Formins and microtubules.

Formins have recently been recognized as prominent regulators of the microtubule (MT) cytoskeleton where they modulate the dynamics of selected MTs in interphase and mitosis. The association of formins with the MT cytoskeleton and their action on MT dynamics are relatively unexplored areas, yet growing evidence supports a direct role in their regulation of MT stability independent of their activity on actin. Formins regulate MT stability alone or in combination with accessory MT binding proteins that have previously been implicated in the stabilization of MTs downstream of polarity cues. As actin and MT arrays are typically remodeled downstream of signaling pathways that orchestrate cell shape and division, formins are emerging as excellent candidates for coordinating the responses of the cytoskeletal in diverse regulated and homeostatic processes.

A new decoder for the optimum recovery of nonadditive watermarks.

Watermark detection, i.e., the detection of an invisible signal hidden within an image for copyright protection or data authentication, has classically been tackled by means of correlation-based techniques. Nevertheless, when watermark embedding does not obey an additive rule, or when the features the watermark is superimposed on do not follow a Gaussian pdf, correlation-based decoding is not the optimum choice. A new decoding algorithm is presented here which is optimum for nonadditive watermarks embedded in the magnitude of a set of full-frame DFT coefficients of the host image. By relying on statistical decision theory, the structure of the optimum is derived according to the Neyman-Pearson criterion, thus permitting to minimize the missed detection probability subject to a given false detection rate. The validity of the optimum decoder has been tested thoroughly to assess the improvement it permits to achieve from a robustness perspective. The results we obtained confirm the superiority of the novel algorithm with respect to classical correlation-based decoding.

Improved wavelet-based watermarking through pixel-wise masking.

A watermarking algorithm operating in the wavelet domain is presented. Performance improvement with respect to existing algorithms is obtained by means of a new approach to mask the watermark according to the characteristics of the human visual system (HVS). In contrast to conventional methods operating in the wavelet domain, masking is accomplished pixel by pixel by taking into account the texture and the luminance content of all the image subbands. The watermark consists of a pseudorandom sequence which is adaptively added to the largest detail bands. As usual, the watermark is detected by computing the correlation between the watermarked coefficients and the watermarking code, and the detection threshold is chosen in such a way that the knowledge of the watermark energy used in the embedding phase is not needed, thus permitting one to adapt it to the image at hand. Experimental results and comparisons with other techniques operating in the wavelet domain prove the effectiveness of the new algorithm.

A quasi-Euclidean norm to speed up vector median filtering.

For reducing impulsive noise without degrading image contours, median filtering is a powerful tool. In multiband images, as for example color images or vector fields obtained by optic flow computation, a vector median filter can be used. Vector median filters are defined on the basis of a suitable distance, the best performing distance being the Euclidean. Euclidean distance is evaluated by using the Euclidean norm which is quite demanding from the point of view of computation given that a square root is required. In this paper an optimal piece-wise linear approximation of the Euclidean norm is presented which is applied to vector median filtering.

Capacity of full frame DCT image watermarks.

The evaluation of the number of bits that can be hidden within an image through digital watermarking is a crucial topic, which has been addressed only for additive watermarks. The evaluation of watermark capacity is very important because it allows to put a theoretical upper bound on the amount of information that can be hidden into an image by a given watermarking procedure, regardless of the watermark extraction technique. It is the purpose of this work to suggest a methodology for the evaluation of the watermark capacity in a nonadditive, non-Gaussian framework, and to discuss the results we obtained by applying it to a set of standard images.

Genetic interactions in yeast between Ypt GTPases and Arf guanine nucleotide exchangers.

Two families of GTPases, Arfs and Ypt/rabs, are key regulators of vesicular transport. While Arf proteins are implicated in vesicle budding from the donor compartment, Ypt/rab proteins are involved in the targeting of vesicles to the acceptor compartment. Recently, we have shown a role for Ypt31/32p in exit from the yeast trans-Golgi, suggesting a possible function for Ypt/rab proteins in vesicle budding as well. Here we report the identification of a new member of the Sec7-domain family, SYT1, as a high-copy suppressor of a ypt31/32 mutation. Several proteins that belong to the Sec7-domain family, including the yeast Gea1p, have recently been shown to stimulate nucleotide exchange by Arf GTPases. Nucleotide exchange by Arf GTPases, the switch from the GDP- to the GTP-bound form, is thought to be crucial for their function. Sec7p itself has an important role in the yeast secretory pathway. However, its mechanism of action is not yet understood. We show that all members of the Sec7-domain family exhibit distinct genetic interactions with the YPT genes. Biochemical assays demonstrate that, although the homology between the members of the Sec7-domain family is relatively low (20-35%) and limited to a small domain, they all can act as guanine nucleotide exchange factors (GEFs) for Arf proteins, but not for Ypt GTPases. The Sec7-domain of Sec7p is sufficient for this activity. Interestingly, the Sec7 domain activity is inhibited by brefeldin A (BFA), a fungal metabolite that inhibits some of the Arf-GEFs, indicating that this domain is a target for BFA. These results demonstrate that the ability to act as Arf-GEFs is a general property of all Sec7-domain proteins in yeast. The genetic interactions observed between Arf GEFs and Ypt GTPases suggest the existence of a Ypt-Arf GTPase cascade in the secretory pathway.

