52 research outputs found

    Effect of frequency difference on sensitivity of beats perception

    Get PDF
    Two vibrations with slightly different frequencies induce the beats phenomenon. In tactile perception, when two pins of different frequencies stimulate the fingertips, an individual perceives a beats caused by a summation stimulus of the two vibrations. The present study demonstrates experimentally that humans can perceive another vibration based on the beats phenomenon when two tactile stimuli with slightly different frequencies are stimulated on the finger pad with a small contactor in different locations at the same time. Moreover, we examined the amplitude of the detection threshold to be able to perceive beats phenomenon on the index finger with 5 carrier frequency (63.1, 100, 158.5, 251.2, and 398.1 Hz) and 4 beats frequency (2.5, 3.98, 6.31, and 10 Hz) when two stimuli 1 mm distance apart are vibrated at a slightly different frequency. From the experiments, it is concluded that the amplitude threshold to be able to perceive beats decreases as the standard frequency increases under 398 Hz. Furthermore, from comparing the absolute detection threshold and beats detection threshold, as the carrier frequency increases, the required amplitude at two pins for the detection of beats decreases compared to absolute vibration

    EBV, HHV8 and HIV in B cell non Hodgkin lymphoma in Kampala, Uganda

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>B cell non Hodgkin lymphomas account for the majority of lymphomas in Uganda. The commonest is endemic Burkitt lymphoma, followed by diffuse large-B-cell lymphoma (DLBCL). There has been an increase in incidence of malignant lymphoma since the onset of the HIV/AIDS pandemic. However, the possible linkages of HHV8 and EBV to the condition of impaired immunity present in AIDS are still not yet very clearly understood.</p> <p>Objectives</p> <p indent="1">1. To describe the prevalence of Epstein-Barr virus, Human Herpes virus 8 and Human Immunodeficiency Virus-1 in B cell non Hodgkin lymphoma biopsy specimens in Kampala, Uganda.</p> <p indent="1">2. To describe the histopathology of non Hodgkin lymphoma by HIV serology test result in Kampala, Uganda</p> <p>Method</p> <p>Tumour biopsies specimens from 119 patients with B cell non Hodgkin lymphoma were classified according to the WHO classification. Immunohistochemistry was used for detection of HHV8 and in situ hybridization with Epstein Barr virus encoded RNA (EBER) for EBV. Real time and nested PCR were used for the detection of HIV.</p> <p>The patients from whom the 1991-2000 NHL biopsies had been taken did not have HIV serology results therefore 145 patients biopsies where serology results were available were used to describe the association of HIV with non Hodgkin lymphoma type during 2008-2009.</p> <p>Results</p> <p>In this study, the majority (92%) of the Burkitt lymphomas and only 34.8% of the diffuse large B cell lymphomas were EBV positive. None of the precursor B lymphoblastic lymphomas or the mantle cell lymphomas showed EBV integration in the lymphoma cells.</p> <p>None of the Burkitt lymphoma biopsies had HIV by PCR. Of the 121 non Hodgkin B cell lymphoma patients with HIV test results, 19% had HIV. However, only 1(0.04%) case of Burkitt lymphoma had HIV. All the tumours were HHV8 negative.</p> <p>Conclusions</p> <p>The majority of the Burkitt lymphomas and two fifths of the diffuse large B cell lymphomas had EBV. All the tumours were HHV8 negative. Generally, the relationship of NHL and HIV was weaker than what has been reported from the developed countries. We discuss the role of these viruses in lymphomagenesis in light of current knowledge.</p

    Affinity for self antigen selects T<sub>reg</sub> cells with distinct functional properties

    Get PDF
    The manner in which regulatory T cells (Treg cells) control lymphocyte homeostasis is not fully understood. We identified two Treg cell populations with differing degrees of self-reactivity and distinct regulatory functions. We found that GITR(hi)PD-1(hi)CD25(hi) (Triple(hi)) Treg cells were highly self-reactive and controlled lympho-proliferation in peripheral lymph nodes. GITR(lo)PD-1(lo)CD25(lo) (Triple(lo)) Treg cells were less self-reactive and limited the development of colitis by promoting the conversion of CD4(+) Tconv cells into induced Treg cells (iTreg cells). Although Foxp3-deficient (Scurfy) mice lacked Treg cells, they contained Triple(hi)-like and Triple(lo)-like CD4(+) T cells zsuper< T cells infiltrated the skin, whereas Scurfy Triple(lo)CD4(+) T cells induced colitis and wasting disease. These findings indicate that the affinity of the T cell antigen receptor for self antigen drives the differentiation of Treg cells into distinct subsets with non-overlapping regulatory activities
    corecore