Phosphorylation Controls Autoinhibition of Cytoplasmic Linker Protein-170

Cytoplasmic linker protein (CLIP)-170 is a microtubule (MT) plus-end-tracking protein that regulates MT dynamics and links MT plus ends to different intracellular structures. We have shown previously that intramolecular association between the N and C termini results in autoinhibition of CLIP-170, thus altering its binding to MTs and the dynactin subunit p150^Glued (J. Cell Biol. 2004: 166, 1003–1014). In this study, we demonstrate that conformational changes in CLIP-170 are regulated by phosphorylation that enhances the affinity between the N- and C-terminal domains. By using site-directed mutagenesis and phosphoproteomic analysis, we mapped the phosphorylation sites in the third serine-rich region of CLIP-170. A phosphorylation-deficient mutant of CLIP-170 displays an “open” conformation and a higher binding affinity for growing MT ends and p150^Glued as compared with nonmutated protein, whereas a phosphomimetic mutant confined to the “folded back” conformation shows decreased MT association and does not interact with p150^Glued. We conclude that phosphorylation regulates CLIP-170 conformational changes resulting in its autoinhibition.     

P-24MUCINOUS ASCITES - AN APPROACH TO CYTOLOGICAL CLASSIFICATION

Objective:  Recent national guidelines (NHSCSP Document 20) recommend the referral of patients having the first occurrence of mild dyskaryosis. We evaluated the usefulness of this guideline and determined the positive predictive value (PPV) of conventional smears (CS) and ThinPrep samples (TP) reported as the first occurrence of mild dyskaryosis.
Methods:  This was a retrospective study where we looked at the cases of mild dyskaryosis from January'05 to June'05 received at our laboratory. Of these, the cases of mild dyskaryosis at the first instance were only taken into consideration. Histological diagnosis of these cases where available were retrieved from the laboratory database and were correlated with the cytological findings.
Results:  There were 1016 cases, which were reported as mild dyskaryosis. Out of them, 51.1% (519 cases) were first report of mild dyskaryosis: 61.8% (321 cases) and 38.2% (198 cases) were CS and TP respectively. Of these, 181 CS (56.4%) and 120 TP (60.6%) had a histological follow up. The results showed that 54.1% CS and 56.7% TP had a low-grade outcome, 26.0% CS and 25.8% TP had a high-grade outcome and 19.9% CS and 17.5% TP had a normal outcome. The PPV of mild dyskaryosis for CIN1 or worse result was 53.0% and 50.0% in CS and TP respectively. The PPV of mild dyskaryosis for CIN1 only was 27.1% and 24.2% in CS and TP respectively.
Discussion:  The difference in PPV for both systems is statistically insignificant. This result endorses usefulness of colposcopic referral after the first report of mild dyskaryosis.     

Resource dependence and attitudes of local people toward conservation of Kabartal wetland: a case study from the Indo-Gangetic plains

Wetlands are rapidly disappearing from the earth's surface because of agricultural conversion and other land-use changes. The Indo-Gangetic biogeographic zone is a water-surplus area and it abounds in numerous wetlands and floodplains. Kabartal is one such freshwater wetland ecosystem situated in the mid Ganges basin. The wetland not only supports a large population of migratory and residential waterfowl but also plays an equally important role in the local economy and livelihoods of people. The objective of this paper is to examine the different wetland–society linkages, resource dependence, and attitudes of the people living in the peripheral villages of Kabartal. The results indicate that 67% of people depend on the wetland for different types of subsistence and commercial goods including fodder, fuel wood, construction materials, and fish. Kabartal wetland, like many other wetlands of the region, is used simultaneously for rice cultivation, fishing, and many other uses. This has resulted in conflict between different stakeholder groups. The non-settlement of land rights in the Kabartal sanctuary area has further complicated the situation. Agriculture was rated as the most important use of the wetland and was the basic source of income in the area. This was apparent from the attitudes of people, and most of the respondents demanded draining of the water to make more land available for agriculture. The study reveals the high dependence of people in low-income groups on wetland resources. In such a scenario, although the concept of conservation is well supported, the economic conditions of people dictate otherwise. A general lack of awareness about the ecological functions of wetlands points to the need for conservation education. Managing the wetland on the basis of zone concepts and involving local people in alternative income-generating activity by use of extension programs has been suggested as a means of reducing pressure on agricultural land and also reducing the threat to Kabartal wetland.     

A structural constitutive model considering angular dispersion and waviness of collagen fibres of rabbit facial veins

Background  

Structural constitutive models of vascular wall integrate information on composition and structural arrangements of tissue. In blood vessels, collagen fibres are arranged in coiled and wavy bundles and the individual collagen fibres have a deviation from their mean orientation. A complete structural constitutive model for vascular wall should incorporate both waviness and orientational distribution of fibres. We have previously developed a model, for passive properties of vascular wall, which considers the waviness of collagen fibres. However, to our knowledge there is no structural model of vascular wall which integrates both these features.     

