-binding protein 1 (4E-BP1) phosphorylation status) was also increased ( P < 0.05). In addition, eukaryotic elongation factor 2 (eEF2) phosphorylation was significantly reduced ( P < 0.05). Protein synthesis and cell signalling (phosphorylation status) was unchanged in the control group ( P > 0.05).
We conclude that anabolic nutrients alter the phosphorylation status of both AMPK- and mTOR-associated signalling proteins in human muscle, in association with an increase in protein synthesis not only via enhanced translation initiation but also through signalling promoting translation elongation.     

Defense of the ansatz for dynamical hierarchies

Gross and McMullin [Artificial Life, 7, 355-365] criticize the conclusions of our article on dynamical hierarchies [Artificial Life, 7, 329-353]. In this note we respond to their criticisms. After clarifying our ansatz, we argue that the simulations presented by Gross and McMullin present no evidence against the ansatz, in part because their simulations use a different simulation framework, and in part because their simulations are no less complex than ours. We also clarify why the micelles in our simulations are third-order emergent structures, and why we emphasize realism in our simulation.     

Falloposcopy in conjunction with laparoscopy: possibilities and limitations

Falloposcopy is a transvaginal microendoscopic technique to explore the human Fallopian tube from the uterotubal ostium to the fimbrial end. Falloposcopy provides a unique possibility to visualize endotubal disease and may be used therapeutically for removal of debris and for cutting down filmy intraluminal adhesions. To assess the clinical performance of falloposcopy as part of an infertility investigation, a total of 43 women scheduled for laparoscopy as part of an investigation of infertility had a falloposcopy performed in conjunction with the laparoscopy. All women were investigated at Danderyd Hospital, Stockholm and Akademiska Hospital, Uppsala, during 1995 and 1996. Images from the endosalpinx were obtained in 26 of 43 women (60.5%). In 10 women (23.3%), it was possible to obtain images from both tubes. No images were of sufficient quality to describe the entire tubal mucosa in detail. Falloposcopy represents a unique tool for visualization of endotubal disease and may provide a valuable instrument for in-vivo exploration of tubal physiology. However, certain technical problems limit the usefulness of this method in routine clinical practice. These technical problems have to be solved before falloposcopy can achieve a central position in investigation and treatment of tubal disease.      

Cytomegalovirus infection in heart transplant recipients: Preliminary results of a controlled trial of intravenous gamma globulin

Cytomegalovirus (CMV) infection is a major problem during the first twelve weeks after cardiac transplantation. Reactivation of endogenous virus, blood transfusion, and the transplanted heart are sources for CMV infection. Not only can disseminated CMV infection contribute directly to mortality, but CMV infection predisposes to superinfection with bacterial and fungal pathogens. Studies in mice, the premature neonate, and bone marrow transplant recipients suggest that passive immunization with CMV antibody has a modifying effect on CMV infection. By prophylactic administration of intravenous immune globulin in a controlled randomized fashion to cardiac transplant recipients we will address the question of whether passively acquired antibody prevents or modifies infection with CMV or other viral, bacterial, and fungal infections. Thirteen patients undergoing cardiac transplantation at Stanford University were randomized to receive or not receive intravenous immune globulin (IGIV) at a dose of 20 ml/kg twenty-four hours post transplantation and then weekly thereafter for a period of 10 weeks. Six patients seronegative for CMV antibody were randomized separately from seven who were seropositive for CMV antibody. Seven patients randomly selected from these two groups received IGIV. In patients seronegative for CMV, administration of IGIV resulted in serum titers of 1:10,000–1:30,000 measured by radioimmunoassay. Antibody titers were maintained at levels of 1:10,000 to 1:30,000 throughout the 10 week period post transplantation. Antibody remained detectable up to 8 weeks after the last infusion. No significant increases in CMV antibody levels were detectable after IGIV administration in patients seropositive for CMV antibody prior to transplantation. The administration of IGIV in thirty-two large and repeated doses was safe and well tolerated in cardiac transplant recipients. Serum levels of CMV antibody comparable to those observed in normal CMV seropositive individuals were achieved in CMV seronegative transplant recipients and were maintained throughout the period of greatest risk for CMV infection.