Modification of Resistance to Streptococcus pneumoniae by Dietary Ethanol, Immunization, and Murine Retroviral Infection

Hallmarks of the acquired immune deficiency syndrome (AIDS) are immunologic alterations, frequently associated with opportunistic infections. To study such associations, LP-BM5 murine retrovirus infection was used as a murine model of AIDS. Retrovirally infected and uninfected mice were fed a 5% (v/v) ethanol diet for 55 days and then fed a 7% v/v ethanol diet for the final 7 days to assert the role of ethanol as a cofactor in development of murine AIDS. There was a reduction in polymorphonuclear neutrophils count in ethanol-fed groups. Neutrophils increased in retrovirus-infected groups, except those vaccinated 10 days before challenge with live bacteria. The percentage of splenic lymphocytes in the retrovirus-infected group was reduced in comparison with controls. Survival of the mice challenged intraperitoneally with Streptococcus pneumoniae was increased by vaccination and suppressed by dietary alcohol. Retrovirus infection caused a much faster death rate after bacterial challenge than nonretrovirus infected controls. Vaccination played an important role in delaying the death rate in all treated groups. Transferring spleen cells from healthy, unimmunized mice also enabled the retrovirally infected mice to survive the bacterial infection longer. Enhancement of resistance to S. pneumoniae by vaccination and transfer of immunocompetent cells to mice immunosuppressed by retroviral infection show the potential to use immunomodulation to affect disease resistance in AIDS.     

mTOR signaling: implications for cancer and anticancer therapy

Mounting evidence links deregulated protein synthesis to tumorigenesis via the translation initiation factor complex eIF4F. Components of this complex are often overexpressed in a large number of cancers and promote malignant transformation in experimental systems. mTOR affects the activity of the eIF4F complex by phosphorylating repressors of the eIF4F complex, the eIF4E binding proteins. The immunosuppressant rapamycin specifically inhibits mTOR activity and retards cancer growth. Importantly, mutations in upstream negative regulators of mTOR cause hamartomas, haemangiomas, and cancers that are sensitive to rapamycin treatment. Such mutations lead to increased eIF4F formation and consequently to enhanced translation initiation and cell growth. Thus, inhibition of translation initiation through targeting the mTOR-signalling pathway is emerging as a promising therapeutic option.     

Alcohol and Murine Acquired Immunodeficiency Syndrome Suppression of Resistance to Cryptosporidium parvum Infection during Modulation of Cytokine Production

The effects of inoculation of LP-BM5 murine leukemia retrovirus and chronic ethanol (5% v/v) ingestion on immunomodulation and Cryptosporidium parvum infection in C57BL/6 female mice were evaluated. The intestinal mucosae of retrovirally immunosuppressed animals were heavily colonized by Cryptosporidium parasites, and oocysts shedding in the feces persisted throughout the duration of the study. Mortality was exacerbated by murine retrovirus infection alone and exacerbated with concomitant chronic alcohol feeding (42.8 and 69.4%). Chronic ethanol ingestion decreased production of interferon-γ and soluble interleukin-2 receptor released in supernatants of splenocytes when stimulated with concanavalin A, compared with the control group. Decreased production of interferon-γ and interleukin-2 receptor was further exacerbated due to retrovirus infection. Tumor necrosis factor production by splenocytes stimulated with lipopolysaccharide, however, was significantly increased because of retrovirus infection. LP-BM5 retrovirus infection alone as well as with concomitant ethanol feeding altered cytokine production, which might have led to immunodeficiency. These changes may help explain the enhanced persistence of Cryptosporidiosis.     

Rates of protein synthesis--a review

The rates of protein synthesis can be measured by a variety of methods including pulse labeling, massive precursor administration, Scornik method, continuous feeding of labeled precursor, infusion, and pellet implantation. Each technique has some advantages and disadvantages. Massive precursor administration and infusion are the most widely used. The advantage of massive precursor administration is its simplicity, however, the amino acid concentration used is much higher than physiological levels. Infusion, however, is much more complicated as a technique and requires complicated calculations. The synthesis rates can also be calculated from degradation curves. Some of the above techniques can be used both in vivo and in vitro, and also for different organs (Shahbazian et al. (1987), Int. J. Dev. Neurosci., 5: 39-42). The brain has rapid rates of protein synthesis both in vivo and in vitro, the latter being much lower for adults.     

The complications of full-pelvic irradiation with particular emphasis to external beam therapy.

62 Patients with uterine carcinoma of cervix treated with high-dose large-volume full-pelvic irradiation given through co-axial-opposing pair portals over the anterior and posterior pelvis. Of these patients, 29 also received a single course of intracavitary radium supplementary to external beam irradiation. Only the severe complications which required surgical intervention have been analyzed, In the group of 33 patients who received only external irradiation, 4 developed such complications (12.1%).The overall incidence of those complications was about 19.3%. It is concluded that the treatment with hidh-dose large-volume full-pelvic irradiation technique, utilizing two opposing parallel pelvic portals, carries an incidence of morbidity 3-4 times the acceptable level and should be discouraged. Alternative techniques are discussed.     

