A note on the food of the Norway lemning

Norway lemming droppings remaining from the high 1963 population in Jämtland (mid-Sweden) were examined microscopically for an evaluation of food species present. The findings from this were compared with the occurrence of these species growing on the mountains. It is tentatively concluded that lemmings are exercising a degree of selectivity in their choice of food species, but the reasons for this choice still remain obscure.     

Lectin histochemistry of the mast cell: A light microscopical study

Summary The purpose of this study was to determine if human mast cell granules contain non repeating oligosaccharide sequences. The binding of lectins to human mast cell granules was studied using a panel of 11 lectins variously selective for bothN- andO-linked oligosaccharide sequences. The tissues were principally derived from cutaneous neurofibromata and benign and malignant breast diseases, that is, readily available human material with a known high content of mast cells. Lectin-binding sites in the formalin-fixed paraffin-embedded or resin-embedded material were visualized by means of biotinylated lectins and an avidin—peroxidase technique for light microscopy. The results indicate that human mast cell granules contain abundantN-linked sequences, but few or noO-linked residues. These sequences appear to be mostly in the form of non-bisected highly branched or smaller biantennate sequences, although variable positive binding with erythrophyto-haemagglutinin was observed, indicating some degree of bisection.     

Sodium butyrate suppresses the transforming activity of an activated N-ras oncogene in human colon carcinoma cells

The transforming activity of DNA from a newly established undifferentiated human colon carcinoma cell line (MIP-101) was tested in the NIH-3T3 transfection assay. Southern blot analysis of the transfectant DNA revealed the presence of a human N-ras oncogene. Treatment of MIP-101 cells with the maturational agent sodium butyrate induced a more normal phenotype, including diminished growth rate, elimination of anchorage independent growth, and decreased tumorigenicity (R. Niles, S. Wilhelm, P. Thomas, and N. Zamcheck (1988) J. Cancer Invest. 6, 39). Here we report that there is a significant reduction in the transforming efficiency of the DNA from butyrate-treated MIP-101 cells. A nonspecific reduction in total DNA uptake as an explanation for these findings was eliminated by showing that there was similar uptake and expression of the thymidine kinase gene from the DNA of butyrate-treated and control MIP cells. Butyrate treatment had no detectable effect on the overall structure, methylation, and level of expression of the human N-ras gene from MIP-101 cells. An NIH-3T3 transformant ability after treatment with sodium butyrate. Although butyrate suppressed several transformed properties similar to MIP-101 cells, DNA from control and treated cultures had an identical level of transforming activity. The results suggest that the environment of the MIP cells may contain additional elements not present in the NIH-3T3 transformants which are required to observe the effect of butyrate on reduction of transforming activity.     

CCR5- and CXCR4-Utilizing Strains of Human Immunodeficiency Virus Type 1 Exhibit Differential Tropism and Pathogenesis In Vivo

CCR5-utilizing (R5) and CXCR4-utilizing (X4) strains of human immunodeficiency virus type 1 (HIV-1) have been studied intensively in vitro, but the pathologic correlates of such differential tropism in vivo remain incompletely defined. In this study, X4 and R5 strains of HIV-1 were compared for tropism and pathogenesis in SCID-hu Thy/Liv mice, an in vivo model of human thymopoiesis. The X4 strain NL4-3 replicates quickly and extensively in thymocytes in the cortex and medulla, causing significant depletion. In contrast, the R5 strain Ba-L initially infects stromal cells including macrophages in the thymic medulla, without any obvious pathologic consequence. After a period of 3 to 4 weeks, Ba-L infection slowly spreads through the thymocyte populations, occasionally culminating in thymocyte depletion after week 6 of infection. During the entire time of infection, Ba-L did not mutate into variants capable of utilizing CXCR4. Therefore, X4 strains are highly cytopathic after infection of the human thymus. In contrast, infection with R5 strains of HIV-1 can result in a two-phase process in vivo, involving apparently nonpathogenic replication in medullary stromal cells followed by cytopathic replication in thymocytes.     

Influence of gibberellic and abscisic acids and the growth retardant,CCC, upon plastid development

Summary Gibberellic acid (GA₃) enhances ultrastructural morphogenesis of plastids in greening cereals whilst abscisic acid (ABA) and CCC have the reverse effect over a shorter period. GA₃ application counteracts the ABA and CCC inhibition of membrane development and, over longer periods of greening, the fastest rate of chloroplast development is shown in the presence of both GA₃ and ABA. Experiments with isolated etioplasts show that the ABA inhibition of development also occurs and can be counteracted with GA₃ treatment but no individual enhancement of plastid morphogenesis by GA₃ was detected.Ribulose 1,5-diphosphate carboxylase (RuDPC) acitvity was also increased with applications of GA₃ and reduced with ABA treatment. The initial levels of RuDPC activity in the presence of CCC were concentration dependant; high in 10^-3 M CCC and low in 10^-6 M CCC but activity returned to normal levels after CCC application was stopped. Experiments with isolated etio-chloroplasts gave similar results but levels of RuDPC activity declined rapidly in both illuminated and un-illuminated incubated suspensions of intact etioplasts.     

siRNA against presenilin 1 (PS1) down regulates amyloid β42 production in IMR-32 cells

Background  

One of the pathological hallmarks of Alzheimer's disease (AD) is the deposition of the ~4 kDa amyloid β protein (Aβ) within lesions known as senile plaques. Aβ is also deposited in the walls of cerebral blood vessels in many cases of AD. A substantial proportion of the Aβ that accumulates in the AD brain is deposited as Amyloid, which is highly insoluble, proteinaceous material with a β-pleated-sheet conformation and deposited extracellularly in the form of 5-10 nm wide straight fibrils. As γ-secretase catalyzes the final cleavage that releases the Aβ42 or 40 from amyloid β -protein precursor (APP), therefore, it is a potential therapeutic target for the treatment of AD. γ-Secretase cleavage is performed by a high molecular weight protein complex containing presenilins (PSs), nicastrin, Aph-1 and Pen-2. Previous studies have demonstrated that the presenilins (PS1 and PS2) are critical components of a large enzyme complex that performs γ-secretase cleavage.     

Interet diagnostique d’une injection intracaverneuse de 20 μg de Prostaglandine E1 dans l’impuissance

Intracavernous injection of 20 μg of prostaglandin E1 (PGE1) was carried out in 130 impotent patients. The erectile response was compared to the results of arteriological investigations including nocturnal penile tumescence and rigidity monitoring (NPTR) in 59 patients. The response of 60 patients positively categorized as exclusively psychogenic or vasculogenic was also compared to the pattern of the response to 80 mg of papaverine observed in a previous study by the same authors. The PGE1 test may not discriminate psychogenic from wholly organic patients since its results are not correlated to those of NPTR. It helps for the screening of vasculogenic impotence. Lack of response or a partly rigid response is consistent with this actiology but is not specific for it. A fully response makes it unlikely. Compared to papaverine, PGE1 induces less non rigid responses in psychogenic patients (15% versus 35% with papaverine) and more fully rigid responses in vasculogenic patients (respectively 12% and 5 %). Consequently the specificity of the PGE1 test is higher but its sensitivity lower than that of papaverine so that there is no clear difference in the effectiveness of the tests. Nevertheless the PGE1 test should be preferred, because it is safer. Prolonged erections occured in only 5 patients, and all ceased spontaneously. However 4 presented severely painful erections.