Induction of ppp(A2''p)nA-dependent RNase in murine JLS-V9R cells during growth inhibition.

We recently reported that interferon induces the synthesis of ppp(A2'p)nA(n = 2 to greater than or equal to 4) (2-5A)-dependent RNase in the murine cell line JLS-V9R. These cells normally contain very low levels of the nuclease; after interferon treatment, however, they develop levels approaching those found in murine L or Ehrlich ascites tumor cells. Here, we report a similar increase in the nuclease levels in JLS-V9R cells during the transition from the subconfluent actively growing state to the confluent stationary phase. Levels of 2-5A synthetase increased in parallel with the nuclease. The induced levels of both the nuclease and synthetase returned to low basal amounts after trypsinization, dilution, and culturing of the cells at subconfluent densities. The addition of anti-murine interferon (alpha + beta) antibodies to the medium did not affect the induction of the nuclease nor could any interferon be detected in the culture supernatants as determined by the lack of antiviral activity. The increase in the enzymes was not, therefore, due to the spontaneous production of interferon. The induction of the nuclease during confluency preceded an inhibition of [3H]-thymidine incorporation by the cells into DNA. The regulation of the 2-5A-dependent RNase in JLS-V9R cells may, therefore, be related to the control of cell growth.     

Vagotomy and gallbladder function

The effect of vagotomy on gallbladder function was investigated in a clinical and experimental study. In the clinical study both the size of the gallbladder and its capacity to respond to cholecystokinin were evaluated radiologically before and after vagotomy. In studies in the rabbit, both the immediate effect of vagotomy on the gallbladder and the effect of varying doses of cholecystokinin on gallbladder pressure were studied before and after vagotomy. In studies in the cat the long-term effect of vagotomy was studied with respect to the histology of the gallbladder and the composition of bile.The clinical investigation showed that vagotomy was followed by a significant increase in the volume of the gallbladder and that the effect of the cholecystokinin on the gallbladder remained unchanged after vagotomy. In experiments in the rabbit it was found that cholecystokinin in a dose of 1 unit/kg body weight exerted a somewhat lesser effect on gallbladder pressure after vagotomy than before, while after vagotomy a dose, approximately four times greater, resulted in a stronger gallbladder response. Further, the experiments showed that the chemical composition of the bile seemed to be altered after vagotomy, while the gallbladder remained histologically essentially unchanged.     

Long-term Lyme disease antibiotic therapy beliefs among New England residents

Most physicians prescribe Lyme disease antibiotic therapy regimens that are recommended by the Centers for Disease Control and Prevention, the Infectious Disease Society of America, and the National Institutes of Health. An alternative approach by some physicians consists of prolonged antibiotic treatment for >2 months because they believe that Lyme disease often results in persistent Borrelia burgdorferi infection. Understanding how patients perceive the disease is important for effective doctor-patient communication. We conducted interviews and surveys on Block Island, Rhode Island, and Storrs, Connecticut, to explore the public perception of persistent symptoms following Lyme disease and the need for long-term treatment. Most of our participants believed that symptoms and the Lyme disease bacteria can persist after antimicrobial therapy for Lyme disease. When asked about the value of continuing antibiotic treatment for >2 months, about half thought that it was sometimes useful and about a quarter thought it was always useful. Almost all of the respondents stated that they knew people who had experienced Lyme disease, and these personal observations were more frequently cited as an important source of Lyme disease information than official sources such as medical professionals. We conclude that healthcare workers should review the scientific literature regarding appropriate therapy for Lyme disease, discuss such information with their patients, and identify sources of information that their patients can review. Medical societies, private foundations, and State and Federal Health agencies should increase efforts to educate physicians and the general public about the standard diagnosis and treatment of Lyme disease and provide additional funding to determine why some people experience persistent symptoms following this infection.     

Xenotransplantation of immunodeficient mice with mobilized human blood CD34+ cells provides an in vivo model for human megakaryocytopoiesis and platelet production

The study of megakaryocytopoiesis has been based largely on in vitro assays. We characterize an in vivo model of megakaryocyte and platelet development in which human peripheral blood stem cells (PBSCs) differentiate along megakaryocytic as well as myeloid/lymphoid lineages in sublethally irradiated nonobese diabetic/severe combined immunodeficient (NOD-SCID) mice. Human hematopoiesis preferentially occurs in the bone marrow of the murine recipients, and engraftment is independent of exogenous cytokines. Human colony-forming units-megakaryocyte (CFU-MK) develop predominantly in the bone marrow, and their presence correlates with the overall degree of human cell engraftment. Using a sensitive and specific flow cytometric assay, human platelets are detected in the peripheral blood from weeks 1 to 8 after transplantation. The number of circulating human platelets peaks at week 3 with a mean of 20 x 10(9)/L. These human platelets are functional as assessed by CD62P expression in response to thrombin stimulation in vitro. Exogenous cytokines have a detrimental effect on CFU-MK production after 2 weeks, and animals treated with these cytokines have no circulating platelets 8 weeks after transplantation. Although cytokine stimulation of human PBSCs ex vivo led to a significant increase in CFU-MK, CD34+/41+, and CD41+ cells, these ex vivo expanded cells provided only delayed and transient platelet production in vivo, and no CFU-MK developed in vivo after transplantation. In conclusion, xenogeneic transplantation of human PBSCs into NOD/SCID mice provides an excellent in vivo model to study human megakaryocytopoiesis and platelet production.     

Hepatic involvement in patients with human immunodeficiency virus infection: discrepancies between AIDS patients and those with earlier stages of infection

The effect of human immunodeficiency virus (HIV) infection on type and severity of liver disease was studied in 61 HIV-positive patients who did not have AIDS and in 45 AIDS patients. Liver biopsies revealed viral hepatitis in 12 of 18 non-AIDS patients but in only 4 of 34 AIDS patients (P less than .0005, Fisher's exact test). Acute, non-A non-B, and chronic active hepatitis B were seen exclusively in the non-AIDS group; however, chronic persistent hepatitis B was seen in both groups. In 9 of 18 AIDS patients intra vitam liver histopathology established diagnoses of opportunistic infections or tumors. Tissue reaction to certain pathogens, such as hepatitis B virus, mycobacteria, and cryptococci, seems to be milder in AIDS patients than in others who are HIV positive or the expected reaction of the normal host. This is likely because of impaired cell-mediated immunity in patients with advanced HIV disease.     

The CEBPA gene is down-regulated in acute promyelocytic leukemia and its upstream promoter, but not the core promoter, is highly methylated

Impairment of CCAAT Enhancer Binding Protein alpha (CEBPA) function is a common finding in acute myeloid leukemia; nevertheless, its relevance for acute promyelocytic leukemia pathogenesis is unclear. We analyzed the expression and assessed the methylation status of the core and upstream promoters of CEBPA in acute promyelocytic leukemia at diagnosis. Patients with acute promyelocytic leukemia (n = 18) presented lower levels of CEBPA expression compared to healthy controls (n = 5), but higher levels than those in acute myeloid leukemia with t(8;21) (n = 9) and with inv(16) (n = 5). Regarding the core promoter, we detected no methylation in 39 acute promyelocytic leukemia samples or in 8 samples from controls. In contrast, analysis of the upstream promoter showed methylation in 37 of 39 samples, with 17 patients showing methylation levels over 30%. Our results corroborate data obtained in animal models showing that CEBPA is down-regulated in acute promyelocytic leukemia stem cells and suggest that epigenetic mechanisms may be involved.