Cannabinoid inhibition of guinea-pig intestinal peristalsis via inhibition of excitatory and activation of inhibitory neural pathways.

Since activation of cannabinoid CB1 receptors inhibits gastrointestinal transit in the mouse, this study analyzed the action of the cannabinoid receptor agonist methanandamide on distension-induced propulsive motility. Peristalsis in luminally perfused segments of the guinea-pig isolated ileum was elicited by a rise of the intraluminal pressure. The pressure threshold at which peristaltic contractions were triggered was used to quantify drug effects. Methanandamide (0.1-3 microM) inhibited peristalsis as deduced from a concentration-related increase in the peristaltic pressure threshold, an action that was prevented by the CB1 receptor antagonist SR141716A (1 microM) per se, which had no effect on peristalsis. The distension-induced ascending reflex contraction of the circular muscle was likewise depressed by methanandamide in a SR141716A-sensitive manner, whereas indomethacin-induced phasic contractions of the circular muscle were left unchanged by methanandamide. The anti-peristaltic action of methanandamide was inhibited by apamin (0.5 microM), attenuated by N-nitro-L-arginine methyl ester (300 microM) and left unaltered by suramin (300 microM), pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (150 microM) and naloxone (0.5 microM). It is concluded that methanandamide depresses intestinal peristalsis via activation of CB1 receptors on enteric neurons, which results in blockade of excitatory motor pathways and facilitation of inhibitory pathways operating via apamin-sensitive K+ channels and nitric oxide.     

Proinflammatory cytokine production by mitogen-stimulated peripheral blood mononuclear cells (PBMCs) in trauma patients fed immune-enhancing enteral diets

Widespread metabolic changes associated with injury facilitate the delivery of nutrients to the immune system. The effect of specific nutrients administered by the enteral route on the immune response in trauma victims is not well understood. The purpose of this study was to examine whether the synthesis of proinflammatory cytokines (tumor necrosis factor-alpha [TNF-alpha], interleukin-1 beta [IL-1 beta], and interleukin-6 [IL-6]) by peripheral blood mononuclear cells (PBMCs) are influenced by the nature of the dietary fat in critically injured trauma victims. We measured plasma TNF-alpha, IL-1 beta, and IL-6 and their release stimulated by phytohemagglutinin (PHA) and endotoxin (lipopolysaccharide, LPS) from PBMCs of 13 severely injured (injury severity score = 30 +/- 2) patients once within 48-60 h after injury and then after 7 d of enteral feeding (1.5 g protein[P].kg-1.d-1). Group I (n = 6) received diet A (Crucial) and group II (n = 7) received diet B (Impact). The plasma levels of TNF-alpha and IL-1 beta in trauma patients are not significantly different from those in healthy volunteers, but plasma IL-6 levels are significantly increased (five times) in severely injured patients. Stimulation of TNF-alpha and IL-1 beta secretion by LPS and PHA were significantly higher in patients than in control subjects; in contrast, there was no stimulation of IL-6 because of trauma or nutritional support by either of the diets. Stimulation of IL-1 beta by LPS was normalized by Crucial but was further enhanced by Impact. The higher fat content in Crucial may contribute in part to the apparent immunomodulation. Crucial seems to be a better choice in correcting the nutritional deficiency.     

Reduced proportion of Purkinje cells expressing paternally derived mutant Mecp2308 allele in female mouse cerebellum is not due to a skewed primary pattern of X-chromosome inactivation

Rett syndrome (RTT) is an X-linked disorder caused by mutations in the methyl CpG binding protein 2 (MECP2) gene. The pattern of X-chromosome inactivation (XCI) is thought to play a role in phenotypic severity. In the present study, patterns of XCI were assessed by lacZ staining of embryos and adult brains of mice heterozygous for a X-linked Hmgcr-nls-lacZ transgene on a mutant mouse model of RTT. We found that there was no difference between the lacZ staining patterns in the brain of wild-type and heterozygous mutant embryos at embryonic day 9.5 (E9.5) suggesting that Mecp2 has no effect on the primary pattern of XCI. At 20 weeks of age, there was no significant difference between XCI patterns in the Purkinje cells in the cerebellum of heterozygous mutant and wild-type mice when the mutant allele was inherited from the mother. However, when the mutant allele was paternally inherited, a significant difference was detected. Thus, parental origin of the mutation may have a bearing on phenotype through XCI patterns. An estimation of the Purkinje cell precursor number based on XCI mosaicism revealed that, when the mutation was paternally inherited, the precursor number was less than that in the wild-type mice. Therefore, it is likely that the number of precursor cells allocated to the Purkinje cell lineage is affected by a paternally inherited mutation in Mecp2. We also observed that the pattern of XCI in cultured fibroblasts was significantly correlated with patterns in the Purkinje cells in mutant animals but not in wild-type mice.