RF lesion generation.

Although the technique of RF lesion generation is a well-established medical technique, most professionals using it do not understand the basic principles of electronics by which the phenomenon occurs. A review of this with special attention to the 'indifferent' or 'dispersive' electrode would lead to better practice and less adverse effects, such as patient skin burns.     

Prevalence of soft tissue oral lesion in elderly and its relations with deleterious habits

doi: 10.1111/j.1741‐2358.2011.00618.x Prevalence of soft tissue oral lesion in elderly and its relations with deleterious habits Introduction: With ageing, the oral mucosa becomes more susceptible to external stimuli. Objective: To investigate the prevalence of soft tissue oral lesion in elderly and its relations with deleterious habits. Materials and methods: It was a quantitative research conducted at the dental clinic of UNIFOR, Fortaleza‐CE, in the period from 1998 to 2006. The sample consisted of all 756 records of the elderly, and the data were processed by SPSS 15.0 (SPSS, Inc., Chicago, IL, USA). Results: The majority (63.0) were women, age 60–92, mean age 67 ± 6. The most significant proportions were married (48.4%), retired (42.3%) and incomplete primary school (31.5%). It was found a prevalence of 18.3% of oral lesions, with the risk being 1.6 times higher (p = 0.030) among youngest (up to 65 years) and 1.7 times higher among smokers (p = 0.048). Although this risk is 1.6 times higher among those who drank alcohol, it was not statistically significant (p = 0.122). Conclusion: The elderly showed a high prevalence of oral lesion, being the youngest, the smokers and the alcohol consumers those most vulnerable to the emergence of these diseases. Dental services need to implement programs of elderly care and health education, essential to clarify the risks and their associations with oral diseases, aiming to promote health.     

The effect of arginine and its metabolites on tissue culture of rat myocardium

In was demonstrated using the method of organotypic culture that arginine and its metabolites: cutrulline, ornitine and especially urea, in ultralow doses stimulated the myocardium proliferation in mature rats. Only nitric oxide (NO) possessed the antiproliferative effect. The cytrulline effect was similar to the arginine effect. The metabolism of these amino acids is intimately interrelated so the cytrulline can be used in the clinic practice as an "argininepreserved" preparation. The antiproliferative NO effect can be delayed by thiole-containing preparations: glulathione and unithiole.     

Cell cycle control at the first restriction point and its effect on tissue growth

Cell cycle is controlled at two restriction points, R ₁ and R ₂. At both points the cell will commit apoptosis if it detects irreparable damage. But at R ₁ an undamaged cell also decides whether to proceed to the S phase or go into a quiescent mode, depending on the environmental conditions (e.g., overpopulation, hypoxia). We consider the effect of this decision at the population level in a spherical tissue {r < R(t)}. We prove that if the cells have full control at R ₁, they can manipulate the size of R(t) to ensure that 0 < c ≤ R(t) ≤ C < ∞; simulations further show that R(t) can be made nearly stationary. In the absence of such control, R(t) will either increase to ∞ or decrease to 0. The mathematical model and analysis involve a system of PDEs in {r < R(t)}.     

Monocyte thromboplastin (tissue factor): complementary effect of lymphocytes upon its generation by endotoxin-stimulated monkey (Macaca fuscata) cells

Monkey (Macaca fuscata) mononuclear leukocytes were stimulated to produce thromboplastin (tissue factor) upon exposure to lipopolysaccharide, LPS. The stimulation was dose-related in the concentration range of 10(-5) to 10(-1) micrograms/ml of LPS. Lipid A portion of the LPS molecule was essential to induce the leukocyte ability for tissue factor generation. Thus, a lipid-lipid interaction between LPS and the cells is a plausible trigger for eliciting the ability. Approximately 50% of the tissue factor thus produced appeared to be located on the cell surface, at which the coagulation cascade is probably initiated via the activation of factor VII. Among monkey mononuclear cell populations, monocytes were responsible for LPS-induced tissue factor production. Lymphocytes amplified the basal ability of monocytes to produce the factor by two-fold at physiological lymphocyte-monocyte ratios of 8:1 to 10:1. This indicates a complementary effect of lymphocytes upon the LPS-mediated monocyte ability. The medium supernatant from LPS-stimulated lymphocytes affected the monocyte competence while the stimulated lymphocytes did not. This result suggests that a soluble product of lymphocytes, i.e., lymphokine-like mediator, but not the cellular entity, participates in LPS-induced tissue factor production of monocytes.     

Human recombinant tissue type plasminogen activator and its effect on microvascular thrombosis in the rabbit

A new potent thrombolytic agent, human tissue type plasminogen activator (t-PA), has become available for study through recombinant DNA technology. In this series of experiments, we have tested t-PA in a reliable microvascular thrombosis model previously developed in our laboratory. Its action in preventing thrombus formation and lysing fresh clot by direct local infusion and systemic infusion was tested. The results revealed that t-PA was able to keep locally infused vessels open for 4 hours and reopen them after they were allowed to clot in 100 percent of the animals tested. Those vessels exposed only to systemic levels of t-PA achieved by the same local infusion remained thrombosed and were unaffected. Laboratory studies showed no evidence of activation of the systemic lytic state or alteration in coagulation parameters. t-PA has proved to be a protein with characteristics that make it attractive for use in microvascular surgery. The results suggest that further research may lead the way toward clinical use.