The Action of the Hexokinase Inhibitor 2‐deoxy‐d‐glucose on Cryptosporidium parvum and the Discovery of Activities against the Parasite Hexokinase from Marketed Drugs

Cryptosporidium parvum is one of the major species causing mild to severe cryptosporidiosis in humans and animals. We have previously observed that 2‐deoxy‐d ‐glucose (2DG) could inhibit both the enzyme activity of C. parvum hexokinase (CpHK) and the parasite growth in vitro. However, the action and fate of 2DG in C. parvum was not fully investigated. In the present study, we showed that, although 2DG could be phosphorylated by CpHK to form 2DG‐6‐phosphate (2DG6P), the anti‐cryptosporidial activity of 2DG was mainly attributed to the action of 2DG on CpHK, rather than the action of 2DG or 2DG6P on the downstream enzyme glucose‐6‐phosphate isomerase (CpGPI) nor 2DG6P on CpHK. These observations further supported the hypothesis that CpHK could serve as a drug target in the parasite. We also screened 1,200 small molecules consisting of marketed drugs against CpHK, from which four drugs were identified as CpHK inhibitors with micromolar level of anti‐cryptospordial activities at concentrations nontoxic to the host cells (i.e. hexachlorphene, thimerosal, alexidine dihydrochloride, and ebselen with EC₅₀ = 0.53, 1.77, 8.1 and 165 μM, respectively). The anti‐CpHK activity of the four existing drugs provided us new reagents for studying the enzyme properties of the parasite hexokinase.     

Cytochemical localization of DNA loop attachment sites to the nuclear lamina and to the inner nuclear matrix

Summary The rat liver nuclear matrix, obtained by endogenous nuclease digestion and extraction with low and high lonic strength media, contains residual DNA fragments that are considered to represent the attachment sites of the chromatin domains to the nucleoskeleton. These sites, protected against nuclease digestion by their binding with the nucleoskeleton proteins, should be either mainly linked to the peripheral lamina or to the inner nuclear matrix. The DNA fragment distribution at the level of the different components of the nuclear matrix has been evaluated in samples embedded in Epon and in hydrophilic resins by means of the DNase-gold technique. The labeling obtained suggests that the chromatin loops are prevailingly associated with the interior of the matrix; in fact about twice of the label is present in the inner matrix with respect to the peripheral lamina area.These results confirm the hypothesis that in interphase the chromatin maintains an organization similar to that of chromosomes, with loops radiating from a central scaffold, instead of being mainly attached to the lamina as otherwise suggested.     

Effect of sex hormones on lipid peroxidation in the necrotic liver of rat

Influence of sex-hormones on hepato-toxicosis induced by 2 halogenalkanes viz. carbon tetrachloride and trichloroethylene has been studied in rats. Rate of peroxidative decomposition thus measured by determining malonaldehyde has shown the protective effects of testosterone on CCl4 toxicity but an additive effect on injury caused by trichloroethylene, whereas progesterone failed to offer protection against their toxicity. Modification in histopathological lesions thus caused by these hormones have also been studied and discussed.     

A Qualitative Exploration of Sexual Risk and HIV Testing Behaviors among Men Who Have Sex with Men in Beirut,Lebanon

Men who have sex with men (MSM) may account for most new HIV infections in Lebanon, yet little is known about the factors that influence sexual risk behavior and HIV testing in this population. Qualitative interviews were conducted with 31 MSM living in Beirut, and content analysis was used to identify emergent themes. Mean age of the participants was 28.4 years, and all identified as either gay (77%) or bisexual (23%). Half reported not using condoms consistently and one quarter had not been HIV-tested. Many described not using condoms with a regular partner in the context of a meaningful relationship, mutual HIV testing, and a desire to not use condoms, suggesting that trust, commitment and intimacy play a role in condom use decisions. Condoms were more likely to be used with casual partners, partners believed to be HIV-positive, and with partners met online where men found it easier to candidly discuss HIV risk. Fear of infection motivated many to get HIV tested and use condoms, but such affect also led some to avoid HIV testing in fear of disease and social stigma if found to be infected. Respondents who were very comfortable with their sexual orientation and who had disclosed their sexuality to family and parents tended to be more likely to use condoms consistently and be tested for HIV. These findings indicate that similar factors influence the condom use and HIV testing of MSM in Beirut as those observed in studies elsewhere of MSM; hence, prevention efforts in Lebanon can likely benefit from lessons learned and interventions developed in other regions, particularly for younger, gay-identified men. Further research is needed to determine how prevention efforts may need to be tailored to address the needs of men who are less integrated into or do not identify with the gay community.