Regulation of hematopoiesis II: the role of polyamine inhibition on helper or suppressor influences of the thymus

We have previously suggested in murine model systems, that two cell subpopulations with differing proliferative capacity, from the thymus, modify the growth of erythroid progenitor cells in vitro. In order to further characterize these populations, we have specifically inhibited polyamine biosynthesis; this pathway is essential for the process of cell replication. Thus, alpha-difluoromethyl ornithine (DFMO) was used to block the conversion of ornithine to putrescine, the first and rate- limiting step in polyamine biosynthesis. We observed a threefold increase in hematopoietic progenitors (CFU-S and CFU-E) from bone marrow in animals treated with DFMO. We further examined the effect of DFMO on accessory "helper" and "suppressor" cells from the thymus and observed an increase in helper activity with an elimination of suppressor activity. All of these effects of DFMO were specific for inhibition of polyamine biosynthesis, since simultaneous addition of the depleted biosynthetic product, putrescine, restored suppressor activity. We conclude that polyamine biosynthesis is required acutely for accessory cell regulation of hematopoiesis.     

Detection of hepatitis B virus in plasma using flow cytometric analyses of polymerase chain reaction-amplified DNA incorporating digoxigenin-11- dUTP

Blood donations are routinely screened by multiple serologic assays for antigens/antibodies associated with infection by blood-borne viruses, including hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency viruses (HIV-1 and HIV-2), and human T-cell lymphotropic virus (HTLV-I and HTLV-II). A direct detection of these viruses would be more effective for the prevention of transfusion- transmitted infections than the indirect measurement of the variable host immune response to these agents. Because the polymerase chain reaction (PCR) for viral gene amplification offers the most sensitive and direct means of detecting viruses in blood, we have developed a nonisotopic PCR procedure for the detection of HBV, chosen as a prototype. The problems, common to previously described PCR methods, of nucleic acid extraction and inhibition of the PCR by plasma proteins were overcome by isolation of HBV from plasma by means of 450-microns polystyrene beads covalently coated with monoclonal antibody to the Pre- S1 region of the viral envelope protein. Detergent lysis and proteinase K digestion of the immunocaptured virions isolated from plasma released the HBV DNA. A modified PCR-amplification protocol, incorporating digoxigenin-labeled dUTP in the amplified gene products followed by hybridization with a specific biotinylated oligonucleotide probe bound to streptavidin-coated 2.8-microns magnetic beads, allowed flow cytometric analyses of HBV-specific PCR products by means of antibodies to digoxigenin labeled with fluorescein isothiocyanate. The endpoint serial dilutions of pedigreed human plasma samples containing chimpanzee infectious dose (CID50) of 10(7) for adw and CID50 of 10(7.5) for the ayw subtypes were compared in repeated testing of PCR products by our immunoreactive bead (PCR-IRB) assay. HBV DNA was consistently detected in a 5 x 10(-10) dilution of each sample. In testing 20 coded specimens of blood donors, with or without serologic markers of HBV infection, the PCR-IRB was specific and more sensitive than the PCR analyses by slot blot hybridization with radioactive probe. The PCR-IRB assay can be adapted for simultaneous detection of multiple blood-borne viruses by an automated flow cytometric analysis system.     

Indications for vascular grafts as hemodialysis access: consensus from experience in Italy

Introduction: In Italy, the use of arteriovenous grafts (AVG) is limited (1-5 %) due to different approaches to vascular access (VA) management as compared to other Countries, where guidelines (which may not apply to the Italian setting) have been produced. Therefore, the Study Group (GdS) on VA of the Italian Society of Nephrology produced this position paper, providing a list of 8 recommendations built upon current guidelines. Methods: The most controversial and innovative issues of existing guidelines have been summed up in 12 different statements. We selected 60 Italian dialysis graft experts, nephrologists and vascular surgeons (PP1SIN Study Investigators). They were asked to express their agreement/disagreement on each issue, thus creating a new method to share and exchange information. Results: Most of them agreed (consensus > 90%) on specific criteria set to choose AVG over native AVF (nAVF) and tunnelled venous catheter (tVC) and on the necessary conditions to implant them. They did not fully agree on the use of AVG in obese patients, in patients at risk of developing ischemia, on the priority of AVG as an alternative to brachial-basilic fistula with vein transposition, and in case of a poorly organized setting regarding graft maintenance. Keeping in mind that the nAVF should be preferred whenever is feasible, AVGs are indicated when superficial veins are unavailable or to repair a nAVF (bridge graft). An AVG is an alternative to tVC if the expected patient survival is long enough to guarantee its clinical benefits.     

Physiological roles of dopamine and neuropeptides in the retina

Summary— The retina is a highly complex nervous tissue that converts light into patterns of electrical action potentials in order to process visual information. To carry out its function as a transducer and processor of visual information, the retina must be structurally and biochemically organized to send a coherent signal to the visual areas of the brain. In recent years, a number of biologically active substances have been demonstrated to be located within neurons in the retina. Most of them are thought to be involved in the modulation of the signal and its transmission to the brain through the optic nerve. The present paper attempts to summarize the immunocytochemical distribution and physiology of some neuronally localized substances in the mammalian retina, namely dopamine and neuropeptides.     

The role of the gut in migraine: the oral 51-Cr EDTA test in recurrent abdominal pain

Sixteen children with recurrent abdominal pain (or: "recurrent syndrome"), regarded as migraine equivalent in childhood, were submitted to the 51-Cr EDTA gut permeability test. The results were compared with those obtained in 10 healthy young adults and in 11 control children. The gut permeability in the recurrent syndrome was significantly higher than in healthy adults and control children (p less than 0.0006): The following results were obtained: 4.83 +/- 0.40 (mean +/- SEM) in the children with recurrent abdominal pain, and 2.35 +/- 0.24 2.51 +/- 0.21 in the healthy young adults and control children, respectively. The implications of these findings as far as migraine is concerned, are discussed.     

Olfactory function after mild traumatic brain injury

Objective: The aim of this study was to determine the incidence of olfactory dysfunction after mild traumatic brain injury (MTBI). Damage to the olfactory bulbs or frontal cortex has been reported in MTBI, but olfactory dysfunction after MTBI has not been studied in a prospective way before.

Design: Patients with first-time MTBI were included. Patients' olfactory threshold values (Hyposmia Utility Kit by Olfacto-Labs®) were measured 2 weeks after the trauma. Associations between olfactory threshold values and individual symptoms and S-100B and NSE concentrations were examined, using multiple linear regression analysis, adjusting for the influence of age.

Results: Twenty-two per cent of 111 included patients had hyposmia and 4% had anosmia. Thresholds at 2 weeks showed no significant associations with the presence of symptoms at the ER, nor with early concentrations of S-100B or NSE.

Conclusions: Although a high prevalence of olfactory dysfunction was found, no correlation was found between olfactory dysfunction and acute parameters of MTBI.