High promutagen activating capacity of yeast microsomes containing human cytochrome P-450 1A and human NADPH-cytochrome P-450 reductase

Yeast Saccharomyces cerevisiae strains have been constructedthat co-express cDNAs coding for the human cytochrome P-450enzymes CYP1A1 or CYP1A2 in combination with human NADPH-cytochromeP-450 reductase (oxidoreductase). Microsomal fractions preparedfrom the strains were able to efficiently activate various drugsto Salmonella mutagens. These experiments demonstrated thata functional interaction occurred between the respective humanenzymes in the yeast microsomes. For every drug tested, themicrosomes containing CYP enzymes and oxidoreductase were 2-to 4-fold better in activation than the corresponding microsomesthat contained CYP alone. Interestingly, co-expression of CYP1A2with oxidoreductase resulted in a decrease of 7-ethoxyresorufin-O-deethylaseactivity, a problem which is related to this specific substrate.Using the microsomes, it was demonstrated that aflatoxin B₁,was activated to a mutagen not only by CYP1A2 but also by CYP1A1.In contrast, benzo[a]pyrene was exclusively activated by CYP1A1whereas CYP1A2 was inactive. The drug 3-amino-1-methyl-5H-pyrido[4,3-b]indole(Trp-P-2) was activated by CYP1A2 and to a lesser extent byCYP1A1. A strong substrate specificity was observed with thetwo structurally related heterocyclic arylamines 2-amino-3,4-dimethylimidazo[4,5-f]quinoline(MeIQ) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQ_x).MeIQ_x was activated efficiently by both CYP enzymes, whereasMeIQ was only activated by CYP1A2 and not by CYP1A1. The factthat microsomes from vector transformed control strains wereunable to activate any of the drugs studied underlines the suitabilityof these microsomes for metabolic studies. Moreover, the presenceof suitable marker genes in the yeast strains will enable usto study mitotic recombination and gene conversion events inducedby drugs that require metabolic activation.     

The Sisyphus Syndrome in Health Revisited

Health care may be similar to Sisyphus work: When the task is about to be completed, work has to start all over again. To see the analogy, consider an initial decision to allocate more resources to health. The likely consequence is an increased number of survivors, who will exert additional demand for health care. With more resources allocated to health, the cycle starts over again. The objective of this paper is to improve on earlier research that failed to find evidence of a Sisyphus syndrome in industrialized countries. This time, there are signs of such a cycle, which however seems to have faded away recently.JEL classification: I10, J10     

Fire-settng behavior associated with Klinefelter syndrome

This is a report on a male patient with a previous history of psychotic disorder who was arrested for arson. During the following hospitalization in a psychiatric unit, a genetic syndrome, namely Klinefelter syndrome (47,XXY), was diagnosed. The association between firesetting behavior and Klinefelter syndrome is reviewed, and the underlying explanatory hypothesis is discussed.     

A novel microvascular approach to treatment of the high undescended testicle

A 9-year-old boy presented for evaluation of bilateral nonpalpable testes. Despite a negative human Chorionic gonadotropin (hCG) simulation test, laparoscopy found high undescended testicles on both sides. The authors report the unusual microvascular approach utilized to accomplish testicular transfer into the scrotum and discuss the diagnostic difficulties experienced in this case. J Pediatr Surg 37:1501-1503.     

Isolation of adenoviruses from baboons (Papio sp.) with respiratory and enteric infections

Summary Simian adenoviruses were isolated from swabs and tissues of 6 newborn baboons which showed symptoms of pneumo-enteritis. Sixty isolates were found to be the same simian adenovirus (V340) as described previously. Three isolates were identified as SA7 virus. V340 virus was isolated consistently from oral and rectal swabs during the course of the disease and from various tissues from 3 animals which succumbed. The three SA7 viruses were isolated from rectal swabs of two animals during their convalescence. The consistent isolation of V 340 virus and the specific immune response to V 340 virus in the convalescent sera of the 3 surviving animals are indicative of a causative role of this virus in the pathogenesis of this disease. The frequent isolation of species of theKlebsiella-Aerobacter group, among others, indicates bacterial involvement in the disease process. Their exact role in the pathogenesis remains to be ascertained.This work was supported in part by U.S.P.H.S. grant GM-FR-13252-03 and W.H.O. grant 22/181/27.     

