Preliminary studies on antipyretic and analgesic properties of Taverniera abyssinica

In an attempt to ascertain the pharmacological basis of the use of the marketed traditional drug Taverniera abyssinica A. Rich. (Amharic name Dingetegna), crude extracts as well as purified substances of this plant were tested for their antipyretic and analgesic properties. Antipyretic activity was determined on rats made hyperthermic by yeast injection and analgesic activity was determined by the hot plate, as well as the acetic acid induced writhing, methods. The study showed that the plant possesses significant antipyretic and analgesic activities.     

Performance characteristics of a rapid new immunochromatographic test for detection of antibodies to human immunodeficiency virus

A new immunochromatographic rapid test (Rapid Check HIV 1 and 2; Núcleo de Doen?as Infecciosas) for the detection of antibodies to human immunodeficiency virus type 1 and type 2 in human samples (whole blood, serum, and plasma) was evaluated and compared to the commercially available Determine (Abbott Laboratories). When whole-blood samples were evaluated, the specificity and sensitivity of both tests were 100%. However, when plasma samples were used, sensitivity for the Rapid Check HIV 1&2 and the Determine tests were 100 and 98.58%, respectively. The observed specificity for plasma samples was 98.94% for the Rapid Check HIV 1&2 and 96.97% for the Determine test. The results presented here are encouraging and support the adoption of both tests as an alternative to enzyme-lined immunosorbent assay and/or Western blots in regions where laboratorial infrastructure is not available or for use in the management of occupational accidents for healthcare workers.     

Alteration of the follicular basement membrane in non-obese diabetic mice with spontaneous autoimmune thyroiditis

The follicular basement membrane (FBM) prevents thyroglobulin from escaping to the peri-follicular space, where it can act as an antigen to induce experimental thyroiditis. Laminin, a component of the FBM, is responsible for directing cell migration and stimulates greater adhesion of activated T lymphocytes. Our purpose was to study the expression of laminin in the thyroid of NOD mice, which have a propensity for autoimmune diseases, including thyroiditis. Thirty NOD mice between 3 and 42 weeks old were studied. Eight had thyroiditis and 22 showed no inflammatory infiltration. An immunohistochemical examination using the streptavidin-biotin-peroxidase technique was conducted on paraffin-embedded tissue sections, with a polyclonal antilaminin antibody. Antigen retrieval was achieved through pepsin digestion and microwave irradiation in citrate buffer. Staining for laminin was restricted to the basement membrane. In thyroids with no infiltration, laminin was shown as a fine, continuous brown line in the basement membrane. In 6 out of the 8 cases of thyroiditis, clearcut interruption and destruction of the FBM was observed, particularly when the follicles were located in lymphocyte infiltrated areas or when there was fibrosis. There were significant alterations in the pattern of the FBM with extensive areas of discontinuity in the distribution of laminin. Such discontinuities could facilitate antigen exposure, especially thyroglobulin, which may contribute to autoimmune thyroiditis in NOD mice.     

Circuit dynamics and coding strategies in rodent somatosensory cortex

Previous experimental studies of both cortical barrel and thalamic barreloid neuron responses in rodent somatosensory cortex have indicated an active role for barrel circuitry in processing thalamic signals. Previous modeling studies of the same system have suggested that a major function of the barrel circuit is to render the response magnitude of barrel neurons particularly sensitive to the temporal distribution of thalamic input. Specifically, thalamic inputs that are initially synchronous strongly engage recurrent excitatory connections in the barrel and generate a response that briefly withstands the strong damping effects of inhibitory circuitry. To test this experimentally, we recorded responses from 40 cortical barrel neurons and 63 thalamic barreloid neurons evoked by whisker deflections varying in velocity and amplitude. This stimulus evoked thalamic response profiles that varied in terms of both their magnitude and timing. The magnitude of the thalamic population response, measured as the average number of evoked spikes per stimulus, increased with both deflection velocity and amplitude. On the other hand, the degree of initial synchrony, measured from population peristimulus time histograms, was highly correlated with the velocity of whisker deflection, deflection amplitude having little or no effect on thalamic synchrony. Consistent with the predictions of the model, the cortical population response was determined largely by whisker velocity and was highly correlated with the degree of initial synchrony among thalamic neurons (R(2) = 0.91), as compared with the average number of evoked thalamic spikes (R(2) = 0.38). Individually, the response of nearly all cortical cells displayed a positive correlation with deflection velocity; this homogeneity is consistent with the dependence of the cortical response on local circuit interactions as proposed by the model. By contrast, the response of individual thalamic neurons varied widely. These findings validate the predictions of the modeling studies and, more importantly, demonstrate that the mechanism by which the cortex processes an afferent signal is inextricably linked with, and in fact determines, the saliency of neural codes embedded in the thalamic response.     

Inclusion of satellites in an 18/21 translocation chromosome shown by ammonical-silver staining (sat-banding) in case of partial trisomy 18.

A male infant with a partial trisomy 18 and a 46,XY, --21, t(18;21)(18qter replaced by 18q12::21 p13 replaced by 21 qter) chromosome complement is described. The translocation chromosome is of special interest because it includes the satellites of chromosome 21. This was shown by differential satellite staining with the ammoniacal-silver technique.     

A fertile male with cystic fibrosis: molecular genetic analysis.

