Elevated levels of p53 antigen in cultured skin fibroblasts from patients with hereditary adenocarcinoma of the colon and rectum and its relevance to oncogenic mechanisms

Skin fibroblasts (SFs) from patients with adenomatosis of the colon and rectum (ACR) were shown, in general, to express elevated amounts of the p53 antigen as determined by immunoprecipitation with the monoclonal antibody PAb421. Infection with simian virus 40 (SV40) induced expression of the p53 antigen in SFs from normal individuals and further amplified its expression in ACR cells. The half-lives of the p53 antigen in mock-infected ACR cells and in SV40-transformed normal or ACR cells were about 2 and 15 hours, respectively. No immediate differences were detected in the coding segment of the human p53 gene between normal and ACR cells by either Southern or Northern blot analysis. These results suggest that over-expression of the p53 antigen is due, in part, to the increased stability of the p53 antigen in ACR cells. Over-expression represents an early event that is possibly associated with initiation and promotion of inherited colon cancer.     

Intravenous fentanyl increases natural killer cell cytotoxicity and circulating CD16(+) lymphocytes in humans.

Opioids, including fentanyl, are often administered to patients who may be at risk for the consequences of impaired immune function. We performed a clinical study to test the effects of the synthetic opioid fentanyl on human immune function. Participants received an IV fentanyl initial dose of 3 microg/kg followed by a 2-h IV infusion of 1.2 microg x kg(-1) x h(-1). Peripheral blood was drawn before and after fentanyl administration to test for neutrophil phagocytic function, neutrophil antibody-dependent cell cytotoxicity, natural killer cell cytotoxicity, percentage of lymphocyte populations, T-lymphocyte proliferative response, and in vivo antibody response to a pneumococcal vaccine inoculation given at the end of the fentanyl infusion. Fentanyl exposure under the conditions of this study caused a rapid and significant increase in natural killer cell cytotoxicity, which was coincident with an increase in the percentage of CD16(+) and CD8(+) cells in peripheral blood. Fentanyl did not significantly affect any of the other immune measurements. IMPLICATIONS: Many previous studies have suggested that opioid drugs can impair immune resistance in patients who may be at risk for infection. This study suggests that the opioid fentanyl, when given to healthy humans without coexisting diseases, does not suppress immune resistance. On the basis of these results, the use of fentanyl should not be restricted because of concerns that it may suppress immune function.     

Decreased necrotizing fasciitis capacity caused by a single nucleotide mutation that alters a multiple gene virulence axis

Single-nucleotide changes are the most common cause of natural genetic variation among members of the same species, but there is remarkably little information bearing on how they alter bacterial virulence. We recently discovered a single-nucleotide mutation in the group A Streptococcus genome that is epidemiologically associated with decreased human necrotizing fasciitis (“flesh-eating disease”). Working from this clinical observation, we find that wild-type mtsR function is required for group A Streptococcus to cause necrotizing fasciitis in mice and nonhuman primates. Expression microarray analysis revealed that mtsR inactivation results in overexpression of PrsA, a chaperonin involved in posttranslational maturation of SpeB, an extracellular cysteine protease. Isogenic mutant strains that overexpress prsA or lack speB had decreased secreted protease activity in vivo and recapitulated the necrotizing fasciitis-negative phenotype of the ΔmtsR mutant strain in mice and monkeys. mtsR inactivation results in increased PrsA expression, which in turn causes decreased SpeB secreted protease activity and reduced necrotizing fasciitis capacity. Thus, a naturally occurring single-nucleotide mutation dramatically alters virulence by dysregulating a multiple gene virulence axis. Our discovery has broad implications for the confluence of population genomics and molecular pathogenesis research.     

Dorsal root sensitivity to interleukin-1 beta, interleukin-6 and tumor necrosis factor in rats

The release of inflammatory cytokines caused by a disrupted disc may play a critical role in pain production at nerve endings, axons, and nerve cell bodies. Herniated disc tissue has been shown to release inflammatory cytokines such as interleukin-1 beta (IL-1beta), interleukin-6 (IL-6), tumor necrosis factor (TNF), and other algesic chemicals. This study was designed to characterize the effects of these proinflammatory cytokines on the somatosensory neural response at the dorsal root level in rats. It is hypothesized that their effects on nerve endings in disc and adjacent tissue contribute to low-back pain, and the effects on dorsal root axons and ganglia contribute to radiculopathy and sciatica. Surgically isolated sacral dorsal roots were investigated by electrophysiologic techniques. IL-1beta, IL-6, or TNF (100 ng, each) were applied onto the dorsal roots. Neural responses and mechanosensitivity of the receptive fields were evaluated over time. The results showed that 3 h after each cytokine application, the neural activity was statistically decreased. The mechanical sensitivity of the receptive fields increased at 90 min following IL-1beta or TNF application, and returned to normal more than 3 h after IL-1beta application. IL-1beta, IL-6, and TNF may be neurotoxic to dorsal root axons. Furthermore IL-1beta and TNF may sensitize the peripheral receptive fields. This study suggests that dorsal roots may be impaired by these proinflammatory cytokines.     

Epidemic community-associated methicillin-resistant Staphylococcus aureus: recent clonal expansion and diversification

Emerging and re-emerging infectious diseases, especially those caused by drug-resistant bacteria, are a major problem worldwide. Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) appeared rapidly and unexpectedly in the United States, resulting in an epidemic caused primarily by isolates classified as USA300. The evolutionary and molecular underpinnings of this epidemic are poorly understood. Specifically, it is unclear whether there has been clonal emergence of USA300 isolates or evolutionary convergence toward a hypervirulent phenotype resulting in the independent appearance of similar organisms. To definitively resolve this issue and understand the phylogeny of USA300 isolates, we used comparative whole-genome sequencing to analyze 10 USA300 patient isolates from eight states in diverse geographic regions of the United States and multiple types of human infection. Eight of 10 isolates analyzed had very few single nucleotide polymorphisms (SNPs) and thus were closely related, indicating recent diversification rather than convergence. Unexpectedly, 2 of the clonal isolates had significantly reduced mortality in a mouse sepsis model compared with the reference isolate (P = 0.0002), providing strong support to the idea that minimal genetic change in the bacterial genome can have profound effects on virulence. Taken together, our results demonstrate that there has been recent clonal expansion and diversification of a subset of isolates classified as USA300. The findings add an evolutionary dimension to the epidemiology and emergence of USA300 and suggest a similar mechanism for the pandemic occurrence and spread of penicillin-resistant S. aureus (known as phage-type 80/81 S. aureus) in the 1950s.