Regularization of optic flow estimates by means of weighted vector median filtering.

Vector median filtering has been recently proposed as an effective method to refine estimated velocity fields. Here, the use of a weighted vector median filtering is suggested to improve the regularization of the optic flow field across motion boundaries. Information about the confidence of the estimated pixel velocities is exploited for the choice of the filter weights. Experimental results, on both synthetic and real-world sequences, show the effectiveness of the proposed procedure.

[Trend of circulating eosinophils in healthy children and children suffering from infectious diseases. A retrospective study]. / Andamento degli eosinofili circolanti nel bambino sano e nel bambino affetto da malattia infettiva. Studio retrospettivo.

INTRODUCTION: Acute bacterial and viral infections are accompanied by a marked diminution in circulating eosinophils in the blood. This forms part of the host's physiological response to acute infection and was first studied in adults early this century. The aims of this study were to check whether eosinopenia during acute phlogosis is a phenomenon present in pediatric patients, and whether the trend is comparable to the experimental models reported; to describe the trend of circulating eosinophils in the remission process. METHODS: A retrospective study was performed in 34 children hospitalised in the Pediatric Hospital of AUSL 2-Lucca (Italy) for bacterial or viral infective diseases documented by cell culture or presumed diagnosed. Children with the following characteristics were excluded from the study: 1) blood samples collected for hemochrome analysis at times other than normal (7-8 a.m.); 2) cortisone treatment administered up to 5 days prior to blood sample and/or during hospitalisation; 3) positive personal anamnesis for manifest allergic diseases. On admittance (children during acute phase) and at the start of remission, an absolute count of circulating eosinophils was performed in these children using an automatic globule counter. Sixty-six children with non evident infective and/or inflammatory diseases were included in the study as a control group. This group was also selected in the same way as infective subjects. RESULTS: The mean number of circulating eosinophils was 288 (+/- 248) in the control group, 46 (+/- 58) in subjects at the acute phase of infective pathology and 252 (+/- 162) in infective patient during the remission phase. The difference between the two means was statistically significant. This characteristic falling and rising trend of circulating eosinophils was found in 33 of the 34 infective subjects examined. CONCLUSIONS: Eosinophil values found in control subjects are broadly in line with those reported in the literature. Eosinopenia during the course of acute infection and the early rise during remission represent a characteristic phenomenon indicating the body's "normal" response to a non-parasitic infection. Both eosinophil levels, namely in the control group (288/mm3) and in acute-phase subjects (46/mm3), should be regarded as "normal" provided they refer to the appropriate situation. The precocity and precision with which the eosinophil trend follows the phases of the infection underlines the value of the assay of these cells as a reliable parameter for monitoring acute infection. There are also indications that, in an inflammatory situation, the behaviour of circulating eosinophils may provide a practical clinical marker of the predominant lymphocyte pattern (Th1 or Th2), as well as the phase of phlogosis, active or remission.

[Pattern of circulating eosinophils in allergic children suffering from infectious disease]. / Andamento degli eosinofili circolanti nel bambino allergico affetto da malattia infettiva.

BACKGROUND AND AIM: Both bacterial and viral acute infections are accompanied by a typical fall in the number of circulating eosinophils followed, at remission, by a rapid return to starting values. The aim of this study was to check whether this typical pattern can be observed in atopical children. MATERIALS AND METHODS: A retrospective study was performed in a group of atopical subjects (mainly asthmatic) suffering from intercurrent infectious diseases (mainly bronchopneumonia); circulating eosinophils were assayed during the acute phase of disease and during remission. The control group consisted of 21 atopic children without signs or symptoms of infectious diseases. RESULTS: The mean number of circulating eosinophils was 412.6 +/- 199.8 in the control group of allergic children 25.1 +/- 39.7 in the group with acute infectious diseases and 241 +/- 137.5 in the group of children with infectious diseases during remission. The differences between the group of children with infectious diseases and that in remission were statistically significant. The typical pattern of the fall and rise of circulating eosinophils was observed in 9 out of 10 children with acute infections. The cut-off proposed as the discriminating factor between acute phase infection and subjects in remission or without infectious diseases was 100 eosinophils/mm3. CONCLUSIONS: During the course of infective pathologies in allergic subjects there is an abrupt and significant reduction in circulating eosinophils followed, during remission, by a return to levels comparable to those in controls. Eosinophil assay therefore appears to be a useful parameter to monitor acute infection in allergic subjects. In particular, increased eosinophil levels are an early indicator that the infection has been overcome and remission is in progress. The authors repropose the hypothesis that eosinophils play a double role that alternates between activating the allergic phlogosis and eliminating non-allergic phlogosis, depending on the cytokinic context in which this occurs.