A family study is presented in which the father of a girl with severe cystic fibrosis (CF) was also found to have CF but was mildly affected. He was diagnosed with three positive sweat tests including one after suppression with fludrocortisone. Genetic analysis showed that he is a compound heterozygote with the delta F508 CF mutation associated with haplotype B and a second CF mutation associated with haplotype C. In this unusual, fertile CF male, the late age of diagnosis (30 years) and the mild clinical picture suggest that the compound genotype (delta F508/other CF mutation) determines a much less severe form of the disease which might have gone unnoticed in the absence of a severely affected child. The implications of these findings for genetic counselling of families with CF are discussed.     

Utility of Major Leukocyte Subpopulations for Monitoring Secondary Cytomegalovirus Infections in Renal-Allograft Recipients by PCR

The feasibility of the major peripheral blood leukocyte (PBL) subsets for use in qualitative and quantitative PCR to monitor secondary cytomegalovirus (CMV) infection and ganciclovir therapy was assessed with 188 blood samples derived from 40 CMV immunoglobulin G-positive renal-allograft recipients. In pp65 antigen-positive patients all leukocyte fractions, but only 79.5% of plasma preparations, were PCR positive. In pp65 antigen-negative samples from patients after antiviral treatment only 7.3% of polymorphonuclear cell (PMNL) samples, but 81.8% of peripheral blood mononuclear cells (PBMC), and 10.9% of plasma samples remained PCR positive. Similarly, in patients with latent infections only 5.0% of PMNL, but 51.7% of PBMC preparations, and 8.0% of plasma samples were PCR positive. Regarding patients with active CMV infection, CMV DNA copy numbers in PMNL correlated significantly with pp65 antigen-positive cell counts before and after onset of ganciclovir therapy. Significant differences in CMV DNA copy numbers in PMNL and plasma were observed (i) between patients with symptomatic infection and those with asymptomatic infection and (ii) between patients with active infection and those with latent infection. In contrast, PBMC harbored equally low CMV DNA levels both in patients with active infection and those with latent infections, and no decline of CMV DNA load in PBMC was observed during antiviral treatment. We conclude that detection of CMV DNA in PMNL, not in PBMC, is associated with active infections and is more sensitive than detection of CMV DNA in plasma. Negative PCR results for PMNL after antiviral therapy indicate recovery, and fewer unwanted positive results occur compared to PBMC and plasma. Therefore, purified PMNL should be preferred for analysis by qualitative CMV PCR to avoid unwanted positive results. The CMV DNA load in PBMC compared with that in PMNL is negligible during active infection, so mixed PBL are sufficient for use in quantitative PCR.     

Properties of the surround response mechanism of cat retinal ganglion cells and centre-surround interaction

1. The properties of the surround response mechanism of on-centre cells and its interaction with the centre mechanism were studied by recording from single optic tract fibres. In many of the experiments the spatial distribution of the light within the retinal image of the stimuli was measured.

2. Pure surround responses of on-centre cells were isolated using a centrally located steady light which selectively desensitized (adapted) the centre mechanism. This permitted a peripheral flashing stimulus whose luminance varied over a range as great as 1·38 log units to elicit surround responses which, for any given cell, were of invariant shape. The rate of decay of the firing frequency of the spike burst at `off' varied from cell to cell. The general characteristics of such pure surround responses to squarewave stimuli were described. The plot of the magnitude of pure responses against stimulus luminance, at constant background conditions, was curvilinear.

3. The pure surround response of two off-centre cells was isolated; it was similar in shape to the pure centre response of on-centre cells.

4. Interaction of centre and surround mechanisms of on-centre cells was studied by eliciting a pure central and a pure surround response from the same cell. The electronically obtained algebraic sum of these two pure responses equalled the mixed response of the ganglion cell to simultaneous presentation of the stimuli which evoked the pure responses when presented singly. This is probably best explained by algebraic summation of centre and surround inputs.

5. The pure surround response from two cells to a fixed flashing stimulus was attenuated by a steady field adapting light, both when this was superimposed upon the stimulus and when not superimposed. In the latter case, (i) when the spatial separation between the flashing stimulus and the adapting light was at a minimum, less than 10% of the adapting flux fell inside the boundaries of the stimulating flux, and (ii) the response was attenuated also if the adapting light was in the geometric centre of the receptive field. These results indicate that the adaptation pool of the surround mechanism extends to the central portions of the receptive field.

6. Nearly half the cells tested did not yield pure surround responses. This was probably due to differences, within the ganglion cell population, (i) of the spatial distribution of the ratio of centre to surround signal sensitivity and (ii) of differences in the ratio of centre to surround adaptivity in the receptive field middle. It was not due to excess adaptive flux falling outside the region of maximal centre mechanism adaptivity, nor due to excess stimulus flux falling inside the region of maximal signal sensitivity.

     

Acridine orange--RNA histofluorescence of sarcomas and small round cell tumors of childhood.

Forty-nine pediatric malignant neoplasms were stained with acridine orange (AO) fluorochrome to qualitatively evaluate cytoplasmic RNA content. The application of AO as a supplementary stain in surgical pathologic diagnosis is based on the premise that specific neoplastic cell types characteristically and consistently contain few or many cytoplasmic ribosomes. Primitive tumors such as Ewing's sarcoma and primitive neuroectodermal tumors showed negative or low-intensity AO-RNA cytoplasmic staining. Differentiated sarcomas such as rhabdomyosarcomas and lymphomas exhibited moderate to strong AO-RNA cytoplasmic fluorescence. Acridine orange--RNA staining provides an easy, convenient, and inexpensive adjunct in the histopathologic differential diagnosis of sarcomas. It is particularly useful for distinguishing Ewing's sarcomas from other small round cell sarcomas of childhood.