Superantigen overcomes resistance of IL-6-deficient mice towards MOG-induced EAE by a TNFR1 controlled pathway

Experimental autoimmune encephalomyelitis (EAE) induced by myelin oligodendrocyte glycoprotein peptide 35-55 (MOG) leads to a chronic form of disease characterized by demyelination, inflammation and gliosis in the central nervous system (CNS). Recently IL-6 and LT alpha were found to be required for induction of the disease. The main features associated with EAE resistance of IL-6(-/-) and LT alpha(-/-) mice were reduced T cell proliferation and endothelial activation. As shown here treatment of MOG-immunized IL-6(-/-) mice with staphylococcal enterotoxin B (SEB)reversed their resistance to MOG-induced EAE. SEB failed to restore susceptibility to EAE in LT alpha(-/-) mice. The effect of SEB to induce EAE in IL-6(-/-) mice depends on TNF receptor type 1 (TNFR1) signaling because IL-6/TNF/LT alpha(-/-) and IL-6/TNFR1(-/-) are refractory to SEB. TNFR1 is involved in SEB induced trafficking of T cells into the CNS as evidenced by the failure to up-regulate VCAM-1 on CNS endothelium and lack of accumulation of V beta 8(+) T cells in the CNS of IL-6/TNFR1(-/-) mice upon immunization with MOG and treatment with SEB. The course of SEB triggered EAE in MOG immunized IL-6(-/-) mice was characterized by reduced severity and duration of clinical manifestations, which were associated with a significant drop of CNS infiltrating neutrophils and MIP-2 expression after peak disease. Taken collectively the effect of SEB to overcome EAE resistance points to a transient IL-6 independent but TNFR1 dependent proinflamatory pathway in EAE pathogenesis and suggests a crucial function for IL-6 in disease perpetuation.     

Electron microscopic tracing of pathogenetic events in intestinal chlamydial infections of newborn calves

Pathogenetic events of the penetration of the intestinal mucosa were studied ultrastructurally after oral inoculation of neonatal calves with chlamydial strain LW-613. Chlamydiae adsorbed to the brush border of intestinal epithelial cells and were taken up by endocytosis. Chlamydial replication occurred in the supra-nuclear region of these cells which subsequently degenerated and liberated chlamydiae into the gut lumen and into the lamina propria mucosae. Inter-cellular edema, breakdown of the basal border of the intestinal epithelial cells, and festooning and ultimate loss of the basal lamina facilitated penetration of chlamydiae into the lamina propria mucosae and its cellular components, including the endothelial cells of the lymphatic system. Infected endothelial cells liberated chlamydiae into the lymphatic circulation leading to chlamydemia and systemic infection involving lymph nodes, parenchymal organs and joints.     

Induction of oral tolerance to cellular immune responses in the absence of Peyer's patches

Systemic hyporesponsiveness occurs following oral administration of antigen (oral tolerance) and involves the uptake and processing of antigen by the gut-associated lymphoid tissue (GALT), which includes Peyer's patches (PP) lamina propria lymphocytes and mesenteric lymph nodes (MLN). Animals with targeted mutations of genes in the tumor necrosis factor (TNF) family have differential defects in the development of peripheral lymphoid organs including PP and MLN, and provide a unique opportunity to investigate the role of GALT structures in the induction of oral tolerance. Oral tolerance could not be induced in TNF/lymphotoxin (LT) alpha-/- mice, which are devoid of both PP and MLN, although these animals could be tolerized by intraperitoneal administration of antigen, demonstrating the requirement for GALT for oral tolerance induction. LTbeta-/- mice and LTalpha/LTbeta+/- animals do not have PP but could be orally tolerized, as measured by IFN-gamma production and delayed-type hypersensitivity responses by administration of both low or high doses of ovalbumin. To further investigate the requirement for PP, we tested the progeny of LTbeta-receptor-IgG-fusion-protein (LTbetaRigG)-treated mice, which do not form PP but have an otherwise intact immune system. Although these animals had decreased fecal IgA production, they could be orally tolerized. Our results demonstrate that PP are not an absolute requirement for the induction of either high- or low-dose oral tolerance, although oral tolerance could not be induced in animals devoid of both PP and MLN.     

Severity of symptoms and demyelination in MOG-induced EAE depends on TNFR1

The individual role of tumor necrosis factor receptor 1 (TNFR1) and TNFR2 signaling in experimental autoimmune encephalomeylitis (EAE) was investigated using mice lacking TNFR1 (TNFR1-/-), TNFR2 (TNFR2-/-) as well as double receptor (TNFR1/2-/-) and double ligand (TNF/LT alpha-/-) knockout mice. In wild-type (wt) mice immunized with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 the clinical course is characterized by an acute disease onset with peak disease scores and a consecutive chronic phase lasting up to 60 days. Compared to control mice, TNF/LT alpha-deficient mice showed a significant delay in disease onset and a remarkable reduction in demyelination which was, however, associated with increased inflammation. In TNFR1-/- and TNFR1/2-/- mice, the disease course was comparable to TNF/LT alpha-deficient mice but rather monophasic and less severe at late time points. Likewise only minimal spinal cord demyelination became apparent. In contrast, the course of EAE in TNFR2-/- mice was severe and associated with remarkable demyelination. Taken together these findings define TNFR1 as crucial mediator in MOG-induced EAE and suggest a protective role for TNFR2 signaling in the clinical course of EAE.