In vitro inactivation of human immunodeficiency virus by ascorbic acid.

In vitro inactivation of cell-free human immunodeficiency virus (CFHIV) was investigated by mixing replication-competent virions with aliquots of a culture medium (RPMI) containing increasing amounts (62.5-500 micrograms/ml) of ascorbic acid (AA) at pH7. Similarly, mixtures of CFHIV and 500 micrograms/ml AA in whole blood (WB) and leukocyte depleted blood (LDB) were made; control mixtures containing either CFHIV or AA alone in each experiment were included. After holding the mixtures for 3 h at 4 degrees C, the tubes containing WB and LDB mixtures were centrifuged to remove the blood cells. The respective supernatants, including the control aliquots, were layered over 0.5 x 10(6) MT2 cells in quadruplicate wells in microtitre plates. After 1 h of incubation at 37 degrees C in an atmosphere of 5.0% carbon dioxide to permit contact of viable virions, the fluid in each well was replaced with RPMI containing 20% fetal bovine serum (FBS). The incubation was then continued at 37 degrees C for 5 days. On the basis of (1) absence of syncytia formation, (2) 100% viability of MT2 cells as compared with the cell controls, (3) absence of p24 antigen in the culture supernates, and (4) absence of HIV DNA in MT2 cells, we conclude that 500 micrograms/ml AA, in (a) RPMI, (b) WB, or (c) LDB, inactivated CFHIV in vitro. Furthermore, we determined that addition of 500 micrograms/ml AA to platelet concentrates did not adversely affect the platelet function tests during 5 days of storage at room temperature. These data warrant further work to evaluate the mechanism of CFHIV inactivation by treatment of blood products with AA.

Taurine and ellagic acid: two differently-acting natural antioxidants.

Naturally occurring antimutagenic compounds are extensively analyzed for their capacity to protect cells from induced damage. We selected two agents, taurine and ellagic acid, treated in the literature as antioxidants, but whose activity is insufficiently known. This paper reports on the ability of these agents to act against damage induced by mitomycin-C and hydrogen peroxide in Chinese hamster ovary cells cultivated in vitro. Cytogenetic and cytofluorimetric analyses were performed. Ellagic acid proved to have more than one mechanism of action, probably as a scavenger of oxygen species produced by H2O2 treatment, and as a protector of the DNA double helix from alkylating agent injury. In our experimental conditions, taurine seems able to scavenge oxygen species.

Plasma gastrin and somatostatin levels in newborn infants receiving supplementary formula feeding.

Plasma gastrin and somatostatin concentrations were measured by radioimmunoassay in exclusively formula-fed infants and in breast-fed infants receiving supplementary formula during the first five postnatal days. Infants exclusively formula fed had a progressive increase in mean plasma gastrin concentration from 109 +/- 42 pmol/l (mean +/- SD) on the first day to 236 +/- 103 pmol/l on the fifth day after birth (p = 0.0001). Breast-fed infants receiving supplementary formula had similar hormone concentrations as formula-fed infants of corresponding postnatal age and they also had a significant increase in hormone levels from the first to the fifth day (p = 0.0001). A positive relationship was found between gastrin concentration and ingested milk volume: Rs = 0.51, n = 105, p = 0.0001. The high gastrin concentrations most probably reflect enhanced hormonal release from the gastrin-producing cells in response to increasing volumes of milk ingested by the infant. The mean plasma somatostatin concentration on the first day after birth was 18 +/- 6 pmol/l. No significant change occurred during the first five postnatal days, independent of feeding type.

The relationship of plasma cholecystokinin levels to different feeding routines in newborn infants.

Plasma cholecystokinin concentrations were measured with radioimmunoassay in breast fed infants in Sweden (n = 101) and formula fed infants in Italy (n = 119). Blood samples were collected from the infants during the first five postnatal days, just before feeding in a cross-sectional way. We found no significant difference in the hormone concentration in relation to age, in breast fed or in formula fed infants. Breast fed infants had significantly higher plasma hormone concentrations than formula fed infants during the postnatal period 0-5 days: 2.8 pmol/l (1-10 pmol/l), median (range) versus 2.2 pmol/l (1-25 pmol/l), (P < 0.02). It cannot be excluded that the results were influenced by the circumstances that the samples were collected from two separate populations. However, the higher hormone levels in breast fed infants may also be the expression of the fact that natural feeding per se promotes cholecystokinin secretion in newborn infants.

[Post-traumatic deformities of the lower limbs. Pathogenetic and treatment considerations]. / Le deformità post-traumatiche degli arti inferiori. Considerazioni patogenetiche e trattamento.

The authors studied post-traumatic deformities of the lower limbs, outlining the main pathological features. Furthermore they describe the different progression of the pathology in adults and children, due to their different capability for adaptation. Finally, they report in detail on their two-years experience in using the Ilizarov external fixator.